[Federal Register Volume 69, Number 147 (Monday, August 2, 2004)]
[Proposed Rules]
[Pages 46110-46111]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-17477]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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  Federal Register / Vol. 69, No. 147 / Monday, August 2, 2004 / 
Proposed Rules  

[[Page 46110]]



NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

RIN 3150-AH29


Risk-Informed Changes to Loss-of-Coolant Accident Technical 
Requirements

AGENCY: U.S. Nuclear Regulatory Commission.

ACTION: Availability of draft rule conceptual basis, draft rule 
language and notice of public meeting.

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SUMMARY: The Nuclear Regulatory Commission (NRC) is making available 
the draft rule conceptual basis and the draft rule language for a new 
Sec.  50.46a, and conforming changes to Sec. Sec.  50.34, 50.46, 50.46a 
(to be redesignated as Sec.  50.46b), 50.109, and 10 CFR part 50, 
Appendix A, General Design Criterion 35, concerning emergency core 
cooling systems (ECCS) for light-water nuclear power reactors. The 
amended regulations would permit power reactor licensees to implement a 
voluntary risk-informed alternative to the current requirements for 
analysis of loss-of-coolant accidents and for ECCS in 10 CFR 50.46. The 
availability of the draft rule conceptual basis and draft rule language 
is intended to inform stakeholders of the current status of the NRC's 
activities to risk-inform 10 CFR 50.46, but the NRC is not soliciting 
formal public comments on the information at this time. The NRC has 
scheduled a public meeting for August 17, 2004, at which stakeholders 
are invited to inform the NRC of possible nuclear power plant 
modifications that might be sought under such a rule and their 
associated costs and benefits. The NRC plans to use this information in 
preparing the regulatory analysis for the rule.

DATES: A public meeting is scheduled on August 17, 2004, at 9 a.m. in 
the Auditorium of the NRC's offices located at Two White Flint North, 
11545 Rockville Pike, Rockville, Maryland. Should it become necessary 
to change the date or time of this meeting, the NRC will provide the 
revised information in a meeting notice posted on the NRC's public Web 
site at http://www.nrc.gov/public-involve/public-meetings/meeting-schedule.html#NRR.

ADDRESSES: The public meeting will be held in the Auditorium of the 
NRC's offices located at Two White Flint North, 11545 Rockville Pike, 
Rockville, Maryland. The draft rule conceptual basis and draft rule 
language can be viewed and downloaded electronically via the NRC's 
rulemaking Web site at http://ruleforum.llnl.gov. Along with other 
publicly available documents related to this rulemaking, the draft 
information may be viewed electronically on public computers in the NRC 
Public Document Room (PDR), located at One White Flint North, 11555 
Rockville Pike, Rockville, MD 20852, Room O-1 F21, and open to the 
public on Federal workdays from 7:45 a.m. until 4:15 p.m. The PDR 
reproduction contractor will make copies of documents for a fee.
    Publicly available NRC documents created or received in connection 
with this rulemaking are also available electronically via 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 
Document Access and Management System (ADAMS), which provides text and 
image files of NRC's public documents. The draft rule conceptual basis 
and draft rule language are available under ADAMS accession number 
ML042080299. If you do not have access to ADAMS, or if there are 
problems in accessing the documents located in ADAMS, contact the NRC 
PDR Reference staff at (800) 397-4209, (301) 415-4737 or by e-mail at 
[email protected].

FOR FURTHER INFORMATION CONTACT: Richard Dudley, Policy and Rulemaking 
Program, Division of Regulatory Improvement Programs, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001; telephone: (301) 415-1116; Internet: [email protected].

SUPPLEMENTARY INFORMATION:
    In a staff requirements memorandum dated July 1, 2004, the 
Commission directed the staff to propose a risk-informed alternative 
rule to the current requirements in 10 CFR 50.46. The NRC is making 
preliminary versions of the draft rule conceptual basis and draft rule 
language available to inform stakeholders of the current status of the 
NRC's activities to risk-inform 10 CFR 50.46. This draft rule 
conceptual basis may be subject to significant revisions during the 
rulemaking process. To meet the Commission's schedule, the NRC is not 
soliciting early public comments on this draft rule conceptual basis 
and draft rule language. No stakeholder requests for a comment period 
will be granted at this stage in the rulemaking process. Stakeholders 
will have an opportunity to comment on the rule conceptual basis and 
rule language when it is published as a proposed rule.
    Under this risk-informed alternative, the NRC would establish 
requirements, in a new Sec.  50.46a, which would divide the existing 
spectrum of LOCA pipe break sizes up to the double-ended rupture of the 
largest reactor coolant system pipe into two regions. Each region will 
be subject to different ECCS analysis requirements, commensurate with 
likelihood of the break. Loss-of-coolant accidents in the smaller break 
size region (up to and including a ``transition break size'') will be 
analyzed by the methods, assumptions and criteria currently used for 
LOCA analysis; accidents in the larger break size region (from the 
transition break size up to the double-ended rupture of the largest 
reactor coolant system pipe) may be analyzed by less stringent methods 
based on their lower likelihood. Although loss-of-coolant accidents for 
breaks larger than the transition break size will become beyond design-
basis accidents, the NRC will promulgate regulations ensuring that 
licensees maintain the ability to mitigate pipe breaks up to the 
double-ended rupture of the largest reactor coolant system pipe. Since 
LOCAs in the larger break size region would be required to be 
mitigated, such accidents would remain separate from severe accidents, 
which are addressed by voluntary industry guidelines.
    Licensees who perform new LOCA analyses using the new risk-informed 
alternative requirements may find that their plant designs are no 
longer limited by certain parameters associated with previous analyses. 
Changing these limitations could enable licensees to

