[Federal Register Volume 64, Number 16 (Tuesday, January 26, 1999)]
[Notices]
[Pages 3988-3991]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-1702]
[[Page 3988]]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 40-3453; License No. SEA-917]
Atlas Corporation; Director's Decision Under 10 CFR 2.206
SUMMARY: Notice is hereby given that a request for Hearing and Petition
for Leave to Intervene (Petition) filed by the State of Utah (State)
has been reviewed by the staff as a petition under 10 CFR 2.206, in
accordance with 10 CFR 2.1205(l)(2). For reasons explained in
Director's Decision DD-99-02, dated January 20, 1999, the Petition has
been denied.
On August 2, 1988, Atlas Corporation (Atlas) submitted an
application for a license amendment to revise its site reclamation plan
for uranium mill tailings at its site near Moab, Utah. On April 4,
1994, notice of Receipt of Application and notice of Opportunity for
Hearing on the application were published in the Federal Register. 59
FR 16,665 (1994). On July 13, 1998, the State filed its Petition
stating that if the Petition is found to be untimely that it be treated
as a 10 CFR 2.206 petition in accordance with 10 CFR 2.1205(l)(2). The
Petition was filed by Denise Chancellor, Assistant Attorney General on
behalf of the State. By Memorandum and Order dated August 13, 1998, the
Presiding Officer determined that the Petition was inexcusably late and
would be treated as a petition under 10 CFR 2.206, in accordance with
10 CFR 2.1205(l)(2). On October 22, 1998, notice of receipt of the
Petition was published in the Federal Register. 63 FR 56667 (1998).
In its Petition, the State asserted that if Atlas were to proceed
with its reclamation plan as approved by the Nuclear Regulatory
Commission, it would be in violation of 10 CFR Part 40, Appendix A. The
Petition was referred to the Director of the Office of Nuclear Material
Safety and Safeguards. As provided by Section 2.206 and discussed in
the Federal Register notice, appropriate action was taken on this
Petition. The staff reviewed the specific assertions made by the State
and concluded that the Petition should be denied. The basis for the
staff's conclusions are detailed in Director's Decision DD-99-02, dated
January 20, 1999. A copy of the Director's Decision is available for
inspection at the Commission's Public Document Room at 2120 L Street,
N.W., Washington, DC 20555.
FOR FURTHER INFORMATION CONTACT: Myron Fliegel, Petition Manager,
Telephone (301) 415-6629.
Dated at Rockville, Maryland, this 20 day of January, 1999.
For the Nuclear Regulatory Commission.
Carl J. Paperiello,
Director, Office of Nuclear Material Safety and Safeguards.
Director's Decision Under 10 CFR 2.206
I. Introduction
On August 2, 1988, Atlas Corporation (Atlas or licensee) submitted
an application for a license amendment to revise its site reclamation
plan for uranium mill tailings at its site in Moab, Utah. On April 4,
1994, notice of Receipt of Application and notice of Opportunity for
Hearing on the application were published in the Federal Register. 59
FR 16665 (1994). On July 13, 1998, the State of Utah (State or Utah)
filed the State's Request for Hearing and Petition for Leave to
Intervene (Petition). By Memorandum and Order dated August 13, 1998,
the Atomic Safety and Licensing Board determined that the petition was
inexcusably late and would be treated as a petition under 10 CFR 2.206,
in accordance with 10 CFR 2.1205(l)(2).
In its Petition, the State asserts that if Atlas were to proceed
with its reclamation plan as approved by the U.S. Nuclear Regulatory
Commission (NRC), it would not meet the requirements of 10 CFR Part 40,
Appendix A. More specifically, the State asserts that the rock apron
design (armoring the side slope and toe of the tailings pile) does not
provide reasonable assurance against engineering failure at the Atlas
Uranium Tailings Site, and thus does not satisfy Appendix A. As bases
for its assertion it is stated that the unpredictability of flood
events, erosion, and vegetation growth along the river banks makes
computation of the probability of river migration extremely difficult
and that, therefore, conservatism should be built into how the tailings
pile is armored. The State, furthermore, references an April 2, 1998,
memorandum from its Department of Environmental Quality, Division of
Radiation Control (DRC), wherein it is stated that: (1) There are two
different conceptual designs for the Atlas tailings pile apron--one
presented by Atlas and accepted by NRC, and the second presented by the
U.S. Army Corps of Engineers (ACE); (2) assumptions and inputs to the
conceptual models result in the size, gradation, and volume of rock
necessary to protect the tailings pile from erosion by the Colorado
River; (3) the DRC staff has concluded that the ACE approach is more
protective of the tailings pile side slopes; and (4) the DRC staff
disagrees with the NRC conclusion that the Atlas design provides the
necessary protection of the tailings pile in the event of river
migration. A letter acknowledging receipt of the Petition and its
status for consideration pursuant to 10 CFR 2.206 was sent to the State
on September 26, 1998.
