[Federal Register Volume 62, Number 210 (Thursday, October 30, 1997)]
[Proposed Rules]
[Pages 58792-58838]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28647]
[[Page 58791]]
_______________________________________________________________________
Part III
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 194
Criteria for the Certification and Recertification of the Waste
Isolation Pilot Plant's Compliance With the 40 CFR Part 191 Disposal
Regulations: Certification Decision; Proposed Rule
Federal Register / Vol. 62, No. 210 / Thursday, October 30, 1997 /
Proposed Rules
[[Page 58792]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 194
[FRL-5915-1]
RIN 2060-AG85
Criteria for the Certification and Re-Certification of the Waste
Isolation Pilot Plant's Compliance With the 40 CFR Part 191 Disposal
Regulations: Certification Decision
AGENCY: Environmental Protection Agency.
ACTION: Proposed rule; opening of public comment period.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (``EPA'') is proposing to
certify that the Department of Energy's (``DOE'') Waste Isolation Pilot
Plant (``WIPP'') will comply with the radioactive waste disposal
regulations set forth at 40 CFR Part 191 (Environmental Standards for
the Management and Disposal of Spent Nuclear Fuel, High-Level and
Transuranic Radioactive Waste). EPA is required to evaluate whether the
WIPP will comply with EPA's standards for the disposal of radioactive
waste by the WIPP Land Withdrawal Act (``LWA'') of 1992, as amended.
EPA's certification of compliance, if finalized, would allow the
emplacement of radioactive waste in the WIPP to begin, provided that
all other applicable health and safety standards have been met. The
proposed certification would allow Los Alamos National Laboratory to
ship TRU waste from specific waste streams for disposal at the WIPP.
However, the proposed certification is subject to several conditions,
notably that EPA must approve site-specific waste characterization
measures and quality assurance plans before allowing other waste
generator sites to ship waste for disposal at the WIPP. The Agency
proposes to amend 40 CFR Part 194 by adding an appendix describing
EPA's certification, and by adding a definition. Finally, EPA is
proposing its decision, also pursuant to the LWA, that DOE does not
need to acquire existing oil and gas leases near the WIPP in order to
meet the disposal regulations. Today's notice marks the beginning of a
120-day public comment period on EPA's proposed certification decision,
and on the other proposed actions described above.
DATES: Comments on today's proposal must be received by February 27,
1998. Public hearings on today's proposal will be held in New Mexico. A
separate announcement will be published in the Federal Register to
provide public hearing information.
ADDRESSES: Comments should be submitted, in duplicate, to: Docket No.
A-93-02, Air Docket, Room M-1500 (LE-131), U.S. Environmental
Protection Agency, 401 M Street, SW., Washington, DC 20460. See
additional docket information in the SUPPLEMENTARY INFORMATION.
FOR FURTHER INFORMATION CONTACT: Betsy Forinash or Scott Monroe;
telephone number (202) 233-9310; address: Radiation Protection
Division, Center for the Waste Isolation Pilot Plant, Mail Code 6602-J,
U.S. Environmental Protection Agency, 401 M Street SW., Washington, DC
20460. For copies of the Compliance Application Review Documents
supporting today's proposal, contact Scott Monroe at the above phone
number and address.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Background
II. Statutory Authority
III. Purpose and Scope of Today's Action
IV. Limits of EPA's Regulatory Authority at the WIPP
V. Public Participation
A. Advance Notice of Proposed Rulemaking (ANPR)
B. Public Hearings on ANPR
C. Additional Public Input
D. Public Comments on ANPR
E. Completeness Determination
F. Public Comments on Completeness
G. Proposed Certification Decision
H. Final Certification Decision
I. Dockets
VI. National Academy of Sciences Report on the WIPP
VII. Codification of EPA's Certification Decision
VIII. Determination of Whether the WIPP Complies with the Disposal
Regulations
A. Basis for EPA's Compliance Determination
B. Compliance Application Review Documents (CARDs)
IX. Section 194.14, Content of Compliance Certification Application
A. Site Characterization
B. Disposal System Design
C. Results of Assessments
D. Input Parameters to Performance Assessments
E. Assurance Requirements
F. Waste Acceptance Criteria
G. Background Radiation
H. Topographic Maps
I. Past and Current Meteorological Conditions
J. Other Information Needed for Demonstration of Compliance
K. Conclusion
X. General Requirements
A. Section 194.22, Quality Assurance
B. Section 194.23, Models and Computer Codes
1. Conceptual models
a. Description of conceptual models
b. Alternative conceptual models
c. Future states of the disposal system and peer review
d. Public comments
2. Progression from conceptual models to computer codes
a. Mathematical models
b. Public comments on mathematical models
c. Numerical models
d. Computer codes
3. Quality assurance
4. Documentation of models and codes
a. Theoretical background
b. Descriptions of models
c. Parameters
d. Public comments on parameter values
e. Software licenses
f. Parameter correlation
5. EPA's independent testing
C. Section 194.24, Waste Characterization
D. Section 194.25, Future State Assumptions
E. Section 194.26, Expert Judgment
F. Section 194.27, Peer Review
XI. Containment Requirements
A. Section 194.31, Application of Release Limits
B. Section 194.32, Scope of Performance Assessments (PA)
C. Section 194.33, Consideration of Drilling Events in PA
D. Section 194.34, Results of PA
1. Complementary cumulative distribution functions (CCDFs)
2. Generation of the full range of CCDFs
3. Probability distributions and random sampling of uncertain
parameters
4. Sufficient number of CCDFs generated
5. Compliance of the mean CCDF
XII. Assurance Requirements
A. Section 194.41, Active Institutional Controls
B. Section 194.42, Monitoring
C. Section 194.43, Passive Institutional Controls
D. Section 194.44, Engineered Barriers
E. Section 194.45, Consideration of the Presence of Resources
F. Section 194.46, Removal of Waste
XIII. Individual and Ground-water Protection Requirements
A. Section 194.51, Consideration of Protected Individual
B. Section 194.52, Consideration of Exposure Pathways
C. Section 194.53, Consideration of Underground Sources of
Drinking Water
D. Section 194.54, Scope of Compliance Assessments (CA)
E. Section 194.55, Results of CA
1. Uncertainty of CA
2. Probability distributions for uncertain parameters
3. Sampling of uncertain parameters
4. Sufficient number of estimates generated
5. Display full range of CA results
6. Compliance with radiation dose and radionuclide concentration
limits
XIV. Land Withdrawal Act Section 4(b)(5)(B) Leases
XV. Administrative Requirements
A. Executive Order 12866
B. Regulatory Flexibility
C. Paperwork Reduction Act
[[Page 58793]]
D. Unfunded Mandates Reform Act
E. Executive Order 12898
I. Background
Congress authorized development and construction of the Waste
Isolation Pilot Plant (``WIPP'') in 1980 ``for the express purpose of
providing a research and development facility to demonstrate the safe
disposal of radioactive wastes resulting from the defense activities
and programs of the United States.'' 1 The U.S. Department
of Energy (``DOE'' or ``the Department'') is developing the WIPP near
Carlsbad in southeastern New Mexico as a potential deep geologic
repository for the disposal of defense transuranic (``TRU'')
radioactive waste. TRU waste consists of materials containing alpha-
emitting radio-isotopes, with half-lives greater than twenty years and
atomic numbers greater than 92, in concentrations greater than 100
nano-curies per gram of waste.\2\ Most TRU waste proposed for disposal
at the WIPP consists of items that have become contaminated as a result
of activities associated with the production of nuclear weapons, e.g.,
rags, equipment, tools, protective gear, and organic or inorganic
sludges. Some TRU waste is mixed with hazardous chemicals. Some of the
waste proposed for disposal at the WIPP is currently stored on Federal
lands across the United States, including locations in Colorado, Idaho,
New Mexico, Nevada, Ohio, South Carolina, Tennessee, and Washington.
Much of the waste proposed for disposal at the WIPP will be generated
in the future as weapons are disassembled and additional facilities are
decontaminated and decommissioned.
---------------------------------------------------------------------------
\1\ Department of Energy National Security and Military
Applications of Nuclear Energy Authorization Act of 1980, Pub. L.
96-164, section 213.
\2\ WIPP Land Withdrawal Act, Pub. L. 102-579, section 2(18), as
amended by the 1996 WIPP LWA Amendments, Pub. L. 104-201.
---------------------------------------------------------------------------
Before disposal of radioactive waste can begin at the WIPP, the
U.S. Environmental Protection Agency (``EPA'' or ``the Agency'') must
certify that the WIPP facility will comply with EPA's radioactive waste
disposal regulations.3 The purpose of today's action is to
propose EPA's certification decision.
---------------------------------------------------------------------------
\3\ WIPP LWA, section 8(d).
---------------------------------------------------------------------------
II. Statutory Authority
EPA's oversight of the WIPP facility is governed by the WIPP Land
Withdrawal Act (``LWA''), passed initially by Congress in 1992 and
amended in 1996. The LWA delegates to EPA three main tasks, to be
completed sequentially, for reaching a compliance certification
decision. First, EPA must finalize general regulations which apply to
all sites--except Yucca mountain--for the disposal of highly
radioactive waste.4 The regulations, located at Subparts B
and C of 40 CFR Part 191 (``disposal regulations''), limit the amount
of radioactive material which may escape from a disposal facility, and
protect individuals and ground water resources from dangerous levels of
radioactive contamination. The disposal regulations were published in
the Federal Register in 1985 and 1993.5
---------------------------------------------------------------------------
\4\ WIPP LWA, section 8(b).
\5\ 50 FR 38066-38089 (September 19, 1985) and 58 FR 66398-66416
(December 20, 1993).
---------------------------------------------------------------------------
Second, EPA must develop, by rulemaking, criteria to implement and
interpret the generic radioactive waste disposal regulations
specifically for the WIPP. EPA issued these ``WIPP Compliance
Criteria,'' which are found at 40 CFR Part 194, in 1996.6
The criteria describe in detail what information DOE must submit for
EPA's review, and clarify the basis on which EPA's compliance
determination will be made.
---------------------------------------------------------------------------
\6\ 61 FR 5224-5245 (February 9, 1996), ``Criteria for the
Certification and Re-certification of the Waste Isolation Pilot
Plant's Compliance with the 40 CFR Part 191 Disposal Regulations.''
(Certain aspects of the Compliance Criteria were challenged in the
Court of Appeals for the D.C. Circuit. The Court upheld the
Compliance Criteria in their entirety. State of New Mexico v. Envt'l
Protection Agency, No. 96-1107 (D.C. Cir. June 6, 1997)).
---------------------------------------------------------------------------
Third, EPA must review information submitted by DOE and publish a
certification decision.7 Today's action constitutes EPA's
proposed certification decision as required by section 8 of the LWA. On
October 29, 1996, DOE submitted a compliance certification application
(``CCA'') containing information intended to demonstrate that WIPP will
comply with the disposal regulations. Since then, DOE has submitted
additional information. On May 22, 1997, EPA announced that DOE's
application was deemed to be complete. (62 FR 27996-27998) EPA's
evaluation of whether the WIPP will comply with the disposal
regulations is made by comparing the CCA and other relevant
information--including supplementary information requested by EPA from
DOE, and the results of EPA's confirmatory audits and inspections--to
the WIPP Compliance Criteria. The Administrator's certification of
compliance depends on DOE demonstrating that it has satisfied the
specific requirements of the WIPP Compliance Criteria.
---------------------------------------------------------------------------
\7\ WIPP LWA, section 8(d).
---------------------------------------------------------------------------
III. Purpose and Scope of Today's Action
Today's action is limited primarily to the certification decision
required under section 8(d) of the LWA. In addition, the proposal
addresses the provision of section 4(b)(5)(B) of the LWA which requires
EPA to determine whether existing oil and gas leases in the vicinity of
the WIPP must be acquired by DOE. EPA has decided that it is
appropriate to include this determination in this rulemaking because
Congress explicitly conditioned emplacement of wastes in the repository
on DOE's acquisition of the specified leaseholds, unless EPA determines
that such acquisition is not required. (LWA, section 7(b)(2)) While
Congress' mandate that EPA make this determination is separate and
apart from the section 8(d) mandate to conduct the WIPP certification
proceeding pursuant to notice-and-comment rulemaking procedures, EPA
nonetheless believes it appropriate to address the leases in this
rulemaking. The determination of whether potential drilling on the
specified leases could possibly affect the integrity of the repository
is closely related to the similar determinations that must be made
under Secs. 194.32(c) and 194.54(b) of the Compliance Criteria.
Moreover, EPA is committed to the intent of Congress, clearly expressed
in the LWA, that the public be involved in these important regulatory
determinations. Therefore, by including this decision in this proposal,
EPA is providing the public with the opportunity for input on this
matter.
The Agency is proposing to add to the Compliance Criteria an
appendix describing EPA's certification decision and to define the term
``Administrator's authorized representative.'' Except for these
additions, EPA's proposed decision regarding WIPP's compliance does not
otherwise amend or affect the final disposal regulations (at Subparts B
and C of 40 CFR Part 191), or the final WIPP Compliance Criteria (at
Subparts A through D of 40 CFR Part 194).
Today's proposal does not address all the actions required of EPA
by the LWA. For example, the proposal does not address compliance with
EPA's radioactive waste management regulations--found in Subpart A of
40 CFR Part 191--which are referenced in section 9(a)(1)(A) of the LWA.
Instead, the Agency has issued, in a separate action, guidance
describing how EPA intends to implement Subpart A at the
WIPP.8 For copies of the WIPP Subpart
[[Page 58794]]
A Guidance (Document Number EPA 402-R-97-001), call the EPA WIPP
Information Line at 1-800-331-WIPP, or write to Betsy Forinash, Center
for the Waste Isolation Pilot Plant, Mail Code 6602-J, U.S.
Environmental Protection Agency, 401 M Street, SW., Washington, DC
20460.
---------------------------------------------------------------------------
\8\ 62 FR 9188 (February 28, 1997), Notice of Availability for
``Guidance for the Implementation of EPA's Radiation Protection
Standards for Management and Storage of Transuranic Waste at the
Waste Isolation Pilot Plant ('WIPP Subpart A Guidance').''
---------------------------------------------------------------------------
Finally, today's proposal does not address requirements of the LWA
which must be fulfilled by other regulatory agencies. Enforcement of
some parts of the hazardous waste regulations, for example, has been
delegated to the State of New Mexico. The State's authority for such
actions as issuing a hazardous waste operating permit for the WIPP is
in no way constrained by EPA's proposed certification decision.
IV. Limits of EPA's Regulatory Authority at the WIPP
As discussed above, the LWA conveys specific responsibilities on
EPA to ensure the safety of the WIPP as a permanent disposal facility.
The Agency's primary responsibility, described in section 8 of the LWA,
is to determine whether the WIPP facility will comply with EPA's
disposal regulations. Members of the public have expressed, in written
comments and in oral testimony on the Advanced Notice of Proposed
Rulemaking for today's proposal, a desire for the Agency to oversee
other aspects of WIPP's operation. In response to such concerns, EPA
must clarify that its authority to regulate DOE and the WIPP is limited
by the LWA and other statutes which delineate EPA's authority to
regulate radioactive materials in general. The limitations on EPA's
authority necessarily limit the scope of the current rulemaking.
Several commenters suggested that EPA should explore alternative
methods of waste disposal--such as neutralizing radioactive elements--
before proceeding with a certification decision. Others stated that the
WIPP should be opened immediately because underground burial of
radioactive waste is less hazardous than the current strategy of above-
ground storage. EPA must conduct its WIPP activities in accordance with
the intent of Congress as expressed in the LWA. Congress did not
delegate to EPA the authority to abandon or delay the WIPP because
future technologies might evolve and eliminate the need for the WIPP.
Also, Congress did not delegate to EPA the authority to weigh the
competing risks of leaving radioactive waste stored above ground
compared to disposal of waste in an underground repository. These
considerations are outside the authority of the EPA as established in
the LWA and, thus, necessarily outside the scope of this rulemaking.
Some commenters requested that EPA consider certain factors in
making its certification decision. These factors include: reviews by
organizations other than EPA, safety at other DOE facilities, and the
political or economic motivations of interested parties. Pursuant to
the LWA, EPA's certification decision must be made based on the WIPP
Compliance Criteria at 40 CFR Part 194, and in accordance with
requirements governing informal rulemaking proceedings. EPA is tasked
only with examining the scope and quality of relevant information, and
comparing such information to the objective criteria of 40 CFR Part
194. Where relevant, the Agency has considered public comments and
outside reviews which support or refute technical positions taken by
DOE. Emotional pleas, comments on the motives of interested parties,
and the safety of sites or disposal methods other than the WIPP are
factors that are not relevant to a determination of whether DOE has
demonstrated compliance with the WIPP Compliance Criteria, and are
therefore outside the scope of this rulemaking.
In addition, the hazards of transporting radioactive waste from
storage sites to the WIPP have been of great concern to the public. EPA
has received numerous public comments, oral and written, concerning the
possible transport of TRU waste to the WIPP. Transportation is entirely
outside EPA's general authority for regulating radioactive waste.
Moreover, in the LWA, Congress did not authorize any role for EPA with
respect to transportation. Congress addressed transportation issues by
requiring DOE to (1) use only shipping containers approved by the
Nuclear Regulatory Commission; (2) notify in advance States and Indian
Tribes of the transport of TRU waste through their jurisdictions; (3)
provide technical assistance and funding to ensure that jurisdictions
along WIPP transportation routes receive appropriate training for
accident prevention and emergency preparedness; (4) provide
transportation safety assistance to States or Indian tribes through
whose jurisdictions TRU waste will be transported; and (5) study
transportation alternatives. (LWA, section 16) Transportation of
radioactive waste is regulated by the Nuclear Regulatory Commission and
the U.S. Department of Transportation. Because all transportation
requirements for the WIPP are established and enforced by other
regulators, EPA does not address the issue further in this proposal.
V. Public Participation
Section 8(d)(2) of the LWA requires that the Administrator's
certification decision be conducted by informal (or ``notice-and-
comment'') rulemaking pursuant to Section 553 of the Administrative
Procedure Act (``APA''). Notice-and-comment rulemaking under the APA
requires that an agency provide notice of a proposed rulemaking, an
opportunity for the public to comment on the proposed rule, and a
general statement of the basis and purpose of the final rule
adopted.9
---------------------------------------------------------------------------
\9\ 5 U.S.C. 553.
---------------------------------------------------------------------------
The WIPP is a first-of-a-kind project, and New Mexico citizens have
expressed a great deal of interest in the safety of the site. The WIPP
Compliance Criteria, at Subpart D of 40 CFR Part 194, established a
process of public participation that exceeds the APA's basic
requirements, and provides the public with the opportunity to
participate in the regulatory process at the earliest opportunity. The
WIPP Compliance Criteria contain provisions that require EPA to:
publish an advance notice of proposed rulemaking (``ANPR'') in the
Federal Register; allow public comment on DOE's compliance
certification application (``CCA'') for at least 120 days, prior to
proposing a certification decision; hold public hearings in New Mexico,
if requested, on the CCA; provide a minimum of 120 days for public
comment on EPA's proposed certification decision; hold public hearings
in New Mexico on EPA's proposal; produce a document summarizing the
Agency's consideration of public comments on the proposal, and maintain
informational dockets in the State of New Mexico to facilitate public
access to the voluminous technical record, including the CCA. EPA
either has or will comply with each of these requirements.
In addition, EPA has taken other measures to assure that the public
is involved in the present rulemaking. EPA allowed the New Mexico
Environment Department, the New Mexico Environmental Evaluation Group,
and more recently, the New Mexico Attorney General's Office as well, to
observe meetings between EPA and DOE staff to discuss technical issues
during the pre-proposal period. EPA also committed to summarize all
meetings between EPA and DOE (including management level meetings
[[Page 58795]]
and meetings between EPA and DOE legal staff) and to place such
summaries in the public docket. While these commitments are not
required by the APA, EPA believes that they are useful given the
importance of this rulemaking to the nation as a whole, and New Mexico
in particular.
A. Advance Notice of Proposed Rulemaking (ANPR)
EPA received DOE's CCA on October 29, 1996. Copies of the CCA and
all the accompanying references submitted to EPA were placed in EPA's
dockets in New Mexico and Washington, DC. Upon receipt of the CCA, EPA
immediately began its review of the application in accordance with 40
CFR 194.11, ``Completeness and accuracy of compliance applications.''
On November 15, 1996, the Agency published in the Federal Register (61
FR 58499) an ANPR announcing that the CCA had been received, and
announcing the Agency's intent to conduct a rulemaking to certify
whether the WIPP facility will comply with the disposal regulations.
The notice also announced a 120-day public comment period, requested
public comment ``on all aspects of the CCA,'' and stated EPA's intent
to hold public hearings in New Mexico.
B. Public Hearings on ANPR
The EPA published a separate notice in the Federal Register
announcing hearings to allow the public to address all aspects of DOE's
certification application. (62 FR 2988) Public hearings were held on
February 19, 20 and 21, 1997, in Carlsbad, Albuquerque and Santa Fe,
New Mexico, respectively. All individuals who requested an opportunity
to address the EPA panel during the hearings were afforded five minutes
if they were representing themselves, or ten minutes if they were
representing a group. In Albuquerque and Santa Fe, EPA extended the
hours of the hearings in order to accommodate all individuals who
requested that they be allowed to address the panel.
C. Additional Public Input
In addition to the public hearings, EPA held three days of meetings
in New Mexico, on January 21, 22 and 23, 1997, with the principal New
Mexico Stakeholders, including the New Mexico Attorney General's
Office, the New Mexico Environmental Evaluation Group, Concerned
Citizens for Nuclear Safety, Citizens for Alternatives to Radioactive
Dumping, and Southwest Research and Information Center. Detailed
summaries of these meetings were placed in Docket A-93-02, Category II-
E.
D. Public Comments on ANPR
The Agency received over 220 sets of written and oral public
comments in response to the ANPR. All comments received on the ANPR
were made available to members of the public through the public docket.
(Docket A-93-02, Category II-H) In accordance with 40 CFR 194.61(f),
DOE submitted to the Agency additional information specifically
addressing many of the comments received; these submittals were treated
by EPA as public comments.
The Agency reviewed all public comments submitted during the ANPR
120-day comment period or presented at the preliminary meetings with
stakeholders. Public comments received in response to the ANPR
generally focused on the completeness of the CCA, specific technical
issues relating to compliance with the disposal regulations, and EPA's
approach to public participation in accordance with the provisions of
the WIPP Compliance Criteria, and pursuant to the LWA and the APA.
The EPA is providing responses to these comments in this preamble
as well as in the compliance application review documents (``CARDs'')
which are part of today's proposed certification decision. The CARDs
also address late comments--and comments on completeness (see below)--
received after the close of the public comment period (on March 17,
1997) but before August 8, 1997. All relevant public comments, whether
received in writing, or orally during the public hearings, were
considered by the Agency as the proposed certification decision was
developed. Comments received after August 8 were considered by EPA, to
the extent possible, in its development of the proposed rule, but were
not addressed in CARDs because of time constraints. Such comments will
be addressed in the Response to Comments document for EPA's final
certification decision.
E. Completeness Determination
Section 8(d)(1)(B) of the LWA establishes a one-year time frame for
the Administrator to reach a certification decision regarding WIPP's
compliance with the disposal regulations. Section 8(d)(4) of the LWA
requires that EPA make its certification determination only after DOE
has submitted the ``full application'' to EPA. The Compliance Criteria,
at Sec. 194.11, interpret these requirements to mean one year from
receipt of a ``complete'' certification application from DOE. This
assures that the one-year review period is devoted exclusively to
substantive, meaningful review of the CCA.
Upon receipt of the CCA in October 1996, EPA began reviewing the
CCA for both completeness and, to the extent possible, technical
adequacy. Pursuant to section 8(d)(1) of the LWA, EPA provided requests
to DOE for specific information needed for completeness on December 19,
1996. (Docket A-93-02, Item II-I-1, Attachment 1) DOE submitted the
requested information with letters dated January 17, January 24,
February 7, February 14, and February 26, 1997. (This correspondence is
available in Docket A-93-02, Category II-I.) On May 16, 1997, the
Administrator informed the Secretary, in writing, that the CCA was
complete. The completeness determination was announced in the Federal
Register on May 22, 1997. (62 FR 27996-27998)
The determination of completeness meant only that all sections of
the disposal regulations and Compliance Criteria had been addressed in
the CCA. The completeness determination did not state or imply that
compliance with the disposal regulations or WIPP Compliance Criteria
had been achieved. In short, the completeness determination was an
interim administrative step to announce that the CCA contained the
information necessary for the Agency to proceed with its technical
evaluation of compliance.
Moreover, section 8(d)(1) of the LWA specifically allows EPA to
request additional information ``as needed to certify'' at any time.
EPA made such additional requests in letters to DOE dated December 19,
1996, and February 18, March 19, April 17, April 25, June 6, and July
2, 1997. (Docket A-93-02, Items II-I-1, II-I-9, II-I-17, II-I-25, II-I-
27, II-I-32, and II-I-37, respectively)
F. Public Comments on Completeness
The Agency received numerous public comments regarding the timing
of the Administrator's completeness determination. While some comments
stated that the CCA was administratively complete upon submission,
others argued that the CCA was incomplete and simply should be returned
to DOE. The latter set of commenters expressed that it was not
appropriate for the Agency to close the public comment period on the
ANPR prior to the Administrator's determination of completeness, and
that the public hearings should be delayed until after the completeness
determination. Other commenters
[[Page 58796]]
requested an additional 120-day comment period after the completeness
determination was issued, as well as an additional set of public
hearings during such a comment period.
In making its completeness determination, EPA considered public
comments which explicitly addressed the issue of completeness and were
submitted to the docket or to EPA's Office of Radiation and Indoor Air.
In response to concerns expressed by commenters, the Agency notified
the public in the Federal Register announcement regarding the
completeness determination that EPA would continue to accept public
comments on the CCA subsequent to the completeness determination. (62
FR 27997) (Comments on completeness received before August 8, 1997, are
addressed in more detail in the CARDs supporting this proposal.
Comments received after August 8 will be addressed in the Response to
Comments document for EPA's final certification rule.) In accordance
with Sec. 194.62, the public is being afforded a 120-day period in
which to comment on today's proposal. This comment period will provide
the public with another opportunity to comment on DOE's CCA, as well as
an opportunity to address EPA's proposed certification decision.
Public comments received during and after the ANPR comment period
also requested that EPA clarify what specific material constitutes the
``complete'' CCA. This concern was raised because, at EPA's request,
DOE supplemented the docket with substantial additional materials
beyond what was initially submitted on October 29, 1996. Many of the
issues raised by public comments were addressed in a December 19, 1996
letter to DOE in which EPA identified additional information necessary
for the CCA to constitute a complete application. (Docket A-93-02, Item
II-I-1, Attachment 1) To address completeness concerns, EPA requested
additional information on (among other topics) site conditions,
documentation of computer codes, and the effects of explosions--issues
all identified in public comments. DOE submitted the requested
information with letters dated January 17, January 24, February 7,
February 14, and February 26, 1997. The complete CCA consists of the
application that was submitted to EPA on October 29, 1996, and
supplementary materials provided by DOE that were identified by EPA, in
the December 19 letter, as necessary for completeness. A list of the
specific items that comprise the complete application is located in
Docket A-93-02, Item II-G-29. All correspondence between DOE and EPA
regarding completeness of the CCA is available in the Agency's public
dockets. (Docket A-93-02, Category II-I)
Other issues raised by commenters, such as fluid injection
scenarios, were not considered relevant to the completeness
determination and instead were addressed by EPA in its technical
comments to DOE.
G. Proposed Certification Decision
Today's Notice of Proposed Rulemaking for certification fulfills
the requirements of the WIPP Compliance Criteria at Sec. 194.62.
Today's notice announces the Administrator's proposed decision,
pursuant to section 8(d)(1) of the LWA, as amended, to issue a
certification that the WIPP facility will comply with the disposal
regulations, and solicits comment on the proposal. Today's notice also
marks the beginning of a 120-day public comment period on EPA's
proposed certification decision. Finally, today's notice announces that
public hearings will be held in New Mexico during the public comment
period. Further information on the hearings will be provided in a
subsequent Federal Register notice. Any comments received on today's
notice will be made available for inspection in Docket A-93-02,
Category IV-D.
H. Final Certification Decision
The Agency will publish a final rule in the Federal Register
announcing the Administrator's final decision, pursuant to section
8(d)(1) of the LWA and in accordance with the Compliance Criteria at 40
CFR 194.63, whether to issue a certification that the WIPP facility
will comply with the disposal regulations. EPA will review comments
submitted on EPA's proposed decision. (Comments regarding the ANPR and
completeness that are addressed in the CARDs for the proposed rule have
already been considered and will not be addressed again in the Response
to Comments document for the final rule.) A document summarizing
significant comments and issues arising from comments received on
today's Notice of Proposed Rulemaking, as well as the Administrator's
response to such significant comments and issues, will be prepared and
will be made available for inspection in Docket A-93-02.
I. Dockets
In accordance with 40 CFR 194.67, EPA maintains a public docket
(Docket A-93-02) that will contain all information used to support the
Administrator's proposed and final decisions on certification. The
Agency established and maintains the formal rulemaking docket in
Washington, D.C., as well as informational dockets in three locations
in the State of New Mexico (Carlsbad, Albuquerque, and Santa Fe). The
docket consists of all relevant, significant information received to
date from outside parties and all significant information considered by
the Administrator in reaching a proposed certification decision
regarding whether the WIPP facility will comply with the disposal
regulations. Copies of the CCA were placed in Category II-G of the
docket. Supplementary information received from DOE in response to EPA
requests was placed in Categories II-I and II-G.
The hours and locations of EPA's public information dockets are as
follows: Docket No. A-93-02, located in room 1500 (first floor in
Waterside Mall near the Washington Information Center), U.S.
Environmental Protection Agency, 401 M Street, S.W., Washington, D.C.,
20460 (open from 8:00 a.m. to 4:00 p.m. on weekdays); (2) EPA's docket
in the Government Publications Department of the Zimmerman Library of
the University of New Mexico located in Albuquerque, New Mexico, (open
from 8:00 a.m. to 9:00 p.m. on Monday through Thursday, 8:00 a.m. to
5:00 p.m. on Friday, 9:00 a.m. to 5:00 p.m. on Saturday, and 1:00 p.m.
to 9:00 p.m. on Sunday); (3) EPA's docket in the Fogelson Library of
the College of Santa Fe in Santa Fe, New Mexico, located at 1600 St.
Michaels Drive (open from 8:00 a.m. to 12:00 midnight on Monday through
Thursday, 8:00 a.m. to 5:00 p.m. on Friday, 9:00 a.m. to 5:00 p.m. on
Saturday, 1:00 p.m. to 9:00 p.m. on Sunday); and (4) EPA's docket in
the Municipal Library of Carlsbad, New Mexico, located at 101 S.
Halegueno (open from 10:00 a.m. to 9:00 p.m. on Monday through
Thursday, 10:00 a.m. to 6:00 p.m. on Friday and Saturday, and 1:00 p.m.
to 5:00 p.m. on Sunday). As provided in 40 CFR Part 2, a reasonable fee
may be charged for photocopying docket materials.
VI. National Academy of Sciences Report on the WIPP
The National Academy of Sciences (``NAS'') has long considered the
issue of proper disposal of radioactive wastes. The NAS first discussed
the likely suitability of salt formations as a medium for geologic
disposal of high-level radioactive wastes in 1957.10 A later
study recommended the use of
[[Page 58797]]
bedded salt formations for geologic disposal. 11
---------------------------------------------------------------------------
\10\ National Research Council (NRC), ``The Disposal of
Radioactive Wastes on Land'' (National Academy Press 1957).
\11\ NRC, ``Disposal of Solid Radioactive Wastes in Bedded Salt
Deposits'' (National Academy Press 1970).
---------------------------------------------------------------------------
The NAS has provided specific scientific and technical guidance to
DOE regarding the WIPP since the inception of the NAS WIPP Committee in
1978. In October 1996, the NAS released a report assessing the long-
term safety and performance of the WIPP disposal system. The report is
available in Docket A-93-02, Item II-A-38. The WIPP committee's
schedule did not allow for review of the CCA submitted to EPA in
October 1996; instead, the committee examined a preliminary performance
assessment (``PA'') conducted in 1992, and draft versions of DOE's CCA.
For this reason and others, the NAS noted that the report was ``a
review of ongoing activities and should be viewed as a progress report
rather than a final evaluation.'' 12
---------------------------------------------------------------------------
\12\ NRC, ``The Waste Isolation Pilot Plant: A Potential
Solution for the Disposal of Radioactive Waste'' (National Academy
Press 1996), p. 12.
---------------------------------------------------------------------------
The report reiterates NAS belief that salt is an attractive medium
for geologic isolation of radioactive waste. Based on its review of the
1992 PA, the committee found no credible or probable scenario for
release of radionuclides from the WIPP if it is undisturbed by human
intrusion. The report concluded that disturbed scenarios--i.e., those
involving deliberate or unintentional human intrusion--could compromise
the integrity of the disposal system. Finally, the committee
recommended several changes intended to produce a more technically
defensible and more easily understood PA.
EPA considered the NAS report in developing its proposed
certification decision. Specific recommendations on alternative
modeling approaches or other improvements to the 1992 PA were
considered by EPA in evaluating whether the CCA is adequate. The Agency
treated such recommendations as public comments on the ANPR, and
responds in detail to particular issues in the CARDs supporting today's
proposal. EPA did not give substantial consideration to the committee's
general conclusions on the PA because, subsequent to the NAS review,
EPA required numerous changes to the preliminary PA considered by the
committee. The committee recommended that human intrusion scenarios
could be made less speculative by refining probability estimates for
the occurrence of future human activities, but suggested neither a
methodology for doing so, nor an alternative approach to human
intrusion which could be implemented within the framework of the
Compliance Criteria.13
---------------------------------------------------------------------------
\13\ NAS never submitted official comments on proposed 40 CFR
Part 194. In contexts other than the WIPP report, however, NAS has
acknowledged the impossibility of making decisions regarding nuclear
waste disposal based solely on scientific information: ``[I]t became
clear in the course of our work that designing the standards
requires making decisions based as much or more on policy
considerations than on science. It is equally clear that there is no
sharp dividing line between science and policy.'' [NRC, Technical
Bases for Yucca Mountain Standards (National Academy Press, 1995),
p. viii] The rulemaking process used to develop the WIPP compliance
criteria provided a forum for EPA to gather and weigh scientific
evidence, public concerns, and other policy issues regarding the
treatment of human intrusion in PA.
---------------------------------------------------------------------------
VII. Codification of EPA's Certification Decision
The requirements which apply to the rulemaking process used to
develop EPA's certification decision (including measures for soliciting
and considering public input) do not prescribe what form the final
decision must take. In analogous situations where EPA issues or denies
hazardous waste no-migration petitions for landfills or other sites,
public notice of the decision is provided by publication in the Federal
Register, and such notice serves as the record of EPA's action.
