[Federal Register Volume 73, Number 148 (Thursday, July 31, 2008)]
[Notices]
[Pages 44778-44779]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-17543]
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NUCLEAR REGULATORY COMMISSION
[NRC-2008-0332]
Notice of Availability and Solicitation of Public Comments on
Documents Under Consideration To Establish the Technical Basis for New
Performance-Based Emergency Core Cooling System Requirements
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice of availability and request for public comment.
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SUMMARY: The Nuclear Regulatory Commission (NRC) is announcing the
availability of Research Information Letter (RIL) 0801, ``Technical
Basis for Revision of Embrittlement Criteria in 10 CFR 50.46'' and
NUREG/CR-6967, ``Cladding Embrittlement During Postulated Loss-of-
Coolant Accidents,'' and is seeking public comment on these documents.
The NRC is soliciting comment on the subject documents to confirm that
a sufficient technical basis exists to proceed with new performance-
based regulations on emergency core cooling system (ECCS) acceptance
criteria, and to identify issues that may arise with respect to
experimental data development or regulatory costs or impacts of new
requirements.
DATES: Comments on these documents should be submitted by September 5,
2008. Comments received after this date will be considered to the
extent practical, but assurance of consideration cannot be given to
comments received after this date.
ADDRESSES: Members of the public are invited and encouraged to submit
comments by mail to Michael Lesar, Chief, Rulemaking, Directives and
Editing Branch, Office of Administration, Mail Stop T6-D59, U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001.
You may also submit comments electronically at the federal
rulemaking portal, http://www.regulations.gov; search on rulemaking
docket ID: NRC-2008-0332.
To ensure efficient and complete comment resolution, comments
should include references to the section and page numbers of the
document to which the comment applies, if possible. Comments will be
discussed during a 10 CFR 50.46(b) public workshop tentatively
scheduled for September 2008 (specific date and location to be noticed
separately).
You can access publicly available documents related to this notice
using the following methods: Federal e-Rulemaking Portal: Documents
related to this action, including public comments, are accessible at
the federal rulemaking portal, http://www.regulations.gov, by searching
on rulemaking docket ID: NRC-2008-0332. The NRC also tracks all
rulemaking actions in the ``NRC Regulatory Agenda: Semiannual Report
(NUREG-0936).''
NRC's Public Document Room (PDR): The public may examine and have
copied for a fee, publicly available documents at the NRC's PDR, Public
File Area O-1F21, One White Flint North, 11555 Rockville Pike,
Rockville, Maryland.
NRC's Agencywide Document Access and Management System (ADAMS): RIL
0801, Technical Basis for Revision of Embrittlement Criteria in 10 CFR
50.46'' (ADAMS ML081350225) and NUREG/CR-6967, ``Cladding Embrittlement
During Postulated Loss-of-Coolant Accidents'' (ADAMS ML081780360) are
available electronically at the NRC's Electronic Reading Room at http://www.nrc.gov/NRC/reading-rm/adams.html. From this page, the public can
gain entry into ADAMS, which provides text and image files of NRC's
public documents. If you do not have access to ADAMS or if there are
any 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 FURTHER INFORMATION CONTACT: Paul M. Clifford, Division of Safety
Systems, Office of Nuclear Reactor Regulation, telephone: (301) 415-
4043, e-mail: [email protected].
SUPPLEMENTARY INFORMATION: In early 2003, the Commission directed the
NRC staff to complete the technical basis and move forward with
rulemaking to establish improved, performance-based ECCS acceptance
criteria in 10 CFR 50.46(b), ``Acceptance Criteria for Emergency Core
Cooling Systems for Light-Water Nuclear Power Reactors.'' The NRC
sponsored an extensive research and testing program at Argonne National
Laboratory (ANL) to develop the body of technical information needed to
support the new regulations. This information has been summarized in
RIL 0801 and the detailed experimental results are contained in NUREG/
CR-6967. Because of the importance of this regulation, the staff has
decided to release the technical documentation for domestic and
international public comment. With this approach, the NRC can address
stakeholder questions and respond to comments early in the process. The
[[Page 44779]]
public is invited to comment on the adequacy of this technical
information, including the following:
I. Technical Basis
1. RIL 0801 Figure 1 provides the measured embrittlement threshold
for all fresh and irradiated cladding specimens investigated during the
ANL research program. Hydrogen dependent post-quench ductility
regulatory criteria, similar to the lines on this figure, may be
established from these experimental results.
