[Federal Register Volume 72, Number 133 (Thursday, July 12, 2007)]
[Proposed Rules]
[Pages 38030-38033]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-13539]
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NUCLEAR REGULATORY COMMISSION
10 CFR Part 50
[Docket No. PRM-50-87]
Raymond A. Crandall; Receipt of Petition for Rulemaking
AGENCY: Nuclear Regulatory Commission.
ACTION: Petition for rulemaking; notice of receipt.
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SUMMARY: The Nuclear Regulatory Commission (NRC) has received and
requests public comment on a petition for rulemaking dated May 17,
2007, filed by Raymond A. Crandall (petitioner). The petition was
docketed by the NRC and has been assigned Docket No. PRM-50-87. The
petitioner is requesting that the NRC amend the regulations that govern
domestic licensing of production and utilization facilities to
eliminate the specific criteria related to the radiological doses for
control room habitability at nuclear power plants. The petitioner
believes that the current deterministic radiological dose requirements
for control room habitability have resulted in several negative safety
consequences, including an increased risk to public safety.
DATES: Submit comments by September 25, 2007. Comments received after
this date will be considered if it is practical to do so, but assurance
of consideration cannot be given except as to comments received on or
before this date.
ADDRESSES: You may submit comments by any one of the following methods.
Please include the following number (PRM-50-87) in the subject line of
your comments. Comments on petitions submitted in writing or in
electronic form will be made available for public inspection. Because
your comments will not be edited to remove any identifying or contact
information, the NRC cautions you against including personal
information such as social security numbers and birth dates in your
submission.
Mail comments to: Secretary, U.S. Nuclear Regulatory Commission,
Washington, DC 20555. Attention: Rulemaking and Adjudications staff.
E-mail comments to: [email protected]. If you do not receive a reply e-
mail confirming that we have received your comments, contact us
directly at (301) 415-1966. You may also submit comments via the NRC's
rulemaking website at http://ruleforum.llnl.gov. Address comments about
our rulemaking website to Carol Gallagher, (301) 415-5905; (e-mail
[email protected]). Comments can also be submitted via the Federal
eRulemaking Portal http://www.regulations.gov.
Hand deliver comments to 11555 Rockville Pike, Rockville, Maryland,
between 7:30 am and 4:15 pm on Federal workdays.
Publicly available documents related to this petition may be viewed
electronically on the public computers located at the NRC Public
Document Room (PDR), O1 F21, One White Flint North, 11555 Rockville
Pike, Rockville, Maryland. The PDR reproduction contractor will copy
documents for a fee. Selected documents, including comments, may be
viewed and downloaded electronically via the NRC rulemaking Web site at
http://ruleforum.llnl.gov.
Publicly available documents created or received at the NRC after
November 1, 1999 are also available electronically at the NRC's
Electronic Reading Room at http://www.nrc.gov/reading-rm/adams.html.
From this site, the public can gain entry into the NRC's Agencywide
Documents Access and Management System (ADAMS), which provides text and
image files of NRC's public documents. If you do not have access to
ADAMS or if there are
[[Page 38031]]
problems in accessing the documents located in ADAMS, contact the NRC
PDR Reference staff at 1-800-397-4209, 301-415-4737 or by e-mail to
[email protected].
For a copy of the petition, write to Michael T. Lesar, Chief,
Rulemaking, Directives and Editing Branch, Division of Administrative
Services, Office of Administration, U.S. Nuclear Regulatory Commission,
Washington, DC 20555-0001. The petition is also available
electronically in ADAMS at ML071490250.
FOR FURTHER INFORMATION CONTACT: Michael T. Lesar, Office of
Administration, U.S. Nuclear Regulatory Commission, Washington, DC
20555. Telephone: 301-415-7163 or Toll-Free: 1-800-368-5642 or E-mail:
[email protected].
SUPPLEMENTARY INFORMATION:
Background
The NRC has received a petition for rulemaking dated May 17, 2007,
submitted by Raymond A Crandall (petitioner). The petitioner requests
that the NRC amend 10 CFR Part 50, ``Domestic Licensing of Production
and Utilization Facilities.'' Specifically, the petitioner requests
that 10 CFR 50.67, ``Accident source term'' and ``Criterion 19--Control
room'' in Appendix A to Part 50, ``General Design Criteria for Nuclear
Power Plants'' be amended by eliminating the specific criteria related
to the radiological doses for control room habitability at nuclear
power plants.