14 Because of the one-of-a-kind nature of the WIPP facility,
EPA has determined that it is appropriate to provide a more permanent
record of the Agency's decision. To that end, EPA's decision is being
published in the Federal Register and also will be codified as an
appendix to the WIPP Compliance Criteria at 40 CFR Part 194. A lasting
record of EPA's certification decision will be established since the
appendix will be included each time in the future that the Code of
Federal Regulations is compiled and published.
---------------------------------------------------------------------------
\14\ See, e.g., the RCRA Conditional No-Migration Petition, 55
FR 47709.
---------------------------------------------------------------------------
VIII. Determination of Whether the WIPP Complies With the Disposal
Regulations
The proposed rule states the Agency's determination that the WIPP
will comply with the disposal standards and Compliance Criteria, taken
as a whole. In addition, the proposal specifies all conditions which
apply to the certification. As noted previously, EPA's certification of
compliance depends on DOE satisfying the specific requirements of the
WIPP Compliance Criteria. The ensuing sections of the SUPPLEMENTARY
INFORMATION address each of the technical WIPP Compliance Criteria in
turn; the Agency describes the basis for evaluating compliance with
each criterion, and discusses briefly how the CCA submitted by DOE, and
other relevant information, demonstrated compliance with EPA's
requirements. CARDs provide more detailed support for EPA's proposed
decisions regarding compliance with individual criteria. The CARDs are
available for public review in Docket A-93-02, Category III-B. See
``additional docket information'' in the SUPPLEMENTARY INFORMATION.
Not all sections of the WIPP Compliance Criteria are discussed
below because not all the provisions of 40 CFR Part 194 are directly
relevant to an evaluation of compliance with the disposal regulations.
Some sections of 40 CFR Part 194--such as Sec. 194.1, ``Purpose, scope
and applicability''--are entirely administrative in nature. Other
sections, including those related to public participation, address
procedural aspects of the certification rulemaking. Still others refer
to future actions which may occur, such as inspections or the need to
suspend an existing certification. Such criteria are not relevant to
EPA's analysis of whether information in the CCA and elsewhere
demonstrates that the WIPP site will comply with EPA's disposal
regulations. Some of these criteria are addressed elsewhere in the
SUPPLEMENTARY INFORMATION. For example, EPA's adherence to the public
participation requirements of the LWA and 40 CFR Part 194 is documented
under ``public participation.''
A. Basis for EPA's Compliance Determination
EPA's proposed certification decision is based on the entire record
available to the agency, which is contained in Docket A-93-02. The
record consists of the complete DOE CCA, supplementary information
submitted by DOE in response to EPA requests for additional information
for technical sufficiency, technical reports generated by EPA and EPA
contractors, EPA audit reports, and public comments submitted on EPA's
ANPR for the certification decision.
Thus, as contemplated by Congress, EPA's compliance determination
is based on more than the ``complete'' application. (LWA, section
8(d)(1)) EPA also relied on materials prepared by the Agency or
submitted by DOE in response to EPA requests for specific additional
information necessary to address technical sufficiency concerns.
Examples of such documents include EPA technical and audit reports and
letters submitted by DOE (i.e., those contained in Docket A-93-02,
Category II-I).
In response to public comments regarding the precise materials EPA
considered in reaching today's proposed decision, the CARDs reference
the
[[Page 58798]]
relevant portion(s) of the October 29, 1996, CCA and any supplementary
information that was relied on in reaching a particular proposed
compliance decision. All materials which informed EPA's proposed
decision have been placed in the WIPP dockets or are otherwise publicly
available. EPA has specified in the docket the location of all
reference materials to aid the public in its evaluation of such
information. A full description of the supporting documentation for
EPA's proposed decision and a full list of the DOE compliance
documentation considered by the Agency are located at Docket A-93-02,
Item III-B-1. Through these means, the Agency believes the public will
have a clear indication of what materials constitute the complete CCA,
and what materials constitute the record basis for EPA's proposed
certification decision.
B. Compliance Application Review Documents (CARDs)
The preamble for today's proposed rule describes the basis for the
Agency's compliance determination for each of the relevant WIPP
Compliance Criteria. The detailed technical rationale for EPA's
proposed decision is contained in the Compliance Application Review
Documents (CARDs) supporting today's action. Taken as a whole, the
CARDs are analogous to the Background Information Document usually
provided for EPA rulemakings. These documents are found at Docket A-93-
02, Item III-B-2.
The CARDs discuss DOE's compliance with the individual requirements
of the WIPP Compliance Criteria. Each CARD is a section in the document
which is numbered according to the section of 40 CFR Part 194 to which
it pertains. For example, CARD 23 addresses Sec. 194.23, ``Models and
Computer Codes.'' In the section of each CARD called ``Compliance
Review Criteria,'' EPA restates the specific requirement and identifies
the relevant information expected in the CCA, as described in the
``Compliance Application Guidance for the WIPP: A Companion Guide to 40
CFR Part 194'' (``CAG,'' EPA 402-B-95-014, March 1996). EPA also
clarifies the Agency's rationale for evaluating the CCA's completeness
and technical adequacy.
After explaining the Agency's compliance review criteria, each CARD
summarizes DOE's approach to compliance and describes EPA's compliance
review. CARDs also list additional EPA technical support documents and
any other references used by EPA in rendering a proposed decision on
compliance. All technical support documents and references are found in
Docket A-93-02 with the exception of generally available references and
those documents already maintained by DOE or its contractors in
locations accessible to the public. DOE has committed to make such
documents readily available to the public. Instructions for obtaining
access to DOE documents can be found at Docket A-93-02, Item III-B-1.
Finally, CARDs contain EPA's response to comments received on the
Agency's ANPR of November 15, 1996 (61 FR 58499) and on other comments
received prior to August 8, 1997. For more discussion of EPA's response
to these comments, see ``Public Participation'' in the SUPPLEMENTARY
INFORMATION.
For technical information or more detailed discussion on EPA's
evaluation of compliance with any individual provision of 40 CFR Part
194, readers should refer to the corresponding CARD in Docket A-93-02,
Item III-B-2.
IX. Section 194.14, Content of Compliance Certification Application
40 CFR Part 194 sets out those elements which the Agency requires
to be in a complete compliance application. In general, compliance
applications must include information relevant to demonstrating
compliance with each of the individual sections of 40 CFR Part 194 to
determine if the WIPP will comply with the Agency's radioactive waste
disposal regulations at 40 CFR Part 191, Subparts B and C. The Agency
published the ``Compliance Application Guidance for the Waste Isolation
Pilot Plant: A Companion Guide to 40 CFR Part 194'' (``CAG'') which
provided detailed guidance on the submission of a complete compliance
application.
Any compliance application must include, at a minimum, basic
information about the WIPP site and disposal system design, and must
also address all the provisions of the Compliance Criteria; these
requirements are embodied in Sec. 194.14. The documentation required in
the Compliance Criteria is important to enable a rigorous, thorough
assessment of whether the WIPP facility will comply with the disposal
regulations.
Much of the information referenced by DOE as demonstrating
compliance with Sec. 194.14, and EPA's review of the information, was
principally used to demonstrate compliance with other sections of the
Compliance Criteria. Thus, this section of the preamble discusses many
of the requirements of Sec. 194.14 only briefly because they are fully
discussed in other sections of the preamble. EPA thoroughly reviewed
DOE's compliance certification application (``CCA'') submitted on
October 29, 1996, and additional information submitted by DOE.
A. Site Characterization
40 CFR 194.14(a) requires DOE to describe the characteristics of
the WIPP site, including the natural and engineered features that may
affect the performance of the disposal system. The characteristics of
the site and identification of potential pathways are crucial to the
conceptual models and computer modeling that is done to determine
compliance with the containment requirements at 40 CFR 191.13 and the
individual and ground-water protection requirements. In addition to a
general understanding of the site, EPA required specific information on
hydrologic characteristics with emphasis on brine pockets, anhydrite
interbeds, and potential pathways for transport of waste. EPA also
required DOE to project how geophysical, hydrogeologic and geochemical
conditions of the disposal system would change due to the presence of
waste.
EPA examined the CCA and determined that it and the supplemental
information provided by DOE contained an adequate description of the
WIPP geology, geophysics, hydrogeology, hydrology and geochemistry of
the WIPP disposal system and its vicinity, and how these conditions
change over time. The CCA discussed that very few potential pathways
exist for radionuclide transport. DOE projected future geophysical,
hydrogeologic and geochemical conditions due to the presence of waste.
A brief overview of the site is provided below.
The WIPP is located in the Delaware Basin of New Mexico and Texas
and is approximately 26 miles southeast of Carlsbad, New Mexico. This
area of New Mexico is currently arid, but precipitation increases were
accounted for in the performance assessment (``PA''). The Delaware
Basin contains thick sedimentary deposits (over 15,000 feet (4572
meters) thick) that overlay metamorphic and igneous rock (1.1 to 1.5
billion years old). The WIPP repository is a mine constructed
approximately 2,150 feet (655 meters) below ground surface in the
Permian age (200-250 million years old) Salado Formation,
which is composed primarily of salt (halite).
DOE considered the primary geologic units of concern to be (from
below the repository to the surface): (1) Castile Formation
(``Castile''), consisting of
[[Page 58799]]
anhydrite and halite with pressurized brine pockets found locally
throughout the vicinity of the WIPP site; (2) Salado Formation
(``Salado''), consisting primarily of halite with some anhydrite
interbeds and accessory minerals and approximately 2,000 feet (600
meters) thick; (3) Rustler Formation (``Rustler''), containing salt,
anhydrite, clastics, and carbonates (primarily dolomite), with the
Culebra dolomite member of the Rustler as the unit of most interest;
and, (4) Dewey Lake Red Beds Formation (``Dewey Lake''), consisting of
sandstone, siltstone and silty claystone. The geologic formations below
these were included in the screening of features, events, and
processes, but were not included in PA calculations because they did
not affect the performance of the disposal system. See Sec. 194.32 for
a detailed discussion of screening of features, events, and processes.
DOE indicated that the major geologic process in the vicinity of
the WIPP is dissolution. To the west, the slight (one degree) dip in
the Salado has exposed the formation to dissolution processes, and
commenters argued that lateral dissolution processes will affect the
WIPP's ability to contain radionuclides. However, DOE estimated that
the dissolution front will not reach the WIPP site for at least
hundreds of thousands of years--well past the regulatory time frame.
EPA agrees with DOE's conclusion that while deep dissolution has
occurred elsewhere in the Delaware Basin, the process of deep
dissolution, if it occurs under the WIPP site, would occur at such a
slow rate that it would not affect the containment capabilities of the
WIPP during the regulatory time period.
Many commenters suggested that WIPP can not contain radionuclides
because WIPP is in a region of karst (topography created by the
dissolution of rock). EPA reviewed information submitted by DOE and
stakeholders regarding the occurrence and development of karst at the
WIPP (e.g., Docket A-93-02, Items II-H-46 and II-D-102). EPA concluded
that while the WIPP site is in a karst region and karst features are
found to the west of the site in Nash Draw, only limited evidence
exists that dissolution-related features occur near the WIPP boundary
(e.g., well WIPP-33). These features are neither pervasive nor
associated with any identified preferential groundwater flow paths or
anomalies. WIPP field mapping and site-specific hydrologic information
(e.g., well tracer tests) do not indicate that any cavernous or other
karst-related flow is present at the WIPP site. As stated in a
technical document submitted by one commenter, ``the karst phenomena do
not appear to warrant a rejection of the WIPP site.'' (Docket A-93-02,
Item II-D-102) EPA agrees and concludes that karst is not a problem at
WIPP and that geologic evidence of the last approximately 500,000 years
and results from DOE's groundwater modeling indicate that future
development of karst at the WIPP is not likely.
DOE conducted geologic studies and field measurements as part of
its evaluation of the hydrology of the WIPP site and identified two
potential pathways for radionuclides in the disposal system: the
Culebra dolomite and Salado anhydrite markerbeds 138 and 139. However,
only the Culebra dolomite has the capability to transmit significant
amounts of radionuclides. The Salado markerbeds have very low
permeability and are the primary pathways in the undisturbed case. The
results of the CCA PA indicated that radionuclide transport through the
anhydrites does not contribute significantly to total releases. The
Culebra dolomite is a potential pathway only in intrusion scenarios.
Commenters stated that the Dewey Lake should be considered a potential
pathway and thus needed better characterization; however, the CCA PA
results indicated that no contaminated brine traveled up an intrusion
borehole past the Culebra to the Dewey Lake or other units. While DOE
did identify the Dewey Lake as a potential underground source of
drinking water, the CCA PA results indicated that the Dewey Lake did
not play an active role in radionuclide release scenarios. EPA
concludes that the Culebra dolomite and the Salado anhydrite markerbeds
138 and 139 are the only ground-water radionuclide transport pathways
in the disposal system.
As the primary radionuclide pathway during an intrusion, the
Culebra was the subject of many public comments, especially related to
karst (discussed above), Kd values (distribution
coefficients used in calculating the retardation factor) and
geochemistry and flow directions. In DOE's conceptual model the Culebra
is characterized as a fractured dolomite that has dual-porosity and
acts to physically retard movement of contaminants. In a dual-porosity
rock unit, ground-water is believed to flow through the fractures, but
water and contaminants can access the pore space within the rock matrix
away from the fractures. Movement of water and contaminants into the
pore space slows (retards) their respective forward movement. This
physical retardation is necessary in order to have chemical
retardation. In the process of chemical retardation, contaminants
diffuse from the fractures into the pore space where they can adsorb
onto the rock mass.
The CCA indicated that there were no contributions to total
releases from the ground-water pathway. This was due, in large part, to
the fact that radionuclides adsorbed into the Culebra dolomite did not
move with the ground-water flow. That is, the movement of the
radionuclides were retarded with respect to the ground-water flow. The
estimate of the extent of the retardation was based on laboratory tests
using crushed rocks and small columns of rock. EPA concluded that the
laboratory tests were conducted appropriately and that the
Kd values DOE derived from this testing are reasonable given
the experimental evidence. However, EPA believes that a lognormal
distribution is a more appropriate representation of the data
distribution, and required the use of a lognormal distribution in the
Performance Assessment Verification Test (PAVT). For further discussion
of the PAVT, refer to the preamble for Sec. 194.34.
DOE indicated in the CCA that there is considerable variation in
the groundwater chemistry of the Culebra member of the Rustler
Formation. In addition, DOE provided supplemental information
pertaining to Culebra groundwater flow and geochemistry which contended
that the observed geochemistry and flow directions can be explained
with the ground-water basin modeling. (Docket A-93-02, Item II-I-17)
The ground-water basin model addressed near surface hydrologic
conditions (including the water table and potential recharge areas) and
reconciled inconsistencies between the geochemistry data and the
current ground-water flow direction.
The probability of intercepting a Castile brine reservoir (i.e.,
brine pocket) and the characteristics of a brine reservoir once it has
been hit were the subject of many public comments as well as a source
of EPA concern. Because of the low permeability of the Salado
Formation, there is no natural connection between a Castile brine
pocket and the waste panel area. However, in the case of a deep
drilling intrusion that goes through a waste panel and into the
Castile, it is possible that the drilling will intercept brine in the
Castile and create a pathway for Castile brine to flow into the
repository and interact with the waste.
In the 1992 PA, Sandia National Laboratory (``SNL'') considered the
probability of hitting a brine pocket under the waste area an uncertain
parameter that required sampling over a
[[Page 58800]]
range of 0.25 to 0.62. This range of probabilities was based on
geophysical work that suggested brine may be present. For the CCA PA,
SNL conducted a new analysis based on a geostatistical analysis of oil
and gas wells in the vicinity of WIPP. From this study, SNL identified
the probability of hitting brine as 0.08, partly because the brine is
expected to be in fractures that are oriented vertically or slightly
less than vertical. EPA reviewed the CCA and public comments and
concluded that, while the probability of hitting a brine pocket may be
low, there was no justification for assuming a fixed value for such an
uncertain parameter. EPA therefore directed DOE, for the PAVT, to
change the probability of hitting a brine pocket to a range that
incorporated low to moderate probabilities (0.01 to 0.6).
The potential volume of brine reservoirs was also the subject of
numerous comments claiming that, in the PA, DOE underestimated the
brine volume. DOE assumed that passive institutional controls
(``PICs'') will limit the available brine pocket volume to that within
the area covered by the surface berm used to mark the subsurface
location of the waste panels. EPA reviewed information in the CCA,
public comments, and the SNL Records Center. EPA concluded that the
approach of excluding Castile brine pocket volumes based on the waste
panel ``foot print'' is inappropriate because the efficacy of drilling
in the area outside the berm cannot be reasonably defined. EPA directed
DOE, for the PAVT, to change the brine pocket volume to a volume that
is more representative of data from site characterization activities
(i.e., the WIPP-12 exploratory well). The PAVT also omits the credit
for PICs.
The results of the PAVT indicated that changing the probability of
hitting a brine pocket has a negligible effect on releases, but
changing the brine volume from 160,000 cubic meters to 17 million cubic
meters does have a noticeable effect on releases for the scenarios in
which a brine pocket is hit. Nevertheless, the PAVT results indicated
that, even with these changes combined with other parameter changes,
the PAVT results are similar to those in the CCA and still meet the
containment requirements by more than one order of magnitude. EPA
believes that the PAVT verifies that the original CCA Castile brine
reservoir parameters were adequate for use in PA and comparison against
the radioactive waste containment requirements. See the preamble for
Sec. 194.34(f) for additional information on the results of the PAVT.
EPA agrees with DOE's conclusion in the CCA that the most important
extractable resources near the WIPP are hydrocarbons, potassium salts
(potash), and water. DOE indicated that some of the geologic formations
below the repository area contain oil and gas resources that are
currently being exploited in the Delaware Basin. According to DOE's
analysis, most of the water in the vicinity of the WIPP is highly
saline, with the closest dependable potable aquifer associated with the
Capitan Reef at the edge of the Basin. With respect to potash, the CCA
indicated that only the 4th and 10th potash zones qualify as economic
reserves. Commenters noted that the extent of potash identified by DOE
is different than that identified by the Bureau of Land Management in
its map of resources. EPA concludes that DOE's presentation is
reasonable, given the 40 CFR Part 194 requirements that DOE assess
resources relative to those currently being mined.
The projected effect of waste on the disposal system are primarily
limited to gas generation that increases repository pressure and
actinide solubility. Gas will be generated: (1) By corrosion of metals
and (2) as a byproduct of microbial degradation of cellulosics,
plastics and rubbers. Gas generation primarily affects spallings (due
to high pressures) and direct brine releases (due to high pressures and
increasing solubility). DOE indicated that magnesium oxide (``MgO'')
backfill emplaced with transuranic waste would mitigate the solubility-
enhancing effects of carbon dioxide from waste degradation. EPA concurs
with DOE's assessment. Refer to Sec. 194.44 for further discussion of
the effects of MgO.
Although commenters questioned DOE's characterization of the WIPP
site, especially the hydrology, EPA concluded after extensive review
that DOE identified, characterized, and used in the calculations the
major components of the geologic and hydrologic system around the WIPP.
DOE provided a detailed discussion of the geology and identified the
few geologic units that are important to PA. DOE also identified that
very few geologic units could transmit fluids and transport
radionuclides; after an intrusion, only the Culebra dolomite is a
significant pathway above the Salado with other overlying units not
receiving any contaminated brine. EPA reviewed DOE's discussion on
dissolution and karst and concludes that these processes are not
currently significant and will not affect WIPP over the regulatory time
period. EPA disagreed with DOE's characterizations of the Castile brine
pocket and required changes for the PAVT; however, PAVT results
verified that the original parameters were acceptable for use in the
PA.
B. Disposal System Design
Section 194.14(b) requires DOE to describe the design of the
disposal system, including natural and man-made materials, and
architectural and structural aspects of the disposal system. DOE also
must describe the computer codes and standards that have been applied
to the design and construction of WIPP.
The CCA contained a general description of the WIPP facility and a
detailed description of the underground disposal system (including the
engineered barriers in the repository and shaft system as well as the
geologic units). The WIPP repository is an underground mine that will
eventually have eight panels (each of which will include seven
football-field long rooms) connected by drifts. Waste will be emplaced
in the WIPP through the waste shaft. An exhaust shaft, salt handling
shaft, and air intake shaft also penetrate the WIPP repository. The
underground mine is attended by surface equipment and buildings that
will handle waste prior to its emplacement in the WIPP. DOE intends to
pack bags of magnesium oxide (``MgO'') around the waste containers, and
will seal each panel after it is filled with waste. The Salado salt
will eventually ``creep'' and close WIPP rooms and panels. The WIPP was
designed to take advantage of this encapsulation so that transuranic
waste emplaced in the WIPP will be completely enveloped by salt, thus
minimizing the potential for waste migration.
The major disposal system engineered features related to long-term
performance are the general design, shaft seals, panel closures,
borehole plugs, and the additional engineered barrier of backfill
around the waste. The purpose of the shaft seal system is to limit
fluid flow within the shafts after the WIPP is decommissioned and to
ensure that the disposal system shafts will not become pathways for
radionuclide release. The shaft seal system has 13 elements that fill
the shaft with engineered materials possessing high density and low
permeability, including concrete, clay, compacted salt, cementitious
grout, and earthen fill. DOE identified the compacted salt column as
the most critical element in the long-term performance of the shaft
seal. The compacted salt column component of the system within the
Salado is intended to serve as the
[[Page 58801]]
primary long-term barrier by limiting fluid transport along the shaft
during the 10,000-year regulatory period. The other components of the
shaft seal within the Salado are intended to prevent migration of
radionuclides in the short term and protect the compacted salt column
until it is sufficiently consolidated to act as an effective long-term
barrier. Components of the seal system within the Rustler are intended
to limit the commingling of groundwater between the water bearing
members. The seal system overlying the Rustler will consist of
compacted earthen fill. The shaft seal design in the CCA received
extensive technical review by DOE, and was also subjected to an
independent design review. EPA concludes that the shaft seal design is
adequate because the system can be built and is expected to function as
intended.
The purpose of borehole plugs is to mitigate the potential for
migration of contaminants toward the accessible environment. DOE
indicated that it will abide by the applicable State oil and gas well
plugging requirements. While there are four deep research wells drilled
in the disposal system, DOE stated that ``the ERDA-9 exploratory hole
was the only hole within the underground development area which was
permitted to penetrate the Salado formation to the underground facility
horizon.'' ERDA-9 did not penetrate an area that will become a waste
panel and DOE has indicated that abandoned boreholes more than a meter
away from the waste can be screened out of PA due to low consequence.
EPA agrees with DOE's assessment that these boreholes are not
significant to performance of the disposal system and can be screened
out of PA.
The primary long-term effect of the panel closure will be to block
the flow of brine between panels. DOE provided four design options for
panel closures but did not specify in the CCA which panel closure
option would be used at WIPP, an omission that was pointed out in
public comments. (Docket A-93-02, Item II-H-10) In reviewing the four
panel closure design options, EPA identified Option D in the CCA as the
most robust design, and reviewed that design as the basis for an
evaluation of compliance. EPA found that the design for Option D would
be expected to perform as described, but that the use of a Salado mass
concrete (consistent with the type specified for the shaft seal system)
rather than fresh water concrete would be more consistent with the
permeability assumptions used in PA. EPA determined that such a design
is adequate to achieve the long-term performance modeled in PA, and
therefore proposes to find that DOE complies with Sec. 194.14(b).
However, because EPA is basing its proposed compliance determination on
the Option D panel seal design, the EPA is also proposing to establish
a certification condition requiring DOE to implement the Option D
design, with Salado mass concrete replacing fresh water concrete. (See
Condition 1 in the proposed Appendix A to 40 CFR Part 194.) Although
EPA's sensitivity analysis indicates that the panel closure
permeability is not a sensitive parameter, especially with the
disturbed rock zone at the same or higher permeability, the Agency
believes it is important to ensure that the proposed design on which
compliance was based is actually implemented at the site. Because of
the presence of the disturbed rock zone, EPA expects that gas flow
between panels for long-term performance purposes would be relatively
unaffected by the design choice.
C. Results of Assessments
Section 194.14(c) requires the CCA to present the results of
assessments of the WIPP's performance, given human intrusion into the
disposal system (performance assessment) and undisturbed conditions
(compliance assessment). EPA determined that DOE's results showed
compliance with the containment (Sec. 191.13), individual
(Sec. 191.15), and ground water (40 CFR Part 191, Subpart C)
requirements of the disposal regulations. Refer to discussions of
Sec. 194.34 and Sec. 194.55 for EPA's full evaluation of results of
assessments. Based on EPA's finding that information submitted by DOE
was sufficient for compliance with Secs. 194.34 and 194.55, the Agency
proposes to find that DOE also complies with Sec. 194.14(c).
D. Input Parameters to Performance Assessments
40 CFR 194.14(d) requires DOE to describe the input parameters to
the PA and discuss the basis for their selection. DOE provided
descriptions of input parameters to the PA. EPA's evaluation of this
information is addressed in the discussion of Sec. 194.23 of this
preamble. Based on EPA's finding that information was sufficient for
compliance with Sec. 194.23, the Agency proposes to find that DOE also
complies with Sec. 194.14(d).
E. Assurance Requirements
Section 194.14(e) requires documentation of measures taken to meet
the assurance requirements. EPA considers DOE to have complied with
Sec. 194.14(e) if it provided the information required for Secs. 194.41
through 194.46. Based on EPA's determination of compliance for all six
assurance requirements (active institutional controls, monitoring,
passive institutional control, engineered barriers, consideration of
the presence of resources, and removal of waste), EPA proposes to find
that DOE also complies with Sec. 194.14(e).
F. Waste Acceptance Criteria
Section 194.14(f) requires DOE to describe waste acceptance
criteria and the measures taken to assure adherence to such criteria.
EPA reviewed documentation provided by DOE and observed DOE audits and
other activities, and concluded that DOE provided satisfactory
descriptions of actions that will be followed to ensure adherence to
the waste acceptance criteria. EPA therefore proposes to find DOE in
compliance with Sec. 194.14(f). Refer the preamble discussion of
Sec. 194.24 for a complete discussion of EPA's review of waste
acceptance criteria and other waste characterization information.
G. Background Radiation
40 CFR 194.14(g) requires DOE to describe the background radiation
in air, soil and water in the vicinity of the disposal system and the
procedures employed to determine such radiation. DOE provided
information regarding the levels of background radiation in air, soil,
surface water, sediments, groundwater, and biota. DOE also provided a
description of the procedures used to determine the background
radiation. DOE indicated that background radiation in the vicinity of
the WIPP site is influenced by natural sources of radiation, fallout
from nuclear tests, and one local research project (Project Gnome,
which involved the underground detonation of a nuclear device on
December 10, 1961, at a site approximately 8 miles (13 kilometers)
southwest of the WIPP site).
EPA found that DOE provided sufficient discussion of background
radiation levels and associated procedures to monitor these media for
radiation. EPA, therefore, proposes to find that DOE complies with
Sec. 194.14(g).
H. Topographic Maps
40 CFR 194.14(h) requires DOE to provide one or more topographic
maps of the vicinity of the disposal system. At least one map must show
boundaries of the controlled area and the location of active, inactive
and abandoned injection and withdrawal wells in the controlled area and
in the vicinity of the disposal
[[Page 58802]]
system. The CCA must include topographic maps with a contour interval
sufficient to show clearly the pattern of surface water flow in the
vicinity of the disposal system.
DOE provided four topographic maps that show the pattern of surface
water flow in the vicinity of the WIPP. The CCA included three figures
showing the locations of the controlled area within the U.S. Public
Land Survey coordinate system, as well as a map showing the location of
active, inactive, and abandoned injection and withdrawal wells in the
controlled area and in the vicinity of the disposal system. EPA
reviewed the topographic maps provided in the CCA to determine their
sufficiency. EPA determined that DOE met the requirements of
Sec. 194.14(h) because it provided multiple, appropriately scaled,
topographic maps of the vicinity of the disposal system.
I. Past and Current Meteorological Conditions
40 CFR 194.14(i) requires DOE to describe past and current
climatologic and meteorological conditions in the vicinity of the
disposal system. DOE is also required to project how these conditions
are expected to change over the regulatory time frame.
DOE described past glaciation events, climatic changes, and
precipitation and temperature averages. DOE also discussed how
historical climatic conditions were used to anticipate climatic
conditions 10,000 years in the future. DOE described current climatic
conditions in the WIPP area, including summaries of recent rainfall,
temperature, and wind data. DOE discussed how climate changes were
incorporated in conceptual models.
Based on public comments and EPA's review of the CCA, EPA requested
additional information on dissolution. Supplemental information
submitted by DOE addressed EPA's concerns. EPA concluded that the
description of past and present climatic changes and associated impacts
on the WIPP disposal system were adequately addressed, and therefore
proposes to find DOE in compliance with Sec. 194.14(i).
J. Other Information Needed for Demonstration of Compliance
40 CFR 194.14(j) requires DOE to provide additional information,
analyses, tests, or records determined by the Administrator or the
Administrator's authorized representative to be necessary for
determining compliance with 40 CFR Part 194. After receipt of the CCA
dated October 29, 1996, EPA formally requested additional information
from DOE in seven letters dated December 19, 1996, and February 18,
March 19, April 17, April 25, June 6, and July 2, 1997. (Docket A-93-
02, Items II-I-1, II-I-9, II-I-17, II-I-25, II-I-27, II-I-33, and II-I-
37, respectively). The information requested in these letters was
necessary for EPA's completeness determination and technical review.
EPA staff and contractors also reviewed records maintained by DOE or
DOE's contractors (e.g., records kept at the Sandia National
Laboratories Records Center in Albuquerque, New Mexico). No additional
laboratory or field tests were conducted by DOE at EPA's specific
direction; however, DOE did conduct and document laboratory tests after
October 29, 1996, in order to present additional data to the Conceptual
Model Peer Review Panel.
The preamble for other sections of the Compliance Criteria discuss
in greater detail DOE's responses to EPA's formal requests for
additional information and any other supplementary information reviewed
by EPA after October 29, 1996. All documents sent to EPA are available
in the EPA docket. Additional documentation that was not sent to EPA
but was reviewed by the Agency (e.g., calculations of actinide
solubility for americium, plutonium, thorium and uranium) is also
publicly available. Documentation of peer review panel meetings
conducted after receipt of the CCA has been placed in the EPA docket.
See Docket A-93-02, Item III-B-1 for further information on the
location of all documentation reviewed by EPA.
EPA determined that DOE responded adequately to EPA's formal
requests for additional information, analyses, and records; and
therefore proposes to find that DOE complies with Sec. 194.14(j).
K. Conclusion
Based on the information provided in the CCA and additional
information submitted by DOE, EPA proposes that DOE demonstrates
compliance with all subsections of Sec. 194.14. For additional
information on EPA's evaluation of compliance for Sec. 194.14, see CARD
14.
X. General Requirements
The general requirements of 40 CFR Part 194, Subpart C, are
intended to ensure that any compliance certification application
(``CCA'') is based on dependable and verifiable information and that
EPA has the right to confirm the accuracy of such information. Although
they have no direct corollary in the disposal regulations, EPA issued
these requirements in implementing the disposal regulations because the
Agency believes that a reasonable expectation of compliance with the
containment requirements (discussed in subsequent portions of this
preamble) can be achieved only if the information and methods used to
conduct performance assessments are valid and reliable. To that end,
the general requirements at Secs. 194.22 through 194.27 establish
requirements for quality assurance programs, models and computer codes,
waste characterization, future state assumptions, expert judgment, and
peer review.
A. Section 194.22, Quality Assurance
Section 194.22 establishes quality assurance (``QA'') requirements
for the WIPP. QA is a process for enhancing the reliability of
technical data and analyses underlying DOE's CCA. Section 194.22
requires DOE to (a) establish and execute a QA program for all items
and activities important to the containment of waste in the disposal
system (including waste characterization activities, environmental
monitoring, field measurements, computer codes, procedures for expert
elicitation, disposal system designs, and data), (b) qualify data that
were collected prior to implementation of the required QA program, (c)
assess data for their quality characteristics, to the extent
practicable, (d) demonstrate how data are qualified for their use in
the CCA, and (e) allow verification of the above measures through EPA
inspections. The DOE's QA program must adhere to specific Nuclear
Quality Assurance (``NQA'') standards and requirements issued by the
American Society of Mechanical Engineers (``ASME'').
The EPA assessed compliance with the QA requirements in two ways.
First, EPA reviewed QA information in the CCA and associated reference
documents. EPA's second level of review consisted of visits to the WIPP
site, as well as WIPP-related facilities, to perform audits and
inspections to verify DOE's compliance with the QA requirements. For
example, EPA conducted audits to verify the proper execution of the QA
program at DOE's Carlsbad Area Office (``CAO''), Sandia National
Laboratories (``SNL''), and Westinghouse's Waste Isolation Division
(``WID'') at the WIPP facility. In this way, EPA was able to review
voluminous records required by the NQA standards, but not required to
be submitted as part of the CCA.
Section 194.22(a)(1) requires DOE to adhere to a QA program that
implements the requirements of the following: (1) ASME NQA-1-1989
edition; (2) ASME NQA-2a-1990 addenda, part 2.7, to ASME NQA-2-1989
edition; and (3) ASME NQA-3-
[[Page 58803]]
1989 edition (excluding Section 2.1 (b) and (c), and Section 17.1).
DOE incorporated these requirements in the Quality Assurance Program
Document (``QAPD'') contained in the CCA. The QAPD is the documented
plan for the WIPP project, as a whole, to comply with the NQA
requirements; it applies to all activities and items important to
containment of waste in the WIPP. The QAPD addresses the 18 basic
requirements of NQA-1, including supplemental requirements as
established by NQA-1; the computer software requirements as established
by NQA-2a, part 2.7; and the collection of scientific and technical
information requirements for site characterization of high level
nuclear waste repositories as established by NQA-3. The QAPD is
implemented by DOE's CAO, which provides overall coordination of WIPP
activities and has authority to audit all other organizations
associated with waste disposal at the WIPP (such as WID, SNL and waste
generator sites) to ensure that their lower-tier QA programs conform to
the QAPD. EPA audited DOE's QA program at CAO and determined that DOE
properly adhered to a QA program that implements the NQA standards and
requirements. Therefore, EPA proposes to find DOE in compliance with
Sec. 194.22(a)(1). (For information on the incorporation of NQA
requirements into lower tier program plans, refer to the subsequent
discussion of Sec. 194.22(a)(2), which addresses specific activities
under the direct control of organizations other than DOE's CAO.)
Section 194.22(a)(2)(i) requires DOE to include information which
demonstrates that the QA program has been established and executed for
waste characterization activities and assumptions. In the CCA, DOE
provided the QAPD and referenced criteria for the review and approval
of a site-specific Quality Assurance Project Plan (``QAPjP'') to
address technical criteria and implementation procedures. The CCA
listed five waste generator site QAPjPs that have been approved by DOE.
