RIS 2007-06, Regulatory Guide 1.200 Implementation
| ML070650428 | |
| Person / Time | |
|---|---|
| Issue date: | 03/22/2007 |
| Revision: | 0 |
| From: | Michael Case NRC/NRR/ADRO |
| To: | |
| References | |
| RG-1.200 RIS-07-006 | |
| Download: ML070650428 (7) | |
March 22, 2007
NRC REGULATORY ISSUE SUMMARY 2007-06REGULATORY GUIDE 1.200 IMPLEMENTATION
ADDRESSEES
All holders of or applicants for operating licenses for nuclear power reactors under Title 10 ofthe Code of Federal Regulations (10 CFR) Part 50, except those who have permanently ceasedoperations and have certified that fuel has been permanently removed from the reactor vessel.All holders of or applicants for early site permits, early site reviews, standard designcertification, standard design approvals, combined operating licenses, manufacturing licenses, or duplicate design licenses under 10 CFR Part 52.
INTENT
The U.S. Nuclear Regulatory Commission (NRC) is issuing this regulatory issue summary (RIS)to inform addressees of how the NRC will implement its technical adequacy review of plant- specific probabilistic risk assessments (PRAs) used to support risk-informed licensing actions after the issuance of Regulatory Guide (RG) 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities."This RIS requires no action or written response on the part of an addressee.
BACKGROUND
AND INFORMATIONOver the past 30 years, the NRC and the nuclear industry have performed many PRAs forvarious purposes and uses, with the scope, depth, and technical content dictated by the specific purpose and us Encouraging the use of PRA in all regulatory matters, the NRC issued a policy statement on the use of PRA methods in NRC activities, in the Federal Register on August 16, 1995 (60 FR 42622). Since then, the NRC has used PRAs for many applications; including generic safety issue prioritization, regulatory analysis in support of rulemaking and backfits, reactor oversight and inspection programs, and risk-informed regulatio At the same time, the nuclear industry increasingly uses PRA to support their operating and licensing processes, including risk-informed license amendment requests, relief requests, configuration risk management, and design certification and licensing of new reactors. As a result, PRAs are becoming a mainstream regulatory tool and are providing valuable inputinto the decisionmaking process for plant design, operation, and maintenanc Consequently, confidence in the information derived from a PRA must be high. That is, the scope of the analysis must be sufficiently broad and the accuracy of the technical content must be of sufficient rigor to justify the specific results and insights from the PRA supporting the decision under consideration.As the application of PRAs in decisionmaking increases, the staff has employed differentapproaches to ensure that the PRA has sufficient scope and technical adequacy for the specific applicatio In 1998, the NRC issued RG 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," and Standard Review Plan (SRP) Chapter 19, "Use of PRA in Plant-Specific Risk-Informed Decisionmaking: General Guidance." These guidance documents describe how to apply PRAto support licensing actions and determine the technical acceptability of the PRA for specificapplications.In March 1999, the General Accounting Office (GAO) issued GAO/RCED-99-95, "NuclearRegulation: Strategy Needed to Regulate Safety Using Information on Risk." GAO identified issues for NRC to resolve to successfully implement a risk-informed regulatory approac Among these issues, GAO indicated that more attention was needed to "develop standards on the scope and detail of risk assessments needed for utilities to determine that changes to their plants' design will not negatively affect safety."PRA standards have been under development by the American Society of MechanicalEngineers (ASME) and American Nuclear Society (ANS) for many year In addition, reactor owners' groups have been developing and applying a PRA peer review program for several year The staff briefed the Commission on its concerns regarding PRA quality and the standardsdevelopment effort in the Risk-Informed Regulation Implementation Plan on March 31, 200 In an April 18, 2000, staff requirements memorandum (SRM), the Commission directed the staff to
"provide its recommendations to the Commission for addressing the issue of PRA quality until the ASME and ANS standards have been completed, including the potential role of an industry PRA certification process." Subsequently, on December 18, 2003, the Commission issued SRM COMNJD-03-0002, "Stabilizing the PRA Quality Expectations and Requirements" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML033520457). In this SRM, the Commission approved implementation of a phased approach to achieving an appropriate quality for PRAs for NRC risk-informed regulatory decisionmakin The Commission described the phased approach in an attachment to the SRM and directed the staff to develop an action plan that would define a practical strategy for its implementatio The staff submitted its action plan in SECY-04-0118 on July 13, 2004 (ADAMS Accession Nos. ML041470505 and ML04153009), which the Commission subsequently approved in an SRM dated October 6, 2004 (ADAMS Accession No.