The NRC has determined that the petition meets the threshold
sufficiency requirements for a petition for rulemaking under 10 CFR
2.802. The petition was docketed by the NRC as PRM-50-87 on May 25,
2007. The NRC is soliciting public comment on the petition for
rulemaking.
Discussion of the Petition
The petitioner notes that the current regulations provide specific
dose criteria, based on deterministic radiological dose analyses
performed by the licensee and reviewed by the NRC staff for
demonstrating the acceptability of the control room design for
radiological release events. NRC regulatory guides and standard review
plans provide the methodologies used to perform dose analyses that are
incorporated into a licensee's site-specific technical specifications
(TS). However, the petitioner believes that the deterministic dose
analysis methodology and associated regulatory process has resulted in
several negative safety consequences. The petitioner states that these
consequences include:
(1) Control designs that are not optimum for ensuring continued
control room habitability and may increase the probability of control
room evacuation.
(2) Site procedures for mitigation of dose consequences to control
room personnel that are not optimum for ensuring control room
habitability and are inconsistent with more effective mitigation
strategies.
(3) Unnecessary challenges to safety systems, such as increased
challenges to the Emergency Diesel Generators if control room
ventilation system fans are used early in an accident to meet analysis
assumptions.
(4) TS action statement requirements that require a plant shutdown
for failure to meet a control room dose analysis input assumption and
result in a net increase in the risk to the public.
(5) TS surveillance requirements that cannot be cost-justified
based on the risk significance that results in expenditures that could
be used on risk-significant improvements.
The petitioner believes the suggested amendments would eliminate
the specific radiological dose acceptance criteria; the need for
deterministic dose analyses; and the need for the associated regulatory
process, including the TS imposed to ensure compliance. The petitioner
also states that the proposed change does not eliminate the requirement
for the control room to be designed to ensure safe conditions under
accident conditions, but would eliminate what he believes are safety
concerns with the current regulation.
The petitioner states that because the primary objective of control
room habitability is to ensure continuous occupancy, the primary focus
should be on minimization of whole body doses from noble gases. The
petitioner believes that the current regulation is inconsistent with
the goal of allowing the control room operator to remain in the control
room to mitigate accident consequences. He states that some common
designs focus on compliance with existing criteria, such as a filtered
air-intake pressurization design, and increase the probability that the
control room will have to be evacuated. The petitioner has concluded
that the current requirements and operational criteria are established
to minimize the thyroid dose at the expense of increasing the whole
body dose. The petitioner notes that the dose from increased iodine
concentration can be mitigated by use of potassium iodide (KI) or
respiratory protection, but that the current requirements do not permit
these mitigating techniques for radiological releases to be used in
design analyses. The petitioner believes it is inconsistent that credit
for respiratory protection is permitted in control room habitability
toxic gas release evaluations, but not for design analyses.
The petitioner also states that current procedures for dose
mitigation are simplified to be consistent with the licensing basis
hypothetical analysis and that these analyses have resulted in
procedures that may not be an optimum mitigation strategy for more
likely conditions. The petitioner believes that mitigation strategies
should be based on overall risk reduction that would involve strategies
for more likely conditions. The petitioner has concluded that the
current mitigation strategies are based on one set of fixed
hypothetical conditions that are unlikely as a result of the required
deterministic dose analysis specified in the existing regulation.
The petitioner states that procedures for dose mitigation must be
consistent with the licensing basis and may not be the optimum
mitigation strategy for the more likely conditions. The petitioner
states that control room dose models do not model dispersion as a
period during the day with higher concentrations while the plume is
blowing towards the control room and then a period of zero
concentration for the rest of the day. Instead, analysis methods
simplify this effect by assuming that a lower concentration is present
continuously. The petitioner states that if procedures were revised to
include a purge mode strategy, a calculated increase in consequences in
the simplistic design basis analysis would result.