DOE proposed that sites also will prepare site certification Quality
Assurance Plans (``QAPs'') that, together with the QAPjPs, are intended
to establish all the NQA requirements applicable to waste
characterization.15 EPA finds that the QAPD, as it applies
to waste characterization, is in conformance with the NQA requirements.
As discussed below, the Agency intends to verify the adequacy of site-
specific QA programs in the future.
---------------------------------------------------------------------------
\15\ NQA-1 (Element II-2) requires that organizations
responsible for activities affecting quality (in the case of the
WIPP, affecting the containment of waste in the disposal system)
must have documented QA programs in accordance with the applicable
NQA requirements. The documentation for such programs is commonly
referred to as a ``quality assurance program plan,'' or ``QAPP.''
For WIPP waste generator sites, the role of the QAPP is fulfilled by
documents with other titles, such as the QAP or the QAPjP. The ``TRU
QAPP'' referenced by DOE in the CCA is not a QAPP as described by
the NQA standards; rather, it is a technical document that describes
the quality control requirements and performance standards for
characterization of TRU waste coming to the WIPP facility. The TRU
QAPP is addressed more specifically in the preamble discussion of
Sec. 194.24, ``Waste Characterization.''
---------------------------------------------------------------------------
Another important activity related to waste characterization is the
ability to track waste shipped to and emplaced in the WIPP. The WIPP
Waste Information System (``WWIS'') is a computer database and
reporting program that will track and tally the waste that comes to the
WIPP. The WWIS is covered by QA programs both at the WID and at waste
generator sites. At Westinghouse, the WID QAPD, which addresses the
specific requirements of the NQA standards, governs operation of the
system. In September 1997, EPA performed an inspection of the WID QA
program applicable to the WWIS. At that time, the WWIS was demonstrated
to be operational, and EPA determined that a QA program had been
properly executed for the WWIS in accordance with the applicable NQA
requirements.
The Compliance Criteria require that QA programs be established and
executed specifically with respect to the use of process knowledge and
a system of controls for waste characterization. (Secs. 194.22(a)(2)(i)
and 194.24(c)(3) through (5)) To accomplish this, waste generator site-
specific QA programs and plans must be individually examined and
approved by EPA to ensure adequate waste characterization programs are
in place before EPA allows individual waste generator sites to
transport waste for disposal at the WIPP. Since waste characterization
activities have not begun for most TRU waste generator sites and
storage facilities, EPA has not yet evaluated the compliance of many
site-specific QA plans (QAPs and, where applicable, QAPjPs) and
programs.
To date, one WIPP waste generator site, Los Alamos National
Laboratory (``LANL''), has been approved by EPA to have established
adequate QA programs (encompassed in a QAP and QAPjP) and to have
properly executed QA procedures in accordance with the applicable NQA
requirements. Prior to approval of LANL's site-specific QA program, EPA
conducted an audit of DOE's overall WIPP QA program and approved its
capability to perform audits in accordance with the requirements of
NQA-1. EPA then inspected three DOE audits of LANL's QA program. Based
on the results of the inspections, the EPA inspectors determined that
the QA program had been properly executed at LANL. Therefore, EPA
proposes to find that the requirements of Sec. 194.22(a)(2)(i) have
been met for the WID QAPD, the WWIS, and waste characterization
activities at LANL.
With respect to other waste generator sites, EPA proposes to
certify compliance with Sec. 194.22(a)(2)(i) conditioned on separate,
subsequent approvals from EPA that site-specific QA programs for waste
characterization activities and assumptions have been established and
executed in accordance with applicable NQA requirements at each waste
generator site.
As waste generator facilities subsequent to LANL establish QA
programs, EPA will assess their compliance with NQA requirements. In
making any determination to approve a site-specific QA program for a
waste generator, EPA will conduct an audit or an inspection of a DOE
audit of a waste generator site. EPA will publish a notice in the
Federal Register announcing its scheduled audit or inspection of a DOE
audit and will provide at least a 30-day comment period during which
interested parties may submit written comments. EPA will place in the
docket copies of the site-specific QA program documents and other
documentation relevant to the audit or audit inspection. Thus, the
Agency's decision whether to approve the establishment and execution of
a QA program at a specific waste generator site will be informed by
both public comments and the results of the Agency's own independent
evaluation of the site's compliance with the applicable NQA
requirements.
EPA believes that approval of site specific QA programs is required
by, and that this proposed procedure is consistent with the provisions
of Sec. 194.22(a)(2)(i) because it requires DOE to demonstrate
``establishment and execution'' of quality assurance programs for waste
characterization assumptions and activities at the individual waste
generator sites prior to shipment of wastes from such sites. EPA
requests comment on whether the Agency should place a condition on its
certification of compliance at WIPP consisting of future demonstrations
by DOE that QA programs have been established and executed at
individual waste generator sites, prior to shipment of TRU waste to
WIPP from such sites. In particular, EPA requests comment on
[[Page 58804]]
its preliminary conclusion that the proposed procedures for determining
whether adequate quality assurance programs have been established and
executed by DOE are consistent with Part 194. However, if, based upon
public comment on today's proposed action, EPA concludes that it would
be appropriate to make clarifying changes to Part 194 that specifically
set forth these procedures, EPA may do so as part of its final action
on today's proposal.
EPA will indicate its approval of site-specific QA programs by a
letter from the Administrator's authorized representative to the
Department; a copy of the letter will be placed in EPA's public docket.
(As part of the certification rulemaking, EPA is proposing to define
the Administrator's authorized representative as the ``director in
charge of radiation programs at the Agency,'' in order to clarify the
delegation of responsibilities for 40 CFR Part 194, including
activities such as requesting additional information from DOE, and
inspecting and approving quality assurance programs.) After approval of
site-specific QA programs, EPA will exercise its authority under
Secs. 194.21 and 194.22(e) to conduct unfettered inspections of
approved waste generator sites to confirm that the approved plans are
being properly maintained for waste characterization activities. For
specific language on the quality assurance conditions of compliance,
see Condition 2 of the proposed Appendix A to 40 CFR Part 194. For
further discussion of waste characterization programs and certification
of individual waste streams from generator sites, see the discussion of
Sec. 194.24 in this preamble.
Section 194.22(a)(2)(ii) requires DOE to include information which
demonstrates that the QA program has been established and executed for
environmental monitoring, monitoring of performance of the disposal
system and sampling and analysis activities. Westinghouse's WID was
responsible for implementing this requirement under the WID QAPD
described in the CCA. The WID developed a WIPP Environmental Monitoring
Plan (``EMP''), which applies to current site characterization and also
to proposed pre-closure monitoring in accordance with Sec. 194.42. The
EMP included QA procedures for radiological and non-radiological
environmental monitoring. Also included in the EMP were sample
handling, laboratory procedures, required records and reports, and data
analyses guidelines. DOE stated that the EMP is consistent with
applicable elements of ASME NQA-1.
The EPA determined during its audit of WID that the requisite QA
program had been established and executed for environmental monitoring,
sampling and analysis activities. Therefore, EPA proposes to certify
compliance with Sec. 194.22(a)(2)(ii). Continued adherence to the
executed QA program as it applies to disposal system monitoring will be
confirmed by EPA in future inspections under its authority at
Secs. 194.21 and 194.22(e).
Section 194.22(a)(2)(iii) requires DOE to include information which
demonstrates that the QA program has been established and executed for
field measurements of geologic factors, groundwater, meteorologic, and
topographic characteristics. EPA conducted an audit of the WID QA
program and found the QAPD to be adequate and to be implemented in
accordance with the applicable NQA requirements. Therefore, EPA
proposes to find DOE in compliance with Sec. 194.22(a)(2)(iii).
Section 194.22(a)(2)(iv) requires DOE to include information to
demonstrate that the QA program has been established and executed for
computations, computer codes, models and methods used to demonstrate
compliance with the disposal regulations. In the CCA, DOE provided the
CAO QAPD, which incorporates the application NQA requirements for
computation and computer code information. Software development and
management are controlled in accordance with criteria established by
SNL software QA procedures and the WID QAPD. EPA reviewed information
in the CCA and conducted audits of both SNL and WID QA programs. The
Agency found that DOE's computer codes were documented in a manner that
complies with the applicable NQA requirements, and that DOE's software
QA procedures were implemented in accordance with ASME NQA-2a, part
2.7. EPA therefore proposes to determine that DOE complies with
Sec. 194.22(a)(2)(iv).
Section 194.22(a)(2)(v) requires DOE to include information which
demonstrates that the QA program has been established and executed for
procedures for implementation of expert judgment elicitation. EPA found
that the requirements of this regulation were met with the
implementation of CAO Team Procedure (``TP'') 10.6 (Revision 0), CAO
Team Plan for Expert Panel Elicitation (Revision 2), and CAO Technical
Assistance Contractor (``CTAC'') Experimental Programs Desktop
Instruction No.1 (Revision 1). EPA proposes to find DOE in compliance
with Sec. 194.22(a)(2)(v). The process of expert judgment elicitation
is discussed in further detail in the preamble for Sec. 194.26 of the
Compliance Criteria.
Section 194.22(a)(2)(vi) requires DOE to include information which
demonstrates that the QA program has been established and executed for
design of the disposal system and actions taken to ensure compliance
with the design specifications. Design work for the repository sealing
system was conducted under the SNL QA program. The repository seal
system design was extensively reviewed by DOE, SNL, WID, and CAO
Technical Assistance Contractor personnel, as well as independent
design reviewers. The QA procedures established and implemented by SNL
and WID address the requirements of the NQA standards; design
verification was accomplished by a combination of NQA-1 Supplement 3S-1
methods. EPA audits of SNL and WID showed that the QA programs are
adequate and properly executed. Therefore, EPA proposes to find DOE in
compliance with Sec. 194.22(a)(2)(vi).
Section 194.22(a)(2)(vii) requires DOE to include information which
demonstrates that the QA program has been established and executed for
the collection of data and information used to support compliance
applications. SNL adequately addressed these requirements by
implementing numerous QA procedures to ensure the quality of data and
information collected in support of the WIPP. EPA's audit of SNL
concluded that the QA program was adequate and appropriately
implemented. Therefore, EPA proposes to find DOE in compliance with
Sec. 194.22(a)(2)(vii).
Section 194.22(a)(2)(viii) requires DOE to include information
which demonstrates that the QA program has been established for any
other item or activity not listed above that is important to the
containment of waste in the disposal system. DOE has not identified any
other item or activity important to waste isolation in the disposal
system that require QA controls to be applied as described in the CAO
QAPD. EPA has also not identified to date any other items or activities
which require controls. However, EPA has reviewed the CAO QAPD and
conducted audits of the CAO, SNL, and WID QA programs. The EPA audits
determined that the QA organizations of CAO, WID, and SNL have
sufficient authority, access to work areas, and organizational freedom
to identify other items and activities affecting the quality of waste
isolation. Therefore, EPA proposes to find DOE in compliance with
Sec. 194.22(a)(2)(viii).
[[Page 58805]]
Section 194.22(b) requires DOE to include information which
demonstrates that data and information collected prior to the
implementation of the QA program required by Sec. 194.22(a)(1) have
been qualified in accordance with an alternate methodology, approved by
the Administrator or the Administrator's authorized representative,
that employs one or more of the following methods: peer review;
corroborating data; confirmatory testing; or a QA program that is
equivalent in effect to Sec. 194.22(a)(1) ASME documents. The CCA
listed existing data that were reviewed by an Independent Review Team
and that DOE determined to have been collected under a QA program
equivalent to the NQA standards. DOE also provided information on
NUREG-1297 peer reviews that were conducted to qualify existing data
for engineered systems, natural barriers, waste form, and disposal room
data. Finally, DOE identified data from literature sources.
EPA conducted two audits that traced new and existing data to their
qualifying sources. The two audits found that equivalent QA programs
and peer review had been properly applied to qualify existing data used
in the PA. EPA also concluded that the use of existing data from peer-
reviewed technical journals was appropriate, since the level of such
reviews was likely to provide QA equivalent to NUREG-1297 peer reviews
conducted by DOE. Therefore, EPA proposes to find DOE in compliance
with Sec. 194.22(b). Furthermore, the Agency is proposing to approve
the use of any one of the following three methods for qualification of
existing data: (1) peer review, conducted in a manner that is
compatible with NUREG-1297; (2) a QA program that is equivalent in
effect to ASME NQA-1-1989 edition, ASME NQA-2a-1990 addenda, part 2.7,
to ASME NQA-2-1989 edition, and ASME NQA-3-1989 edition (excluding
Section 2.1(b) and (c) and Section 17.1); or (3) use of data from a
peer-reviewed technical journal.
Sections 194.22(c)(1) through (5) require DOE to provide
information which describes how all data used to support the compliance
application have been assessed, to the extent practicable, for specific
data quality characteristics (``DQCs''). In the CCA, DOE stated that in
most cases it was not practicable to document DQCs for parameters, but
asserted that the intent of DQCs was fulfilled by other QA programs and
quality control measures. In response to EPA's request for additional
information, DOE clarified but did not substantially alter its
approach. (Docket A-93-02, Items II-I-17 and II-I-24)
The Agency agrees that it is not appropriate to apply DQCs to
parameters in the PA (e.g., anhydrite permeability parameter), but
believes that they can be applied to measured data (i.e., field
monitoring and laboratory experiments) on which parameter values are
based. Because DOE misinterpreted EPA's requirements as applying to
parameters, EPA found that the CCA and supplementary information did
not systematically or adequately address DOE's consideration of DQCs
for measured data. Therefore, the Agency reviewed additional
materials--primarily data record packages at the SNL records center--to
independently determine whether DQCs had been assessed for data used in
PA. Data record packages document measured data considered by DOE in
developing parameter values. EPA found that for recent data (five to
ten years old), DOE's experimental program plans in the data record
packages generally addressed data quality in measured data, including
accuracy, precision, representativeness, completeness, and
comparability during measurement and collection.
For older existing data, EPA found less documentation of assessment
of DQCs. However, laboratory notebooks--which provide first-hand
documentation of measurement procedures and results--supporting data
record packages provided some information related to the quality of
measurements (e.g., how well DOE's measured values compared with values
found in peer-reviewed publications). Many existing data were also
subject to peer review in order to qualify them for use in the
compliance application; EPA concluded that the peer review panels
considered the use of DQCs in determining that such data were adequate.
EPA also agreed with DOE's argument in supplementary information that
for most of the existing data, collection under a program equivalent to
the NQA standards in Sec. 194.22(a)(1) provided adequate evidence that
the quality of data had been evaluated and controlled. Finally, EPA
concurred with DOE's conclusion that the uncertainties in measured data
reflected in DQCs have a small effect on compliance certainty, compared
to other uncertainties in the PA (such as extrapolation of processes
over 10,000 years).
Based on its review of data record packages, the Agency finds that
DOE has assessed DQCs, to the extent practicable, for data used in the
compliance application. EPA thus proposes to find that DOE complies
with Sec. 194.22(c). The Agency expects that DOE will assess DQCs for
future waste characterization and monitoring activities; EPA will
confirm assessment of DQCs for such measured data through inspections
and evaluation of any compliance re-certification applications.
Section 194.22(d) requires DOE to provide information which
describes how all data are qualified for use. SNL generated a table
providing information of how all data in the PA were qualified. EPA
audited the existing QA programs and determined that the data were
qualified for use by independent and qualified personnel in accordance
with NQA requirements. On this basis, EPA proposes to find DOE in
compliance with Sec. 194.22(d).
Section 194.22(e) allows EPA to verify execution of QA programs
through inspections, record reviews, and other measures. As discussed
above, EPA has conducted numerous audits of DOE facilities, and intends
to conduct future inspections of waste generator site-specific QA plans
under its authority. The Agency plans to conduct additional
inspections, including audits, of CAO, SNL, and WID prior to publishing
a final certification decision. The purpose of these inspections will
be to verify that the QA programs for these organizations--which have
already been found to be properly executed in accordance with the
applicable NQA requirements--are being appropriately maintained. EPA
will docket the results of these inspections, but will not consider
them for the purpose of the proposed or final rule unless the
inspections result in new information that indicates that the programs
are no longer in conformance with the applicable NQA requirements.
In summary, EPA proposes to find DOE in compliance with the
requirements of Sec. 194.22 subject to the condition that EPA
separately approve the establishment and execution of site-specific QA
programs for waste characterization activities at waste generator
sites. (See Condition 2 of the proposed Appendix A to 40 CFR Part 194.)
For further information on EPA's evaluation of compliance for
Sec. 194.22, refer to CARD 22.
B. Section 194.23, Models and Computer Codes
Section 194.23 sets forth specific requirements for the models and
computer codes used to calculate the results of performance assessments
(``PA'') and compliance assessments. In order for these calculations to
be reliable, DOE must properly design and implement the computer codes
used in
[[Page 58806]]
the PA. Design of computer codes begins with the development of
conceptual models. Conceptual models consider the design of the
repository and the features, events, processes, and scenarios that may
occur at the WIPP which could affect the containment or release of
radionuclides. In order for the final computer codes to obtain
realistic solutions, the underlying conceptual models must be sound.
DOE must next develop mathematical models from the conceptual models.
Mathematical models set up a mathematical expression to describe the
conditions in the repository and its surroundings. Numerical models are
then created to describe how to solve the equations in the mathematical
models. Since most of the mathematical models are sufficiently complex
that analytical solutions are not possible, numerical models are used
to provide iterative, approximate solutions to the mathematical models.
Finally, DOE must program the numerical solutions from the numerical
models into computer codes that perform calculations to estimate the
cumulative releases of radionuclides caused by all significant
processes and events.
In examining models and computer codes, EPA evaluated the
development of the underlying conceptual models, evaluated the
derivation of mathematical models and implementation of numerical
models and computer codes, verified the quality assurance of computer
codes, and performed its own independent computer calculations. In
order to allow EPA to evaluate the underlying conceptual models,
Sec. 194.23 of the compliance criteria requires descriptions of
conceptual models and scenario construction (Sec. 194.23(a)(1)),
consideration of alternative conceptual models (Sec. 194.23(a)(2)), and
documentation of peer review of the conceptual models
(Sec. 194.23(a)(3)(v)). To ensure proper implementation of these
conceptual models, Sec. 194.23 also requires documentation that: future
states of the disposal system are reasonably represented by conceptual
models (Sec. 194.23(a)(3)(i)); mathematical models (or algorithms)
reasonably represent the conceptual models (Sec. 194.23(a)(3)(ii));
numerical models (or solution methods) provide stable solutions to the
mathematical models (Sec. 194.23(a)(3)(iii)); and computer codes
accurately implement the numerical models and are free from coding
errors and produce stable solutions (Sec. 194.23(a)(3)(iv)). In
addition, DOE must describe the theoretical background of models and
their method of analysis; how the computer codes operate and were
developed; methods of data collection, data reduction and analysis;
parameters developed from source data; the structure of the computer
codes and a complete listing of source codes; and the effects of
parameter correlation (Secs. 194.23(c)(1) through (6)). Section
194.23(b) requires DOE to document that models and computer codes were
developed in accordance with the specified QA requirements contained in
the ASME NQA standards. Finally, Sec. 194.23(d) requires DOE to provide
all necessary data, information, software, and any other material to
enable EPA to conduct its own independent computer simulations.
1. Conceptual Models
a. Description of Conceptual Models. Section 194.23(a)(1) requires
the CCA to describe the conceptual models and the scenarios used in the
CCA PA calculations. DOE developed 24 conceptual models to describe the
WIPP disposal system. DOE also undertook an extensive screening process
to determine which features, events, and processes (FEPs) were
applicable to the disposal system. From the list of applicable FEPs,
DOE developed scenarios to describe both undisturbed performance
(natural processes and events) and disturbed performance (human
intrusion, including mining and deep drilling) of the repository. The
CCA included scenarios that satisfy the specific requirements of
Secs. 194.32 and 194.33 concerning the scope of PA and consideration of
drilling events in PA. (See preamble discussions of Secs. 194.32 and
194.33 for further details.)
EPA reviewed the descriptions of the 24 conceptual models and the
scenario construction methods in the CCA and supplementary information
and found them to be presented with sufficient clarity to permit full
understanding of the descriptions and methods. However, both EPA and
public commenters did not believe that DOE had performed sufficient
analyses to rule out the potential effects of fluid injection related
to oil production on the disposal system. Therefore, EPA required DOE
to perform additional analyses of fluid injection. Based on
supplementary information provided by DOE, EPA concluded that fluid
injection can be screened out from the PA based upon low consequences
to disposal system performance. EPA and commenters also had concerns
about DOE's conceptual model for spallings.\16\ The results of the
spallings model were eventually determined to be reasonable and
adequate for use in PA. For further discussion of the spallings model,
refer to the discussion of models and computer codes later in this
section.
---------------------------------------------------------------------------
\16\ ``Spallings'' refers to releases of solids forced up and
out of an intrusion borehole by gas pressure in the repository.
---------------------------------------------------------------------------
The CCA and supporting documents contain a complete and accurate
description of each of the conceptual models used and the scenario
construction methods used. The conceptual models include those
characteristics and attributes of the WIPP disposal system and its
surroundings that adequately describe the possible future performance
of the disposal system. The conceptual models contain appropriate
simplifications of the characteristics, attributes, and processes of
the disposal system. The scenario construction descriptions include
sufficient detail to understand the basis for selecting some scenarios
and rejecting others and are adequate for use in the CCA PA
calculations. Based on its review of DOE's descriptions of the
conceptual models and the scenario construction procedures presented in
the CCA and supporting documents, the Agency proposes to determine that
the DOE has demonstrated compliance with the requirements of
Sec. 194.23(a)(1).
b. Alternative Conceptual Models. Section 194.23(a)(2) requires the
CCA to describe plausible, alternative conceptual models that DOE
seriously considered but did not use to support compliance, and to
explain why DOE decided the alternative conceptual model does not
accurately portray performance of the disposal system. This requirement
allows EPA to evaluate whether the conceptual models underlying the PA
and compliance assessment are appropriate and adequate.
DOE provided information on alternative conceptual models in the
CCA, both in its discussion of FEPs and in its documentation of the
conceptual models peer review panel. The peer review panel identified
no major issues concerning alternative models.
EPA reviewed information on alternative conceptual models in the
CCA and in documentation from the peer review panel. EPA requested, and
DOE provided, supplementary information containing a focused, detailed
description of plausible alternative conceptual models considered but
not used in the PA. DOE also explained the reasons why these
alternative models were not used to
[[Page 58807]]
describe the performance of the repository. EPA determined that DOE
sufficiently documented the rationale and approach used to select the
conceptual models employed in the CCA PA and to reject other models.
As discussed elsewhere in this section, the conceptual models peer
review panel and EPA had concerns specifically with the spallings
conceptual model. Because the conceptual models peer review panel
initially judged the spallings model used in the CCA to be inadequate,
DOE developed an alternative mechanistically-based computational
approach to estimate the volume of spallings released to the accessible
environment. The volumes of radioactive waste to be released that were
calculated by the alternative mechanistically-based model were less
than one tenth those predicted in the model used in the CCA. Because
the original spallings model results used in the CCA were conservative,
the conceptual models peer review panel and EPA found the predicted
results from the original model to be acceptable for use in the PA.
Based on information provided in the CCA together with
supplementary information provided by DOE in response to specific EPA
requests, EPA concluded that DOE provided an adequate and complete
description of alternative conceptual models seriously considered but
not used in the CCA. DOE provided adequate discussion of why these
alternative models were not deemed to adequately portray the
performance of the disposal system. Therefore, EPA proposes to find DOE
in compliance with Sec. 194.23(a)(2).
c. Future States of the Disposal System and Peer Review. Section
194.23(a)(3)(i) requires the CCA conceptual models and scenarios to
reasonably represent future states of the disposal system. Section
194.23(a)(3)(v) requires the CCA to document that conceptual models
have undergone peer review in accordance with Sec. 194.27, which
requires that the peer review meets the guidance of NUREG-1297. Under
this guidance, the peer review must include the following: A listing of
the reviewers; requirements for the acceptability of each reviewer;
individual statements by peer reviewers reflecting dissenting views, if
any; a discussion of the conceptual models peer reviewed; an evaluation
of data and information used to develop conceptual models; an
evaluation of the validity of conceptual model assumptions; an
evaluation of alternative conceptual models; an evaluation of the
uncertainty in the conceptual models and a discussion of consequences
if the conceptual model chosen is inappropriate for the site; a
statement indicating the adequacy of the conceptual models used for the
disposal system; a statement of the accuracy of the results based on
the conceptual models employed; and a discussion of the validity of the
conclusions drawn based on the conceptual models. As part of the review
of adequacy of the conceptual models, peer reviewers considered whether
conceptual models reasonably represented future states of the disposal
system. The NUREG-1297 requirements and the process of peer review are
discussed in greater detail in the preamble for Sec. 194.27.
DOE convened a conceptual models peer review panel to review the 24
conceptual models used in the CCA PA. During the initial review, the
panel found that 11 models were not adequate and 13 models were
adequate for use in PA. The panel initially found the 11 conceptual
models to be inadequate for a variety of reasons, mostly related to the
adequacy of assumptions incorporated in the conceptual models and the
amount of supporting data or analyses for certain features of the
conceptual models. Based on additional information provided by DOE and
three subsequent review sessions, the panel found all the models to be
adequate for use in PA except the spallings model. They found that the
original CCA PA spallings model did not reasonably represent possible
future states of the disposal system because it did not fully model all
potential mechanisms that may cause pressure-driven solid releases. The
panel ultimately concluded, based on substantial analytical and
experimental work provided by DOE, that the spallings values used in
the CCA are reasonable for use in PA. The panel found that, while the
spallings model does not accurately represent the future state of the
disposal system, its inaccuracies are of an overly conservative nature,
and in fact, may overestimate the actual waste volumes that would be
expected to be released by the spallings process.
EPA concurs with the conceptual model peer review panel's findings,
based upon the results of DOE's analysis and development of an
alternative model for spallings, which showed that the CCA PA spallings
model overestimates spallings releases by up to ten times or more. The
peer review panel's findings considered whether conceptual models
reasonably represented future states of the disposal system. EPA does
not propose to determine that the spallings model ``reasonably
represents possible future states of the repository.'' The additional
modeling conducted by DOE, and the additional data developed by DOE,
however, provide a substantial basis for EPA to conclude that the
results of the spallings model are adequate and useful for the purpose
for which conceptual models are intended, i.e., to aid in the
determination of whether the WIPP will comply with the disposal
regulations during the regulatory time period. Because the spallings
model produces reasonable and conservative results, EPA proposes to
accept it for purposes of demonstrating compliance with
Sec. 194.23(a)(3)(i).
The information on peer review in the CCA and in supplementary
information demonstrates that all conceptual models have undergone peer
review consistent with the requirements of Sec. 194.27. Therefore, the
Agency proposes to find that DOE has demonstrated compliance with the
requirements of Sec. 194.23(a)(3)(v).
d. Public Comments. During the public comment period on the Advance
Notice of Proposed Rulemaking (``ANPR''), EPA received numerous
comments challenging various aspects of the spallings model. EPA and
the conceptual models peer review panel, among others, shared concerns
about the adequacy of the spallings model and on numerous occasions
informed DOE of their concerns. In response to these concerns, DOE did
substantial additional work, developed a mechanistically-based model
and supported this model with experimental data. The peer review panel
concluded that the spallings model used in the CCA PA calculated
release volumes that were reasonable and probably conservative. On this
basis, and as discussed above, EPA proposes that it is appropriate to
accept the results from the spallings model for purposes of
demonstrating compliance with Sec. 194.23(a)(3)(i).
EPA also received public comments on the ANPR concerning modeling
of fluid injection. Commenters expressed concern that the CCA PA
calculations did not model possible effects of pressurized brine
injection that may fracture the anhydrite beds near WIPP, enter the
repository, become contaminated and flow to various release points. EPA
required DOE to perform extensive supplementary analyses to evaluate
the effects that brine injection could have on the repository. EPA also
performed independent analyses to address concerns related to brine
injection. EPA has determined that brine injection does not pose an
unacceptable risk and that associated scenarios can be reliably
screened from further consideration.
[[Page 58808]]
2. Progression From Conceptual Models to Computer Codes
Most of the requirements of Sec. 194.23(a)(3) concern the Agency's
evaluation of the progression from conceptual models to computer codes
used in the CCA PA and compliance assessment. Each requirement in
Secs. 194.23(a)(3)(i) through (iv) is intended to ensure that DOE has
correctly implemented the steps between development of the underlying
conceptual models and encoding the computer software that implements
the PA and compliance assessment calculations. The initial step of
evaluating the fundamental conceptual models is discussed above.
a. Mathematical Models. Section 194.23(a)(3)(ii) requires the CCA
to document that mathematical models incorporate equations and boundary
conditions which reasonably represent the mathematical formulation of
the conceptual models. This requirement is intended to ensure that PA
calculations are based upon mathematical equations that truly implement
the conditions in the fundamental conceptual models. Many of the
mathematical equations are partial differential equations, which
consider rates of change; thus, codes incorporating these mathematical
models need initial and boundary conditions between which the rates of
change in the equations will operate.
DOE documented the development of each computer code used in PA and
compliance assessment, including the associated mathematical models and
numerical models. This information was contained primarily in Users
Manuals, Validation Documents, Implementation Documents, and
Requirements Document & Verification and Validation Plans for each CCA
PA computer code. EPA reviewed information supplemental to the CCA for
each CCA PA computer code and evaluated whether the mathematical models
incorporate equations and boundary conditions which reasonably
represent the mathematical formulation of the conceptual models.
EPA reviewed the mathematical model equations and boundary
conditions for the following codes: PANEL, BRAGFLO, NUTS, FMT, SANTOS,
BRAGFLO__DBR, GRASP-INV, SECOFL2D, SECOTP2D, CCDFGF, and CUTTINGS__S.
These are the codes DOE used to model the behavior of the repository
and its surroundings and to compute results of the PA calculations. The
codes PANEL, BRAGFLO, NUTS, FMT, and SANTOS incorporate mathematical
model equations that implement the conceptual models for predicting
future characteristics of the waste repository. These five codes
simulate the following effects, respectively: concentrations of
radioactive waste in brine within the waste-containing panels in the
repository; flow of brine and gas in the repository; solubility and
transport of radionuclides released from the repository; solubility of
radionuclides in the repository; and collapse of the repository through
salt creep closure of the Salado. The computer code BRAGFLO__DBR
describes waste dissolution in brine and transport of the contaminated
brine through direct brine releases. The three computer codes GRASP-
INV, SECOFL2D, and SECOTP2D mathematically describe flow and transport
of waste-laden brine in the Culebra dolomite. The computer code
CUTTINGS__S incorporates mathematical model equations modeling releases
of radioactive waste upon intrusion of a drill bit into the repository.
The computer code CCDFGF computes complementary cumulative distribution
functions (``CCDFs'') for the results of PA.
In general, EPA found that the descriptions of mathematical
formulations were adequately explained and were reasonable. The Agency
found that DOE adequately documented and described simplifications of
conceptual models in the CCA. EPA also concluded that DOE provided an
adequate technical basis to support the mathematical formulations. EPA
tested each of the codes with functional tests to verify that each
computer code would perform according to its functional
requirements.17 This analysis and testing indicated that
equations and boundary conditions were properly incorporated into the
mathematical models and that boundary conditions were reasonable
representations of how the conceptual models should be implemented.
---------------------------------------------------------------------------
\17\ A functional requirement specifies how the code is intended
to operate, including inputs and outputs.
---------------------------------------------------------------------------
EPA encountered problems with the governing equations of the
mathematical models and the representation of the boundary conditions
in the codes CUTTINGS__S, SECOFL2D, SECOTP2D, NUTS and BRAGFLO. EPA
specified that the equations in the codes be corrected and that the
changes to the codes be documented. The Agency later required DOE to
perform additional calculations in a Performance Assessment
Verification Test (``PAVT'') in order to verify that the cumulative
impact of all necessary corrections to input parameters, conceptual
models, and computer codes used in PA was not significant enough to
necessitate a new PA. For the PAVT, DOE used corrected versions of the
BRAGFLO, NUTS and SECOTP2D computer codes. The results of the PAVT
demonstrate that the cumulative impact of all these necessary
corrections did not require new PA runs. DOE resolved all of EPA's
questions related to the equations that make up the mathematical models
and the incorporation of the boundary conditions of the various codes
by correcting the codes and performing the PAVT.
Based on information contained in the CCA and supporting
documentation for each code, EPA concludes that the mathematical models
used to describe the conceptual models incorporate equations and
boundary conditions which reasonably represent the mathematical
formulation of the conceptual models. DOE resolved all issues raised by
the Agency. DOE has provided an adequate technical basis to support the
mathematical formulations used in the PA. Therefore, the Agency
proposes to find DOE in compliance with Sec. 194.23(a)(3)(ii).
b. Public Comments on Mathematical Models. During the public
comment period on the ANPR, EPA received comments on aspects of the
mathematical models. Several commenters felt that the mathematical
models in the CCA PA, particularly those related to ground-water flow
in the Culebra dolomite, did not account sufficiently for three-
dimensional processes and boundary conditions. A DOE report provided a
detailed sensitivity analysis of ground-water flow characteristics in
the Culebra. This report concluded that the majority of ground-water
flow through the Culebra is horizontal. (Docket A-93-02, Item II-G-1,
Reference #147) From the perspective of calculating the potential
consequences to repository performance, neglecting vertical leakage
into and out of the Culebra is conservative. EPA believes that the two-
dimensional modeling approach used in the PA for ground-water flow in
the Culebra dolomite is conservative and adequate. EPA also reviewed
the FEP screening analysis related to flow of brine and gas in the
repository and concluded that there are only minor differences between
the two-dimensional and three-dimensional computations. Therefore, EPA
believes that the two-dimensional geometry used in the BRAGFLO computer
code is reasonable and appropriate for the CCA PA.
EPA also received public comments on the ANPR concerning the
modeling
[[Page 58809]]
of ground-water flow and radionuclide transport processes in the
Culebra. Commenters stressed that scientific understanding of ground-
water flow in fractured rock systems is still developing and that DOE
requires greater documentation of processes and parameters embodied in
the CCA PA. EPA notes in response to public comments that DOE conducted
an extensive investigative program to improve its theories of ground-
water flow and radionuclide transport through the Culebra. Although
these activities have greatly improved the understanding of the
geohydrologic system, EPA recognizes that a degree of uncertainty will
always exist when attempting to make predictions about the performance
of WIPP 10,000 years into the future. EPA required DOE to address this
uncertainty in its PA by assigning ranges and distributions to
uncertain variables, such as fracture spacings, distribution
coefficients, porosities and transmissivity. EPA also required DOE to
perform further analysis using different parameter values and
distributions in the PAVT. EPA believes that this approach to handling
uncertainty is appropriate because the uncertainty will be captured by
the ranges and distributions assigned to parameters.
c. Numerical Models. Section 194.23(a)(3)(iii) requires
documentation that numerical models provide numerical schemes which
enable the mathematical models to obtain stable solutions. Although
some mathematical models can be solved directly, many of the
mathematical equations used in PA for the WIPP are so complex that they
require the use of numerical solution methods to provide an approximate
solution. It is important that solutions to the mathematical models be
stable because unstable solutions may make it impossible to proceed to
the next step in obtaining PA results or may call into question the
results of the model.
