[Federal Register Volume 77, Number 96 (Thursday, May 17, 2012)]
[Notices]
[Pages 29391-29393]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-11958]


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NUCLEAR REGULATORY COMMISSION

[NRC-2012-0110]


An Approach for Probabilistic Risk Assessment in Risk-Informed 
Decisions on Plant-Specific Changes to the Licensing Basis

AGENCY: Nuclear Regulatory Commission.

ACTION: Draft regulatory guide; request for comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC or the Commission) 
is issuing for public comment four (4) draft regulatory guides (DGs), 
DG-1285, ``An Approach for Probabilistic Risk Assessment in Risk-
Informed Decisions on Plant-Specific Changes to the Licensing Basis,'' 
(proposed Revision 3 of Regulatory Guide [RG] 1.174); DG-1286, ``An 
Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice 
Testing,'' (proposed Revision 1 of RG 1.175); DG 1287, ``An Approach 
for Plant-Specific, Risk-Informed Decisionmaking: Technical 
Specifications'' (proposed Revision 2 of RG 1.177); and DG-1288, ``An 
Approach for Plant-Specific Risk-Informed Decisionmaking for Inservice 
Inspection of Piping'' (proposed Revision 2 of RG 1.178). These guides 
describe methods the NRC staff considers acceptable for plant-specific, 
risk-informed decisionmaking on specific licensee activities.

DATES: Submit comments by June 29, 2012. Comments received after this 
date will be considered if it is practical to do so, but the NRC is 
able to ensure consideration only for comments received on or before 
this date. Although a time limit is given, comments and suggestions in 
connection with items for inclusion in guides currently being developed 
or improvements in all published guides are encouraged at any time.

ADDRESSES: You may access information and comment submissions related 
to this document, which the NRC possesses and are publicly available, 
by searching on http://www.regulations.gov under Docket ID NRC-2012-
0110. You may submit comments by any of the following methods:
     Federal rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2012-0110. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-492-
3668; email: [email protected].
     Mail comments to: Cindy Bladey, Chief, Rules, 
Announcements, and Directives Branch (RADB), Office of Administration, 
Mail Stop: TWB-05-B01M, U.S. Nuclear Regulatory Commission, Washington, 
DC 20555-0001.
     Fax comments to: RADB at 301-492-3446.
    For additional directions on accessing information and submitting 
comments, see ``Accessing Information and Submitting Comments'' in the 
SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Robert Carpenter, U.S. Nuclear 
Regulatory Commission, Washington, DC 20555-0001, telephone: 301-251-
7483 or email: [email protected].

SUPPLEMENTARY INFORMATION: 

I. Accessing Information and Submitting Comments

A. Accessing Information

    Please refer to Docket ID NRC-2012-0110 when contacting the NRC 
about the availability of information regarding this document. You may 
access information related to this document, which the NRC possesses 
and is publicly available, by any of the following methods:
     Federal Rulemaking Web Site: Go to http://www.regulations.gov and search for Docket ID NRC-2012-0110.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may access publicly available documents online in the NRC 
Library at http://www.nrc.gov/reading-rm/adams.html. To begin the 
search,

[[Page 29392]]

select ``ADAMS Public Documents'' and then select ``Begin Web-based 
ADAMS Search.'' For problems with ADAMS, please contact the NRC's 
Public Document Room (PDR) reference staff at 1-800-397-4209, 301-415-
4737, or by email to [email protected]. The DGs and their 
corresponding regulatory analysis are available electronically under 
the following ADAMS Accession Numbers: DG-1285 (ML12012A006 and 
ML12013A089), DG-1286 (ML12017A053 and ML12017A052), DG-1287 
(ML12017A054 and ML12017A059), and DG1288 (ML12017A076 and 
ML12017A077).
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.
    Regulatory guides are not copyrighted, and NRC approval is not 
required to reproduce them.

B. Submitting Comments

    Please include Docket ID NRC-2012-0110 in the subject line of your 
comment submission, in order to ensure that the NRC is able to make 
your comment submission available to the public in this docket.
    The NRC cautions you not to include identifying or contact 
information that you do not want to be publicly disclosed in your 
comment submission. The NRC will post all comment submissions at http://www.regulations.gov as well as enter the comment submissions into 
ADAMS. The NRC does not routinely edit comment submissions to remove 
identifying or contact information.
    If you are requesting or aggregating comments from other persons 
for submission to the NRC, then you should inform those persons not to 
include identifying or contact information that they do not want to be 
publically disclosed in their comment submission. Your request should 
state that the NRC does not routinely edit comment submissions to 
remove such information before making the comment submissions available 
to the public or entering the comment submissions into ADAMS.