The petitioner states that the design requirements in the current
regulations result in unnecessary challenges to safety systems. The
petitioner cites an example during an assumed loss-of-coolant accident
(LOCA) and states that a common design requirement specifies that the
normal control room ventilation must isolate when a safety injection or
containment isolation signal occurs. The petitioner believes it would
be more logical to delay control room isolation until radioactivity is
detected in the control room or it is known that a radioactive plume is
blowing towards the control room. The petitioner suggests that
mitigating design strategies should be based on overall risk reduction
designed for more likely conditions, not on one set of fixed
hypothetical conditions that the petitioner believes is unlikely.
The petitioner states that current radiological dose mitigation
analyses also result in inappropriate TS action
[[Page 38032]]
statements. The petitioner explains that radiological dose analyses
differ from other types of engineering calculations. The petitioner
states that even though most engineering analyses involve some amount
of uncertainty, the results reasonably match what can be expected
during a real event. The petitioner cites the thermal hydraulic
analyses for an assumed LOCA event and explains that conservatism is
built into the model, and that numerous assumptions go into the
analysis to demonstrate that fuel damage will not occur due to
overheating. The petitioner states that for other assumptions such as
the temperature of the safety injection water or the flow rate of the
safety injection pump, uncertainty is limited by specifying an
acceptable value for such a parameter in the TS. The petitioner
believes that TS requirements for a safety injection system that cannot
meet design requirements impose a shutdown requirement.
The petitioner states that a large break LOCA is usually the
limiting accident for control room habitability design and that the
associated radiological analysis requires multiple inputs, including
the source term, which is the amount of radioactivity released from the
reactor core that can reach the environment. The petitioner explains
that the source term assumption can vary by many orders of magnitude
and that total curies released is not the only consideration. The
calculated and actual dose during an event depends on the nuclide mix
of the release, decay time since reactor shutdown, the fraction of
particulate nuclides that become airborne, and the chemical form of the
source term. The petitioner also states that many uncertainties are
considered in these models that include the removal mechanism for the
various nuclides; the release pathway and forces that cause a release
by that pathway; atmospheric dispersion; and dose modeling that depends
on the size of an exposed individual, their breathing rate, biological
removal mechanisms, etc.
The petitioner believes that the combined probability of all
assumptions being at the high end of uncertainty is so small that the
design basis event will not be realistic and makes each assumption
meaningless for predicting actual results. The petitioner cites the
Three Mile Island accident as an example when the dose analysis input
assumptions had no significance in predicting the actual consequences
of the event. The petitioner states that for control room habitability
TS, the analyses assumptions and results are even further removed from
any significance because there is no direct public impact from not
meeting control room habitability system requirements, any dose an
operator receives can be mitigated by KI, and the dose limit is overly
restrictive. The petitioner states that the potential indirect impact
on public safety of having to evacuate the control room can be easily
avoided, regardless of the control room habitability system status. The
petitioner has concluded that this means ``there is insignificant
safety significance to the TS associated with control room habitability
and yet there are shutdown requirements.''
The petitioner notes that in the past, the NRC has specified on
numerous occasions that the inability to meet the assumptions or
criteria of control room habitability analyses has low safety
significance. The petitioner states that the primary basis for the low
safety significance was usually due to the existence of mitigating
actions such as the issuance of KI tablets to ensure continued
occupancy of the control room and to justify continued operation. The
petitioner believes that to evaluate the net public safety risk
associated with these TS shutdown requirements, small but quantifiable
public risks associated with the shutdown of a nuclear power plant must
be considered that include but are not limited to the:
(1) Risk associated with bringing the plant through a transient and
another thermal cycle;
(2) Airborne pollutants released by the fossil units required to
operate to make up for lost power; and
(3) Potential for challenging electric power grid stability with
the public risk associated with the possibility of rolling blackouts or
brownouts, or under the worst conditions of grid stability, the
potential for a loss of offsite power at multiple nuclear power
facilities.
The petitioner states that the shutdown requirement increases the
net public risk and has concluded that the shutdown requirement needs
to be eliminated because it is only imposed as a ``matter of
compliance'' that he believes results from the way the input
assumptions are treated when using deterministic calculations.