The relevant information was contained in supplemental information
from DOE, including Analysis Packages for each code and the documents
described in the previous section. This documentation includes testing
results for problems that are very similar to those solved by the
code(s) in the CCA PA, in order to evaluate the stability of solutions
from the numerical schemes used to solve the mathematical model
equations. DOE also maintained a computational record of whether any of
the codes experienced stability problems during the CCA PA
calculations. The codes that use numerical solvers include: SANTOS,
CUTTINGS__S, SECOFL2D, SECOTP2D, PANEL, BRAGFLO, BRAGFLO__DBR, NUTS,
and GRASP-INV.
EPA reviewed all the relevant documentation on numerical solution
schemes contained in the CCA and supplementary information about each
code. EPA also executed DOE code verification tests to search for
possible stability problems. EPA's review identified stability concerns
related to the following codes: CUTTINGS__S, SECOFL2D, SECOTP2D, and
NUTS. In the case of the NUTS and SECOTP2D codes, DOE was able to make
minor changes to the codes to correct their stability problems. EPA's
concerns regarding potential stability problems with CUTTINGS__S and
SECOFL2D were alleviated after DOE provided results from further
stability and code verification testing that showed these problems had
been corrected. DOE satisfactorily resolved all EPA concerns regarding
code stability issues.
Based on the CCA and supplementary information provided by DOE, the
Agency determines that DOE provided sufficient technical information to
document the numerical models used in the CCA. Based on verification
testing, EPA determined that the numerical models produced stable
solutions. DOE resolved stability problems with the BRAGFLO, NUTS,
SECOFL2D and SECOTP2D computer codes by completing code revisions and
supplementary testing requested by the Agency. Therefore, EPA proposes
to find DOE in compliance with Sec. 194.23(a)(3)(iii).
d. Computer Codes. Section 194.23(a)(3)(iv) requires documentation
that computer models accurately implement the numerical models, such
that computer codes are free of coding errors and produce stable
solutions. This is the final step to ensure that the underlying
conceptual models are implemented correctly in the PA calculations and
to ensure that the PA calculations will yield valid results.
To ensure that PA computer codes accurately implement the numerical
models and are free of coding errors, DOE adopted a number of Quality
Assurance Procedures for each step in the software development process.
(See also the preamble discussions of Secs. 194.22 and 194.23(b).) DOE
documented information on the software development process in Users
Manuals, Validation Documents, Implementation Documents and
Requirements Document & Verification and Validation Plans for each
computer code.
EPA performed an independent review of the CCA PA computer codes
used to support the PA. As part of this review, EPA executed functional
tests established by DOE for each of the codes to verify that each
computer code performed according to its functional requirements, and
to verify that the computer codes accurately implemented the numerical
models, were free of coding errors, and produced stable solutions. The
codes that EPA reviewed and tested include: SANTOS, CUTTINGS__S,
SECOFL2D, SECOTP2D, CCDFGF, LHS, PANEL, BRAGFLO, BRAGFLO__DBR, FMT,
NUTS, GRASP-INV and ALGEBRA. EPA also reviewed all of the relevant
documentation pertaining to each of the major codes described above.
EPA identified issues related to coding errors for the following
codes: SECOFL2D, SECOTP2D, and NUTS. To address these concerns, EPA
requested that DOE perform a number of additional analyses. In the
process of responding to EPA's concerns, DOE discovered, rectified and
documented several minor coding errors. Results from an impact analysis
by DOE indicated that the coding errors would have very little impact
on the WIPP's compliance with the disposal regulations. These issues
were resolved to EPA's satisfaction.
Based on the CCA and supplementary information, the Agency
determined that DOE provided sufficient technical information to
document the numerical models used in the CCA. Based on verification
testing, EPA determined that the computer codes accurately implement
the numerical models and that the computer codes are free of coding
errors and produce stable solutions. DOE resolved coding error problems
that EPA initially encountered by performing code revisions and
supplementary testing requested by the Agency. Therefore, the Agency
proposes to conclude that DOE has demonstrated compliance with
Sec. 194.23(a)(3)(iv).
3. Quality Assurance
Section 194.23(b) requires that computer codes used in the CCA must
be documented in a manner that complies with the quality assurance
requirements of ASME NQA-2a-1990 addenda, part 2.7, to ASME NQA-2-1989
edition. This requirement is intended to ensure proper development and
documentation of software and to identify any potential problems. Based
on EPA audits and CCA review, EPA found that code documentation meets
the NQA requirements, and thus proposes to find that DOE complies with
Sec. 194.23(b). See the preamble discussion of Sec. 194.22(a)(2)(iv),
Quality assurance, for further discussion of EPA's evaluation of
compliance.
[[Page 58810]]
4. Documentation of Models and Codes
Sections 194.23(c)(1) through (6) contains a number of requirements
related to documentation of models and computer codes. These
requirements allow EPA to evaluate the design of the models, to
evaluate the numerical values selected to describe the repository and
its surroundings, and to operate the software used to perform the PA
calculations.
DOE documented the development of computer software in a series of
documents that supplement the CCA. The information that EPA reviewed
was contained primarily in Analysis Packages, User's Manuals,
Validation Documents, Implementation Documents and Requirements
Document & Verification and Validation Plans for each code. DOE used
these documents to track development of software codes beginning from
the conceptual model stage, and continuing through derivation of the
mathematical equations and their solutions, setting computational
requirements for computer codes, designing the computer software,
programming the software, and testing the codes after they are
programmed. Among the types of information found in these documents are
general descriptions of the models, descriptions of the theoretical
background of models, discussions of the limits of the models,
instructions for executing computer codes, information on the required
input and output formats with examples, reports on testing of the
computer codes, structure of the computer codes, source
codes,18 and sources of data used to support parameter
values used in the models and codes.
---------------------------------------------------------------------------
\18\ ``Source code'' means the written description of each step
the computer code will follow when it is executed.
---------------------------------------------------------------------------
a. Theoretical Background. Section 194.23(c)(1) requires the CCA to
describe the theoretical backgrounds of each model and the method of
analysis or assessment used by each model. EPA evaluated whether DOE's
descriptions of the computer codes provided sufficient detail to
determine if the codes are formulated on a sound theoretical
foundation, and whether DOE provided clear documentation describing
exactly how each of the codes was used to support the PA. The codes
that EPA reviewed include: CUTTINGS__S, SECOFL2D, SECOTP2D, CCDFGF,
LHS,19 PANEL, BRAGFLO, BRAGFLO__DBR, NUTS, FMT, GRASP-INV,
SANTOS and ALGEBRA.20 These codes describe the repository,
the movement of radionuclides in contaminated brine through the
overlying Culebra dolomite, releases of radionuclides when a drill
penetrates the repository, and calculations of releases for final
results of the PA. EPA located the majority of the information in the
Users Manuals and Analysis Packages for each code, found in the Sandia
National Laboratories WIPP Record Center.
---------------------------------------------------------------------------
\19\ LHS, or Latin Hypercube Sampling, is a code that selects or
``samples'' a numerical value from a distribution of probable values
for a parameter. For more information on LHS, see the preamble
discussion of the requirements of Sec. 194.34.
\20\ The ALGEBRA computer code manipulates input data and
initial conditions that allow other codes to perform their
calculations.
---------------------------------------------------------------------------
In a few cases, EPA initially found the theoretical description of
the computer codes to be inadequate. Most notably, the mathematical
description of the solution precipitation model contained in the NUTS
code, which predicts radionuclide transport in the repository and in
units underlying the Culebra, was absent from the documentation. DOE
addressed EPA's concerns by providing supplementary reports that
describe in detail those theoretical discussions that were originally
deficient. With respect to the documentation pertaining to the method
of analysis, EPA found the descriptions in the Analysis Packages for
each code to be sufficiently complete. In several instances, EPA
requested that DOE clarify the written documentation, which DOE did.
Based on information contained in the Users Manual and Analysis
Packages for each code and supplementary information requested by EPA
to address specific problems uncovered in the course of the compliance
review, EPA found that DOE has provided sufficient documentation so
that individuals knowledgeable in the subject matter have sufficient
information to judge whether the codes are formulated on a sound
theoretical foundation, and whether the code has been used properly in
the PA. EPA also found that the level of documentation is consistent
with the ASME requirements for quality assurance as well as consistent
with recent standards on ground-water modeling published by the
American Society for Testing and Materials (ASTM). Therefore, EPA
proposes to determine that DOE has complied with the requirements of
Sec. 194.23(c)(1).
b. Descriptions of Models. Section 194.23(c)(2) requires the CCA to
document the following kinds of information: general descriptions of
the models; discussions of the limits of applicability of each model;
detailed instructions for executing the computer codes, including
hardware and software requirements; input and output formats with
explanations of each input and output variable and parameter; listings
of input and output files from a sample computer run; and reports on
code verification, bench marking, validation,21 and quality
assurance (``QA'') procedures. Section 194.23(c)(3) requires
documentation of the structure of the computer codes in detail and
complete listings of the source codes.
---------------------------------------------------------------------------
\21\ Verification, bench marking and validation are steps in
testing computer codes to ensure they operate as intended.
Verification means that the aspect of the code being tested matches
known solutions. Bench marking means that solutions from the code
are compared to results from an outside reference or ``bench mark''
calculation, for more complicated situations where the solutions to
a problem may not be known exactly. Validation means all aspects of
the code work together properly.
---------------------------------------------------------------------------
The codes that EPA reviewed include: CUTTINGS__S, SECOFL2D,
SECOTP2D, CCDFGF, LHS, PANEL, BRAGFLO, BRAGFLO__DBR, NUTS, FMT, GRASP-
INV, SANTOS and ALGEBRA. The supplemental information from DOE that
documented code development was described above in this section. DOE
also set forth a number of objectives regarding issues that must be
covered in code documentation to meet the QA criteria outlined in
Sections 4 and 6 of the ASME NQA-2a-1990 addenda, part 2.7, to ASME
NQA-2-1989.
EPA reviewed the supplemental documents, executed the computer
codes, and evaluated the code verification, bench marking, and
validation documentation. During its review, EPA identified a number of
areas where the Agency initially judged the documentation to be
inadequate. EPA required the Department to perform an analysis on the
NUTS computer code, to develop a code requirement and test the
statistical validity of certain aspects of the GRASP-INV code, to
provide evidence that the GRASP-INV code was tested in a manner
consistent with its implementation in the PA, and to document a sample
computer run that corresponds to calculation of the CCA PA results. DOE
provided this additional supporting analysis and documentation and
satisfied EPA's concerns.
DOE submitted all of the source code listings and a detailed
description of the structure of computer codes in the Implementation
Documents for each code. With this information, a user can compile the
source code and install it on a computer system identical to that used
in the CCA PA calculation. EPA found that DOE submitted all of the
source code listings. EPA identified no
[[Page 58811]]
problems with the detailed descriptions of the structure of the
computer codes.
EPA found that the CCA and supplementary information included an
adequate description of each model used in the calculations, a
description of limits of applicability of each model, detailed
instructions for executing the computer codes, hardware and software
requirements to run these codes, input and output formats with
explanations of each input and output variable and parameter, listings
of input and output files from sample computer runs, and reports of
code verification, bench marking, validation, and QA procedures that
are adequate for use in the CCA PA. EPA also found that DOE adequately
provided a detailed description of the structure of the computer codes
and supplied a complete listing of the computer source code in
supplementary documentation to the CCA. The documentation of computer
codes describes the structure of computer codes with sufficient detail
to allow EPA to understand how software subroutines are linked. The
code structure documentation shows how the codes operate to provide
accurate solutions of the conceptual models. Therefore, EPA proposes to
determine that DOE has demonstrated compliance with Secs. 194.23(c) (2)
and (3).
c. Parameters. Section 194.23(c)(4) requires detailed descriptions
of data collection procedures, data reduction and analysis, and code
input parameter development. Parameters are numerical values or ranges
of numerical values used to describe different physical and chemical
aspects of the repository, the geology and geometry of the area
surrounding the WIPP, and possible scenarios for human intrusion. Some
parameter values are well-established physical constants, such as the
Universal Gas Constant or atomic masses of radionuclides. Parameters
also can be physical, chemical or geologic characteristics that DOE
established by experimentation. DOE has also assigned parameters to
aspects of human intrusion scenarios, such as the diameter of a drill
bit used to drill a borehole that might penetrate the repository.
DOE discussed information supporting parameter development in the
CCA and in parameter records located in the SNL WIPP Record Center. The
records at SNL Record Center include WIPP parameter entry forms,
Parameter Records Packages, Principal Investigator Records Packages,
Data Records Packages, and Analysis Packages. DOE uses all of these
documents to explain the full development of parameter values used as
inputs to the CCA PA calculations.
The Agency reviewed the CCA, parameter documentation and record
packages for approximately 1,600 parameters used as input values to the
CCA PA calculations. EPA further reviewed parameters record packages
and documentation in detail for 465 parameters important to performance
of the disposal system. The Agency selected parameters to review in
depth based on the following criteria: parameters that were likely to
contribute significantly to releases or seemed to be poorly justified;
parameters that control various functions of the CCA PA computer codes
that were likely to be important to calculations of releases and
important to compliance with the containment requirements of
Sec. 191.13; and other parameters the Agency used to evaluate the
overall quality of SNL's documentation traceability. The Agency
examined DOE's parameter documentation to see if the following elements
were present: detailed listings of code input parameters and the
parameters that were sampled; codes in which the parameters were used
and the computer code names of the sampled parameters; descriptions of
the sources of data; descriptions of the parameters, data collection
procedures, data reduction and analysis, and code input parameter
development; discussions of the linkage between input parameter
information and data used to develop the input information; discussions
of the importance of the sampled parameters relative to final
calculations of releases, correlations among sampled parameters, and
how these are addressed in PA; a listing of the sources of data used to
establish parameters; and data reduction methodologies used for CCA PA
parameters, including an explanation of QA activities.
After its initial review, the Agency found that DOE had a great
deal of documentation available in the SNL Records Center supporting
most of the parameters used in the CCA PA. However, EPA had some
concerns about the completeness of the list of CCA PA parameters, the
description and justification to support the development of some code
input parameters, and the traceability of data reduction and analysis
of parameter-related records. The Agency did not agree with the
technical justification of some parameter values and probability
distributions. The Agency did not find adequate documentation to
support one of DOE's professional judgement parameters, the waste
particle size value (expressed as a particle diameter). Other
parameters such as professional judgment parameters and some parameters
that were used in DOE's 1992 PA calculations were found to have
adequate documentation to support the value used in the CCA PA
calculations.
During its review, EPA found that the following types of
documentation were necessary to improve DOE's records: a comprehensive
database of all parameters used in the CCA PA, a database of all
parameters based on experimental data, ``roadmaps'' that document and
link CCA PA parameters to their sources, complete record packages in
the SNL Record Center, background documentation on the development of
those parameters that were originally used in DOE's 1992 PA
calculations and again were used in the CCA PA calculation, and
adequate explanations of why the 149 professional judgment parameters
in the comprehensive parameter database did not need expert
elicitation. DOE provided all of these pieces of documentation,
primarily by improving the quality of the records stored in the SNL
WIPP Records Center. The Agency did not accept the use of professional
judgement to derive the waste particle size parameter, and thus
required DOE to use the process of expert elicitation to develop the
value for this parameter. (See also the preamble discussion for
Sec. 194.26 regarding expert elicitation for the waste particle size.)
After subsequent review and evaluation of the SNL WIPP Record Center
records and after completion of expert elicitation, EPA was satisfied
with the additional documentation provided by DOE for these areas of
concern.
The Agency requested further documentation from DOE, expressing
concern about information supporting 58 parameters. EPA divided these
parameters into those parameters lacking supporting evidence, those
parameters that have records supporting values other than those
selected by DOE, and those parameters that are not explicitly supported
by the relevant data or information. DOE provided additional
information supporting some of the parameters of concern to EPA. The
Agency also performed its own sensitivity analyses for the parameters
to determine if changes to some parameters have a significant impact on
the final computer calculations. The Agency's concerns were resolved
for thirty-four of these parameters, either by DOE's submission of
additional documentation or by the results of sensitivity analyses
conducted by EPA that indicated that changes to certain parameter
values would not
[[Page 58812]]
significantly impact results of computer calculations.
The Agency later required DOE to perform additional calculations in
a Performance Assessment Verification Test (``PAVT'') in order to
verify that the cumulative impact of all required and other corrections
to input parameters, conceptual models, and computer codes used in PA
was not significant enough to necessitate a new PA. EPA directed DOE to
incorporate modified values or distributions for twenty-four parameters
in the PAVT. The PAVT showed that the calculated releases may increase
by up to three times from those in the original CCA PA, but that the
WIPP is still an order of magnitude below the containment requirements
in Sec. 191.13. For further information about results of the PAVT, see
the preamble for Sec. 194.34, ``Results of PA.'' DOE satisfied EPA's
concerns about the parameters by incorporating EPA's changes to the
parameter values and parameter distributions in the PAVT.
Upon subsequent review and evaluation, EPA determined that DOE,
after additional work and improvement of records in the SNL Record
Center, adequately provided a detailed listing of the code input
parameters; listed sampled input parameters; provided a description of
parameters and the codes in which they are used; discussed parameters
important to releases; described data collection procedures, sources of
data, data reduction and analysis; and described code input parameter
development, including an explanation of QA activities. Therefore, the
Agency proposes to determine that the CCA complies with
Sec. 194.23(c)(4).
d. Public Comments on Parameter Values. During the public comment
period for the ANPR, EPA received comments on specific parameter
values. After the end of the ANPR public comment period, EPA also
received comments on parameter distribution values that the Agency
mandated DOE include in the PAVT.
The Agency performed a thorough review of the parameters and the
parameter development process, as discussed in the previous section. In
its initial review, the Agency found that DOE had a great deal of
documentation supporting most of the parameters used in the CCA PA
available in the SNL Records Center. EPA specifically requested DOE to
perform the PAVT in order to determine the effects of different
parameter distributions for those parameters that concerned EPA and
that appeared to have a significant impact on the results of PA.
e. Software Licenses. Section 194.23(c)(5) requires the CCA to
document any licenses necessary for software used in the PA. DOE stated
that it did not use any software requiring licenses, since software was
developed by DOE or its contractors. EPA concurs with DOE's statement,
and thus proposes to find that the CCA complies with Sec. 194.23(c)(5).
f. Parameter Correlation. Section 194.23(c)(6) requires the CCA to
provide an explanation of the manner in which models and computer codes
incorporate the effects of parameter correlation. Parameters are
correlated if they are not completely independent of each other. For
example, if two parameters are programmed into computer codes so that
both increase or decrease under the same conditions, the two parameters
are correlated. Such a correlation can be directly programmed as an
explicit correlation specified by the computer user. A parameter
correlation also can be programmed into computer codes indirectly
through an induced correlation when one parameter is used to derive a
second parameter in the code. EPA evaluated parameter correlation in
the CCA because an improper parameter correlation may call into
question some parameter values and may even call into question the
validity of the results from PA, depending on how significant the
correlated parameters are.
User-specified (explicit) parameter correlations are introduced
into the CCA PA calculations using a correlation matrix or table in the
Latin Hypercube Sampling (LHS) computer program. Of all the parameters,
only rock compressibility and permeability are explicitly correlated in
the LHS computer code input file. When values that are sampled using
the LHS computer code are used to calculate other values in the CCA PA
calculations, an induced correlation parameter relationship is created
through mathematical formulas used in subsequent computer codes. This
is the prevalent method of correlation used in DOE's PA.
EPA reviewed the documentation in the LHS Users Manual that
explains how parameter correlation is included in the parameter sample
process. EPA also reviewed information in the CCA which discussed the
mathematical methods used to incorporate parameter correlation into the
CCA PA calculations. EPA also reviewed DOE's sensitivity analysis of
the parameters sampled in the CCA PA, which includes a discussion of
the impacts of parameter correlations.
Based on its review of CCA documentation and supplementary
information, EPA determined that DOE has adequately demonstrated the
manner in which the models and computer codes incorporate the effects
of parameter correlation. Specifically, the CCA contains adequate: (1)
Discussions that explain how the effects of parameter correlation are
incorporated; (2) explanations of the mathematical functions that
describe these relationships; and (3) descriptions of the potential
impacts on the sampling of uncertain parameters. The CCA also
adequately documented the effects of parameter correlation for both
conceptual models and the formulation of computer codes, and
appropriately incorporated these correlations in the PA. Thus, the
Agency proposes to find that DOE has demonstrated compliance with the
requirements of Sec. 194.23(c)(6).
5. EPA's Independent Testing
Section 194.23(d) allows EPA to verify the results of computer
simulations used in the CCA by performing independent simulations. This
requirement also requires DOE to provide EPA with data files, source
codes, executable versions of computer software for each model, other
material or information needed to permit EPA to perform independent
simulations, and to access necessary hardware to perform such
simulations within 30 days of a request from EPA. This requirement
ensures that EPA can verify calculations in the CCA and analyze the
potential impact of changes to the PA calculations if changes are made
to computer codes or parameters.
DOE provided EPA with unrestricted access to computer hardware
required to perform simulations related to the CCA. DOE also provided
EPA with access to data files, source codes, and executable computer
codes for each model used in the CCA. DOE provided staff to assist EPA
in executing various verification tests and sensitivity analyses with
DOE hardware and software. EPA performed code verification tests on all
CCA PA computer codes using CCA hardware and software. In some cases,
EPA required DOE to perform additional verification tests. EPA
conducted extensive parameter sensitivity tests using the same system
of CCA PA computer codes. The PAVT was an independent computer
simulation of the WIPP's performance conducted under EPA's authority to
require independent verification computer simulations under
Sec. 194.23(d). DOE provided assistance in all of this work on a timely
basis. Because DOE provided EPA with ready access to the necessary
tools to permit EPA to perform independent simulations using computer
software and hardware employed in the CCA,
[[Page 58813]]
EPA proposes to find DOE in compliance with Sec. 194.23(d). For further
information on EPA's evaluation of compliance for Sec. 194.23, see CARD
23.
C. Section 194.24, Waste Characterization
Section 194.24, waste characterization, generally requires DOE to
identify and describe quantitative information on the chemical,
radiological and physical characteristics of the waste proposed for
disposal at the WIPP that can influence disposal system performance.
The DOE has not demonstrated compliance with all the requirements of
Sec. 194.24 as they pertain to waste characterization activities at
generator sites. Therefore, EPA is proposing certification of
compliance with these requirements, with the condition that DOE must
submit additional information to demonstrate full compliance for waste
generator sites. The proposed conditions of certification are addressed
under EPA's discussion of the requirements at Secs. 194.24(c)(3)
through (5).
Section 194.24(a) requires DOE to describe the chemical,
radiological and physical composition of all existing and to-be-
generated waste, including a list of waste components and their
approximate quantities in the waste. DOE described the existing waste
by combining like waste streams into eleven final waste forms and waste
stream profiles. A waste stream is defined by DOE as waste material
generated from a single process or activity that is similar in
material, physical form, isotopic make-up, and hazardous constituents.
The waste stream profiles contained information on the waste material
parameters, or components, that could affect repository performance.
DOE extrapolated information from the existing waste streams to
determine the amount of to-be-generated waste. DOE's waste profiles
contained appropriate specific information on the components and their
approximate quantities in the waste. Therefore, EPA proposes to find
DOE in compliance with Sec. 194.24(a).
Sections 194.24(b)(1) through (3) require DOE to analyze waste
characteristics and waste components for their impact on disposal
system performance. Waste components affect waste characteristics and
are integral to disposal system performance. For example, the waste
characteristic gas generation is controlled, in part, by the type and
amount of waste components such as metal waste containers and plastic
material. DOE identified waste-related elements pertinent to the WIPP
as part of its screening for features, events, and processes
(``FEPs''). The FEPs used in the performance assessment (``PA'') served
as the basis from which characteristics and associated components were
identified and further analyzed. (Refer to the preamble discussion of
Sec. 194.32, ``Scope of PA,'' for additional information pertaining to
FEPs.)
DOE concluded that six characteristics were expected to have a
significant effect on disposal system performance and were used in PA
(i.e., parameters were identified for each): solubility, formation of
colloidal suspensions containing radionuclides, gas generation, shear
strength of waste, radioactivity of specific isotopes, and TRU activity
at disposal. DOE identified eight waste components influencing the six
significant waste characteristics: Ferrous metals, cellulose,
radionuclide identification, radioactivity of isotopes, TRU activity of
waste, solid waste components, sulfates, and nitrates. Finally, DOE
provided a list of waste characteristics and components assessed, but
determined not to be significant for various reasons such as negligible
impact on PA. EPA found that DOE used a reasonable methodology to
identify and assess waste characteristics and components. The analysis
appropriately accounted for uncertainty and the quality of available
information. Therefore, EPA proposes to find DOE in compliance with
requirements in Secs. 194.24(b)(1) through (3).
Section 194.24(c)(1) requires DOE to specify numeric limits on
significant waste components and demonstrate that, for those limits,
the WIPP complies with the numeric requirements of Secs. 194.34 and
194.55. Either upper or lower limits were established for components
that must be controlled to ensure that the PA results comply with the
containment requirements. DOE explicitly included numeric limits,
identified as fixed values with no associated uncertainty, for four
waste components. Lower limits were established for ferrous and non-
ferrous metals; upper limits were established for cellulosics and free
water. The three components related to radioactivity and radionuclides
were effectively limited by the inventory estimates used in the PA. The
fixed-value limits and radionuclide inventory estimates were included
in the PA calculations through parameters closely related to these
components, and the results demonstrated compliance with EPA's
standards. EPA concurred with DOE that it was not necessary to provide
estimates of uncertainty for waste limits, so long as the PA
demonstrated compliance at the fixed limits.
Explicit limits were not identified for solid waste, sulfates, and
nitrates, even though DOE identified these as components significant to
performance. For solid waste, EPA determined that in the PA, DOE took
no credit for the potential gas-reducing effects of solid waste (i.e,
assumed a lower limit of zero) and demonstrated that the WIPP would
still comply. For nitrates and sulfates, EPA determined that these
components would not significantly affect the behavior of the disposal
system as long as cellulosics were limited. Thus, EPA concurred that it
is unnecessary to specify limits for nitrates, sulfates, and solid
waste. Therefore, EPA proposes to find DOE in compliance with
Sec. 194.24(c)(1).
Section 194.24(c)(2) requires DOE to identify and describe the
methods used to quantify the limits of important waste components
identified in Sec. 194.24(b)(2). DOE proposed to use non-destructive
assay (``NDA'') (e.g., passive active neutron assay), non-destructive
examination (``NDE'') (e.g., radiography), and visual examination
(``VE'') as the methods used to quantify various waste components. The
CCA described numerous NDA instrument systems and described the
equipment and instrumentation found in NDE and VE facilities. DOE also
provided information about performance demonstration programs intended
to show that data obtained by each method could meet data quality
objectives established by DOE. EPA found that these methods, when
implemented appropriately, would be adequate to characterize the
important waste components. Therefore, EPA proposes to find that DOE
has demonstrated compliance with Sec. 194.24(c)(2). (Implementation of
measurement programs at waste generator sites is addressed below for
the requirements at Secs. 194.24(c)(4) and (5).)
Section 194.24(c)(3) requires DOE to demonstrate that the use of
process knowledge to quantify components in waste for disposal conforms
with the quality assurance (``QA'') requirements found in Sec. 194.22.
EPA expected DOE to submit specific information on the process
knowledge to be used at waste generator sites as part of DOE's
certification application. EPA requires such information to conduct
proper regulatory review of whether use of the process knowledge is
appropriate and reliable. DOE provided some information on its overall
plans for using process knowledge in the CCA. DOE did not, however,
provide specific information on the use of process knowledge at any
waste generator site in the CCA, nor did it provide information
[[Page 58814]]
demonstrating establishment of the required QA programs.
After submission of the CCA, EPA subsequently received information
regarding process knowledge to be used at the Los Alamos National
Laboratory (``LANL''). EPA determines DOE to have adequately described
the use of process knowledge for retrievably stored (legacy) debris
waste streams at LANL. EPA has confirmed establishment and execution of
the required QA programs at that waste generator site through
inspections. (See the preamble discussion of Sec. 194.22, ``Quality
Assurance,'' for further information on inspections.) Therefore, the
Agency determines that DOE has demonstrated compliance with the
Sec. 194.24(c)(3) QA requirement for LANL. EPA does not find, however,
that DOE has adequately described the use of process knowledge for any
other waste streams at LANL (other than the retrievably-stored (legacy)
debris waste streams discussed above). Furthermore, DOE has not
demonstrated compliance with Sec. 194.24(c)(3) for any other waste
generator site.
Sections 194.24(c)(4) and (5) require DOE to demonstrate that a
system of controls has been and will continue to be implemented to
confirm that the waste components emplaced in the WIPP will not exceed
the upper limit or fall below the lower limit calculated in accordance
with Sec. 194.24(c)(1). The system of controls must conform to the QA
requirements specified in Sec. 194.22 DOE described a system of
controls over waste characterization activities, such as the
requirements of the TRU QA Program Plan (``TRU QAPP'') and the Waste
Acceptance Criteria (``WAC''). EPA found that the TRU QAPP established
appropriate technical quality control and performance standards for
sites to use in developing site-specific sampling plans. Further, DOE
outlined two phases in waste characterization controls: waste stream
screening/verification (pre-shipment) and waste shipment screening/
verification (pre-receipt of waste at the WIPP). The tracking system
for waste components against their upper and/or lower limits is found
in the WIPP Waste Information System (``WWIS''). If implemented as
proposed, EPA believes that the TRU QAPP, WAC, and WWIS are adequate to
control important components of waste emplaced in the WIPP. EPA audited
DOE's QA programs at CAO, SNL and WID and determined that DOE properly
adhered to QA programs that implement the applicable NQA standards and
requirements. (See the preamble discussion of Sec. 194.22 for further
information.) However, in the CCA, DOE did not demonstrate that the
WWIS is fully functional and did not provide information regarding the
specific system of controls to be used at individual waste generator
sites.
After submission of the CCA, EPA subsequently received information
regarding the system of controls to be used at LANL. The Agency
confirmed through inspections that the system of controls is adequate
to characterize waste and ensure compliance with the limits on waste
components, and also confirmed that a QA program had been established
and executed at LANL in conformance with NQA requirements. Moreover,
DOE demonstrated that the WWIS is functional with respect to LANL--
i.e., that procedures are in place at LANL for adding information to
the WWIS system, that information can be transmitted from LANL and
incorporated into the central database, and that data in the WWIS
database can be compiled to produce the types of reports described in
the CCA for tracking compliance with the waste limits. Therefore, EPA
determines DOE to have demonstrated compliance with Secs. 194.24(c)(4)
and (5) for several waste streams in the category of retrievably stored
(legacy) debris waste at LANL. EPA's proposed determination of
compliance is limited to those retrievably stored (legacy) debris waste
streams that can be characterized using the systems and processes
audited by DOE, inspected by EPA, and found to be adequately
implemented at LANL. 22 EPA does not find, however, that DOE
has demonstrated compliance with Sec. 194.24(c)(4) for any other waste
stream at LANL, or with Secs. 194.24(c)(4) and (5) at any other waste
generator site.
---------------------------------------------------------------------------
\22\ See Docket A-93-02, Item II-I-70 for a list of these
systems and processes. They include characterization methodologies
and relevant procedures, such as that used for entering data into
the WWIS database.
---------------------------------------------------------------------------
In order to ship transuranic waste from other waste generator sites
for emplacement at the WIPP, DOE will have to demonstrate compliance
with the Sec. 194.24(c)(3) through (5) requirements. Compliance with
the requirements as they relate to QA programs will be evaluated and
approved for each generator site in accordance with the language in
Condition 2 (``Quality Assurance'') of the proposed Appendix A to 40
CFR Part 194. To fully comply with these requirements, DOE must also
submit--and EPA must approve--for each waste stream or group of waste
streams, information on how process knowledge will be incorporated into
waste characterization activities, and on the system of controls
proposed for (a) given waste stream(s). A waste stream is defined by
DOE as waste material generated from a single process or activity that
is similar in material, physical form, isotopic make-up, and hazardous
constituents. EPA expects that this information will be contained in
site-specific documents including, for example, site certification
quality assurance plans (``QAPs'') and quality assurance project plans
(``QAPjPs''). All such documentation submitted by DOE regarding plans
for waste characterization of specific waste streams will be placed in
EPA's dockets for public inspection.
As waste generator sites establish waste characterization programs
for new waste streams (or groups of waste streams), EPA will assess
their compliance with the Secs. 194.24(c)(3) and (4) requirements. EPA
will conduct an audit or inspection of a DOE audit at each site to
evaluate the use of process knowledge and the establishment of a system
of controls for each waste stream or group of waste streams. In order
for a site to demonstrate the implementation of a system of controls,
the WWIS must be demonstrated to be functional at any waste generator
site before any waste stream(s) may be shipped from that site for
disposal at the WIPP. By this, EPA means that a waste generator site
must demonstrate that it has procedures in place for entering data into
the WWIS tracking system, and that such data can be transmitted to the
WWIS database so that it is available for compilation and reporting. In
order for EPA to confirm that a system of controls has been adequately
executed in accordance with Sec. 194.24(c)(4), DOE must demonstrate
that measurement techniques and control methods can be implemented for
each waste stream or streams which DOE plans to emplace in the WIPP.
As described in the proposed certification condition, EPA's
decision to approve site-specific plans for the use of process
knowledge and the system of controls--and thus to approve a site to
transport a waste stream for disposal at the WIPP--would be made only
after public comment has been solicited and after EPA has conducted an
audit or an inspection of a DOE audit of the waste generator site.
Therefore, before making any determination to approve the use of
process knowledge or the system of controls, EPA would publish a notice
in the Federal Register announcing its intent to evaluate waste
characterization programs for a given waste stream (or waste streams)
at one or more sites. There would be allowed at least a 30-day comment
period on DOE's proposed programs for process knowledge and a
[[Page 58815]]
system of controls for one or more specific waste streams.