II. Background
In 1997, the NRC staff issued NUREG-1532 ``Final Technical
Evaluation Report for the Proposed Revised Reclamation Plan for the
Atlas Corporation Moab Mill'' (TER), presenting its evaluation of
technical issues related to Atlas Corporation's proposed reclamation
plan for the uranium mill tailings pile. Among the issues considered
was the ability of the proposed erosion protection design to prevent
erosion from various flooding events over long periods of time. One of
the features of the erosion protection design evaluated in the TER was
the ability of the self-launching rock apron to prevent erosion of the
tailings if the Colorado River were to migrate to the pile.
In the TER, the staff concluded that the rock apron provided
adequate protection for the reclaimed tailings pile, in the unlikely
event that the Colorado River migrated several hundred feet and reached
the toe of the pile. The adequacy of the apron design was questioned by
the State and the Grand County Council (GCC). In addition, the GCC
funded a report developed by the ACE that indicated that the rock apron
had not been designed properly. The GCC also solicited the opinions of
vegetation and geomorphic experts and provided those opinions to the
State. These reports, questions, and comments were transmitted to the
NRC staff by the State by letters dated November 10, 1997, and January
9, 1998.
Because the 1997 TER only summarized the NRC staff review of the
rock apron, a supplemental report (SR) was developed to address in
detail the questions and concerns raised by the DRC. The SR addressed
specific aspects of the staff review and provided a detailed technical
basis for the staff's conclusions on the adequacy of the rock apron.
The SR also addressed issues raised by the GCC and the ACE. Specific
topics that were addressed included: (1) Potential for erosion and
migration of the Colorado River; (2) riprap size needed for the side
slopes to protect from overland or overtopping flows; (3) riprap size
needed to protect the side slope from velocities in the river; (4) rock
volume needed; (5) river velocities; (6) vegetation/tamarisk growth and
the
[[Page 3989]]
effects on river flow velocities; (7) ACE design procedures, including
specific discussions of computations and analytical methods; (8)
potential for cohesive soils to affect the performance of the rock
apron; (9) reasonable assurance requirements, NRC staff review
procedures, and other regulatory requirements; (10) post-licensing
monitoring and maintenance; and (11) other conservatisms in the design.
Each of these factors was discussed in a degree of detail that was not
provided in the TER. In addition, specific contentions and questions
raised by the GCC, ACE, and/or DRC were addressed.
III. Discussion
As discussed in the TER, the staff considers that an adequate
design has been provided for the rock apron to be placed at the toe of
the Atlas tailings pile side slope near the Colorado River. This
conclusion is based on many factors, including evaluation of design
details that are very site-specific.
For the Atlas site, the design of the rock apron is affected by
three principal factors: (1) The velocity or shear stress that is used
in various analytical methods to determine the rock size necessary to
resist erosive forces; (2) the analytical methods that are used to
determine rock size, layer thickness, and rock volume; and (3) the
estimated scour depth that is used to determine volume of rock needed
in the apron. For each of these factors, there may be several
acceptable methods for estimating and calculating the parameters. For
example, a designer could assume various combinations of values for
velocity, shear stress, radius of curvature, or other inputs to a
design method and arrive at different estimates of rock size and rock
volume. Also, each parameter requires input data, based to a great
extent on the assumed configuration of the river and other assumptions
related to expected river velocities.
It should also be emphasized that there are many procedures for
determining the rock sizes necessary to resist erosion. Over the years,
various Government agencies and individuals have developed procedures
that best suit their needs, given the degree of conservatism necessary,
the risk to public health and safety, and other factors, such as cost.