The petitioner also states that ``individual input assumptions for
radiological dose analyses have no significance in predicting reality
or the acceptability of results. Even if actual conditions were such
that one of the assumptions was non-conservative by a couple orders of
magnitude, the ultimate result (in this case habitability of the
control room) would still be acceptable due to the significant
conservatisms in the other assumptions and the simplicity of effective
mitigating actions such as the use of KI.''
The petitioner states that although most control room habitability
surveillances can be performed with minimal resources, licensees have
been required to demonstrate the accuracy of the assumption on
unfiltered inleakage using a tracer gas testing method that costs
approximately $100,000 per test and cannot be justified. The petitioner
believes these tests have demonstrated that although inleakage values
assumed in the analyses were non-conservative, there was no safety
significance and continued operation was justified. The petitioner has
concluded that the expenditure for tracer gas testing could be better
used for improvements that would likely be more beneficial to plant
safety and, therefore, the required performance of this test could have
a net negative safety consequence. The petitioner states that previous
surveillances, such as a pressurization test, combined with lessons
learned from tracer gas testing results in an effective preventative
maintenance program to provide a cost-justified approach to ensure that
there are no significant failures of the control room habitability
boundary and an insignificant potential for control room evacuation.
The Petitioner's Proposed Actions
The petitioner suggests that the regulations should be revised to
eliminate the specific radiological criteria for control room
habitability. The petitioner believes this would result in the ability
to revise the industry guidelines to eliminate the specified guidelines
for performing deterministic dose analyses and eliminate all negative
safety consequences discussed in the petition. Specifically, the
petitioner recommends that 10 CFR 50.67(b)(2)(iii) and the second
sentence of Criterion 19 of Appendix A to Part 50 that contain specific
criteria for control room habitability be removed from the regulations.
The petitioner suggests that the current guidelines be replaced
with guidelines that he believes would ensure that the control room
remains habitable under most postulated conditions, such as:
(1) The control room ventilation system should isolate on the
detection of high radiation or toxic gas intake.
(2) The control room should have a minimum of one foot of concrete
shielding (or equivalent) on all surfaces.
(3) Self Contained Breathing Apparatus (SCBAs) and KI tablets
should be readily available for operator
[[Page 38033]]
use. Operators should maintain training in SCBAs.
(4) Procedural controls to maintain a low leakage boundary, such as
preventive maintenance/routine inspection of door seals and dampers
should be implemented.
(5) Procedures should be developed to ensure control room purging
is considered when the outside concentration is less than the inside
concentration.
(6) Existing emergency filtration systems should be maintained to
practical performance criteria.
The petitioner also states that current TS for system performance
would be eliminated and that the administrative portion of the TS could
include a requirement to have a Control Room Habitability Program. The
petitioner believes that because of the low public risk significance of
being outside design guidelines in a Control Room Habitability Program,
a plant shutdown would not be required if it is outside of the
guidelines. Rather, the petitioner believes that the program could
specify that timely actions should be taken to return the plant within
the guidelines. If not complete within 30 days, the petitioner suggests
that a special report would be sent to the NRC with a justification for
continued operation and a proposed schedule for meeting the guidelines.
The petitioner states that removing the specific dose criteria
would not eliminate the need to perform quantitative analyses as
required to demonstrate the acceptability for certain conditions. The
petitioner also states that although the current regulation has no
specific quantitative limits for toxic gases, the guidelines require
quantitative analyses for toxic gas habitability assessments under
certain conditions. The petitioner suggests that as an alternative to
total removal of dose guidelines from the regulations, most of his
concerns could be resolved if the dose criteria were based solely on
the whole body dose from noble gases that he believes is the only
possible dose impact that may result in control room evacuation. The
petitioner suggests, as another option, that most of his concerns would
be resolved if credit for SCBAs and/or KI was allowed in the analysis
of the dose from iodine and particulates. The petitioner also proposes
that the TS be revised to eliminate shutdown requirements for failure
to meet control room habitability requirements.
Dated at Rockville, Maryland, this 6th day of July 2007.
For the Nuclear Regulatory Commission.
J. Samuel Walker,
Acting Secretary of the Commission.
[FR Doc. E7-13539 Filed 7-11-07; 8:45 am]
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