EPA believes that approval of site specific QA programs is required
by, and that this proposed procedure is consistent with the provisions
of Section 194.24(c)(3)-(5) because it requires DOE to (1) demonstrate
application of established and executed quality assurance programs to
use of process knowledge; (2) demonstrate implementation of the
required system of controls; and (3) demonstrate application of
established and executed quality assurance programs to the system of
controls, at the individual waste generator sites prior to shipment of
wastes from such sites. EPA requests comment on whether the Agency
should place a condition on its certification of compliance at WIPP
consisting of future demonstrations by DOE that the Secs. 194.24(c)(3)-
(5) requirements have been met, prior to shipment of TRU waste to WIPP
from such sites. In particular, EPA requests comment on its preliminary
conclusion that the proposed procedures for determining whether
adequate quality assurance programs have been established and executed
by DOE are consistent with 40 CFR Part 194. However, if, based upon
public comment on today's proposed action, EPA concludes that it would
be appropriate to make clarifying changes to 40 CFR Part 194 that
specifically set forth these procedures, EPA may do so as part of its
final action on today's proposal.
EPA's written determination that DOE has demonstrated compliance
with these requirements, as well as the results of any audits or
inspections, would be placed in the public dockets. EPA will confirm
ongoing compliance with these requirements through unfettered access to
waste generator sites for the purpose of conducting inspections under
its authority at Secs. 194.21 and 194.24(h).
Section 194.24(d) requires DOE either to include a waste loading
scheme which conforms to the waste loading conditions used in the PA
and in compliance assessments, or to assume random placement of waste
in the disposal system. DOE elected to assume that radioactive waste
would be emplaced in the WIPP in a random fashion. DOE examined the
possible effects of waste loading configurations on repository
performance (specifically, releases from human intrusion scenarios) and
concluded that the waste loading scheme would not affect releases. DOE
incorporated the assumption of random waste loading in its performance
and compliance assessments (pursuant to Secs. 194.32 and 194.54,
respectively).
The EPA determined that, because DOE had assumed random waste
loading and also had found that potential non-random loading of waste
would not affect releases, a final waste loading plan was unnecessary.
EPA determined that DOE cross-referenced the resultant waste
distribution assumptions from the waste loading plan with the waste
distribution assumptions used in PA, and accurately modeled random
placement of waste in the disposal system. Since EPA concurred with DOE
that a final waste loading plan was unnecessary, DOE does not have to
further comply with Sec. 194.24(f), requiring DOE to conform with the
waste loading conditions, if any, used in the PA and compliance
assessment. EPA proposes to find that DOE complies with Secs. 194.24(d)
and (f).
Section 194.24(e) prohibits DOE from emplacing waste in the WIPP if
its disposal would cause the waste component limits to be exceeded.
Section 194.24(g) requires DOE to demonstrate that the total inventory
emplaced in the WIPP will not exceed limitations on TRU waste described
in the LWA. Specifically, the LWA defines limits for: surface dose rate
for remote-handled (``RH'') TRU waste, total amount (in curies) of RH-
TRU waste, and total capacity (by volume) of TRU waste to be disposed.
(LWA, Section (7)(a)) In order to meet the Secs. 194.24(e) and (g)
limits, DOE intends to rely on the TRU QAPP, WAC, and two-phase waste
characterization (pre-shipment at generator sites, and pre-receipt at
the WIPP). The CCA stated that the WWIS will be used to track specific
data related to each of the LWA limits; by generating routine WWIS
reports, DOE will be able to determine compliance with the imposed
limits. The WWIS will also be used to track information on each of the
important waste components for which limits were established. EPA finds
that the WWIS is adequate to track adherence to the limits, and that
the WWIS has been demonstrated to be fully functional at the WIPP
facility; as discussed above, waste generator sites will demonstrate
WWIS procedures before they can ship waste for disposal at the WIPP.
Therefore, EPA proposes to find DOE in compliance with Secs. 194.24(e)
and (g).
Section 194.24(h) allows EPA to conduct inspections and record
reviews to verify compliance with the waste characterization
requirements. As discussed above, EPA intends to monitor execution of
waste characterization and QA programs at waste generator sites through
inspections and record reviews.
In summary, EPA proposes to find that DOE is in compliance with
Sec. 194.24, and that LANL has demonstrated compliance with
Secs. 194.24(c)(3) through (5) for certain retrievably stored (legacy)
debris waste streams and may therefore ship TRU waste for disposal at
the WIPP (as such shipments relate solely to compliance with EPA's
disposal regulations; other applicable requirements or regulations
still may need to be fulfilled before disposal may commence). EPA's
proposed determination of compliance is limited to those retrievably
stored (legacy) debris waste streams that can be characterized using
the systems and processes audited by DOE, inspected by EPA, and found
to be adequately implemented at LANL.
The Agency also proposes to certify compliance subject to the
condition that DOE may not ship other waste streams for emplacement at
the WIPP until EPA determines that (1) DOE has provided adequate
information on how process knowledge will be incorporated into waste
characterization activities for a particular waste stream at a
generator site, and (2) DOE has demonstrated that the system of
controls described in Sec. 194.24(c)(4) has been established for the
site. In particular, DOE must demonstrate that the WWIS system is
functional for any waste generator site before waste may be shipped,
and that the system of controls can be implemented for each waste
stream which DOE plans to dispose in the WIPP. As discussed in the
preamble for Sec. 194.22 (and in Condition 2 of the proposed Appendix A
to 40 CFR Part 194), DOE must also demonstrate that sites have
established and executed the requisite QA programs described in
Secs. 194.22(a)(2)(i) and 194.24(c)(3) and (5).
The Agency proposes that the decision to allow a waste generator
site to dispose of a waste stream at the WIPP will be made only after
public comments have been solicited on DOE's proposed site-specific
programs and after EPA has conducted an audit or an inspection of a DOE
audit of the waste generator site. EPA will make available, in its
public docket, the site-specific program documents being considered by
the Agency, and will publish a notice in the Federal Register
announcing its intent to evaluate such plans. There will be allowed at
least a 30-day public comment period for interested parties to comment
on DOE's proposed programs for process knowledge and a system of
controls for one or more specific waste streams. EPA also plans to
conduct an
[[Page 58816]]
audit or an inspection of a DOE audit at each site to evaluate the
execution of such plans for pertinent waste streams.
EPA's approval of the plans relevant to compliance with
Secs. 194.24(c)(3) and (4) will be indicated in a letter from the
Administrator's authorized representative to the Department. EPA is
proposing to define the Administrator's authorized representative as
``the director in charge of radiation programs at the Agency'' to
clarify the delegation of responsibilities described in the Compliance
Criteria and in the proposed conditions of certification. A copy of the
approval letter, as well as the results of any inspections, will be
placed in the public dockets. After approval of the site-specific plans
for characterization of (a) waste stream(s), EPA will confirm the
execution of the programs at each waste generator site and continued
compliance with the requirements of Secs. 194.24(c)(3) through (5)
through inspections and audits under its authority at Secs. 194.21,
194.22(e) and 194.24(h). Results of such inspections will be made
available to the public through the Agency's public dockets, as
described in Sec. 194.67.
For specific language on the waste characterization conditions of
certification, see Condition 3 of the proposed Appendix A to 40 CFR
Part 194; for specific language on the quality assurance requirements
that relate to waste characterization, see Condition 2 of the proposed
appendix. For further information on EPA's evaluation of compliance for
Sec. 194.24, refer to CARD 24.
D. Section 194.25, Future State Assumptions
Section 194.25 stipulates that performance assessments (``PA'') and
compliance assessments (``CA'') ``shall assume that characteristics of
the future remain what they are at the time the compliance application
is prepared, provided that such characteristics are not related to
hydrogeologic, geologic or climatic conditions.'' The purpose of the
future state assumptions is to avoid unverifiable and unbounded
speculation about possible future states of society, science,
languages, or other characteristics of mankind. The Agency has found no
acceptable methodology that could make predictions of the future state
of society, science, languages, or other characteristics of mankind.
However, the Agency does believe that established scientific methods
can make plausible predictions regarding the future state of geologic,
hydrogeologic, and climatic conditions. Therefore, Sec. 194.25 focuses
PA and CA on the more predictable significant features of disposal
system performance, instead of allowing unbounded speculation on all
developments over the 10,000-year regulatory time frame.
EPA required DOE to identify and document all future state
characteristics and conditions that are used in the PA and CA. For all
elements of the PA and CA that do not relate to hydrogeologic, geologic
or climatic conditions, DOE was required to assume that characteristics
of the future remain what they are at the time the compliance
application was prepared. DOE was required to document the effects of
potential changes to hydrogeologic, geologic and climatic conditions on
the disposal system. For geologic conditions, EPA required DOE to
address dissolution, near surface geomorphic features and processes,
and subsidence in the geologic units of the disposal system. For
climatic conditions, EPA required DOE use current climatic conditions
for comparison and to consider cycles of increased precipitation.
In accordance with Sec. 194.25(a), DOE provided a description of
the future state assumptions for the features, events and processes
(``FEPs'') used in the PA and CA. Except where specified otherwise
(i.e., Secs. 194.32 and 194.33), DOE assumed that current
characteristics for the FEPS not related to hydrogeology, geology and
climatic conditions will remain constant throughout the 10,000-year
regulatory time frame. EPA reviewed the information in the CCA and
agrees with the future state assumptions that DOE has made. EPA found
this information to be inclusive of all relevant elements of the PA and
CA.
To fulfill the requirements of Sec. 194.25(b)(1), DOE predicted the
potential future hydrogeologic conditions at the WIPP. DOE developed
several future state assumptions about the hydrogeological conditions
of the WIPP, such as increased precipitation impacts on recharge
location and capacity, hydraulic gradient, and transmissivity in the
Culebra member of the Rustler and Dewey Lake formations. In a few
cases, DOE found that hydrogeologic conditions can change with time and
can possibly affect the PA. DOE addressed these potential changes in
the PA. EPA reviewed the adequacy of the uncertainty of key parameter
assumptions, such as the impacts of mining subsidence on Culebra
transmissivity. EPA found that DOE adequately addressed the effects of
mining-induced subsidence on Culebra hydrogeologic conditions. EPA
reviewed the future state assumptions DOE made about hydrogeologic
conditions and concludes that DOE has accurately characterized and
modeled the potential changes from current conditions. EPA found that
DOE's incorporation of these changes into the PA was adequate. Other
potential changes to hydrogeologic conditions, notably those associated
with climate change, are addressed in the discussion of
Sec. 194.25(b)(3).
Section 194.25(b)(2) requires DOE to consider the effects of
potential changes to geologic conditions on the disposal system. DOE
predicted potential future geologic conditions at the WIPP. DOE
analyzed the stratigraphy and physiography of undistributed geologic
conditions, salt creep and excavation-induced stress changes,
geochemistry, seismic activity, disturbed rock zone, dissolution, and
mining in the McNutt potash zone above the repository. DOE also
analyzed the geologic effects of existing boreholes, brine reservoirs,
and drilling intrusions. EPA found DOE's assumptions of the future
geologic conditions to cover the significant geologic units and
conditions that affect PA and determined that the screening arguments
adequately justify the exclusion of the majority of the geological FEPs
from the PA and CA. For additional information on the FEPs included in
the PA and CA, see Sec. 194.32. EPA evaluated the CCA and additional
information provided by DOE at EPA's request regarding the uncertainty
associated with deep dissolution and considers DOE's analysis adequate.
For additional information on both geologic and hydrogeologic
conditions of the WIPP, see Sec. 194.14(a).
Section 194.25(b)(3) requires DOE to consider the effects of
potential changes to climatic conditions on the disposal system. At the
WIPP, availability of water for recharge is the primary concern related
to global climate change. Future global warming would be expected to
continue the trend to less precipitation in the vicinity of the WIPP
(which would be beneficial to disposal system performance). DOE
concluded that global cooling--and increased precipitation--is the
worst case scenario for the WIPP. In accordance with Sec. 194.25(b)(3),
DOE identified and described the effects of increased precipitation in
future cooler climate cycles on the repository. DOE considered
potential increased participation over the next 10,000 years and
incorporated the uncertainty of the effects of this climate change in
the PA through modeling of dissolution, groundwater flow, and potential
radionuclide transport in groundwater. DOE described climate change due
to
[[Page 58817]]
potential natural causes and the resulting changes in recharge rates,
groundwater flow velocity, and flow direction. DOE included models of
the impact of potential climate changes on groundwater flow in the
Culebra over the regulatory time period.
EPA found that the CCA included adequate discussions of the current
and previous climate at the WIPP site and found that DOE addressed the
impacts of potential climate change over the regulatory time frame. EPA
concludes that DOE appropriately considered climate-related factors
such as precipitation, temperature, and evapotranspiration that might
affect groundwater flow in the regional three-dimensional groundwater
basin model. EPA also examined DOE's descriptions of recharge
associated with potential climate change effects and found that DOE
adequately described the uncertainties associated with potential change
to the future climate cycles. For additional information on climate
change ground water flow, see Secs. 194.14(a) and (i).
In addition, EPA evaluated potential hydrogeologic changes related
to climate change, including: groundwater recharge, Culebra flow rate
variations, and water table elevation. EPA evaluated the additional
information DOE provided at EPA's request regarding vertical inflow to
the Dewey Lake Formation and three-dimensional groundwater flow
modeling, and concluded that DOE provided adequate documentation to
sufficiently address the issues. EPA verified that the CCA acknowledges
and quantifies uncertainties in hydrogeologic conditions found in the
site characterization data descriptions and modeling assumptions. EPA
also found that DOE modeled the effects of climate changes during the
next 10,000 years on the groundwater flow in the Culebra. After
reviewing the CCA and the additional information provided by DOE at
EPA's request, EPA concluded that DOE's explanation of uncertainty
associated with the potential wetter climate impacts on Culebra
transmissivities resulting from potential dissolution of fracture
infillings is acceptable.
EPA determined that the overall CCA approach to dealing with
uncertainty, and the examples of conservative assumptions used to
compensate for uncertainty, is consistent with the FEPs list, screening
arguments, and model descriptions. EPA proposes to find DOE in
compliance with Sec. 194.25. For further information on EPA's
evaluation of compliance with Sec. 194.35, refer to CARD 25.
E. Section 194.26, Expert Judgment
The requirements of Sec. 194.26 apply to expert judgment
elicitation. Expert judgment is typically used to elicit two types of
information: numerical values for parameters (variables) that are
measurable only by experiments that cannot be conducted due to
limitations of time, money, and physical situation; and essentially
unknowable information, such as which features should be incorporated
into passive institutional controls to deter human intrusion into the
repository. (61 FR 5228) Quality assurance (``QA'') requirements in
accordance with Sec. 194.22(a)(2)(v) must be applied to any expert
judgment to verify that the procedures for conducting and documenting
the expert elicitation have been followed.
The requirements of Sec. 194.26(a) prohibit expert judgment from
being used in place of experimental data, unless DOE can justify that
the necessary experiments cannot be conducted. Expert judgment may
substitute for experimental data only in those instances in which
limitations of time, resources, or physical setting preclude the
successful and timely collection of data.
The CCA submitted on October 29, 1996, did not identify any expert
elicitation activities. During the Agency's review of PA parameters,
EPA found that inadequate explanation and information was provided on
the derivation of 149 parameters identified in the CCA as resulting
from professional judgment (e.g., code control parameters, physical
constants). The Compliance Criteria do not provide for utilization of
``professional judgment.'' Input parameters are to be derived from data
collection, experimentation, or expert elicitation. EPA requested in
letters to DOE dated March 19, April 17, and April 25, 1997, that DOE
provide additional information on the derivation of the 149 parameters.
(Docket A-93-02, Items II-I-17, II-I-25, and II-I-27) In the absence of
data collection or experimentation, EPA expected DOE to derive these
input parameters through expert elicitation.
DOE responded to EPA's requests by adding information to and
improving the quality of the records stored in the Sandia National
Laboratory (``SNL'') Records Center to enhance the traceability of
parameter values. EPA deemed the documentation provided by DOE adequate
to demonstrate proper derivation of all but one of the so-called
professional judgment parameters--the waste particle size distribution
parameter. The remaining parameters questioned by EPA were found to
have adequate documentation to support the values used in the CCA PA
calculations. For further discussion of the technical review of PA
parameters, see the preamble for Sec. 194.23. EPA required DOE to use
the process of expert elicitation to develop the value distribution for
the waste particle size parameter. (Docket A-93-02, Item II-I-27)
The waste particle size parameter is important in the PA because it
affects the quantity of radioactive materials released in spallings
from inadvertent human intrusion. Because particle diameters are
uncertain and cannot be estimated either directly from available data
or from data collection or experimentation, the waste particle size
parameter had to be based on an elicitation of expert judgment.
DOE conducted the expert judgment elicitation on May 5 through May
9, 1997. The process included: definition of technical issues; public
notification; selection of experts; general orientation and elicitation
training; presentation and review of issues; preparation of expert
analysis by elicitor; discussion of analysis by panel members;
elicitation; recomposition; review and approval of dissenting opinions
provided by experts; and documentation of the process and results. The
results of the expert elicitation consisted of a model for predicting
waste particle size distribution as a function of the processes
occurring within the repository, as predicted by the PA. This particle
size distribution was incorporated in the PAVT calculations; for a
detailed discussion on the sampling of uncertain parameter
distributions, refer to the preamble discussion of Sec. 194.34,
``Results of PA.'' DOE completed a final report entitled, ``Expert
Elicitation on WIPP Waste Particle Size Distributions(s) During the
10,000-Year Regulatory Post-closure Period.'' (Docket A-93-02, Item II-
I-34) EPA proposes to find that DOE complies with Sec. 194.26(a)
because the Agency found adequate support for the derivation of all
parameter values with the exception of the waste particle size
parameter, for which DOE undertook an expert elicitation.
EPA's review of DOE's compliance with the requirements of
Sec. 194.26 principally focused on the conduct of the elicitation
process. Sections 194.26 (b) and (c) set specific criteria for the
performance of an expert judgment elicitation. DOE must: identify the
expert judgments used to support the compliance application; identify
the experts involved in the process; describe the process of eliciting
expert
[[Page 58818]]
judgment; document the results; document that the experts have the
necessary independence and qualifications for addressing the questions
and issues presented; explain the connection between the questions
posed to the expert panel and the manner in which the final report of
the panel is used in the compliance application; adhere to requirements
on the composition of the expert panel, including the fraction of the
panel members who are employed by DOE; assure the public be given the
opportunity to present their views in the expert judgment process; and
document the elicitation process so as to demonstrate a logical
progression from the first statement of issue given to the panel to the
combination and presentation in the final report.
EPA observed DOE's elicitation process and conducted an audit of
the documentation prepared in support of DOE's compliance with
Sec. 194.26. The scope of the audit covered all aspects of the expert
judgment elicitation process, including: panel meetings, management and
team procedures, curriculum vitae of panel members, background
documents, and presentation materials. EPA also assessed compliance
with the QA requirements of Sec. 194.22. EPA found that the
documentation provided by DOE addressed the requirements of
Sec. 194.26(b)(2).
In accordance with Sec. 194.26(b)(1), DOE identified the individual
experts on the panel. EPA found that the expert panel was composed of
six experts, including four from consulting firms and two associated
with universities. Two of the six panel members were DOE contractors at
the time of the elicitation.
Therefore, in accordance with Sec. 194.26(b)(7), the panel included
at least five individuals, two-thirds of whom were not employed by DOE
or DOE contractors. In accordance with Sec. 194.26(b)(3), the panel did
not include individuals who will use the judgments or who maintain, at
any organizational level, a supervisory role or who are supervised by
those who will utilize the judgment. EPA found DOE's documentation to
demonstrate compliance with these requirements.
Based on its review of curriculum vitaes and completed
organizational conflict of interest forms, EPA determined that the
experts on the panel demonstrated the required independence and level
of knowledge required by the questions or issues presented.
(Sec. 194.26(b)(4)) EPA found the background and orientation materials
addressed the relationship among information and issues as well as the
purpose and intent of the judgment, in accordance with
Sec. 194.26(b)(5). The Agency determined that the expert elicitation
met the requirement at Sec. 194.26(b)(6) since the result of the
process was a parameter distribution that could be implemented directly
in the PA. EPA also found that DOE afforded the public an opportunity
to present scientific and technical views to the expert panel.
(Sec. 194.26(c))
Based on the review of expert elicitation supporting documentation
developed by DOE and its contractors, as well as the results of the EPA
audit to verify compliance, EPA proposes to determine that DOE complies
with the requirements of Sec. 194.26 in conducting the required expert
elicitation.
Numerous public comments were received on DOE's statement that it
did not conduct any expert judgement activities in developing the CCA.
As many commenters correctly pointed out, the CCA did not contain
adequate information to allow a reviewer to ascertain whether a large
number of the input parameters were properly derived in accordance with
the explicit requirements of the Compliance Criteria. DOE subsequently
provided additional information, and substantially improved the quality
of the records at the SNL Records Center to make it possible to confirm
that all but one of the suspect input parameters were adequately
supported. For further discussion of EPA's evaluation of compliance
with Sec. 194.26 and related public comments, see CARD 26.
F. Section 194.27, Peer Review
Section 194.27(a) requires DOE to conduct peer review evaluations
related to conceptual models, waste characterization analyses, and the
evaluation of engineered barriers. This section, at Secs. 194.27(b) and
(c)(1), also requires DOE to submit documentation showing that the
required peer reviews were conducted in a manner compatible with NUREG-
1297, ``Peer Review for High-Level Nuclear Waste Repositories.''
(Docket A-92-56, Item III-B-1h) NUREG-1297 is incorporated by reference
in the Compliance Criteria. As stated in NUREG-1297, the purpose of
peer review is to provide confidence in the validity of technical and
programmatic judgments involving scientific uncertainty or ambiguity by
subjecting those judgments to the evaluation of qualified, independent
specialists. (NUREG-1297, p. 2)
DOE completed the required peer reviews and included a description
of the peer review process in the CCA. EPA's CAG indicates the types of
documentation necessary for Sec. 194.27(b) to demonstrate that peer
reviews were conducted in accordance with the NUREG-1297 guidance. For
example, the CCA should show the process by which peer review panels
deliberated, should present the conclusions they reached, and should
show that panel members were qualified and free of conflicts of
interest. EPA reviewed the CCA to determine whether DOE's procedures
and plans for the required peer reviews were consistent with the CAG
and whether the required peer reviews had actually been conducted in
accordance with those procedures and plans.
Many of the documents detailing DOE's implementation of NUREG-1297
are kept by DOE as quality assurance (``QA'') records and were not
included in the CCA but were made available to EPA. EPA first reviewed
the CCA and supplementary reports and confirmed that the required peer
reviews had been conducted. To evaluate the peer review process
further, EPA conducted an audit of DOE's QA records for peer review in
February 1997. The audit consisted of an extensive review of DOE's
records and interviews with DOE staff and contractors who managed the
required peer reviews. The audit raised several isolated findings, but
none of these was sufficient to lead EPA to conclude that any of the
peer reviews had been conducted in a manner incompatible with NUREG-
1297.
EPA proposes to find DOE in compliance with Secs. 194.27(a) and
(b). DOE submitted documentation in the CCA showing that the required
peer reviews had been conducted. DOE's procedures for the conduct of
peer review satisfactorily incorporated the essential elements of
NUREG-1297, as identified in the CAG. The audit conducted by EPA
verified that DOE properly followed its procedures for peer review.
Section 194.27(c)(1) requires DOE to show that the three required
peer reviews, if conducted prior to promulgation of 40 CFR Part 194,
were conducted in accordance with an alternative process substantially
equivalent to NUREG-1297. Because DOE conducted the required peer
reviews after the promulgation of 40 CFR Part 194, this requirement is
not applicable.
Section 194.27(c)(2) requires DOE to document any peer reviews
conducted by DOE other than those required by Sec. 194.27(a). The
additional peer reviews were not required to be compatible with the
guidance in NUREG-1297, but EPA recommended in the CAG that they be
documented in a manner similar to the required peer reviews. EPA
expected
[[Page 58819]]
that documentation would be sufficient to identify the purpose, scope,
membership, and findings of a given peer review.
DOE developed a list of criteria, based principally on guidance in
NUREG-1297, to determine whether a review activity conducted prior to
promulgation of the Compliance Criteria constituted a peer review. DOE
then identified past activities that met the criteria and incorporated
relevant documentation in the CCA. EPA reviewed the materials provided
and found that sixteen peer reviews were properly included in the CCA.
EPA also found that the CCA contained sufficient documentation to allow
EPA to identify the purpose, scope, membership, and findings of those
sixteen peer review activities. Therefore, EPA proposes to find DOE in
compliance with Sec. 194.27(c)(2).
Comments received in regard to peer review expressed mainly two
concerns. First, commenters considered the CCA incomplete because some
peer reviews were reopened after the CCA was sent to EPA in October
1996. EPA requested, received, and docketed pertinent documentation
resulting from the reopened peer reviews prior to determining that the
CCA was complete.
Second, commenters questioned the findings of some peer reviews.
EPA's compliance review for Sec. 194.27(b) focused on the extent to
which the required peer reviews were conducted in a manner compatible
with NUREG-1297. The Agency believes that the critical evaluation of
peer review findings is necessary but not directly relevant to DOE's
compliance with Sec. 194.27. EPA carefully examined the findings of all
peer reviews conducted after the promulgation of 40 CFR Part 194 and
discusses them under the relevant technical sections: quality assurance
(Sec. 194.22), conceptual models (Sec. 194.23), waste characterization
(Sec. 194.24), passive institutional controls (Sec. 194.43), and
engineered barriers (Sec. 194.44). For further information of EPA's
evaluation of compliance for Sec. 194.27, see CARD 27.
XI. Containment Requirements
The disposal regulations include requirements for containment of
radionuclides. The containment requirements at 40 CFR 191.13 specify
that release of radionuclides to the accessible environment shall not
exceed specific limits, which are based on the amount of waste in the
WIPP at the time of disposal. (Sec. 194.31) Assessment of the
likelihood that the WIPP will meet these release limits is conducted
through use of a process known as performance assessment (``PA''). The
WIPP PA essentially consists of a series of computer simulations that
attempt to describe the physical attributes of the disposal system
(site, geology, waste forms and quantities, engineered features) in a
manner that captures the behaviors and interactions among its various
components. The computer simulations require the use of conceptual
models that represent physical attributes of the repository. The
conceptual models are then expressed as mathematical relationships,
which are then translated into computer code. The results of the
simulations show the potential releases of radioactive materials from
the disposal system to the accessible environment over the 10,000-year
regulatory time frame. (Models and computer codes are addressed in more
detail in the preamble for Sec. 194.23 of the general requirements.)
The PA must include both natural and man-made processes and events
which have an effect on the disposal system. It must consider all
reasonable potential release mechanisms from the disposal system and
must be structured and conducted in a way that demonstrates an adequate
understanding of the physical conditions in the disposal system. The PA
must evaluate both human-initiated releases (e.g., via drilling
intrusions) and releases by natural processes that would occur
independently of human activities. The requirements at Secs. 194.32 and
194.33 address the scope of PA and the types of human intrusion which
must be considered in PA.
The results of PA are used to demonstrate compliance with the
containment requirements in 40 CFR 191.13. The containment requirements
are expressed in terms of ``normalized releases'' (discussed in more
depth in subsequent sections of this preamble). The results of PA are
assembled into complementary cumulative distribution functions
(``CCDFs'') which indicate the probability of exceeding various levels
of normalized releases. Section 194.34 of the WIPP Compliance Criteria
imposes specific statistical requirements on the results of PA and on
the single curve used to judge compliance with the containment
requirements.
A. Section 194.31, Application of Release Limits
Section 194.31 indicates that DOE is to quantify releases of
radionuclides from the WIPP in terms of ``cumulative releases,'' which
are calculated from ``release limits.'' Release limits for
radionuclides at a radioactive waste disposal facility must be
calculated in accordance with 40 CFR Part 191, Appendix A. There, a
``release limit'' for a radionuclide is introduced as a measure of the
cumulative amount of radioactivity, measured in curies, that is allowed
to reach the accessible environment (that is, land surface, the
atmosphere, surface waters, oceans, and all the land beyond the
boundary of the WIPP land withdrawal area) over the 10,000 years after
the disposal 23 of radioactive waste. Release limits are to
be calculated using the activity from radioactive waste, in curies,
that will exist in the WIPP at the time of disposal.
---------------------------------------------------------------------------
\23\ ``Disposal'' is defined as ``[P]ermanent isolation of . . .
radioactive waste from the accessible environment with no intent of
recovery whether or not such isolation permits the recovery of such
fuel or waste. For example, disposal of waste in a mined geologic
repository occurs when all of the shafts to the repository are
backfilled and sealed.'' 40 CFR 191.02(l)
---------------------------------------------------------------------------
To calculate normalized releases and release limits, DOE must first
identify all the radionuclides that are present in the waste that it
plans to put in the WIPP (e.g., plutonium-238). Next, the Department
projects which radionuclides will be present in the waste at the time
of disposal, including those isotopes created by radioactive decay
between the time of the waste inventory (approximately 1995) and the
time of disposal (estimated to be the year 2033). DOE then determines
which of these radionuclides emit alpha-particles, have an atomic
number greater than that of uranium (transuranic), and have half-lives
greater than twenty years. These radionuclides comprise the ``TRU
component'' of the waste. The total activity of the TRU component of
the waste, in curies, divided by one million curies, is called the
``waste unit factor.'' For the WIPP, Table 1 of Appendix A of 40 CFR
Part 191 presents values of release limits (in curies) per unit of this
``waste unit factor.''
To obtain the release limit for a radionuclide, DOE must multiply
each release limit value in Table 1 by the numerical value of the waste
unit factor. Finally, to obtain the normalized release for a scenario,
DOE must divide the projected estimated release (obtained from PA
modeling), in curies, for every radionuclide (whether TRU or non-TRU)
by its respective release limit, and sum these quotients.
In the CCA, the Department provided an inventory of the various
radionuclides in the waste expected at the time of disposal, including
those radionuclides in the waste inventory that are currently stored at
different DOE sites, those radionuclides that are projected to be
generated at different DOE sites between 1995 and the time of
[[Page 58820]]
disposal, and those radionuclides that would be created by radioactive
decay between the time of the waste inventory in 1995 and the time of
disposal, approximately in the year 2033. The waste inventory showed
that plutonium and americium produce almost all of the radioactivity
from waste that would be in the WIPP at the time of disposal. Based on
the fifteen radionuclides in the inventory that were transuranic,
alpha-emitting, and had half-lives greater than twenty years, DOE
calculated that the relevant total activity at the time of disposal
would be 3.44 million curies and that the waste unit factor would be
3.44.
DOE used the waste unit factor to obtain the release limit for each
radionuclide found in Table 1 in Appendix A of 40 CFR Part 191. These
release limits were then used in the calculation of cumulative
releases. The Department designated six transuranic radionuclides that
contributed more than 99.9 percent of the activity as ``major
radionuclides.'' The Department calculated the release limits and
relative contributions to releases for the six major radionuclides
using a computer program called EPAUNI. The Department verified the
computer calculations with sample hand calculations.
EPA reviewed DOE's description of the procedure used to estimate
the activity of waste proposed for disposal, examined DOE's hand
calculations, and verified the computer code and output to determine
whether DOE correctly calculated the waste unit factor, including
radioactive decay up to the year 2033. EPA also evaluated whether DOE
appropriately calculated release limits for each major radionuclide and
identified the relative contribution of each major radionuclide.
EPA found DOE's simplification of using the six transuranic
radionuclides that contribute the greatest activity in computer
calculations to be appropriate. Because these six radionuclides would
make up more than 99.9 percent of the activity from the transuranic
waste, DOE's simplification could contribute at most an error of 0.1
percent to its calculations of the contribution to releases from
individual radionuclides, which would not have a significant impact
upon the calculation of release limits or the contribution to releases
from individual radionuclides.
EPA found that the TRU waste component used to calculate the waste
unit factor of 3.44 omitted some waste stored at an off-site facility
at Savannah River. DOE corrected this error by recalculating the waste
unit factor based on a TRU inventory that included the Savannah River
waste; the revised waste unit factor was 3.59. EPA did not require DOE
to recalculate the release limits based on the new value for the waste
unit factor, because using the larger revised factor would have
resulted in higher release limits (and thus, lower normalized
releases). That is, the use of the incorrect value in the CCA is more
conservative than using the correct value of 3.59. The correction of
the error would only show that the WIPP will comply with the disposal
regulations by a wider margin than had been previously demonstrated.
The Agency confirmed that the Department calculated the waste unit
factor of 3.44 and the release limits at the time of disposal in
accordance with the requirements of Appendix A of 40 CFR Part 191. In
addition, the Agency found that the Department correctly identified the
relative contribution of each major radionuclide to releases. Finally,
the Agency confirmed that the computer codes, model results, and hand
calculations were consistent and thus supported the use of the computer
codes. Because the Agency's review concluded that the Department
calculated release limits for the WIPP using an appropriate methodology
and conservative waste inventory estimates, the Agency proposes that
the requirements of Sec. 194.31 have been met. For further information
on EPA's evaluation of compliance for Sec. 194.31, see CARD 31.
B. Section 194.32, Scope of Performance Assessments (PA)
Section 194.32 requires DOE to consider, in the performance
assessment (``PA''), both natural and man-made processes and events
which can have an effect on the disposal system. EPA expected DOE to
consider all features, events and processes (``FEPs'') that may have an
effect on the disposal system. In particular, EPA expected DOE to
consider mining effects on hydraulic conductivity, fluid injection,
future development of leases and existing boreholes in the scope of the
PA. The CCA was also expected to document which FEPs (or sequences or
combinations of FEPs) are included in the PA. DOE is required to
document the decision not to include any feature, event, or process in
the PA. Deep and shallow drilling, over the regulatory time frame, are
addressed in more detail in the preamble discussion of Sec. 194.33.
To fulfill the requirements of Secs. 194.32(a), (d) and (e), DOE
developed and followed a process for considering FEPs in the PA. DOE
initially identified 1,200 FEPs from a list of FEPs developed by the
Swedish Nuclear Power Inspectorate (``SKI''). This list was compiled
and categorized based on location of occurrence and cause by nine
organizations world wide. DOE modified this list to make it relevant to
WIPP. DOE's final list of FEPs was then classified and screened for
consideration in the PA. DOE screened FEPs from consideration in the PA
based on regulatory exemption, low probability and low consequence.
FEPs were then combined to form scenarios. Scenarios were also screened
based on regulations, probability or consequence. The remaining
scenarios were retained for implementation in the PA. The CCA documents
DOE's decision not to include specific FEPs in the PA.
Approximately 237 FEPs were retained for screening. DOE concluded
that 17 of 72 initial natural FEPs should be retained for the PA,
including stratigraphy, shallow dissolution, saturated groundwater,
infiltration, precipitation, and climate change. Of 108 waste and
repository-induced FEPs, DOE concluded that 51 of these should be
retained for the PA, including disposal geometry, waste inventory, salt
creep, backfill chemical composition, actinide solubility, spallings,
and cavings. DOE concluded that 15 of the 57 human-initiated events and
processes should be retained for the PA, including oil and gas
exploration. Examples of FEPs screened from use in the PA include:
lateral dissolution, regional tectonics, salt deformation, mechanical
effects of backfill, liquid waste disposal and groundwater extraction.