Use of any specific one of those procedures, including the ACE
procedure, for determining rock size, is not necessarily ``correct''
nor required. It should be recognized that different methods are used
by different organizations and agencies. ACE's special need to protect
embankments, where erosion or failure could immediately jeopardize many
lives behind those structures, is not necessarily the needs of
designers to provide reasonable assurance of tailings stability, or to
meet the requirements of 10 CFR Part 40, Appendix A.
The staff considers it important to use input parameter values that
can be reasonably expected to affect the rock apron (if the river were
to migrate), not values that are based on very conservative
assumptions. For many situations where streambank erosion is imminent,
a bank configuration can be easily determined, based on observed
conditions. However, in this case, the main river channel is hundreds
of feet away and not threatening the tailings pile, and the rock apron
must be designed for some future unknown configuration of the river.
Therefore, the staff assumed that the river would retain its principal
characteristics, even though it had migrated. Recognizing that exact
characteristics would be difficult to predict, the staff assumed that
the river would retain the same width, depth, radius of curvature, and
velocity. It is also possible that the river would migrate and develop
characteristics such as increased width, decreased depth, decreased
velocity, and increased radius of curvature; such assumptions would
result in lesser rock apron designs being protective of the pile.
In making assumptions such as those discussed above, the staff is
required by 10 CFR Part 40, Appendix A, to have reasonable assurance of
tailings stability. The staff is not required to make a determination
with absolute certainty. Therefore, given the fact that river migration
to the pile in itself is unlikely, the staff is required only to assume
a reasonable configuration, not necessarily an extreme configuration
that maximizes every design parameter or input to a riprap design
method. Recognizing that a considerable amount of judgment is necessary
to predict design conditions at this site , such as river configuration
or river velocity, it is not the position of the NRC staff to assume
the most critical value for every input parameter that is used in every
calculation. Reasonable assurance only requires that input parameters
be selected within a reasonably conservative range of values of the
parameter.
It should be emphasized that the staff does not consider the ACE
analyses or design method to be incorrect or inappropriate. Rather, the
staff considered that the input parameters selected for use in the
analyses were overly conservative for this specific application and do
not represent conditions that can reasonably be expected to occur if
the river were to migrate to the rock apron. In the SR, the staff
provided many reasons to support its conclusion that the licensee's
design was adequate and provided extensive discussion to show that the
ACE report overestimates the riprap sizes and quantity of rock required
for the rock apron to provide reasonable assurance of tailings
stability. In summary, based on independent analyses of the licensee's
proposal and the information provided the DRC and ACE, the staff
concludes that Atlas proposes to use a volume and size of rock that is
larger than the volume and size computed by the staff.
Each of the assertions made by the State in the Petition have been
addressed previously by the staff. The staff provided its initial
findings in its TER and provided further details of the staff analysis
in its supplemental report that was transmitted to the State by letter
dated February 26, 1998. The staff has provided detailed technical
bases for its conclusion that the design of the rock apron meets the
requirements of 10 CFR Part 40, Appendix A.
The State was offered an opportunity to provide additional
information to further address its assertions. The State indicated that
no additional information would be provided for staff review or
consideration.
Each of the State's assertions is addressed in the following
discussions. Each assertion is stated and a brief summary of the
staff's analysis is provided. If additional details are needed, they
may be found in the staff's SR.
Assertion 1. The unpredictability of flood events, erosion, and
vegetation growth along the river banks makes computation of the
probability of river migration very difficult, and therefore
conservatism should be built into the tailings pile design.
The staff agrees that the computation of the probability of river
migration is difficult. However, the staff has concluded that the
potential for migration of the Colorado River to the tailings pile is
very low and has provided several bases supporting that conclusion. The
staff has also concluded that adequate conservatism has been provided
by the apron design to demonstrate that Part 40 requirements have been
met and has provided detailed analyses and technical bases supporting
that conclusion.
First, the staff examined aerial photographs of the Colorado River
in this area, taken over a period of about 47 years. Those photographs
verified
[[Page 3990]]
that very little erosion has occurred over that period of time.
Second, the staff reviewed a report prepared by expert
geomorphologists that addressed the river migration issue. In that
report, it was concluded that river migration was unlikely and that
lateral accretion, rather than erosion, has occurred in some areas near
the pile. Those expert geomorphologists also examined aerial
photographs and concluded that: ``Review of available historical
photographs indicates that the right bank * * * has remained remarkably
fixed spatially.'' (Emphasis added.)
