[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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