[[Page 46111]]

propose a wide scope of design or operational changes up to the point 
of being limited by some other parameter on any of the required 
analyses. Potential changes might include increasing power, modifying 
core peaking factors, removing some accumulators from service, 
eliminating fast starting of one or more emergency diesel generators, 
etc. Some of these design and operational changes could increase plant 
safety. In order to ensure that any design and operational changes do 
not unacceptably reduce plant safety margins or unacceptably increase 
risk, the rule will require that any potential increase in risk 
associated with plant modifications is small and consistent with the 
Commission's Safety Goal Policy Statement (60 FR 42622, August 15, 
1995). The risk-informed 10 CFR 50.46 option will also establish a 
design change evaluation process. The evaluation process will generally 
involve the criteria for risk-informed license amendments similar to 
those in Regulatory Guide 1.174 (ADAMS Accession No. ML023240437). The 
rule would require monitoring of plant risk to ensure that the bases 
for any facility changes made under this rule are maintained. The rule 
would require that proposed facility changes be reviewed and approved 
by the NRC via the routine license amendment process,\1\ including any 
needed changes to the facility's technical specifications. Potential 
impacts of the plant changes on facility security will be evaluated 
during the process for license amendment reviews.
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    \1\ Requirements for this process are specified in 10 CFR 50.90. 
They include public notice of all amendment requests in the Federal 
Register, an opportunity for affected persons to request a public 
hearing, preparation of an environmental analysis, and a detailed 
NRC technical evaluation to ensure that the facility will continue 
to provide adequate protection of public health and safety after the 
amendment is implemented.
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    The NRC intends to periodically evaluate LOCA frequency 
information. If estimated LOCA frequencies significantly change, the 
NRC may revise the transition break size. In such a case, the backfit 
rule (10 CFR 50.109) would not apply. Similarly, if future evaluations 
of LOCA frequency invalidate the bases for a design change made by a 
licensee, that licensee would be required to change the facility and/or 
procedures or make other compensatory changes elsewhere to reduce 
facility risk to acceptable levels. In such cases, the backfit rule (10 
CFR 50.109) also would not apply.
    The NRC's current concept regarding the rule framework, the 
associated technical bases, and early draft rule language will be 
posted on the NRC's rulemaking Web site at http://ruleforum.llnl.gov. 
This draft rule conceptual basis and draft rule language are 
preliminary and may be incomplete in one or more respects. This early 
draft information is being released to inform stakeholders of the 
current status of the 10 CFR 50.46 rulemaking. Periodically, the NRC 
may post updates to the draft rule conceptual basis or draft rule 
language on the rulemaking Web site.
    At the public meeting on August 17, 2004, the NRC would like to 
obtain information about the potential costs and benefits of the above 
rule changes in order to complete the regulatory analysis for the 
proposed rule. After licensees and other stakeholders review the draft 
rule conceptual basis and draft rule language posted on the NRC Web 
site (http://ruleforum.llnl.gov), the NRC would like to obtain 
information as described below.
    1. Estimate the number and type of plants that might pursue this 
voluntary option. Estimate the costs of performing the ECCS reanalyses 
at these plants.
    2. Provide the estimated number and types of plant design changes 
that would be permitted by the ECCS reanalyses at these plants (on a 
per unit basis) and the estimated costs of any decision analyses 
associated with such design changes.
    3. Estimate the costs of additional analyses (apart from the ECCS 
reanalyses) required by the proposed rule to determine the 
acceptability of the above design changes. These costs could include 
but may not be limited to (1) updating probabilistic risk assessments 
(PRAs) to reflect the new design and to meet the PRA quality and scope 
requirements and (2) analyses to determine compliance with the risk 
acceptance criteria and the defense-in-depth criteria.
    4. Estimate the number and types of plant design changes (on a per 
unit basis) that would meet the acceptance criteria for the additional 
analyses.
    5. Estimate the costs of implementing the plant design changes that 
meet the acceptance criteria for the additional analyses.
    6. Estimate any operational costs and/or savings resulting from 
implementing the above design changes.
    7. Estimate any anticipated changes in licensee information 
collection, reporting, and retention burden that could result if this 
rulemaking is implemented.

    Dated in Rockville, Maryland, this 26th day of July, 2004.

    For the Nuclear Regulatory Commission.
Catherine Haney,
Program Director, Policy and Rulemaking Program, Division of Regulatory 
Improvement Programs, Office of Nuclear Reactor Regulation.
[FR Doc. 04-17477 Filed 7-30-04; 8:45 am]
BILLING CODE 7590-01-P