Third, the staff has visited the site several times and has
determined that only some minor erosion of the river banks has occurred
and that this can be attributed to sloughing, rather than erosion from
river velocities. In fact, it was this minor erosion that led the staff
to question the original conclusion of the licensee that the river
would not erode.
Fourth, despite the information available on channel stability, a
conservative approach was taken by Atlas in its reclamation plan by
assuming that the Colorado River would migrate to the tailings pile and
by designing the erosion protection apron to account for that event.
This approach eliminated the need for Atlas to conduct further detailed
analyses of river migration and provided a design that exceeds the
reasonable assurance requirements specified in Part 40, Appendix A.
Fifth, the staff examined the effects of increased vegetation
growth on the erosion potential of the Colorado River. The staff
performed independent calculations and concluded that the potentially
increased density of vegetation and tamarisks in the floodplains of the
river will not significantly affect river velocities. Staff
computations indicate that the maximum velocity will be only slightly
increased in the river channel near the tailings pile. Based on staff
experience with vegetated floodplains and the widespread use of
vegetation to stabilize channel banks, it is also likely that increased
vegetation density of the river will increase the erosion resistance of
the channel banks and floodplain area near the tailings pile.
Assertion 2. There are two different conceptual designs: one
presented by Atlas and accepted by the staff; and the second presented
by the ACE.
The staff has recognized for some time that there are two designs
and that the designs are different. In the SR, the staff addressed the
ACE design and provided a detailed analysis of the ACE method and the
use of various input parameters to the ACE method. The staff performed
a detailed review of the analyses, provided in the ACE report, that
were used to assess the rock requirements for the apron. The staff
evaluated input parameters related to computation of scour depths,
river velocities, increases in river velocities at channel bends, and
factors of safety. The staff also examined the technical basis for the
development of the ACE procedure, including the supporting laboratory
data. The staff's analysis of the ACE report is also discussed in
Assertion 3, below.
Assertion 3. Assumptions and inputs to the conceptual models
results in differences in the size, gradation, and volume of rock
necessary to protect the tailings pile from erosion by the Colorado
River.
The staff has recognized that differences in input parameters can
significantly affect the size and volume of rock required for the rock
apron. Extensive discussion of the ACE report and the ACE design method
were provided in the SR.
Based on its review of the ACE report, the staff concluded that the
design parameters selected for use in the ACE calculations of rock size
were very conservative and did not reflect conditions that are likely
to occur at the rock apron if the river migrated to the tailings pile.
Velocities, radii of curvature, and scour depths were based on
conditions that currently exist upstream, but do not exist in the
vicinity of the apron. Velocities that would affect the apron will
likely be smaller, and radii of curvature greater, than those that
currently exist upstream of the site. In addition, the methods used by
ACE to determine design velocities, increases in velocities in bends,
and scour depths are conservative and incorporate large factors of
safety that may not be necessary to provide reasonable assurance that
Appendix A requirements are met. The staff, however, concluded that if
reasonable and likely, values of channel velocity and channel curvature
are used in the ACE method, the rock apron design proposed by Atlas is
acceptable, even if all the other ACE safety factors are taken into
account.
Assertion 4. The DRC staff has concluded that the ACE approach is
more protective of the tailings pile side slope.
The staff agrees that the ACE design is more conservative than the
design approved and would protect the pile under more severe conditions
if such conditions were to occur. Use of the ACE approach to determine
rock size and volume results in larger quantity of larger rock.
However, the staff has concluded that the design proposed by Atlas is
acceptable and that more and larger rock is not required to meet the
requirements of Appendix A.
In the SR, the staff provided an extensive discussion of how the
reasonable assurance requirements are met by the proposed design.
Further discussion was also provided on the use of standard review
plans and design procedures that reflect an approach to tailings
management that incorporates an appropriate level of safety.
Of considerable importance in the NRC staff's assessment of Atlas'
proposed design of the rock apron is the concept of ``reasonable
assurance.'' NRC regulations require (Part 40, Appendix A, Criterion 6)
``* * * a design which provides reasonable assurance of control of
radiological hazards to * * * be effective for 1000 years* * * .'' This
requirement comes directly from U.S. Environmental Protection Agency
(EPA) requirements in 40 CFR Part 192. These standards do not require
absolute nor even near certainty.