a. Is the technical information presented within NUREG/CR-6967
sufficient in scope and depth to justify specific regulatory criteria
applicable to all current zirconium cladding alloys?
b. Is the technical information presented within NUREG/CR-6967
sufficient in scope and depth to justify periodic testing on as-
fabricated cladding material?
c. Is the technical information presented within NUREG/CR-6967
sufficient in scope and depth to address sensitivities to alloy
composition, trace elements, manufacturing practices, fuel rod burnup,
and transient temperature profile?
2. Section 2 of NUREG/CR-6967 details the experimental techniques
and procedures employed at ANL to assess cladding properties.
a. Were the experimental techniques and procedures adequate for
their intended purpose of defining acceptable fuel criteria (e.g.,
specimen preparation, specimen size, heating/cooling rates, ring-
compression techniques, test temperature, acceptance criteria for post-
quench ductility and breakaway oxidation, etc.)?
b. Is the technical information presented within NUREG/CR-6967
sufficient in scope and depth to address uncertainties related to and
repeatability of measured results?
II. Performance-Based Testing Requirements
1. Due to potential sensitivities to manufacturing processes,
performance based testing may be required to characterize the loss-of-
coolant accident (LOCA) performance of new cladding alloys.
a. Section 2.1 of NUREG/CR-6967 details all of the fresh and
irradiated cladding specimens investigated during the ANL research
program. Is the extent of the ANL material database sufficient to
justify the applicability of experimental results to future cladding
alloys?
b. Conducting testing on irradiated specimens is more difficult and
expensive than similar tests performed on unirradiated specimens. Does
a sufficient technical basis exist to justify testing on hydrogen
charged, unirradiated cladding specimens as a surrogate for irradiated
fuel cladding?
2. Due to potential sensitivities to manufacturing processes,
routine testing may be required to verify material performance. Are
there difficulties or limitations with periodic testing that would make
such a requirement impractical?
III. Implementation
1. Implementing new regulatory criteria for 10 CFR 50.46(b) may
necessitate further testing and new licensing activities (e.g., revised
methods, updated safety analyses, etc.). What is the cost-benefit for
implementing new regulatory requirements similar to those discussed in
RIL 0801?
2. Implementing hydrogen-based regulatory criteria may require the
development of high confidence corrosion and hydrogen pickup models.
a. What type of information is needed to develop such models and is
such information readily available?
b. What performance indicators (e.g., pool-side measurements, hot
cell examinations, etc.) could be used to validate models?
c. What additional regulatory requirements would be necessary to
assure that the fuel is performing in accordance with the approved
models? How will compliance with the rule be demonstrated on a cycle by
cycle basis?
3. Crud deposits on the fuel cladding surface may affect fuel
stored energy, fuel rod heat transfer, and cladding corrosion.
a. What role does plant chemistry and crud deposits play on these
items?
b. How should normal and abnormal levels of crud deposits be
addressed from a regulatory perspective?
The NRC is seeking public comment to receive feedback from the
widest range of interested parties and to ensure that all information
relevant to revision of the embrittlement criteria in 10 CFR 50.46 is
available to the NRC staff. The NRC will review public comments
received on this technical information and incorporate appropriate
changes before starting to develop the proposed revisions to the
regulations. Comments will be discussed during a 10 CFR 50.46(b) public
workshop tentatively scheduled for September 2008 (specific date and
location to be noticed separately).
Dated at Rockville, Maryland, this 21st day of July 2008.
For the U.S. Nuclear Regulatory Commission.
William H. Ruland,
Director, Division of Safety Systems, Office of Nuclear Reactor
Regulation.
[FR Doc. E8-17543 Filed 7-30-08; 8:45 am]
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