ML042800369).The central concept of the action plan requires the development of consensus PRA standardsand associated industry guidance documents, with endorsement by the staf These standards address internal initiating events (including internal flooding), internal fires, and external initiating events for full power and low power and shutdown operation The guidance documents address peer review guidanc The NRC has endorsed the use of PRA with the appropriate clarifications or qualifications in RG 1.200, which was issued initially for trial usebeginning February 200 RG 1.200 provides guidance to licensees for determining the requisite technical adequacy of a PRA and endorses the PRA standards and related industry guidanc Licensees can use RG 1.200 to determine PRA technical acceptability and adequacy in support of risk-informed regulation applications and licensing actions using risk- informed guidanc These applications include 10 CFR 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors." These risk-informed licensing actions using risk-informed regulatory guidance include the following:*RG 1.174, "An Approach for using Probabilistic Risk Assessment in Risk-InformedDecisions on Plant-Specific Changes to the Licensing Basis";*RG 1.177, "An Approach for the Plant-Specific, Risk-Informed Decisionmaking:Technical Specifications";*RG 1.178, "An Approach for Plant-Specific Risk-Informed Decisionmaking InserviceInspection of Piping"; and*RG 1.201, "Guidelines for Categorizing Structures, Systems, and Components inNuclear Power Plants According to Their Safety Significance."In Appendix A to the trial-use issuance of RG 1.200, the NRC endorsed the PRA standard inASME RA-S-2002, "Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications," dated April 5, 2002, and its Addenda A RA-Sa-2003, "Addenda to ASME RA-S-
2002," dated December 5, 200 The ASME PRA standard only addresses Level I (i.e., core damage) and limited Level II (i.e., large early release frequency (LERF)) from internal initiating events (excluding internal fires) occurring during full power operation In Appendix B of the trial-use issuance of RG 1.200, the NRC endorsed the industry peer review process described in NEI 00-02, Revision A3, "Probabilistic Risk Assessment Peer Review Process Guidance,"
dated March 20, 200 This document also provides guidance for performing self assessments to ensure that previously performed peer reviews are properly augmented to fully address the ASME PRA Standard for Level I and LERF. During the RG 1.200 trial-use period, the staff reviewed five pilot plant applications, whichincluded NRC staff site visit The staff evaluated whether RG 1.200 and its associated SRP Section 19.1 provided adequate guidance for demonstrating the technical adequacy of a PRA in the context of a risk-informed license applicatio The staff compiled lessons learned from the pilots and site visits in a memorandum dated June 8, 2005 (ADAMS Accession No. ML051590519).The NRC intends to revise RG 1.200 as additional PRA standards and guidance documents aredeveloped to address other scope areas (e.g., internal fires, external events, low power and shutdown, peer reviews) with the appropriate qualifications and clarification ASME added Addendum B to the ASME RA-S-2002, ASME RA-Sb-2005, "Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications," in December 200 Addendum B addressed the staff comments on the trial-use issuance of RG 1.200 and the concerns raised during a trial application of the ASME standard itsel In addition, the Nuclear Energy Institute (NEI) recently revised their peer review guidanc ANS is scheduled to issue a revised PRA standard for external events by the middle of 2007, a PRA standard for internal fires in the fall of 2007, and a PRA standard for low power and shutdown by the end of 200 Finally, the industry owners' groups expect to complete peer review guidance for internal fires by the middle of 200 The NRC endorsed the ASME and NEI revisions in Revision 1 of RG 1.200 which was issued in January 200
SUMMARY OF ISSUE
In the Phased Approach to PRA Quality Action Plan, the NRC allocated an implementationperiod of 1 year for licensees to adopt the NRC-endorsed PRA standard The implementation period allowed additional time after the NRC's endorsement of a PRA standard to develop or revise the PRA, perform a self-assessment and any necessary peer reviews, and address any findings of these reviews and previous reviews. The staff originally intended that the implementation period for RG 1.200, which endorsed onlythe ASME standard and the NEI peer review process, would begin after the revision to RG 1.200 to address the lessons learned from the pilot The staff completed pilot activities in June 200 However, most licensees delayed implementation of RG 1.200 until the staff finalized its position on Addendum B to the ASME PRA standar Subsequently, many licensees have realized that considerably more resources will be needed to upgrade their PRAs to meet the guidelines for PRA quality in the NRC-endorsed standard At the same time, there are limited industry resources with the requisite PRA expertise to support these upgrade Consequently, the industry has indicated that an additional implementation period is necessaryto upgrade their PRAs to meet the standards.The NRC recognizes the need for an additional implementation period, for routine, limitedscope applications (e.g., single allowed outage time extensions, risk-informed inservice inspection, integrated leak rate testing extensions). Licensees should use this time to develop or revise their PRAs, perform self-assessments and any necessary peer reviews, and address the findings of these reviews and previous reviews, in order to meet the NRC-endorsed standard Thus, the staff will review routine, limited-scope applications using its current practices through December 200 However, for broad-scope applications submitted during this implementation period, the NRC staff will use Revision 1 of RG 1.200 in the performance of these reviews to assess PRA adequac This approach is consistent with the industry guidance documents related to these types of application In this context, broad-scope applications include the following:*10 CFR 50.69 applications,*Risk Management Technical Specification (RMTS) Initiative 4b, "Risk-InformedCompletion Times," applications, *RMTS Initiative 5b, "Risk-Informed Surveillance Frequencies," applications, and
- other risk-informed applications as determined by the NRC (e.g., 10 CFR 50.46aapplications upon promulgation of this rulemaking).In addition, the staff expects that PRAs required under 10 CFR Part 52 will also use NRC-endorsed standards, to the extent practicable. For all risk-informed applications received after December 2007, the NRC staff will useRevision 1 of RG 1.200 to assess technical adequacy. While significant progress has been made in the development of the other PRA standards andrelated guidance documents, these efforts have taken longer than expected and will not meet the original schedule in the Phased Approach to PRA Quality Action Pla The staff attributes the delay to the complex technical nature of the subject matter and the reliance upon volunteers, who can devote their efforts only on a part-time basis, to develop industry consensus standard RIS 2007-06