EPA concluded that the initial FEP list assembled by DOE was
sufficiently comprehensive, in accordance with Secs. 194.32(a) and
(e)(1). In compiling this list, DOE appropriately screened out events
and processes on the basis of probability, consequence or regulatory
requirements. DOE considered and incorporated into the PA numerous
natural processes and events, mining, and deep drilling. DOE considered
shallow drilling and appropriately screened it out on the basis of low
consequence. (See preamble for Sec. 194.33.)
Based on quantitative and qualitative assessments provided in the
CCA and supporting documents, EPA concluded that DOE appropriately
rejected those FEPs that exhibit low probability of occurrence during
the regulatory period, in accordance with Sec. 194.32(d).
Review of the CCA and the submitted supporting documents confirms
that DOE used a thorough process to identify all the appropriate FEPs
as well as the related combinations and sequences that can potentially
occur within the
[[Page 58821]]
regulatory time frame and affect disposal system performance. EPA
determined that the process is sufficiently documented and that DOE
justified the retention and elimination of FEPs. In addition, EPA found
DOE's inclusion of various scenarios in the PA to be reasonable and
justified, and meets the requirement of Sec. 194.32(e)(2). DOE provided
documentation and justification for eliminating those FEPs that were
not included in the PA. In some cases (e.g., fluid injection and
dissolution), the CCA did not provide adequate justification or
convincing arguments to eliminate FEPs from consideration in PA. (Fluid
injection is discussed in more detail below, relative to compliance
with Sec. 194.32(c).) However, DOE provided supplemental information
and analyses to demonstrate compliance with Sec. 194.32(e)(3). EPA
found this supplementary information to be adequate in fulfilling the
requirements to justify FEP exclusion from the PA.
For disturbed scenarios (i.e., human activities), DOE discussed how
mining was incorporated into the PA. DOE identified potash as the only
natural resource currently being mined near the WIPP. DOE, in
accordance with Sec. 194.32(b), used the EPA-specified mining
probability and considered changes in hydraulic conductivity up to 1000
times the base hydraulic conductivity of the Culebra. In its
calculation of the potash area to be mined, DOE considered minable
reserves inside and outside of the controlled area. The Compliance
Criteria require DOE to examine only currently extractable resources,
not to speculate on what other resources may become economically
viable.
EPA verified, through review of the CCA and supporting documents,
that DOE included, in the PA, appropriate changes in the hydraulic
conductivity values for the areas affected by mining. These values for
hydraulic conductivity considered the impact of institutional controls
on mining, mining practices and mineral resources. The area considered
to be mined for potash in the controlled area is consistent with the
requirement of Sec. 194.32(b), that the mined area be based on mineral
deposits of those resources currently extracted from the Delaware
Basin. EPA proposes to find that DOE complies with Sec. 194.32(b).
EPA's review of the CCA raised questions regarding DOE's analysis,
in accordance with Sec. 194.32(c), of human-initiated activities,
including fluid injection. The fluid injection scenario has been of
particular concern to the public because of events that occurred in the
Rhodes-Yates oil field, about 40 miles east of WIPP but outside the
Delaware Basin. An oil well operator, Mr. Hartman, drilling in the
Salado Formation in the Rhodes-Yates Field, encountered a salt water
blowout in an oil development well. In subsequent litigation, the court
found that the source of the water flow was injection water from a
long-term waterflood borehole located more than a mile away.
DOE addressed the fluid injection scenario in the CCA with an
analysis of waterflooding (for enhanced oil recovery) and brine
disposal activities. (Docket A-93-02, Item II-G-1, Reference #611) In
accordance with Sec. 194.32(c), DOE determined that these two
activities were the only fluid injection scenarios that were currently
occurring or could be initiated in the near future in the vicinity of
the WIPP. DOE identified the Bell Canyon Formation under the Salado and
Castile Formations as the primary target for fluid injection for brine
disposal. DOE stated that this scenario had the potential to produce
more brine inflow to the WIPP. DOE modeled the fluid injection scenario
using WIPP geology, and again using the geology identified in the
Rhodes-Yates Field. The two sites differ significantly because the
Castile Formation, which underlies the Salado at the WIPP, is absent in
the Rhodes-Yates Field. DOE assumed that fluid injection activities
would occur continuously for 50 years, and evaluated the subsequent
effects of such injection activities over the entire 10,000-year
regulatory time frame. The modeling results indicated that some brine
could potentially get into the WIPP from fluid injection activities.
However, the amount of brine from the worst case scenario (the
``Rhodes-Yates'' scenario) was low compared to the amount of brine
expected to enter the waste area naturally. DOE thus screened out the
fluid injection scenario on the basis of low consequence.
EPA's review of the CCA raised additional questions regarding DOE's
screening analysis of fluid injection. EPA believes that 50 years is an
accurate estimate for the life of a single oil field, but that it does
not account for the possibility of multiple fields. Because drilling
restrictions currently applicable to potash areas in the Delaware Basin
could be lifted, it is possible that multiple oil fields could be
developed in the foreseeable future near the WIPP. Based on the current
resources and leases in the vicinity of the WIPP, EPA estimated that
oil could still be drilled up to 150 years from now. EPA thus required
DOE to extend the 50-year time frame in its models to 150 years. EPA
also required DOE to use modified values for some input parameters, and
to model the behavior of the disturbed rock zone consistent with
assumptions used in the PA. (Docket A-93-02, Item II-I-17) Finally, EPA
required DOE to provide additional information on the frequency of
fluid injection well failures.
In supplemental work on fluid injection, DOE addressed all the
issues identified by EPA. DOE modified the computer model grid
configuration and added a new model to address concerns raised by both
EPA and stakeholders. DOE researched injection well operating practices
and construction in the Delaware and identified significant differences
between those in the vicinity of the WIPP and the Rhodes-Yates Field.
For example, wells near the WIPP are typically less than ten years old
and are constructed to much higher mechanical standards than the older,
less robust wells found in the Rhodes-Yates Field. DOE identified a
range of well failure scenarios, from undetectable brine flow to
catastrophic well failure. DOE's data indicated that the probability of
a catastrophic well failure in the vicinity of the WIPP is extremely
low. DOE confirmed that the presence of the Castile at the WIPP also
substantially inhibits injected brine movement into the Salado
anhydrite markerbeds.
Public comments on this issue included a detailed report that
contradicted the DOE fluid injection modeling and indicated that fluid
injection activities could overwhelm the WIPP with brine. (Docket A-93-
02, Item II-H-28) EPA has reviewed the report and considers it to model
conditions that are highly unrealistic for the WIPP. For example, all
modeled scenarios assumed that the entire volume of brine was injected
directly into the anhydrite marker beds in the Salado Formation. In
addition, the report modeled the occurrence of fluid injection well
beyond the time frame contemplated by Sec. 194.32(c). The report also
ignored current well construction and fluid injection operating
practices, which are more robust than that used in the 45-year-old
Rhodes-Yates Field.
EPA agreed with commenters that the original fluid injection
screening was not adequate. Thus EPA required DOE to provide additional
information and to do additional modeling. The additional modeling
showed rates of brine inflow (and thus effects on the disposal system)
even smaller than those estimated by the original CCA screening
analysis. DOE provided documented evidence that the well construction
and operating practices near the WIPP are much more robust than that in
the Rhodes-Yates
[[Page 58822]]
well. Both DOE's research and EPA's own review of fluid injection,
indicated that the probability of a long-term fluid injection well
failure is below the regulatory cutoff of 1 in 10,000 over 10,000
years. Based on DOE's modeling and examination of fluid injection
practices, EPA believes that a salt water blowout situation in the
Rhodes-Yates Field is extremely unlikely to occur and affect WIPP's
ability to contain radionuclides. Thus, EPA concurs with DOE that fluid
injection is a low-probability scenario that can be screened out of the
PA based on low consequence.
DOE, in accordance with Sec. 194.32(c), also identified oil and gas
exploration and exploitation, and water and potash exploration as the
only near future human-initiated activities that need to be considered
in the PA. DOE included and assessed the potential effects of existing
boreholes as part of its FEPs screening analysis. DOE concluded that
natural borehole fluid flow through abandoned boreholes would be of
little consequence during current and operational phase activities. In
addition, DOE screened out the occurrence of flow through undetected
boreholes based on low probability.
To further address Sec. 194.32(c), DOE assessed scenarios ranging
from the effects of deep and shallow drilling and mining to undisturbed
disposal system performance. DOE retained the FEPs describing both
undisturbed and disturbed system performance. DOE identified the
specific locations in the CCA that related to modeling of the
individual FEPs. These discussions focused on conceptual model
development, but often linked the conceptualizations with associated
computational (computer) models.
EPA's review of the CCA and supporting documents referenced in the
CCA with respect to Sec. 194.32(c), indicated that DOE adequately
analyzed the possible effects of current and future potential
activities on the disposal system. However, DOE inadequately analyzed
in the application some future activities in the vicinity of the
disposal system, including injection of drilling fluids for brine
disposal and enhanced oil recovery, solution mining, and full
extraction potential of the leaseholds (in the vicinity of WIPP). In
response to the concerns expressed by EPA and stakeholders, DOE
conducted additional analyses and submitted follow-up information. This
information was adequate and EPA concurred with the conclusions,
concluding that DOE's analysis met the requirements of Sec. 194.32(c).
In summary, EPA proposes to find DOE in compliance with
Sec. 194.32. For further information on EPA's evaluation of compliance
for Sec. 194.32, refer to CARD 32.
C. Section 194.33, Consideration of Drilling Events in PA
Section 194.33 requires DOE to make specific assumptions about
future deep and shallow drilling in the Delaware Basin. Section 194.33
requires that the following assumptions be incorporated into the PA:
drilling will occur randomly in space and time; the drilling rate may
vary with the resources; drilling practices will remain constant for a
single resource but may be different for others; and plugging practices
will remain constant, but the permeability of a borehole may change
with time. Deep and shallow drilling practices and related activities
can directly impact the cumulative potential for contaminant release to
ground, surface or geologic units.
For this requirement, EPA required DOE to discuss the resources for
which deep and shallow drilling occur in the Delaware Basin. DOE was
also required to describe the techniques and rates for deep and shallow
drilling for each resource. In these analyses, DOE was required to
document assumptions and sources of information. EPA also required DOE
to document assumptions that DOE made in analyzing the consequences of
drilling events in PA. Finally, DOE was required to evaluate the
effects of boreholes on the properties of the disposal system.
To fulfill the requirements of Sec. 194.33(a), DOE identified
several deep and shallow drilling activities as being present in the
Delaware Basin. DOE identified oil and gas exploration and
exploitation, and water and potash exploration, as the principal
drilling activities to be considered in the PA. The shallow drilling
components of these activities were screened from inclusion in the PA
because DOE considered these activities to be of low consequence to PA
calculations. DOE considered three scenarios in PA for deep drilling:
(1) One or more boreholes penetrate(s) the Castile brine reservoir and
also intersect(s) a repository panel, (2) one or more boreholes
intersect(s) a repository panel, and (3) multiple penetrations of waste
panels, by boreholes of the first or second type, at many possible
combinations of intrusion times, locations and combinations of borehole
types. EPA found that the PA incorporated deep and shallow drilling
events, in accordance with Sec. 194.33(a).
To comply with the requirements of Sec. 194.33(b), DOE incorporated
assumptions into the PA about the severity, frequency and randomness of
human intrusion. DOE considered intermittent and inadvertent drilling,
including exploratory and developmental drilling, as the most severe
human intrusion scenarios and used them to calculate cumulative
radionuclide releases. The drilling rate is one of the most important
parameters affecting compliance with the containment requirements.
Using a publicly available petroleum database, DOE established the rate
of future deep drilling to be 46.8 boreholes per square kilometer per
10,000 years. EPA found that DOE identified the number of deep drilling
events for each resource, and that sources of information used to do so
were thorough and appropriate. (The rate of shallow drilling in the
Delaware Basin was not needed because, as noted above, shallow drilling
was screened from inclusion in the PA based on low consequence.) DOE
applied the deep drilling rate in the PA by randomly sampling with
respect to: (1) The location of a borehole in the repository footprint,
and (2) the time of occurrence during the regulatory time frame. EPA
therefore proposes to find DOE in compliance with Sec. 194.33(b).
DOE evaluated, in accordance with Sec. 194.33(c), the consequences
of drilling events assuming that drilling practices and technology
remain consistent with practices in the Delaware Basin at the time the
certification application was prepared. DOE evaluated borehole drilling
and borehole seal degradation for their effects on properties of the
disposal system and their impact on radionuclide migration and
transport. DOE determined that boreholes can impact radionuclide
migration and transport through cuttings, cavings, spallings and direct
brine releases. In addition, DOE considered the effects of borehole
degradation and its impact on the permeability of borehole plugs.
EPA and public commenters disagreed with the constant value DOE
used in the PA for the short-term (up to 200 years after disposal)
borehole plug permeability. EPA therefore directed DOE to use a range
of borehole plug permeabilities when conducting the EPA-mandated
Performance Assessment Verification Test (``PAVT''). While EPA's
sensitivity analysis indicated that the short-term plug permeability
affected some performance measures, the results of the PAVT
demonstrated that the range of short-term plug permeability values,
compared to the long-term borehole permeability, had little impact on
the results of modeling.
[[Page 58823]]
EPA and public commenters also disagreed with DOE's use of a small
range of values for the long-term borehole plug permeability. (Docket
A-93-02, Item II-I-17) For example, one commenter asserted that DOE
should evaluate both ``perfect plugs'' (i.e., low permeability) and
plugs that ``fail'' (i.e, very high permeability). (Docket A-93-02,
Item II-E-34, comment #113) In the PAVT, the long-term borehole plug
permeability was changed so that the sampled parameter range included
both low and high permeability values to simulate perfect plugs and
borehole plug failure, respectively. Low permeability plugs did
increase releases by increasing repository pressure and allowing more
spallings and direct brine releases. However, the PAVT results
indicated that changing the long-term borehole permeability, in
combination with several other changes requested in public comments
(notably those related to pressurized brine pockets), still would not
cause predicted releases to violate the containment requirements; this
indicates that the original CCA parameter values were acceptable for
comparison to the containment requirements. (See preamble discussion of
Sec. 194.34 for further information on the PAVT.)
EPA reviewed the information contained in the CCA and concluded
that DOE demonstrated that the effects of drilling events have been
adequately considered. EPA found that the documentation in the CCA
demonstrated that DOE thoroughly considered deep and shallow drilling
activities and rates within the Delaware Basin. EPA found that DOE
appropriately screened out shallow drilling from consideration in the
PA. EPA also found that DOE appropriately incorporated the assumptions
and calculations for drilling into the PA as stipulated in
Secs. 194.33(b) and (c). EPA determined that the PA models did not
incorporate the effects of techniques used for resource recovery, in
accordance with Sec. 194.33(d). EPA further concludes that the
information in the CCA is consistent with available data. EPA proposes
to find DOE in compliance with the requirements of Sec. 194.33. For
further information on EPA's evaluation of compliance for Sec. 194.33,
see CARD 33.
D. Section 194.34, Results of PA
The containment requirements at Sec. 191.13 indicate that a
disposal system is to be tested through a PA that predicts the
likelihood of occurrence of all significant processes and events that
may disturb the disposal system and affect its performance, and that
predicts the ability of the disposal system to contain radionuclides.
Section 194.34 of the Compliance Criteria provides specific
requirements for presenting the results of the PA for the WIPP.
The restriction on releases of radioactive material is expressed in
terms of ``normalized releases'' or ``cumulative releases.'' Normalized
releases refer to amounts of radioactivity projected (by means of the
mathematical models of the PA) to be released from the repository over
10,000 years under various physical conditions and intrusion scenarios.
To calculate the normalized release for a given intrusion scenario, one
first obtains the normalized release separately for each individual
radionuclide; this involves dividing the amount projected to be
released, in curies, by its radionuclide-specific release limit, as
calculated in accordance with Appendix A of 40 CFR Part 191. (See the
discussion of release limits for Sec. 194.31 in today's preamble.) One
then adds together the normalized releases for all radionuclides to
determine the overall normalized release for the scenario. Section
191.13 requires that a disposal system be designed so that there is
reasonable assurance that cumulative releases (1) have a probability of
less than one in ten (0.1) of exceeding the calculated release limits,
and (2) have no more than a one in one thousand (0.001) chance of
exceeding ten times the calculated release limits.
Section 194.34 requires DOE to use complementary cumulative
distribution functions (``CCDFs'') to express the results of the PA.
The Department also must document the development of probability
distributions, and the computational techniques used for drawing random
samples from these probability distributions, for any uncertain
parameters used in PA. The PA must include a statistically sufficient
number of CCDFs; in particular, the number of CCDFs must be large
enough to ensure that the maximum CCDF curve exceeds the 99th
percentile of the population of CCDFs, with at least a 95 percent
probability, at the specific values of 1 and 10 for normalized
releases. The CCA must display the full range of CCDFs generated.
Finally, the CCA must demonstrate that the mean of the population of
CCDFs meets the containment requirements of Sec. 191.13 with at least a
95 percent level of statistical confidence.
EPA found that the CCA PA demonstrated that the WIPP meets the
containment requirements of Sec. 191.13 by more than an order of
magnitude in probability. The largest release at any point on the mean
CCDF curve was a normalized release of only 0.3. The PA calculations
indicated no cases where cumulative releases would be ten times greater
than the release limits.
In the process of reviewing the CCA, the Agency and public
commenters raised concerns about certain assumptions and specific
parameter values incorporated into the PA. Also, DOE found some coding
problems in the PA computer software. The Agency therefore directed the
Department to conduct additional modeling that included corrections to
computer coding problems and modifications to parameter values and
distributions. The PAVT also excluded the assumption of credit for
passive institutional controls. EPA required this additional modeling
in the PAVT in order to determine whether the cumulative impact of the
changes in the PA codes and parameters would be small enough that the
WIPP would still meet the containment requirements of Sec. 191.13. (For
further discussion of parameter values, see the discussion of
parameters in the preamble for Sec. 194.23.) The results of the PAVT
showed somewhat higher cumulative release values than the original CCA
PA. However, even these higher cumulative release values were more than
an order of magnitude lower than the containment requirements, at the
probability levels prescribed by Sec. 191.13. Based upon the results of
the CCA PA and the PAVT, EPA proposes to find that the WIPP meets the
containment requirements of Sec. 191.13.
Further discussion of the specific compliance criteria of
Sec. 194.34 follows.
1. Complementary Cumulative Distribution Functions (CCDFs)
Section 194.34(a) requires DOE to report the results of the PA in
the form of ``complementary, cumulative distribution functions''
(``CCDFs''), which may be presented graphically as a set of curves. A
CCDF curve presents the probability that releases from the repository,
caused by all significant processes and events, might exceed any
particular level of cumulative (normalized) release. That is, a point
on a CCDF curve displays, on the vertical axis, the relative number of
release scenarios or ``futures'' that could result in calculated
releases larger than the corresponding normalized release value found
on the horizontal axis. Each CCDF curve starts with a maximum
probability of one on the left side of the graph (i.e., there is a 100%
probability that cumulative releases from the disposal system will be
either zero or greater, and will not take on negative values); and then
decreases toward the right as the normalized release becomes
[[Page 58824]]
larger, and as relatively fewer simulations yield releases that exceed
the corresponding normalized release value.
Each CCDF curve in the CCA is calculated using 10,000 simulations
or ``futures,'' each of which models a ten-thousand year period in
which a series of human intrusion events may occur. (For further
information about how the possible effects of human intrusion are
included in the PA, see the preamble discussions of Secs. 194.32 and
194.33.) A single CCDF curve uses a fixed set of uncertain physical,
chemical and geologic characteristics at the WIPP and its surroundings,
but uses 10,000 different, randomly-determined sequences of intrusion
events. Different CCDF curves are developed by using different
information about the uncertain physical, chemical and geologic
characteristics of the WIPP and its surroundings. The CCA PA included
300 different CCDF curves so that, in all, it calculated normalized
releases for three million different possible futures.
EPA reviewed features, events and processes, scenarios, conceptual
models and computer codes that support CCDF generation. EPA found that
all significant features, events and processes and scenarios were
included in the generation of CCDFs. (See preamble discussions of
Secs. 194.32 and 194.33 for more detailed information on EPA's
evaluation of PA scenarios.) DOE used the same approach in calculating
and presenting results of the Performance Assessment Verification Test
(``PAVT'').
The Agency found that DOE assembled the results of the CCA PA and
the PAVT into CCDFs incorporating all significant processes and events.
Therefore, the Agency proposes to find DOE in compliance with the
requirements of Sec. 194.34(a).
2. Generation of the Full Range of CCDFs
Section 194.34(e) requires the CCA to display the full range of
CCDFs generated. The CCA included all three hundred CCDFs. These were
presented in three graphs, one for each replicate of one hundred CCDF
curves. In addition, DOE provided summary CCDF curves for descriptive
statistics. DOE generated a mean CCDF curve, 95th-percentile confidence
bound curves for the mean, a 10th percentile curve, a median curve, and
a 90th percentile curve for each replicate, and generated a mean curve
and 95th-percentile confidence bound curves for the mean of all three
replicates. The Department also provided the same information for the
PAVT.
EPA determined that the CCA displayed the full range of CCDF curves
over the full range of CCDF values and displays normalized releases
relevant to the determination of DOE's compliance with Sec. 194.34(e).
EPA also concluded that DOE applied the same methodology to the PAVT
for displaying the full range CCDF curves over the full range of
probabilities and normalized releases. Therefore, EPA proposes to find
that DOE has demonstrated compliance with Sec. 194.34(e).
3. Probability Distributions and Random Sampling of Uncertain
Parameters
Section 194.34(b) requires DOE to develop and document probability
distributions for uncertain disposal system parameter values used in
PA. Section 194.34(c) requires DOE to use and to document computational
techniques which draw random samples from across the entire range of
these probability distributions to generate CCDFs.
Parameters are numerical values or ranges of numerical values used
to describe different physical and chemical aspects of the repository,
the geology and geometry of the area surrounding the WIPP, and possible
scenarios for human intrusion. Some parameters are well-established
chemical and physical constants, such as Avogadro's Number or the
Universal Gas Constant. Other parameters describe characteristics
unique to the WIPP, such as the solubility and mobility of specific
actinides in brines in the WIPP. It is not possible to determine a
single, constant value to describe particular characteristics of the
WIPP, in which case one must consider a range of values. The relative
probabilities of occurrence of different uncertain parameter values
within that range can be presented as a mathematical expression known
as a probability distribution. A probability distribution may be
described in terms of statistical parameters such as the average
(mean), median, maximum and minimum values of the parameter, or
standard deviation. Section 194.34(b) requires development and
documentation of these probability distributions.
DOE selected 57 uncertain parameters whose values were to be
obtained through random sampling in the PA. DOE also performed a
sensitivity analysis to show if changes to some parameter values would
affect the results of PA.
The uncertainty in the value of a parameter is built into PA
computer codes by programs that ``sample,'' or select, numeric values
from within the probability distribution for that parameter. Section
194.34(c) requires these sampling techniques to draw random samples
from across the entire range of each probability distribution. This
requirement ensures that PA calculations fully consider the possible
extremes of calculated releases of radioactivity without systematically
underestimating or overestimating releases.
The Department used the Latin Hypercube Sampling (``LHS'') code to
sample the parameter distributions related to physical, chemical and
geologic conditions of the repository and its surroundings. DOE used
Monte Carlo-type random sampling to determine the effects of human
intrusion through drilling or mining. Both codes select values from
across the entire range of the probability distributions. The LHS code
requires fewer samples to cover the entire range of the distribution
because it samples randomly within divisions spread across the entire
probability distribution.
EPA reviewed the parameters used in the modeling, the probability
distributions for the sampled parameters and DOE's sensitivity
analysis. As a result of its review, the Agency found that 58 parameter
values and distributions were not well supported by the data available.
(See the preamble discussion of Sec. 194.23 for further details on
EPA's review of parameters.) EPA performed its own sensitivity analysis
on some parameters to determine if uncertainties in the parameter
values of concern would have a significant impact on the PA. The Agency
concluded that many of the parameters of concern had little impact, but
twenty-four parameters could significantly affect the PA results,
either individually or in combination with other parameters.
As a result of the parameter review, EPA requested that DOE perform
additional modeling. This additional modeling, the PAVT, included,
among other things, parameter value and distribution modifications to
twenty-four parameters that the Agency believed might have a
significant impact on the results of PA. DOE conducted the PAVT using
the same computer codes and the same sampling methodologies as for the
CCA PA, but changed the 24 parameters in accordance with EPA's
direction and modified some of the computer codes in response to EPA's
questions about the codes. DOE conducted 300 simulations for the PAVT,
resulting in 300 CCDF curves, just as for the CCA PA. The results of
the PAVT showed higher normalized releases than those in the CCA PA,
but were still more than an order of
[[Page 58825]]
magnitude below the containment requirements at Sec. 191.13. Thus, the
PAVT incorporated changes that addressed EPA's concerns about PA, and
showed that the resulting releases were still within the containment
requirements. Because the PAVT used identical technical methods to the
CCA PA, EPA concludes that the PAVT results are numerically equivalent
to those that would be obtained by performing a new PA incorporating
the changes required in the PAVT. EPA believes that the PAVT verifies
that the original CCA PA was adequate for comparison against the
radioactive waste containment requirements.
Because DOE has developed and documented the probability
distributions for uncertain disposal system parameter values used in
the PA, EPA proposes to find the DOE to be in compliance with
Sec. 194.34(b). After reviewing the results of sensitivity analyses and
of the PAVT, the Agency concludes that the probability distributions
are adequate. The Agency found that the LHS and Monte Carlo sampling
techniques draw random samples from across the entire ranges of the
probability distributions used for the uncertain disposal system
parameters in the PA. The use of these computational techniques are
documented in the CCA. Therefore, EPA proposes to find that DOE has
demonstrated compliance with Sec. 194.34(c).
4. Sufficient Number of CCDFs Generated
Section 194.34(d) requires DOE to generate a sufficiently large
number of CCDF curves to ensure that, at cumulative releases of 1 and
10, the maximum CCDF exceeds the 99th percentile of the population of
CCDFs with at least a 95-percent probability. Section 194.34(d) also
requires DOE to calculate cumulative release values according to Note 6
of Table 1 in Appendix A of 40 CFR Part 191.
The PA process uses techniques based upon probability theory to
calculate the potential for releases. Because of the many sources of
uncertainty, a computer model could calculate results of billions of
situations without exhausting every possibility. However, running
billions of simulations is not feasible given the cost and time
involved. Furthermore, this is not necessary in order to provide a
reasonable expectation that a disposal system will contain waste and
protect human health and the environment. So long as the PA includes a
large enough number of randomly-produced simulations covering the full
range of possible calculated release values, the results of PA will
yield a valid result that shows whether or not a disposal system meets
the containment requirements of Sec. 191.13. (61 FR 5230) Section
194.34(d) provides a statistical test to determine if the CCA contains
enough CCDF curves: there must be at least a 95 percent probability
that the CCDF curve generated in PA with the highest cumulative release
exceeds the 99th percentile of the entire population of CCDFs (that is,
the full range of possible calculated release values).
As was mentioned above in this section, each CCDF is generated
using a specific set of sampled values from distributions of uncertain
parameters related to the physical, chemical and geologic conditions of
the repository and its surroundings. In the case of the WIPP, the CCA
PA included three sets or replicates of one hundred CCDF curves, for a
total of 300 CCDF curves. Each of the CCDF curves is based upon a
sample of 57 uncertain parameters.
DOE used the LHS code to take samples of the parameter values. The
Department also presented a probabilistic analysis, based on the
definition of the 99th percentile, and determined that there would be a
0.95 probability that at least one CCDF curve will exceed the 99th
percentile so long as the PA includes at least 298 CCDF curves. Since
the CCA PA included 300 CCDF curves, DOE concluded that this was enough
CCDF curves to meet the requirements of Sec. 194.34(d).
EPA agreed with DOE's argument based upon probability and the
definition of the 99th percentile, and concluded that the CCA PA
generated a sufficient number of CCDFs. As another approach to
evaluating compliance with Sec. 194.34(d), EPA also examined the
statistical characteristics of the 300 CCDF curves in the CCA PA. EPA
compared the CCDF curves in the CCA PA to a statistical distribution
that the Agency believes is a plausible description of what the entire
population of all possible CCDFs would produce. EPA found that the
maximum CCDF curve in the CCA PA had a higher cumulative release than
the 99th percentile predicted using the probability distribution which
represents the entire population of CCDFs. Based upon this statistical
analysis, the Agency concluded that there was at least a 95 percent
probability that the maximum CCDF curve would exceed the 99th
percentile of the population of CCDFs.
Section 194.34(d) also requires PA to calculate cumulative release
values according to Note 6 of Table 1 in Appendix A of 40 CFR Part 191.
DOE's approach to calculating cumulative release (or ``normalized
release'') values is described in the introduction to this section of
the preamble. EPA found DOE's approach to be consistent with Note 6 of
Table 1 in Appendix A of 40 CFR Part 191.
EPA found that DOE generated 300 CCDF curves in the PA, using the
appropriate method to calculate cumulative releases, as specified in
Note 6 of Table 1 in Appendix A of 40 CFR Part 191. Because of the
statistical arguments described above, EPA is satisfied that the number
of CCDFs is large enough such that, at cumulative releases of 1 and 10,
the maximum CCDF generated exceeds the 99th percentile of the
population of CCDFs with at least a 0.95 probability. Therefore, EPA
proposes to find that DOE has demonstrated compliance with
Sec. 194.34(d).
5. Compliance of the Mean CCDF
Section 194.34(f) requires the CCA to demonstrate that the mean of
the population of CCDFs meets the containment requirements of
Sec. 191.13 with at least a 95 percent level of statistical confidence.
This statistical demonstration allows DOE to demonstrate compliance
using a finite number of CCDFs, rather than having to generate the
entire (infinitely large) population of CCDFs.
In order to meet the requirements of Sec. 194.34(f), DOE must
calculate the mean CCDF curve from all 300 CCDF curves generated in the
CCA PA, must compute the 95 percent confidence limits for that overall
mean curve, and must compare the 95 percent upper confidence limit CCDF
curve to the containment requirements of Sec. 191.13. The DOE must show
that the mean of its 300 CCDF curves, and the 95th percentile upper
confidence limit on the mean, both lie below a probability of 0.1 at a
cumulative release value of 1, and lie below a probability of 0.001 at
a cumulative release value of 10.
In the CCA, DOE presented the steps used in its PA to generate the
300 CCDF curves. DOE also showed how it then calculated the mean of all
CCDFs, by first computing the mean CCDF for each of the three
replicates of 100 curves, and then averaging those three mean CCDF
curves. Using the three mean CCDF curves, DOE calculated the 95 percent
confidence limits for the overall mean CCDF curve. DOE identified the
mean of all CCDFs generated and the 95 percent confidence limits and
showed that both the mean CCDF and the CCDF for the upper confidence
limit satisfy the containment requirements by more than an order of
magnitude.
[[Page 58826]]
EPA examined DOE's calculations of the mean CCDF curve and the CCDF
curve for the 95 percent confidence limit on the mean, and found that
they were appropriate and were correctly executed. EPA concurred with
DOE's conclusion that both the mean CCDF and the CCDF for the upper
confidence limit satisfy the containment requirements by more than an
order of magnitude.
As discussed above, EPA was dissatisfied with many of the parameter
ranges and values used in PA and had concerns about some codes and the
assumption of credit for passive institutional controls. EPA required
DOE to perform the PAVT to determine whether the cumulative impact of
the changes in PA codes and parameters would require additional PA
runs. DOE applied the same methodology in the CCA PA and in the PAVT
for calculating the mean CCDF curve and the 95 percent upper confidence
limit. The PAVT results demonstrate that the level of statistical
confidence is significantly greater than 95% that the mean of the CCDFs
meets the Sec. 191.13 containment requirements. Therefore, EPA
concludes that the final results of the PAVT are also in compliance
with the containment requirements of Sec. 191.13 and that the results
are presented in accordance with Sec. 194.34(f).
A public comment received on EPA's Advance Notice of Proposed
Rulemaking (ANPR) expressed concern about the fact that at least some
of the CCDF curves in the CCA PA indicated that there would be releases
into the accessible environment. EPA's containment requirements limit
the likelihood of releases at specific levels, but do not require DOE
to demonstrate that no releases of any magnitude will occur. EPA
recognized that some parameters used in CCA PA were questionable, and
required DOE to perform a PAVT that included revised parameters in
order to alleviate concerns such as those raised by the commenter. Less
than one percent of CCDF curves in the CCA PA exceeded normalized
releases of one. EPA concludes that the probabilities of such releases
are still well below the EPA release limits.
The CCA demonstrates that there is at least a 95 percent level of
statistical confidence that the mean of the population of CCDFs meets
the containment requirements of Sec. 191.13. (The PAVT results indicate
that PA would still demonstrate that the WIPP is in compliance with the
containment requirements of Sec. 191.13, even including substantial
modifications to some of the significant uncertain parameters used in
PA.) Therefore, EPA proposes that the WIPP complies with the
containment requirements of Sec. 191.13 and with Sec. 194.34(f). EPA
believes that the WIPP will safely contain radioactive waste for up to
10,000 years after disposal and will protect public health and the
environment. For further information on the EPA's evaluation of
compliance for Sec. 194.34, or on the results of the PA or the PAVT,
see CARD 34.
XII. Assurance Requirements
In 40 CFR 191.14, EPA included six qualitative assurance
requirements to assure that the desired level of protection is achieved
at disposal facilities. (60 FR 5777) The assurance requirements address
active institutional controls, monitoring, passive institutional
controls, engineered barriers, consideration of the presence of
resources, and removal of waste. These measures are designed to
compensate for the inherent uncertainty in projecting the behavior of
natural and engineered components of the repository for many thousands
of years. (50 FR 38072) The assurance requirements are implemented at
the WIPP by Secs. 194.41 through 194.46 of the WIPP Compliance
Criteria.
A. Section 194.41, Active Institutional Controls
Section 194.41 implements the active institutional controls
(``AICs'') assurance requirement. The disposal regulations define AICs
as ``controlling access to a disposal site by any means other than
passive institutional controls, performing maintenance operations or
remedial actions at a site, controlling or cleaning up releases from a
site, or monitoring parameters related to disposal system
performance.'' (40 CFR 191.12) Section 194.41 requires AICs to be
maintained for as long a period of time as is practicable after
disposal; however, contributions from AICs may not be considered in the
PA for more than 100 years after disposal.
In evaluating DOE's compliance with Sec. 194.41, EPA sought a
detailed description of DOE's proposed AICs and how those controls
would be implemented. EPA reviewed this description for thoroughness,
feasibility, and likely effectiveness. DOE proposed to: construct a
fence and roadway around the surface footprint of the repository; post
warning signs; conduct routine patrols and surveillance; and repair
and/or replace physical barriers as needed. DOE also identified other
measures that function as AICs, such as DOE's prevention of resource
exploration at the WIPP and DOE's construction of long-term site
markers. DOE stated that it would maintain the proposed AICs for at
least 100 years after closure of the WIPP, and that the WIPP PA assumed
that AICs would prevent human intrusion for that period.
