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Notice of Issuance of Regulatory Guide

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Nuclear Regulatory Commission.


Notice of Issuance and Availability of Regulatory Guide 1.174, Start Printed Page 28103Revision 2, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis.”

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Donald Helton, Probabilistic Risk Assessment Branch, Division of Risk Analysis, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, telephone 301-251-7594 or e-mail

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I. Introduction

The U.S. Nuclear Regulatory Commission (NRC) is issuing a revision to an existing guide in the agency's “Regulatory Guide” series. This series was developed to describe and make available to the public information such as methods that are acceptable to the NRC staff for implementing specific parts of the agency'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.

Revision 2 of Regulatory Guide 1.174, “An Approach For Using Probabilistic Risk Assessment In Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis,” was issued with a temporary identification as Draft Regulatory Guide, DG-1226. This regulatory guide describes an acceptable method for the licensee and NRC staff to use in assessing the nature and impact of licensing basis (LB) changes when the licensee chooses to support, or is requested by the staff to support, the changes with risk information. The NRC staff will review these LB changes by considering engineering issues and applying risk insights. Licensees that submit risk information (whether on their own initiative or at the request of the staff) should address each of the principles of risk-informed regulation discussed in this regulatory guide. Licensees should identify how their chosen approaches and methods (whether quantitative or qualitative, deterministic or probabilistic), data, and criteria for considering risk are appropriate for the decision to be made.

The guidance provided in this regulatory guide does not preclude other approaches for requesting changes to the LB. Rather, the staff intends for this regulatory guide to improve consistency in regulatory decisions in areas in which the results of risk analyses are used to help justify regulatory action. As such, the principles, process, and approach discussed herein also provide useful guidance for the application of risk information to a broader set of activities than plant-specific changes to a plant's LB (i.e., generic activities), and licensees are encouraged to use this guidance in that regard.

The NRC issues regulatory guides to describe to the public methods that the staff considers acceptable for use in implementing specific parts of the agency's regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants. Regulatory guides are not substitutes for regulations and compliance with them is not required.

II. Further Information

In April 2009, DG-1226 was published with a public comment period of 60 days from the issuance of the guide. The public comment period closed on November 03, 2009. Electronic copies of Regulatory Guide 1.174, Revision 2 are available through the NRC's public Web site under “Regulatory Guides” at​reading-rm/​doc-collections/​.

In addition, regulatory guides are available for inspection at the NRC's Public Document Room (PDR) located at Room O-1F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852-2738. The PDR's mailing address is USNRC PDR, Washington, DC 20555-0001. The PDR can also be reached by telephone at (301) 415-4737 or (800) 397-4209, by fax at (301) 415-3548, and by e-mail to

Regulatory guides are not copyrighted, and NRC approval is not required to reproduce them.

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Dated at Rockville, Maryland, this 4th day of May, 2011.

For the Nuclear Regulatory Commission.

Harriet Karagiannis,

Acting Chief, Regulatory Guide Development Branch, Division of Engineering, Office of Nuclear Regulatory Research.

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[FR Doc. 2011-11832 Filed 5-12-11; 8:45 am]