Several reasons can be offered to justify the appropriateness of a
``reasonable assurance'' requirement, rather than a more conservative
requirement. Of primary importance is that exposure to uranium mill
tailings do not pose an immediate acute risk to the health and safety
of individuals. Rather, the risk posed by tailings is from continual
exposure to low levels of radioactivity and is a long-term cumulative
risk. If control of tailings were lost (for example, if an earthquake
beyond the design basis were to damage the cover and expose tailings),
actions could be taken to repair the damage, with little likelihood of
endangering individuals.
Additionally, uranium mill tailings disposal sites will be under
perpetual government custodial care. If the features providing control
of the tailings were damaged or compromised in the future, the
government custodian could assess the situation and provide repairs.
Although NRC standards require that the design for control of
radiological hazards not rely on maintenance, the concept of
``reasonable assurance'' does not preclude contemplation of government
custodian actions in unusual or unlikely situations.
Finally, the rock apron does not have to withstand a single, severe
event that could occur without warning at any time. This is unlike the
situation in designing protection from earthquakes or severe
precipitation. For those events, the protective design may not be
tested for decades or centuries and then, in a
[[Page 3991]]
very short time, have to perform with a design event. If the Colorado
River were to migrate towards the tailings pile, it would occur over
decades or centuries. There would be ample time to determine whether
the assumptions used in the design of the rock apron (e.g., the scour
depth, river curvature, river velocity, etc.) were correct or
appropriate.
In summary, NRC regulations and EPA standards do not require the
degree of certainty about the potential future threats to the rock
apron that would require an extremely conservative design, but rather
``reasonable assurance'' that the design will protect the tailings
pile.
Assertion 5. The DRC disagrees with the NRC conclusion that the
Atlas design provides the necessary protection of the tailings pile.
DRC asserts that the apron design does not meet the requirements of 10
CFR Part 40, Appendix A.
As discussed in the TER and SR, the staff performed detailed
evaluations of the proposed design. Based on those evaluations, the
staff concludes that: (1) A conservative approach was taken by Atlas in
its reclamation plan by assuming that the Colorado River would migrate
to the tailings pile and by designing the erosion protection apron to
account for that event; (2) the rock size of 11 inches proposed by
Atlas for the rock apron is greater than the rock size of about 2.4
inches required to resist velocities produced by the Colorado River on
the collapsed rock apron, based on the most conservative calculated
channel velocity and considering the effects of channel curvature and
increased shear forces on the outside of channel bends; (3) the volume
of rock provided for the apron is acceptable; (4) the maximum river
velocity that should be used for the design of the rock apron for
reasonable assurance is approximately 5.2 feet per second (ft/sec),
rather than the 6.9 ft/sec used by ACE; (5) the potentially increased
density of vegetation and tamarisks in the floodplains of the river
will not significantly affect river velocities in the channel; (6) the
design parameters selected for use in the ACE calculations of rock size
are very conservative and are not likely to reflect conditions that
will exist at the rock apron, if the river were to migrate to the pile
in the future; (7) cohesive soils that could adversely affect the
performance of the apron are not significantly present; (8) the
requirement of reasonable assurance of site stability for a period of
200-1000 years is met by the proposed apron design; (9) a post-
licensing monitoring and maintenance program will be implemented for
this by the long-term custodian and will help to assure that
requirements are continuously met and to assure that any unexpected
problems occurring at the site will be promptly detected and mitigated;
(10) the current design includes an over-designed volume of 5.3-inch
rock on the side slope of the tailings pile that would be available to
also launch into any gaps formed in the launched 11-sinch rock; (11)
the riprap for the side slopes is designed for a precipitation
intensity approaching the world record rainfall intensity; and (12) the
riprap layer thickness exceeds the design criteria routinely accepted
by the staff; and (13) the rock sizes that will actually be constructed
will likely exceed the sizes proposed by Atlas.
IV. Conclusions and Recommendations
The NRC staff has reviewed the concerns and issues raised in the
State's Petition and has concluded that the rock apron design for the
Atlas reclamation plan complies with 10 CFR Part 40, Appendix A. For
the reasons discussed above, no basis exists for taking any action in
response to the Petition. Accordingly, no action pursuant to Section
2.206 is being taken.
Dated at Rockville, Maryland, this 20th day of January, 1999.
For the Nuclear Regulatory Commission.
Carl J. Paperiello,
Director, Office of Nuclear Material Safety and Safeguards.
[FR Doc. 99-1702 Filed 1-25-99; 8:45 am]
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