II. Further Information

    The NRC is issuing for public comment 4 draft regulatory guides in 
the NRC's ``Regulatory Guide'' series. This series was developed to 
describe and make available to the public such information as methods 
that are acceptable to the NRC staff for implementing specific parts of 
the NRC's regulations, techniques that the staff uses in evaluating 
specific problems or postulated accidents, and data that the staff 
needs in its review of applications for permits and licenses.
    These 4 draft regulatory guides are temporarily identified by their 
task numbers, DG-1285, DG-1286, DG-1287, and DG-1288. The focus of the 
revisions to these RGs addresses the Commission's Staff Requirements 
Memorandum (SRM) (SECY-11-0014, issued 3-15-2011), titled ``Use of 
Containment Accident Pressure in Analyzing Emergency Core Cooling 
System and Containment Heat Removal System Pump Performance in 
Postulated Accidents'' directing the staff to revise the discussion on 
defense-in-depth. Specifically, the SRM stated,

    Because the statements in Regulatory Guide 1.174 are subject to 
different interpretations, the staff should revise this guide using 
precise language to assure that the defense-in-depth philosophy is 
interpreted and implemented consistently. To the extent that other 
regulatory guidance refers to defense in depth, the relevant 
documents should be updated also, as appropriate.

    In reviewing these RGs, it was observed that clarification could be 
added in several other places; for example:
     The use of the terms ``PRA technical acceptability,'' 
``PRA technical adequacy,'' and ``PRA quality'' were not clear.
     References in the RGs, in places, have been either updated 
or are no longer in use.
    Although the focus of this proposed revision is to revise the 
discussion on defense-in-depth, the NRC staff believes that the 
identified clarifications should be addressed. In DG-1285 (proposed 
Rev. 3 of RG 1.174) the terms on PRA technical acceptability, PRA 
technical adequacy, and PRA quality are revised to be consistent with 
RG 1.200, ``An Approach for Determining the Technical Adequacy of 
Probabilistic Risk Assessment Results for Risk-Informed Activities'' 
and the references were updated. It is the intent of the staff, 
following the public review and comment period, to review all four RGs 
and identify administrative changes that will improve the consistency, 
quality, and usability of each guide. Stakeholders and the public are 
requested to provide any input regarding areas in these DGs where 
clarification and improvements may be needed.
    DG-1285, is proposed revision 3 of Regulatory Guide 1.174 dated May 
2011, it provides guidance on an approach the NRC finds acceptable for 
analyzing issues associated with proposed changes to a plant's 
licensing basis and for assessing the impact of these changes on the 
risk associated with plant design and operation. One key element to 
this type of decisionmaking is an engineering analysis of the proposed 
change. As part of the engineering analysis, licensees evaluate the 
impact of the change on maintaining adequate defense-in-depth. This 
proposed revision incorporates additional language and specific 
examples of how maintaining defense-in-depth is achieved when licensees 
use risk-informed analysis of proposed changes to the plant's licensing 
basis.
    DG-1286, is proposed revision 1 of Regulatory Guide 1.175 dated 
August 1998, it provides an approach to using risk-informed 
decisionmaking in developing inservice testing programs for nuclear 
power plants. This revision updates the defense-in-depth evaluation to 
be consistent with the proposed changes to Regulatory Position 2.1.1 in 
draft Regulatory Guide DG-1285, (above) which provides guidance on 
evaluating proposed changes to a plant's licensing basis, including 
changes to the inservice testing program.
    DG-1287, is proposed revision 2 of Regulatory Guide 1.177 dated May 
2011, it describes a method acceptable to the NRC for using 
probabilistic risk analysis to evaluate proposed changes to a plant's 
technical specifications. As in evaluating changes to a plant's 
licensing basis, a key element in evaluating changes to technical 
specifications is an engineering analysis of the proposed change. As 
part of the engineering analysis, licensees evaluate the impact of the 
change on maintaining adequate defense-in-depth. This revision updates 
the defense-in-depth evaluation to be consistent with the proposed 
changes to Regulatory Position 2.1.1 in draft Regulatory Guide DG-1285, 
(above) which provides guidance on evaluating proposed changes to the 
plant's technical specifications.
    DG-1288, is proposed revision 2 of Regulatory Guide 1.178 dated 
September 2003, it provides an approach to using risk-informed 
decisionmaking in developing inservice inspection programs for piping 
in nuclear power plants. This revision updates the defense-in-depth 
evaluation to be consistent with the proposed changes to Regulatory 
Position 2.1.1 in draft Regulatory Guide DG-1285, which provides 
guidance on evaluating proposed changes to a plant's licensing basis, 
including changes to the inservice inspection program for piping 
systems.

    Dated at Rockville, Maryland, this 4th day of May 2012.


[[Page 29393]]


    For the Nuclear Regulatory Commission.

Thomas H. Boyce,
Chief, Regulatory Guide Development Branch, Division of Engineering, 
Office of Nuclear Regulatory Research.
[FR Doc. 2012-11958 Filed 5-16-12; 8:45 am]
BILLING CODE 7590-01-P