EPA reviewed the proposed AICs in connection with the types of
activities that may be expected to occur in the vicinity of the WIPP
site during the first 100 years after disposal (i.e., ranching,
farming, hunting, scientific activities, utilities and transportation,
groundwater pumping, surface excavation, potash exploration,
hydrocarbon exploration, construction, and hostile or illegal
activities). EPA also examined the assumptions made by DOE to justify
the assertion that AICs will be completely effective for 100 years. The
assumptions were that: (1) The fence and signs will convey the message
that the WIPP site is hazardous and protected; (2) legal prohibitions
on resource recovery activities will be enforced; and (3) the time
required to initiate a resource extraction operation will allow routine
site patrols to discover and halt such activities.
EPA found the assumptions regarding longevity and efficacy of the
proposed AICs to be acceptable. This finding was based on the fact that
the types of inadvertent intrusion which AICs are designed to obviate
are not casual activities, but require extensive resources, lengthy
procedures for obtaining legal permission, and substantial time to set
up at the site before beginning.
Section 194.41 prohibits the consideration of contributions from
AICs in the PA for more than 100 years after disposal. Contributions
from AICs in the PA are considered as a reduction in the rate of human
intrusion. EPA reviewed the CCA and the parameter inputs to the PA and
determined that DOE did not assume credit for the effectiveness of
active institutional controls for more than 100 years after disposal.
EPA found the description of each active control measure (fence,
signs, roadways, site maintenance, and security patrols) and its
location to be adequate to support its intended function. Also, EPA
found DOE's assumptions to be sufficient to justify DOE's assertion
that AICs will completely prevent human intrusion for 100 years after
closure. Because DOE adequately described the proposed AICs and the
basis for their assumed effectiveness and did not assume in the PA that
AICs would be effective for more than 100 years, EPA proposes to find
DOE in compliance with Sec. 194.41. For further information on EPA's
[[Page 58827]]
evaluation of compliance for Sec. 194.41, refer to CARD 41.
B. Section 194.42, Monitoring
Section 194.42 implements the assurance requirement that DOE
monitor the disposal system to detect deviations from expected
performance. The monitoring requirement distinguishes between pre- and
post-closure monitoring because of the differences in the monitoring
techniques that may be used during operations (pre-closure) and once
the repository has been backfilled and sealed (post-closure).
Monitoring is intended to provide information about the repository that
may affect the results of the PA or containment of waste.
To meet the criteria of Sec. 194.42, EPA required DOE to conduct an
analysis of the effects of disposal system parameters on the
containment of waste. At a minimum, this analysis must include the
seven specific parameters listed in Sec. 194.42(a). DOE was required to
present the analysis methodology, assumptions and results. DOE also was
required to justify the decision not to monitor any of the parameters
analyzed. (Sec. 194.42(b))
Section 194.42 requires that the screening of parameters be
conducted to develop plans for pre- and post-closure monitoring
described in Secs. 194.42(c) and (d). In accordance with
Sec. 194.42(e), these monitoring plans must: (1) identify the
parameters to be monitored and how the baseline data will be
determined, (2) indicate how the parameters will be used to evaluate
deviations from the expected performance of the disposal system, and
(3) discuss the length of time over which each parameter will be
monitored.
DOE conducted an analysis of disposal system parameters that
included the parameters specified in Sec. 194.42(a), along with other
parameters. The analysis assigned high, medium or low significance to
each parameter for its importance to the containment of waste and to
the verification of predictions about disposal system performance. DOE
then screened parameters out of consideration for monitoring based on
the ability of the parameter to produce meaningful data during the
monitoring period and on whether parameters can be monitored without
violating disposal system integrity.
EPA evaluated the analysis and screening of parameters, including
the methodology, assumptions, and results. EPA found that the analysis
included the required parameters and adequately justified both the
selection and rejection of parameters for inclusion in monitoring
plans. Therefore, EPA proposes to find DOE in compliance with
Secs. 194.42(a) and (b).
Based on the results of its analysis, DOE submitted plans that
identified ten parameters that will be monitored for pre-closure
monitoring, five of which will also be monitored for post-closure
monitoring. The pre-closure monitoring parameters are: (1) Culebra
groundwater composition, (2) change in Culebra groundwater flow, (3)
probability of encountering a Castile brine reservoir, (4) drilling
rate, (5) subsidence measurements, (6) waste activity, (7) creep
closure and stresses, (8) extent of deformation, (9) initiation of
brittle deformation and (10) displacement of deformation features.
Parameters one through five are also post-closure monitoring
parameters. The parameters selected for monitoring included several of
those listed in Sec. 194.42(a), such as creep closure and stresses,
extent of deformation, initiation of brittle deformation, displacement
of deformation features, Culebra ground water composition and flow and
Castile brine reservoir location.
The CCA described how DOE intends to implement monitoring programs
for both pre-and post-closure parameters. The monitoring plans included
information on establishing baseline data, how monitoring data will be
used to evaluate deviations from expected performance and on the length
of time each parameter will be monitored. EPA finds that DOE submitted
monitoring plans in accordance with Secs. 194.42(c), (d), and (e). The
monitoring plans in the CCA addressed both pre-closure monitoring
(planned to begin before emplacement of waste) and post-closure
monitoring (using methods that would not jeopardize containment of
waste in the disposal system), and included information required by the
Compliance Criteria.
EPA proposes to find DOE in compliance with the requirements of
Sec. 194.42. In accordance with its authority under Sec. 194.21, EPA
intends to conduct an inspection of the pre-closure monitoring
activities prior to emplacement of waste to confirm implementation of
the plans detailed in the CCA. The results of this inspection will be
placed in the public dockets described under Sec. 194.67. For further
information on EPA's evaluation of compliance for Sec. 194.42, see CARD
42.
C. Section 194.43, Passive Institutional Controls
The Compliance Criteria at Sec. 194.43 require a description of
passive institutional controls (PICs) that will be implemented at the
WIPP. PICs are measures that do not require human intervention in order
to warn away potential intruders from disposal sites. EPA defined PICs
in the disposal regulations as markers, public records and archives,
government ownership of a site and restrictions on land use at the
site, and any other means of preserving knowledge of a site. (50 FR
38085) PICs are intended to deter unintentional intrusions by people
who otherwise might not be aware of the presence of radioactive waste
at the site.
Sections 194.43(a)(1) through (3) of the Compliance Criteria
implement the disposal regulations by requiring DOE to: (1) identify
the controlled area by markers designed, fabricated, and emplaced to be
as permanent as practicable; (2) place records in local, State,
Federal, and international archives and land record systems likely to
be consulted by individuals in search of resources; and (3) employ
other PICs intended to indicate the location and dangers of the waste.
In accordance with Sec. 194.43(b), DOE also must indicate the period of
time that PICs are expected to endure and be understood by potential
intruders. Finally, DOE is permitted to propose a credit for PICs in
the PA, as explained in Sec. 194.43(c). Such credit must be based on
the proposed effectiveness of PICs over time, and would take the form
of reduced likelihood in the PA of human intrusion over several hundred
years. The Compliance Criteria prohibit DOE from assuming that PICs
could entirely eliminate the likelihood of future human intrusion.
The PICs design proposed by DOE in the CCA calls for the
construction at the WIPP site of a large earthen berm, dozens of
granite monuments, and three granite information rooms, two of which
will be buried for their protection. DOE also proposed to bury
thousands of small markers at shallow depths around the site. All
markers except the berm will be engraved with warning messages in
several languages and of varying complexity.
DOE plans to distribute WIPP records and other information to over
one hundred archives, record centers, professional organizations, and
commercial enterprises in the United States and abroad. Finally, DOE
points to its ownership of the WIPP site as a measure that will
identify the site as Federal property and off limits to resource
exploration.
EPA evaluated whether the proposed markers are ``as permanent as
practicable'' by considering the manner in which DOE accounted for
potential marker failures and by confirming that
[[Page 58828]]
the proposed markers could be fabricated. EPA's analysis of the
proposed markers suggests that they are practicable, although DOE may
decide to revise the design as implementation proceeds. Any such
revisions would constitute a modification of the design and would
therefore require EPA approval in accordance with Secs. 194.65 and
194.66. Also, the CCA showed that the proposed design incorporates
features intended to promote the endurance of markers. Examples of
these features are: redundant markers, highly durable materials with
low intrinsic value, large dimensions, and location both above and
below the surface. EPA proposes to find that the proposed markers are
designed to be as permanent as practicable, in accordance with
Sec. 194.43(a)(1).
With regard to placement of records, DOE has prioritized archives
and record centers in order to target those closest to the WIPP and
most likely to be consulted by resource exploration industries
nationally and abroad. The additional PICs proposed by DOE, which
involve placement of WIPP information on maps and in various reference
materials, also appear to be practicable. Therefore, EPA proposes to
find that DOE complies with Secs. 194.43(a)(2) and (3).
DOE estimated the amount of time that most of the proposed PICs are
expected to endure by comparing them to analogues with similar
properties that have survived to the present. The estimates of
endurance, the lowest of which is at least 2,400 years and the greatest
of which is at least 5,000 years, vary according to the age of
analogues. DOE estimated the length of time that messages and records
are expected to be understood (at least 1,000 years) by making
assumptions about the future and then stating why those assumptions are
reasonable. Because DOE based its design on sound principles, took into
account likely failures of PICs, based estimates of endurance on
relevant analogues, and based estimates of comprehensibility on a
reasonable framework of assumptions, EPA believes that the proposed
design for markers meets the criterion of ``as permanent as
practicable'' and that DOE's estimates for that purpose are acceptable
for compliance with Sec. 194.43(b).
DOE proposed to take most of the steps necessary for implementing
the proposed PICs, such as making arrangements with archives and record
centers and refining marker messages, during the WIPP's operational
period. However, DOE also plans to extend some activities, particularly
testing of markers, over nearly 100 years after closure (i.e., during
the proposed active institutional control period) before finalizing
important aspects of the design, in the belief that future technology
may improve the design. EPA cannot base a regulatory determination that
DOE has demonstrated compliance with the requirements at Sec. 194.43 on
a speculative plan to finalize the required design during the active
institutional control period. It would be inconsistent with Congress'
intent in the LWA for EPA to allow DOE to alter the approved PICs
design after EPA's regulatory function comes to an end.
Rather, EPA's determination must be based on the design proposed in
the CCA. EPA acknowledges that future technological developments might
improve the design of certain PICs components. Should DOE develop
evidence that aspects of the proposed design can be improved during the
operational period, DOE could then request modification of the approved
plan in a recertification application. DOE also will not be precluded
in the future from implementing other measures in addition to those
comprising the final design. During the period that EPA exercises
regulatory oversight over the WIPP, DOE may not alter or delete aspects
of the approved plan in the CCA without notifying EPA and subjecting
the certification to modification, if EPA deems it necessary.
Given that EPA considered the design proposed in the CCA to be
final for the purposes of its compliance review, EPA finds that DOE has
not justified sufficiently the need for additional testing of markers
after closure of the repository or the need to delay implementation for
many years after closure. EPA believes that PICs should be implemented
as soon as possible after the WIPP facility is sealed, and that
measures necessary to prepare for such implementation should be
accomplished during the operational period for the WIPP, unless doing
so would compromise the effectiveness of the CCA design. For example,
EPA believes that it is appropriate and practicable during the
operational period for DOE to establish agreements with national
archives to accept and maintain records related to the WIPP. EPA
therefore proposes to find DOE in compliance with the PICs requirements
at Secs. 194.43(a) and (b), on the condition that DOE submit additional
information to EPA for approval. No later than the final re-
certification application submitted prior to closure of the disposal
system, DOE must provide a schedule for implementing PICs that has been
revised to show that markers will be fabricated and emplaced, and other
measures will be implemented, as soon as possible following closure of
the disposal system. DOE also must describe how testing of any aspect
of the conceptual design will be completed prior to or soon after
closure, and what changes to the design may be expected to result from
such testing. (See Condition 4 of the proposed Appendix A to 40 CFR
Part 194.)
DOE proposed to take a credit of 99 percent over 700 years in the
PA. In other words, DOE requested that the likelihood of human
intrusion into the WIPP during the first 700 years after closure be
reduced to one percent of the drilling rates calculated in accordance
with the requirements of Secs. 194.33(b)(3) and (4). The proposed
credit was based largely on DOE's approach to compliance with
Sec. 194.43(b), which led DOE to conclude that all PICs are ``virtually
certain'' to endure and be understood for at least 700 years. DOE
identified drilling in the wrong location on a properly issued lease as
the only plausible scenario whereby the proposed PICs could fail to
deter an inadvertent intrusion. DOE then surveyed the Delaware Basin
and other areas for such failures and determined that wells were
drilled in the wrong location in 5 out of 429,000 instances, a rate of
0.001 percent. Finally, DOE bounded the failure rate (of 0.001) at 1.0
percent for the sake of conservatism.
EPA agrees with DOE that the proposed PICs appear likely to endure
and be understood for hundreds of years. However, EPA proposes to deny
DOE's request for PICs credit. The reasons for EPA's denial of PICs
credit are discussed briefly below.
First, in promulgating its PICs credit criterion, EPA explicitly
stated that ``the degree to which PICs might reduce the future drilling
rate can be reliably determined only through informed judgment.'' (61
FR 5232) EPA clearly expected the proposed PICs credit to be derived
through an expert elicitation conducted in accordance with the
requirements at 40 CFR 194.26. DOE instead prepared a justification and
submitted it to peer review. EPA regards peer review as qualitatively
different from expert judgment, in which the independent panel itself
prepares the justification.
Second, Sec. 194.43(c) states, ``In no case . . . shall passive
institutional controls be assumed to eliminate the likelihood of human
intrusion entirely.'' DOE's rationale for the proposed credit
repeatedly states that PICs are ``virtually certain'' to eliminate the
likelihood of human intrusion. EPA believes that the
[[Page 58829]]
assertion that PICs are virtually certain (i.e, 99.9 percent) to endure
and be understood is equivalent in effect to assuming that they
eliminate the likelihood of human intrusion entirely. Furthermore,
DOE's estimate of the effectiveness of PICs does not adequately account
for the considerable uncertainty associated with quantifying the
effectiveness of PICs for use in the PA. Specifically, there are
potential failure scenarios that DOE did not account for in developing
the proposed credit. For example, within the next 700 years, someone
could drill based on an incorrect permit, permits may be mistakenly
granted, records of the WIPP could be lost, or a system of permits to
control drilling may be abandoned. While DOE's proposal does not
account conservatively for uncertainty, EPA recognizes that any level
of credit EPA would propose in place of DOE's estimate would be
arbitrary. Finally, EPA found that the issue of quantitative credit for
PICs is of little consequence for the purpose of evaluating the WIPP's
performance, since the removal of PICs credit from computer models (in
the Performance Assessment Verification Test) produced no signification
effect on the WIPP's compliance with EPA's numerical standards.
EPA proposes to determine that DOE complies with Sec. 194.43, on
the condition that additional information on the final PICs design be
submitted for EPA's review no later than the final re-certification
application. For additional information on EPA's evaluation of
compliance for Sec. 194.43, see CARD 43.
D. Section 194.44, Engineered Barriers
Section 194.44 requires that DOE conduct a study of available
options for engineered barriers at the WIPP and submit this study and
evidence of its use with the compliance application. Consistent with
the assurance requirement found at 40 CFR 191.14, which requires the
use of one or more engineered barriers, DOE must analyze the
performance of the complete disposal system, and any engineered
barrier(s) that DOE ultimately implements at the WIPP must be
considered in the PA and EPA's subsequent evaluation.
To comply with this requirement, EPA expected DOE to describe the
engineered barrier(s) selected for implementation at the WIPP. EPA also
expected the CCA to document how the engineered barrier(s) prevents or
substantially delays the movement of water or radionuclides to the
accessible environment, and how it reduces uncertainties in modeling
performance of the disposal system. EPA expected DOE to conduct a
comprehensive evaluation of engineered barrier alternatives in order to
compare the benefits and detriments of various barriers and then use
the results of such a comparison to justify selecting or rejecting a
barrier(s).
In accordance with Sec. 194.44(b), EPA observed DOE's scoping study
and screening process during March and April 1995. The scoping effort
produced a list of 111 potential barriers and combinations of barriers
(including the barriers described in Sec. 194.44(b)), of which 18 were
evaluated against the factors described in Sec. 194.44(c). Although DOE
did not specifically address the waste categories in Sec. 194.44(d),
the study effectively accounted for the categories by analyzing three
waste types (sludges, solid organics, and solid inorganics) and
considering multiple waste processing schemes. DOE's evaluation of
engineered barriers was peer reviewed in accordance with
Sec. 194.27(a)(3). See Sec. 194.27, ``Peer Review,'' for details of
EPA's evaluation of the general peer review process. On the basis of
its evaluation of the benefits and detriments of eighteen engineered
barrier types, DOE concluded that a chemically-buffering backfill was a
high-benefit, low-cost, and practicable engineered alternative. DOE
selected magnesium oxide (MgO) backfill as an engineered barrier, and
proposed to emplace bags of MgO between and around waste containers in
the repository. DOE stated that the backfill will serve to: (1)
substantially delay movement of radionuclides by controlling chemical
conditions in the underground waste panels so that the solubility of
radionuclides in water is reduced, (2) delay movement of water by
reacting with brine to reduce free water in the disposal system, and
(3) fix pH levels within a narrow range, thereby bounding an important
modeling parameter whose value might otherwise be highly uncertain.
EPA found that DOE conducted the requisite analysis of engineered
barriers and selected an engineered barrier designed to prevent or
substantially delay the movement of water or radionuclides toward the
accessible environment. DOE provided substantial documentation in the
CCA and supplementary information that MgO can effectively reduce
actinide solubility in the disposal system. EPA agrees that the
chemical reactions that DOE associated with MgO can occur under
predicted repository conditions. DOE proposed to emplace a large amount
of MgO in and around waste drums in order to provide an additional
factor of safety and thus account for uncertainties in the geochemical
conditions that would affect CO2 generation and MgO
reactions. (For details regarding chemical reactions of MgO, see CARD
24, ``Waste Characterization.'' For further information regarding the
PA modeling of solubility and chemical conditions in the repository,
see CARD 23, ``Models and Computer Codes.'')
Public comments received on EPA's Advance Notice of Proposed
Rulemaking (``ANPR'') questioned two aspects of DOE's treatment of
engineered barriers in the CCA. First, commenters disagreed that
borehole plugs, shaft seals, and panel seals should be treated by DOE
as engineered barriers for the purpose of complying with Sec. 194.44.
EPA found that DOE had treated plugs and seals as part of the baseline
design of the disposal system, not as additional barriers for the
purpose of assurance. The effectiveness of plugs and seals is discussed
as part of EPA's evaluation of the disposal system design under
Sec. 194.14, ``Content of Compliance Certification Applications.''
Second, commenters expressed concern that the CCA did not support
conclusions about the effectiveness of MgO with experimental data or
other documentation. EPA shared this concern and so requested that DOE
provide additional documentation showing that backfill could be
emplaced in the required manner and would function in the disposal
system as proposed. EPA believes that supplementary information sent by
DOE adequately addressed insufficiencies in the CCA.
EPA proposes to find DOE in compliance with Sec. 194.44. For
further information on EPA's evaluation of compliance for Sec. 194.44,
see CARD 44.
E. Section 194.45, Consideration of the Presence of Resources
Section 194.45 implements the assurance requirement that the
disposal system be sited such that the benefits of the natural barriers
of the disposal system compensate for the increased probability of
disruptions to the disposal system resulting from exploration and
development of existing resources. (61 FR 5232) In promulgating this
requirement, EPA determined that the performance assessment (``PA'') is
the appropriate tool to weigh the advantages and disadvantages of the
WIPP site because PA demonstrates whether potential human intrusion
will cause unacceptably high releases of radioactive material from the
disposal facility.
[[Page 58830]]
In accordance with the Compliance Criteria, DOE must demonstrate
that PA has incorporated the potential effects of human activities near
the WIPP prior to disposal, and of drilling and excavation mining over
the regulatory time frame. DOE also must document that the results of
the PA demonstrate compliance with the containment requirements at 40
CFR 191.13. No further demonstration of compliance is needed for
Sec. 194.45.
The Agency confirmed that PA incorporated human intrusion scenarios
and met EPA's release limits in accordance with the WIPP Compliance
Criteria. Based on EPA's findings that DOE complied with requirements
related to scope of PA, conduct of PA, mining and drilling activities
over the regulatory time frame, results of PA, and pertinent assurance
requirements, EPA proposes to determine that DOE has demonstrated
compliance with Sec. 194.45. For further explanation of EPA's proposed
compliance decisions for these related compliance criteria, see
preceding preamble discussions for Sec. 194.14, Sec. 194.23,
Sec. 194.32, Sec. 194.33, Sec. 194.34, Sec. 194.41, and Sec. 194.43.
For further information on EPA's evaluation of compliance for
Sec. 194.45, refer to CARD 45.
F. Section 194.46, Removal of Waste
Section 194.46 requires documentation that the removal of waste
from the disposal system is feasible for a reasonable period of time
after disposal. (61 FR 5244) The intent of this provision is to
implement the assurance requirement at 40 CFR 191.14(f) that ``disposal
systems be selected so that removal of most of the waste is not
precluded for a reasonable period of time after disposal.'' To meet the
criteria of Sec. 194.46, EPA expected the CCA to provide a
comprehensive strategy that showed the manner in which waste could be
removed from the repository for a reasonable period of time after
closure and an estimate of how long after disposal removal of waste
would remain technologically feasible. Although the eventual
disposition of the waste is an important environmental concern, 40 CFR
Part 194 does not require DOE to speculate on the possible location or
hazards of the waste once it is removed from the repository.
In the CCA, DOE presented a five-phase approach to removing waste
from the WIPP repository, including: planning and permitting; initial
above-ground set-up and shaft sinking; underground excavation and
facility set-up; waste location and removal operations; and
decontamination and decommission of the facility. The CCA included a
discussion of techniques that could be used to remove the waste given
the repository conditions at the time of removal, and also discussed
several existing mining techniques that could be used to remove waste
from the WIPP repository.
EPA reviewed the CCA to assess the completeness of the strategy for
removing the waste and the justification of the proposed technology for
removing the waste. EPA believes that the five phases described for
waste removal provide an orderly sequence of planning and
implementation procedures that could be implemented. EPA agrees that
the proposed activities, techniques, and equipment that would be
necessary to remove the waste are all presently feasible.
EPA reviewed the CCA for an estimate of how long after disposal it
would remain technologically feasible to remove the waste. DOE stated
that, using the system and equipment proposed in the CCA, it would be
feasible to remove the waste any time after emplacement. Thus, DOE
appeared to conclude that no features of the disposal system (such as
salt creep) will prevent the removal of waste from the repository as
long as the technology described in the CCA remains available. The CCA
did not address how long the technology might remain available.
EPA agrees that waste removal would be feasible as long as current
technology remains available, but does not believe it is reasonable to
assume that the technology will remain available over the entire
regulatory time frame. To estimate the length of time for which waste
removal would be feasible, EPA considered how long the technology
described in the CCA might remain available. The Agency concluded that,
as long as our present society remains stable, it is reasonable to
conclude that there will likely be a continuity or advancement of
technology which would allow waste removal to occur. In the disposal
regulations, EPA identified 100 years after disposal as a realistic but
conservative limit on how long active controls could be assumed to be
effective--i.e., how long present institutions would remain in place
continuously to enforce such controls. (50 FR 38080) Based on this same
rationale, EPA believes it is reasonable to assume that current
technology will remain available for the 100-year period after
disposal, and therefore that waste removal will remain feasible for
that time. EPA believes that 100 years constitutes a reasonable period
of time after disposal, in accordance with Sec. 194.46. Therefore, EPA
concludes that DOE has met the regulatory requirements for the removal
of waste, and proposes to find DOE in compliance with Sec. 194.46. For
further information on EPA's evaluation of compliance for Sec. 194.46,
see CARD 46.
XIII. Individual and Ground-water Protection Requirements
Sections 194.51 through 194.55 of the Compliance Criteria implement
the individual protection requirements of 40 CFR 191.15 and the ground-
water protection requirements of Subpart C of 40 CFR Part 191.
Assessment of the likelihood that the WIPP will meet the individual
radiation dose limits and radionuclide concentration limits for ground
water is conducted through use of a process known as compliance
assessment (``CA''). Compliance assessments use methods similar to
those of PA (for the containment requirements) but are required to
address only undisturbed performance of the disposal system. Sections
194.51 and 194.52 specify the requirements which must be incorporated
into CA in the analyses of individual radiation doses to protected
individuals. Section 194.53 addresses underground sources of drinking
water. Finally, the criteria specify the scope of CA and establish
statistical requirements on the results of CA in demonstrating
compliance with the individual and ground-water protection requirements
(Secs. 194.54 and 194.55).
A. Section 194.51, Consideration of Protected Individual
Section 194.51 requires DOE to assume in compliance assessments
(``CA'') that an individual resides at the point on the surface where
the dose from radionuclide releases from the WIPP would be greatest.
EPA required that the CCA identify the maximum annual committed
effective dose and the location where it occurs, and explain how DOE
arrived at those results.
DOE's analysis of the WIPP's compliance with Sec. 194.51 and
related sections of the Compliance Criteria was contained in the CCA
and in supplementary information. DOE described its analysis as a
``bounding analysis'' because it assumed that the maximum concentration
of radionuclides was available in underground sources of drinking water
(``USDWs'') and that humans using that water would therefore receive
the maximum dose possible from that pathway.
The bounding analysis was derived from the performance assessment
for the undisturbed scenario. DOE analyzed all potential routes of
release of radioactive
[[Page 58831]]
waste from the repository that could lead to exposure of an individual
and determined that the only release to the accessible environment
would be passage of contaminated water through the interbeds in the
Salado Formation, where the WIPP is situated. In the analysis, DOE
demonstrated that radionuclides migrated horizontally to the accessible
environment in only nine out of 300 realizations.
DOE then assumed that the highest concentration of radionuclides
from the nine realizations was present at the subsurface boundary of
the accessible environment, and that individuals would take water for
consumption or agricultural use directly from this location in the
Salado. DOE stated that it was not necessary to identify a single point
of maximum dose because the analysis assumed that the maximum
radionuclide concentration was available to individuals in brine taken
from the Salado Formation; therefore, the dose from various pathways
would be maximized regardless of an individual's location on the
surface of the accessible environment. For more discussion of DOE's
consideration of pathways in the bounding analysis, see Sec. 194.52,
``Consideration of Exposure Pathways.''
EPA agrees that it was conservative for DOE to base its
calculations of individual dose on the maximum predicted radionuclide
concentrations. EPA also accepts as technically sound DOE's rationale
for not identifying a single geographic point at which individual
committed effective dose is greatest, since under DOE's assumptions,
all points on the surface would result in the same maximum dose.
Therefore, EPA proposes to find DOE in compliance with Sec. 194.51. EPA
discusses whether the results of DOE's dose calculations comply with
the individual protection requirements at 40 CFR 191.15 under the
evaluation for Sec. 194.55, ``Results of CA.'' Due to the relatedness
of the requirements, EPA combined the discussion of DOE's compliance
for Secs. 194.51 and 194.52 (``Consideration of Exposure Pathways'') in
a single Compliance Application Review Document (CARD 51/52).
B. Section 194.52, Consideration of Exposure Pathways
The individual protection requirements focus on the annual
radiation dose of a hypothetical maximally-exposed person living on the
surface just outside the boundary to the accessible environment.
Section 194.52 requires DOE's compliance assessments for the individual
protection requirements to consider all potential exposure pathways for
radioactive contaminants from the WIPP. DOE must assume that an
individual consumes 2 liters per day of drinking water from any
underground source of drinking water in the accessible environment. EPA
expected that DOE would postulate several release pathways and
calculate the dose resulting from each pathway. In the CAG, EPA stated
that DOE could employ simplified exposure models provided that DOE
showed them to be more conservative than more detailed models. (CAG,
pp. 67-68)
DOE's modeling identified only one possible release of
radionuclides to the accessible environment for the undisturbed
performance scenario, resulting from contaminated brine flowing through
the Salado Formation interbeds. DOE's modeling indicated that this
release could occur if there were a significant buildup of gas and
fluid pressure within the WIPP's waste panels.
To assess this potential exposure pathway, DOE conservatively
assumed that Salado brine would be available for human use once it
reached the subsurface boundary of the accessible environment. Water in
the Salado interbeds is actually a highly concentrated brine unsuitable
for drinking; DOE has measured the average concentration of total
dissolved (non-radioactive) solids (``TDS'') in Salado brine as 324,000
milligrams per liter (mg/L). DOE therefore assumed that brine would
have to be diluted with pure water in order to bring the concentration
of TDS down to the highest allowable amount under the standard for
potable water (10,000 mg/L TDS). DOE assumed that this diluted Salado
brine would be consumed at the rate of two liters per day and then
calculated the dose resulting from this single pathway of water
ingestion.
EPA required DOE to expand its analysis to include additional
pathways. This expanded analysis is described in supplementary
information sent by DOE. (Docket A-93-02, Item II-I-10) DOE examined
pathways whereby humans either inhale dust from soil irrigated with
contaminated water or consume agricultural products irrigated with
contaminated water. In the latter case, pathways included plants eaten
directly by humans and milk or beef from cattle whose stock pond
contained contaminated water.
Based on the CCA and the supplementary information described above,
EPA found that DOE assumed in its analysis of pathways that individuals
consume 2 liters per day of water from underground sources. EPA also
conducted independent calculations and concluded that DOE had reliably
reported the doses expected to result from all pathways considered. EPA
discusses whether the results of DOE's dose calculations comply with
the specific requirements of 40 CFR 191.15 under 194.55, ``Results of
Compliance Assessments.''
EPA found that the simplified ``bounding analysis'' employed by DOE
(described under Sec. 194.51 above) was sufficiently conservative not
to require the use of more detailed models. The bounding analysis was
conservative because it assumed unrealistically that brine in the
Salado Formation would be used as a source of water for drinking and
irrigation. In fact, brine in the Salado is not likely to be used as an
underground source of drinking water because it has an extremely high
concentration of TDS. Salado brine would require considerable dilution
in order to meet the criteria for potable water, and dilution would
serve to reduce radionuclide concentrations. There are other, more
likely sources of water than the Salado in the vicinity of the WIPP
(see Sec. 194.53 below), but DOE's modeling demonstrated that
radionuclides from the WIPP would not reach these sources in the
undisturbed scenario.
EPA therefore proposes to find the WIPP in compliance with
Sec. 194.52. Due to the relatedness of the requirements, EPA combined
the discussion of DOE's compliance with Secs. 194.51 (``Consideration
of the Protected Individual'') and 194.52 in a single Compliance
Application Review Document (CARD 51/52).
C. Section 194.53, Consideration of Underground Sources of Drinking
Water
Section 194.53 requires that compliance assessments of the
undisturbed performance scenario consider underground sources of
drinking water (``USDWs'') near the WIPP and their interconnections.
The undisturbed scenario assumes that the disposal system will not be
disturbed by human activities such as drilling or mining. A USDW is
defined at 40 CFR 191.22 as ``an aquifer or its portion that supplies a
public water system, or contains a sufficient quantity of ground water
to do so and (i) supplies drinking water for human consumption or (ii)
contains fewer than 10,000 mg per liter of total dissolved solids.''
DOE identified three potential USDWs near the WIPP--the Culebra
Member of the Rustler Formation, the Dewey Lake Red Beds, and the Santa
Rosa Sandstone of the Dockum Group--despite incomplete data showing
that
[[Page 58832]]
they in fact meet the regulatory definition of a USDW. However, DOE did
not identify a plausible release scenario in undisturbed conditions in
which radionuclides from the WIPP reached these potential USDWs. DOE
found instead that the only plausible release scenario in undisturbed
conditions involved transport of radionuclides by brine laterally
through the Salado Formation (where the WIPP is situated) to the
subsurface boundary of the accessible environment. The concentration of
radionuclides at the subsurface boundary in this scenario represents
the maximum level possible in the accessible environment.
DOE assumed that brine at the subsurface boundary would be directly
available to a hypothetical individual on the surface for use as
drinking water. In other words, DOE assumed that people would draw
water directly from the Salado, thereby bypassing other potential
USDWs, and would thus be exposed to the maximum concentration of
radionuclides. Because DOE assumed the worst-case scenario and did not
attempt to demonstrate in the analysis that transport of radionuclides
through geological formations in the accessible environment would lower
their concentrations, DOE concluded that it was not necessary to
analyze underground interconnections among water bodies.
EPA agrees that the Culebra, Santa Rosa, and Dewey Lake Formations
are the most likely potential USDWs. Also, EPA agrees that it was not
necessary to identify USDW interconnections because of DOE's
conservative assumption that individuals, regardless of their location
on the surface of the accessible environment, would be exposed to the
maximum available concentration of radionuclides in drinking water.
Based on information provided in the CCA, EPA concluded that DOE
adequately considered USDWs in compliance assessments. EPA therefore
proposes to find that DOE complies with Sec. 194.53. EPA discusses
whether the results of DOE's calculations comply with the requirements
of Sec. 191.15 and Subpart C of 40 CFR Part 191 in Sec. 194.55,
``Results of CA.'' For further discussion of EPA's evaluation of
compliance for Sec. 194.53, see CARD 53.
D. Section 194.54, Scope of Compliance Assessments (CA)
Section 194.54 addresses the scope of compliance assessments
(``CA'') conducted to determine compliance with the individual dose and
ground-water protection requirements of the disposal regulations. The
CA must account for the undisturbed performance of the disposal system;
that is, the predicted behavior of the disposal system if it is not
disrupted by human intrusion or the occurrence of unlikely natural
events (Sec. 191.12). As with performance assessment, the CA must
consider features, events, and processes (``FEPs'') and associated
uncertainties. The CA can be considered a ``subset'' of performance
assessment, as CA considers only natural/undisturbed conditions and
past/near-future human induced activities, but does not include long-
term future human-induced activities that are included in performance
assessment.
EPA required DOE to consider FEPs that relate to undisturbed
performance of the disposal system. EPA required DOE to identify how
these FEPs were screened, combined, and used in the CA. DOE was
required to document why any undisturbed scenario FEPs were not
included in the CA. EPA also required the CA to consider activities
that occur in the vicinity of the WIPP and their effect on radionuclide
migration from the site. Specifically, DOE was required to consider
existing boreholes and near future lease development.
To fulfill the requirements of Sec. 194.54(a), DOE developed and
followed a process for considering FEPs in the CA. Out of the initial
list of approximately 72 natural FEPs, DOE eventually included 17 in
the CA. This is the same process that was used in identifying FEPs for
PA; EPA's evaluation of the process is addressed in the preamble
discussion of Sec. 194.32. EPA concluded that the initial FEP list
assembled by DOE was sufficiently comprehensive, in accordance with the
requirements of Sec. 194.54(a). This list appropriately screened out
events and processes on the basis of probability, consequence or
regulatory requirements. DOE considered and incorporated into CA
numerous natural processes and events. DOE adequately documented the
decision not to include FEPs in the CA. (See preamble discussion for
Sec. 194.32.)
DOE, in accordance with the requirements of Sec. 194.54(b),
conducted an analysis of the activities that are expected to occur in
the vicinity of the WIPP in the near future. DOE's assessment of
existing boreholes indicated that natural fluid flow through abandoned
boreholes would be of very little consequence in the near future and
was therefore not included in the CA. In addition to existing
boreholes, DOE addressed a number of activities that could occur in the
vicinity of the WIPP in the near future. These activities were: oil and
gas exploration, exploitation and extraction; potash exploration and
exploitation; fluid injection related to oil and gas production; sulfur
coreholes; hydrocarbon/gas storage; brine wells for solution mining;
and water supply wells. DOE determined that none of these activities
will have an impact on the disposal system in the near future and
therefore did not include them in the CA. DOE examined fluid injection
for inclusion in the CA, but screened it out based on low consequences
to the disposal system if it happened. DOE also provided information on
leases in the WIPP area.
EPA reviewed the CCA analysis of existing boreholes in the vicinity
of the WIPP and their potential impact on radionuclide migration and
agrees with DOE's conclusion that existing boreholes will not affect
the disposal system. EPA and public commenters disagreed with DOE's
initial analysis of the effects of fluid injection and salt water
mining. Upon reviewing supplemental modeling of these scenarios,
conducted by DOE and also independently by EPA, EPA agrees that these
activities were correctly omitted from the CA. (See the preamble for
Sec. 194.32 for further discussion of this additional modeling.) DOE
satisfactorily identified leases near the WIPP and appropriately
estimated the life of the leases for consideration in the CA.
EPA proposes to find DOE in compliance with the requirements of
Sec. 194.54. For further information on EPA's evaluation of compliance
for Sec. 194.54, see CARD 54.
E. Section 194.55, Results of CA
Section 194.55 establishes requirements for analyzing the WIPP's
compliance with the individual and the ground-water protection
requirements of the disposal regulations. These requirements: (1) limit
the possible radiation dose from the WIPP to individuals in the
accessible environment, and (2) limit the degree of radioactive
contamination of groundwater for which the WIPP might be responsible.
Both limitations are required to be analyzed for undisturbed
performance of the disposal system for 10,000 years. (See the
discussion for Sec. 194.54 in today's preamble.)
40 CFR 191.15, the individual protection requirements, requires
that there must be a reasonable expectation that undisturbed
performance of the WIPP disposal system will not cause the annual
committed effective dose equivalent to exceed 15 millirems (150
microsieverts) to any member of the public in the accessible
environment. Subpart C of 40 CFR Part 191, the ground-water protection
requirements, sets requirements on the radiation levels
[[Page 58833]]
in underground sources of drinking water (``USDWs'') by referencing the
standards of the Safe Drinking Water Act at 40 CFR Part 141. In order
to determine compliance with these requirements, DOE must calculate the
maximum individual radiation dose from all pathways, the maximum
concentrations of specific radionuclides in any USDW, and the maximum
annual dose equivalents from radioactivity in any USDW.
Section 194.55 establishes six requirements for computing,
presenting, and evaluating the results of compliance assessments
(``CA''). The requirements of Secs. 194.55(b) through (f) are analogous
to the requirements of Secs. 194.34(b) through (f) for the results of
performance assessment (``PA''). As a result, DOE has been able to use
the same computational techniques and the same computer codes to
perform both PA and CA. The major differences between the analyses for
PA and CA are that: (1) CA considers only undisturbed performance of
the WIPP, and thus does not consider scenarios of human intrusion; (2)
CA requires calculations of doses and radioactivity concentrations in
USDWs, as well as cumulative releases; and (3) CA results are expressed
as a set of dose and concentration values, while PA results are
expressed as a series of complementary cumulative distribution function
(``CCDF'') curves.
1. Uncertainty of CA
Section 194.55(a) requires the CA to consider and to document
uncertainty in the performance of the disposal system. There are two
general sources of such uncertainty. The first is the uncertainty
associated with physical, chemical and geologic conditions within and
around the repository. The CA deals with this by running 300 different
undisturbed-site scenarios, with 300 independent sets of sampled values
for the most important uncertain parameters (i.e., parameters either
that vary from place to place or that simply are not known with
precision, but which have been determined to have a significant effect
on the WIPP's ability to contain radionuclides). The second source of
uncertainty is the lack of detailed knowledge of the ways in which
contaminated ground water might be pumped out and utilized by persons
living near the site in the future. DOE handles this uncertainty
through a conservative bounding calculation on individual doses, which
is intended to demonstrate compliance regardless of any uncertainties.
The bounding calculation is discussed in further detail in the
discussions of Secs. 194.51 and 194.52 in this preamble.
DOE evaluated uncertainty in the amount of contaminants transported
underground using the same method as in the PA, except that uncertainty
from human intrusion scenarios was not considered. For further
information on the treatment of uncertainty in PA, see the discussion
of Sec. 194.34 in today's preamble. EPA found that the conservative
bounding calculation is appropriate, in lieu of further uncertainty
analysis, and that DOE's treatment of uncertainty in CA is sufficient.
Therefore, the Agency proposes to find that WIPP complies with
Sec. 194.55(a).
2. Probability Distributions for Uncertain Parameters
Section 194.55(b) requires DOE to develop and document probability
distributions for uncertain disposal system parameter values used in
CA. This is similar to the requirement for parameter values used in the
PA. DOE uses the same probability distributions for uncertain disposal
system parameter values in both PA and CA calculations. This involves
performing calculations with 300 independent sets of sampled parameter
values for each of the 57 important parameters associated with
uncertain physical, chemical and geological conditions in the
repository and its surroundings. EPA conducted the same evaluation of
probability distributions for CA as for PA.
Upon reviewing DOE's models and computer codes, the Agency
questioned a number of important input parameter values and
distributions used in the PA and in CA. EPA determined that corrections
were necessary for certain input parameters and conceptual models.
Because of concerns that the necessary corrections to these parameters
and conceptual models could have significant effects on the actual
results of modeling, EPA required DOE to demonstrate that the combined
effect of all the parameter and computer code changes required by EPA
was not significant enough to necessitate a new PA. EPA required DOE to
perform 300 simulations in additional PA and CA calculations as a
Performance Assessment Verification Test (``PAVT''). The PAVT
implemented DOE's PA modeling, using the same sampling methods as the
CCA PA, but incorporating parameter values that were selected by EPA.
CA results of the PAVT are discussed below for requirement
Sec. 194.55(f) and PA results of the PAVT are discussed above in
Sec. 194.34 of this preamble. The PAVT results confirmed that the
original PA is sufficiently conservative and indicated that further PA
and CA analysis is not required.
After considerable analyses, including the PAVT, EPA was satisfied
that the parameter values and distributions were adequate for
determining compliance. See the discussion of the requirements of
Sec. 194.34 of this preamble. For the reasons discussed in that
section, EPA also proposes to find the CCA in compliance with
Sec. 194.55(b).
3. Sampling of Uncertain Parameters
Section 194.55(c) requires CA to use computational techniques which
draw random samples from across the entire range of probability
distributions of uncertain parameters. These computational techniques
then must be used to calculate the ranges of estimated radiation doses
to individuals received from all pathways; radionuclide concentrations
in USDWs; and radiation doses received from USDWs. This requirement is
parallel to Sec. 194.34(c), which requires techniques for random
sampling from parameter distributions in the computation of CCDF curves
for the results of PA.
The statistical technique that DOE used in selecting parameter
values in PA, Latin Hypercube Sampling (``LHS''), is also employed in
the calculations of radionuclide concentrations in ground water (which
are then used to calculate individual doses) for the CA. The CA
generated 300 values of contaminant concentrations in ground water (at
the boundary to the accessible environment) and individual annual
radiation doses to assess compliance with Sec. 194.55.
EPA found the LHS technique for drawing samples randomly from
probability distributions of uncertain parameters to be sufficient, as
discussed in this preamble for Sec. 194.34. In addition, EPA determined
that DOE's conceptual model for determining maximum individual exposure
and the GENII-A computer code used to calculate radiation doses were
adequate. The Agency found that DOE has used an appropriate
computational technique, LHS, for sampling widely from the parameter
distributions described in Sec. 194.55(b), and has used it to generate
ranges of radionuclide concentrations in USDWs, doses from the
ingestion of water from USDWs, and all-pathways doses. Therefore, EPA
proposes to find that DOE has demonstrated compliance with
Sec. 194.55(c).
4. Sufficient Number of Estimates Generated
Section 194.55(d) requires that the number of estimates of
radionuclide concentrations in USDWs, doses from
[[Page 58834]]
the ingestion of water from USDWs, and all-pathways doses must be large
enough such that the maximum estimates of doses and concentrations
generated exceed the 99th percentile of the population of estimates
with at least 0.95 probability. This requirement is similar to the
requirement of Sec. 194.34(d) for determining if there is a sufficient
number of CCDF curves in PA analysis. Both requirements have the
purpose of ensuring that enough simulations are generated so that
conclusions drawn from their analyses are statistically justified.
DOE produced 300 CA calculations and used the same statistical
arguments to justify both the number of calculations for CA and the
number of CCDF curves. See the discussion for Sec. 194.34 in this
preamble for a further explanation of DOE's justification and EPA's
review. EPA found that, for random sampling, 300 individual estimates
will provide 0.95 probability that at least one of them will exceed the
population 99th percentile value. Thus, EPA proposes to determine that
the CCA satisfies the requirement of Sec. 194.55(d).
5. Display full range of CA results
Section 194.55(e) requires the CCA to display the full range of
estimated radiation doses and radionuclide concentrations. Section
194.34(e) has a parallel requirement for displaying the full range of
CCDFs generated.
DOE's CA analysis of individual doses started with the findings of
the PA of contamination that has migrated to the accessible environment
in the anhydrite interbeds immediately surrounding the repository in
the case of an undisturbed repository. This analysis generated a full
range of radionuclide concentrations in the ground water. DOE found
that only nine of the three hundred estimates were not negligibly small
(that is, less than 10-18 curies/liter) 24.
Starting with the concentrations in the interbeds, DOE conducted
bounding calculations on individual dose, both from the ingestion of
drinking water and from all exposure pathways combined. These
calculations adopted assumptions that resulted in upper-bound estimates
of dose that are much greater than what any individual might reasonably
be expected to receive. DOE performed this bounding calculation in lieu
of providing descriptive statistics for the estimates such as mean,
median and standard deviation, as stated in EPA's ``Compliance
Application Guidance for the WIPP'' (``CAG''). The criteria and the CAG
allow the use of a bounding calculation as long as the simplified model
is more conservative than more detailed and more complex modes. (CAG,
p. 68)
---------------------------------------------------------------------------
\24\ The Agency agrees with DOE that concentrations of less than
10-18 curies per liter are negligibly small. Such small
concentrations found in the analysis could be due to calculational
error rather than true indicators of radioactive contamination of
USDWs.
---------------------------------------------------------------------------
EPA reviewed the CCA and found that DOE performed a full range of
the necessary calculations to demonstrate compliance with Sec. 191.15
and Subpart C of 40 CFR Part 191. EPA independently estimated and
tabulated the all-pathway and USDW doses in a dose verification
analysis. EPA's results generally agreed with those of the DOE
analysis, although EPA found DOE's calculations to be conservative. EPA
calculated descriptive statistics such as the mean and the 95 percent
confidence interval for doses and concentrations to provide added
assurance of the adequacy of DOE's methodology. Because the CCA
presents specific estimates for each of the non-zero simulations or the
upper bound estimate for those simulations and presents the full ranges
of radionuclide concentrations and radiation doses, EPA proposes to
find that DOE has demonstrated compliance with Sec. 194.55(e).
6. Compliance With Radiation Dose and Radionuclide Concentration Limits
Section 194.55(f) requires the CCA to document that there is at
least a 95 percent level of statistical confidence that the mean and
the median of the range of estimated radiation doses and the range of
estimated radionuclide concentrations meet the requirements of
Sec. 191.15 and Subpart C of 40 CFR Part 191. This requirement is
analogous to Sec. 194.34(f), which requires at least a 95 percent level
of statistical confidence that the mean of the population of CCDFs
meets the containment requirements of Sec. 191.13. In order to meet
this requirement, it is necessary to calculate the lower and upper
limits of the range, the mean, and the median of the estimated doses
and of the radionuclide concentrations.
The limit for individual doses in Sec. 191.15 is an annual
committed effective dose, from all pathways, of 15 mrem/year. The
limits for doses and radionuclide concentrations in USDWs under Subpart
C of 40 CFR Part 191 are a total radioactivity concentration for
radium-226 and radium-228 in any USDW of 5 picocuries per liter of
water (pCi/L); a gross alpha particle radioactivity (including radium-
226 but excluding radon and uranium) in any USDW of 15 pCi/L; and an
annual dose equivalent to the total body or any internal organ from
beta particle and photon radioactivity in any USDW of 4 mrem/year. DOE
calculated a maximum annual committed effective dose equivalent from
exposure through all pathways of 0.93 mrem/year. The CCA reported that
the maximum estimated radium concentration in ground water is 2.0 pCi/
L. The CCA contained the 300 estimated concentrations for the five
radionuclides \241\ Am, \239\ Pu, \238\ Pu, \234\ U, and \230\ Th, and
only nine of these were not negligibly small. The CCA reported the
maximum gross alpha particle concentration as 7.81 pCi/L from \241\ Am,
\239\ Pu, \238\ Pu, \230\ Th and all isotopes of Ra. DOE used its
bounding calculation for dose due to all radionuclides from drinking
USDWs to show that the annual dose equivalent to the whole body from
beta particle and photon radioactivity would be no more than 0.47 mrem/
year. Supplemental analyses conducted by DOE also showed that the
maximum beta particle and photon dose equivalent to any internal organ
was well below the 4 mrem/year regulatory limit; bone surface was
identified as the critical organ for that calculation. The maximum
estimate concentration or dose for each of these is less than the
standard. Because the maximum value for each of these values was less
than the applicable standard, and because the bounding analysis
accounted for sources of uncertainty, DOE concluded that the mean,
median and 95 percent confidence interval values also met the standards
of Sec. 191.15 and Subpart C of 40 CFR Part 191.
EPA commissioned an independent analysis to verify DOE's dose
calculations. In general, EPA's analysis calculated values similar to
those calculated by DOE. EPA also calculated the mean, median and 95
percent confidence intervals of concentrations and doses. EPA's
analysis confirmed that the mean and median values are in compliance
with the requirements of Sec. 191.15 and Subpart C of Part 191.
The PAVT computed thirteen simulations with non-negligible
concentrations of radionuclides in ground water, compared with nine in
the CCA CA. All of these thirteen simulations computed doses of less
than 1 mrem/year, compared to the standard of 15 mrem/year for
individuals. PAVT calculations also demonstrated that the doses to
internal organs and from beta particle and photon radiation in ground
water were several orders of magnitude less than the standard. Thus,
PAVT results indicated that the mean and median dose values and ground-
water concentrations will meet the requirements of Sec. 191.15 and
Subpart C of Part 191.
[[Page 58835]]
Based on the CCA, supplementary documentation provided by DOE, and
the Agency's independent studies, EPA has determined that there is at
least a 95 percent level of statistical confidence that the mean and
the median of the range of estimated radiation doses and the range of
estimated radionuclide concentrations meet the requirements of
Sec. 191.15 and Subpart C of 40 CFR Part 191. Therefore, EPA proposes
to find that DOE has demonstrated compliance with Sec. 194.55(f). For
further information on EPA's evaluation of compliance for Sec. 194.55,
see CARD 55.
XIV. Land Withdrawal Act Section 4(b)(5)(B) Leases
The 1992 WIPP Land Withdrawal Act (``LWA'') (Public Law 102-579)
withdrew the geographical area containing the WIPP facility from all
forms of entry, appropriation, and disposal under public land laws. The
LWA transferred jurisdiction of the land to the Secretary of Energy
explicitly for the use of constructing, operating, and conducting other
authorized activities related to the WIPP. Further, the LWA established
responsibilities for DOE to manage the land withdrawal area and
required submittal of a management plan for that purpose. Under DOE's
management plan, all surface or subsurface mining or oil or gas
production is prohibited at all times on lands on or under the
withdrawal area. (LWA, section 4(b)(5)(A)) However, the LWA exempted,
from the prohibition on oil and gas production, two leases already in
existence. Section 4(b)(5)(B) states that the existing rights under the
two oil and gas leases (Nos. NMNM 02953 and 02953C) (hereafter, ``the
section 4(b)(5)(B) leases'') shall not be affected unless the
Administrator determines, after consultation with DOE and the
Department of Interior, that the acquisition of such leases by DOE is
required to comply with EPA's final disposal regulations at 40 CFR Part
191, Subparts B and C. Before DOE can emplace waste in the WIPP, DOE
must either acquire the leases or the EPA must determine that such
acquisition is not required. (LWA, section 7(b)(2))
In 1977, DOE purchased the leases in the land withdrawal area
between the surface and 6,000 feet (1829 meters) below the surface.
Since DOE owns all land rights down to 6,000 feet, no drilling is
permitted from the surface of the LWA leases. Any drilling that takes
place on the LWA section 4(b)(5)(B) leases must therefore be slant
drilling that is initiated from outside the land withdrawal area. Oil
and gas resources in the southwest area of the site, where the section
4(b)(5)(B) leases are located, are expected to occur below 6000 feet
down to approximately 16,000 feet.
The EPA's determination of whether the section 4(b)(5)(B) leases
must be acquired by DOE depends on an evaluation of drilling activities
very similar to that conducted by DOE for performance assessment
(``PA'') related to the containment requirements at 40 CFR 191.13. In
fact, Sec. 194.32(c) of the WIPP Compliance Criteria requires DOE to
analyze the effects of any activities that occur in the vicinity of the
disposal system prior to or soon after disposal, including the
``development of any existing leases.'' Therefore, in its examination
of the effects of the section 4(b)(5)(B) leases, EPA relied on the
closely related PA analyses conducted by DOE for the purpose of
compliance with Sec. 194.32(c).
For an oil or gas well, the potential life cycle may consist of:
drilling; resource recovery (production); fluid injection for enhanced
secondary production (either by waterflooding techniques or injection
to maintain oil reservoir pressure); reinjection of waste fluids for
disposal; and abandonment. In the PA for the compliance certification
application (``CCA''), DOE conducted several analyses to identify the
potential effects of these activities on the disposal system, with the
exception of production, which is exempted from consideration by
regulation (Sec. 194.33(d)). EPA examined each of DOE's analyses in its
evaluation for the section 4(b)(5)(B) leases.
In its analyses for the PA, DOE concluded that the drilling of a
deep well would adversely affect the disposal system only if the
borehole intersected a waste panel in the underground portion of the
WIPP. Drilling is of concern if the borehole penetrates the waste, and
forces it to the surface, or allows a pathway for long-term transport
of radionuclides. EPA agrees that the effects of drilling a borehole--
and similarly, the effects of resource recovery (oil or gas
production)--would be highly localized, for several reasons. Current
oil and gas production drilling in the area near the WIPP site includes
well casing procedures and borehole plugging practices that would
mitigate the potential impact of future drilling activities. Wells
drilled in the Delaware Basin (which encompasses the entire land
withdrawal area) include at least two sets of steel casing lining the
borehole (deeper wells use three sets of steel casing). Also,
production and injection wells contain an additional set of tubing used
to produce the oil or gas, or to inject fluid into the well. Present
day practice would require multiple failures in these steel casings and
tubings to cause any flow from the oil-or gas-producing zone towards
the disposal system.
Borehole plugging practices near the WIPP site also employ multiple
levels of protection that mitigate the potential impact of oil and gas
operations in the immediate area. The State of New Mexico regulates
borehole plugging practices with a robust series of requirements that
control the flow of fluid in the subsurface (New Mexico Oil
Conservation Division, Order R-III-P). The use of these measures reduce
the chance of any fluid flow toward or into the repository using
current methods and technology.
Fluid injection for brine disposal, waterflood, or pressure
maintenance could affect the disposal system if the injected brine were
to reach the waste area by way of migration through Salado anhydrites
(calcium sulfate rock) (markerbeds 138 or 139). DOE analyzed this
scenario in two different modeling studies (Docket A-93-02, Item II-G-
1, Reference #611, and Item II-I-36) as well as in a study that
identified well construction and operating practices in the vicinity of
WIPP. The results of the modeling studies showed that little or no
brine would be expected to reach the WIPP waste area through the
anhydrite interbeds. The amount of brine that is modeled to reach the
repository in the initial study (Docket A-93-02, Item II-G-1, Reference
#611) is within the amount that is already accounted for in PA, and
does not cause the WIPP to violate the disposal regulations.
An examination of current practice for fluid injection techniques
confirms that the effects of fluid injection can also be expected to be
highly localized. All injection operations in the vicinity of the WIPP
site are controlled by the underground injection control requirements
of the EPA. (40 CFR Parts 144 and 146) The requirements limit the flow
rates of injection fluids and the maximum pressures that can be used in
all injection wells. In addition, the injection well operator is
required to evaluate the area of influence of any injection well before
injection operations can be approved, and the State of New Mexico
monitors the performance of injection operations periodically by
requiring stringent reporting procedures.
Regarding abandonment, DOE indicated (Appendix SCR.3.3.1.4.2 of the
CCA) that abandoned deep boreholes that do not intersect waste panels
have been eliminated from the PA calculations on the basis of low
consequence to the performance of the disposal system. This is because
the rate of fluid flow through a borehole located
[[Page 58836]]
more than a meter away from the waste panels is so small that it would
have an insignificant impact on releases.
EPA's review of DOE's modeling studies and analyses of well
construction and operating practices found that the parameterization
(e.g., injection rate and volumes) and model representation (e.g.,
incorporation of stratigraphy) used in DOE's modeling are consistent
with those characteristics identified independently by EPA for the
region in the southwest part of the land withdrawal area (the location
of the section 4(b)(5)(B) leases). (Docket A-93-02, Item III-B-27)
DOE's analysis of drilling for the PA indicated that deep wells drilled
into the controlled area, but away from the waste disposal rooms and
panels, will not adversely affect the disposal system's capability to
contain radionuclides. A slant-drilled borehole from outside the land
withdrawal area, into the section 4(b)(5)(B) lease area, at least 6000
feet below the surface, would be at least 2400 meters (8000 feet) away
from the WIPP disposal rooms, and would thus have an insignificant
effect on releases from the disposal system (and in turn, on compliance
with the disposal regulations). Based on EPA's findings that DOE
adequately modeled human intrusion scenarios in PA, and on the
additional analyses described above, EPA concludes that potential
activities at the section 4(b)(5)(B) leases do not cause the WIPP to
violate the disposal regulations. Therefore, EPA determines that it is
not necessary for the Secretary of Energy to acquire the Federal Oil
and Gas Leases No. NMNM 02953 and No. NMNM 02953C.
XV. Administrative Requirements
A. Executive Order 12866
Under Executive Order 12866, (58 FR 51,735; October 4, 1993), the
Agency must determine whether the regulatory action is ``significant''
and therefore subject to OMB review and the requirements of the
Executive Order. The Order defines ``significant regulatory action'' as
one that is likely to result in a rule that may:
(1) have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
Pursuant to the terms of Executive Order 12866, it has been
determined that this rule is a ``significant regulatory action''
because it raises novel policy issues which arise from legal mandates.
As such, this action was submitted to OMB for review. Changes made in
response to OMB suggestions or recommendations will be documented in
the public record.
B. Regulatory Flexibility
The Regulatory Flexibility Act (RFA) generally requires an agency
to conduct a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements unless the agency certifies
that the rule will not have a significant economic impact on a
substantial number of small entities. Small entities include small
businesses, small not-for-profit enterprises, and small governmental
jurisdictions. This proposed rule would not have a significant impact
on a substantial number of small entities because it sets forth
requirements which apply only to Federal agencies. Therefore, I certify
that this action will not have a significant economic impact on a
substantial number of small entities.
C. Paperwork Reduction Act
The EPA has determined that this proposed rule contains no
information collection requirements as defined by the Paperwork
Reduction Act (44 U.S.C. 3501 et seq).
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Pub.
L. 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local and tribal
governments and the private sector. Pursuant to Title II of the
Unfunded Mandates Reform Act of 1995 (UMRA) (Pub. L. 104-4), EPA has
determined that this regulatory action is not subject to the
requirements of sections 202 and 205, because this action does not
contain any ``federal mandates'' for State, local, or tribal
governments or for the private sector. The rule implements requirements
specifically set forth by the Congress in the Waste Isolation Pilot
Plant Land Withdrawal Act (Pub. L. 102-579).
E. Executive Order 12898
Pursuant to Executive Order 12898 (59 FR 7629, February 16, 1994),
entitled ``Federal Actions to Address Environmental Justice in Minority
Populations and Low-Income Populations,'' the Agency has considered
environmental justice related issues with regard to the potential
impacts of this action on the environmental and health conditions in
low-income and minority communities. EPA has complied with this
mandate. EPA involved minority and low-income populations early in the
rulemaking process. In 1993 EPA representatives met with New Mexico
residents and government officials to identify the key issues that
concern them, the types of information they wanted from EPA, and the
best ways to communicate with different sectors of the New Mexico
public. The feedback provided by this group of citizens formed the
basis for EPA's WIPP communications and consultation plan.
To assist citizens, including a significant Hispanic population in
Carlsbad and the nearby Mescalero Indian Reservation, stay abreast of
EPA's WIPP-related activities, the Agency developed many informational
products and services. EPA translated into Spanish many documents
regarding WIPP including educational materials and fact sheets
describing EPA's WIPP oversight role and the radioactive waste disposal
standards. EPA also established a toll-free WIPP Information Line,
recorded in both English and Spanish, providing the latest information
on upcoming public meetings, publications, and other WIPP-related
activities. EPA also developed a vast mailing list, which includes many
low-income and minority groups, to systematically provide interested
parties with copies of EPA's public information documents and other
materials. EPA will continue its efforts toward open communication and
outreach during the development of the final rule.
List of Subjects in 40 CFR Part 194
Environmental protection, Administrative practice and procedure,
Nuclear materials, Radionuclides, Plutonium, Radiation protection,
Uranium, Transuranics, Waste treatment and disposal.
Dated: October 23, 1997.
Carol M. Browner,
Administrator.
For the reasons set out in the preamble, 40 CFR Part 194 is
proposed to be amended as follows.
[[Page 58837]]
PART 194--CRITERIA FOR THE CERTIFICATION AND RE-CERTIFICATION OF
THE WASTE ISOLATION PILOT PLANT'S COMPLIANCE WITH THE 40 CFR PART
191 DISPOSAL REGULATIONS
1. The authority citation for part 194 is revised to read as
follows:
Authority: The Waste Isolation Pilot Plant Land Withdrawal Act
of 1992, Pub. L. 102-579, 106 Stat. 4777, as amended by the 1996 LWA
Amendments, Pub. L. 104-201; Reorganization Plan No. 3 of 1970, 5
U.S.C. app. 1; Atomic Energy Act of 1954, as amended, and Nuclear
Waste Policy Act of 1982, as amended, 42 U.S.C. 2011-2296 and 10101-
10270.
2. In Sec. 194.2, a definition is added in alphabetical order to
read as follows:
Sec. 194.2 Definitions.
* * * * *
Administrator's authorized representative means the director in
charge of radiation programs at the Agency.
* * * * *
3. Appendix A to Part 194 is added to read as follows:
Appendix A to Part 194--Certification of the Waste Isolation Pilot
Plant's Compliance with the 40 CFR Part 191 Disposal Regulations and
the 40 CFR Part 194 Compliance Criteria
In accordance with the provisions of the WIPP Compliance Criteria
of this part, the Agency finds that the Waste Isolation Pilot Plant
(``WIPP'') will comply with the radioactive waste disposal regulations
at part 191, subparts B and C, of this chapter. Therefore, pursuant to
Section 8(d)(2) of the WIPP Land Withdrawal Act (``WIPP LWA''), as
amended, the Administrator certifies that the WIPP facility will comply
with the disposal regulations. In accordance with the Agency's
authority under Sec. 194.4(a), the certification of compliance is
subject to the following conditions:
Condition 1: Sec. 194.14(b), Disposal System Design, Panel Seal
System. The Department shall implement the panel seal design designated
as Option D in Docket A-93-02, Item II-G-1 (October 29, 1996,
Compliance Certification Application submitted to the Agency). The
Option D design shall be implemented as described in Appendix PCS of
Docket Item II-G-1, with the exception that the Department shall use
Salado mass concrete (consistent with that proposed for the shaft seal
system, and as described in Appendix SEAL of Docket Item II-G-1)
instead of fresh water concrete.
Condition 2: Sec. 194.22, Quality Assurance. (a) The Secretary
shall not allow any waste generator site other than the Los Alamos
National Laboratory to ship waste for disposal at the WIPP until the
Agency determines that the site has established and executed a quality
assurance program, in accordance with Secs. 194.22(a)(2)(i),
194.24(c)(3) and 194.24(c)(5) for waste characterization activities and
assumptions.
(b) Upon submission by DOE of site-specific quality assurance
program plans, EPA will evaluate the relevant quality assurance program
at the relevant waste generator site by conducting a quality assurance
audit or an inspection of a DOE quality assurance audit. EPA will
publish a notice in the Federal Register announcing its intent to
evaluate the relevant quality assurance program, and soliciting public
comment on the quality assurance program plans and appropriate audit
documentation. A public comment period of at least 30 days will be
allowed.
(c) EPA's written approval that the requisite quality assurance
requirements have been met at a waste generator site will be conveyed
in a letter from the Administrator's authorized representative to the
Department. No such approval shall be granted until after the end of
the public comment period described in paragraph (b) of this condition.
A copy of EPA's approval letter will be placed in the public dockets in
accordance with Sec. 194.67. The results of any audits or inspections
conducted by the Agency to evaluate the quality assurance programs
described in paragraph (a) of this condition will also be placed in the
dockets described in Sec. 194.67.
(d) EPA will conduct inspections, in accordance with Secs. 194.21
and 194.22(e), to confirm the continued compliance of the programs
approved under paragraphs (2)(b) and (c) of this condition. The results
of such inspections will be made available to the public through the
Agency's public dockets, as described in Sec. 194.67.
Condition 3: Sec. 194.24, Waste Characterization. (a) The Secretary
may allow shipment for disposal at the WIPP of retrievably stored
(legacy) debris waste streams, at the Los Alamos National Laboratory
(``LANL''), that can be characterized using the systems and processes
documented in Docket A-93-02, Item II-I-70. The Secretary shall not
allow shipment of any waste from any other LANL waste streams or from
any other waste generator site for disposal at the WIPP until the
Agency determines that the site has:
(1) provided information on how process knowledge will be used for
waste characterization of the waste stream(s) proposed for disposal at
the WIPP,
(2) implemented a system of controls at the site, in accordance
with Sec. 194.24(c)(4), to confirm that the total amount of each waste
component that will be emplaced in the disposal system will not exceed
the upper limiting value or fall below the lower limiting value
described in the introductory text of paragraph (c) of Sec. 194.24. The
implementation of such a system of controls shall include a
demonstration that the site has procedures in place for adding data to
the WIPP Waste Information System (``WWIS''), and that such information
can be transmitted from that site to the WWIS database; and a
demonstration that measurement techniques and control methods can be
implemented in accordance with Sec. 194.24(c)(4) for the waste
stream(s) proposed for disposal at the WIPP.
(b) The Agency will conduct an audit or an inspection of a DOE
audit for the purpose of evaluating the use of process knowledge and
the implementation of a system of controls for each waste stream or
group of waste streams at a waste generator site. The Agency will
announce a scheduled audit or inspection in the Federal Register. In
that notice, the Agency will also solicit public comment on all
appropriate audit documentation, which will be placed in the dockets
described in Sec. 194.67. A public comment period of at least 30 days
will be allowed.
(c) EPA's written approval of the waste characterization programs
described in paragraph (a) of this condition for one or more waste
streams from a waste generator site will be conveyed in a letter from
the Administrator's authorized representative to the Department. No
such approval shall be granted until after the end of the public
comment period described in paragraph (b) of this condition. A copy of
EPA's approval letter will be placed in the public dockets in
accordance with Sec. 194.67. The results of any inspections or audits
conducted by the Agency to evaluate the plans described in paragraph
(a)(1) and (2) of this condition will also be placed in the dockets
described in Sec. 194.67.
(d) The Administrator's authorized representative(s) will conduct
inspections, in accordance with Secs. 194.21 and 194.24(h), to confirm
the continued compliance of the plans approved under paragraphs (b) and
(c) of this condition. The results of such inspections will be made
available to
[[Page 58838]]
the public through the Agency's public dockets, as described in
Sec. 194.67.
Condition 4: Sec. 194.43, Passive Institutional Controls. (a) Not
later than the final re-certification application submitted prior to
closure of the disposal system, the Department shall provide, to the
Administrator or the Administrator's authorized representative:
(1) a schedule for implementing passive institutional controls that
has been revised to show that markers will be fabricated and emplaced,
and other measures will be implemented, as soon as possible following
closure of the WIPP. Such a schedule should describe how testing of any
aspect of the conceptual design will be completed prior to or soon
after closure, and what changes to the design of passive institutional
controls may be expected to result from such testing.
(2) documentation showing that the granite pieces for the proposed
monuments and information rooms described in Docket A-93-02, Item II-G-
1, and supplementary information may be: quarried (cut and removed from
the ground) without cracking due to tensile stresses from handling or
isostatic rebound; engraved on the scale required by the design;
transported to the site, given the weight and dimensions of the granite
pieces and the capacity of existing rail cars and rail lines; loaded,
unloaded, and erected without cracking based on the capacity of
available equipment; and successfully joined.
(3) documentation showing that archives and record centers will
accept the documents identified and will maintain them in the manner
identified in Docket A-93-02, Item II-G-1.
(4) documentation showing that proposed recipients of WIPP
information other than archives and record centers will accept the
information and make use of it in the manner indicated by DOE in Docket
A-93-02, Item II-G-1 and supplementary information.
(b) Upon receipt of the information required under paragraph (a) of
this condition, EPA will place such documentation in the public dockets
identified in Sec. 194.67. The Agency will determine if a modification
to the compliance certification in effect is necessary. Any such
modification will be conducted in accordance with the requirements at
Secs. 194.65 and 194.66.
[FR Doc. 97-28647 Filed 10-29-97; 8:45 am]
BILLING CODE 6560-50-P