ML20304A501

Rev 3 - ACRS Fc Briefing for the Advisory Committee on Reactor Safeguards Full Committee - Final

ML20304A501
Person / Time
Issue date:	11/05/2020
From:	Anders Gilbertson, Shilp Vasavada, Sunil Weerakkody Office of Nuclear Reactor Regulation, Office of Nuclear Regulatory Research
To:
Weerakkody S
References
RG 1.200, Rev 3
Download: ML20304A501 (28)

Text

Regulatory Guide 1.200, Revision 3 Briefing for the Advisory Committee on Reactor Safeguards Full Committee Anders Gilbertson Shilp Vasavada Sunil Weerakkody Technical Lead / Reliability Senior Reliability and Risk Senior Level Advisor and Risk Analyst Analyst NRR/DRA RES/DRA/PRB NRR/DRA/APLC Sunil.Weerakkody@nrc.gov Anders.Gilbertson@nrc.gov Shilp.Vasavada@nrc.gov November 5, 2020

Overview

• Purpose

• Background

• Changes incorporated into Revision 3

• ACRS Subcommittee members feedback

• Primary regulatory driver for Revision 3

• Resolution of public comments on DG-1362

• Path forward RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 2

Purpose To brief the ACRS Full Committee and solicit feedback on the staffs resolution of public comments on the staffs proposed revision 3 to Regulatory Guide (RG) 1.200 (i.e., DG-1362*)

• Available in the Agencywide Document Access and Management System (ADAMS) under accession No. ML19308B636 RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 3

Background

• RG 1.200 provides an approach for determining the technical acceptability of a base probabilistic risk assessment (PRA) model for use in regulatory decisionmaking for light-water reactors (LWRs)

• PRA acceptability is determined with respect to the following aspects of the base PRA:

- Scope

- Level of detail

- Conformance to consensus PRA standard technical elements (i.e., technical robustness)

- Plant representation RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 4

Background - PRA Acceptability Each element depends on the other in order to demonstrate PRA acceptability This paradigm obviates the need for an in-depth staff review of the base PRA model RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 5

Background - PRA Acceptability (cont)

RITS-4b, Risk-Informed Completion Times NFPA-805, Risk-Informed

• Greater reliance Required scope, Fire Protection on PRA level of detail, technical robustness, and

• More flexibility 50.69 SSC Categorization plant for licensee representation TSTF-425, Surveillance

• More complex Frequency Control Prgm. staff review Risk-Informed Inservice Inspection RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 6

Changes incorporated into RG 1.200, Revision 3

• Endorses new industry documents:

- NEI 17-07, Revision 2 (ML19241A615)

• Consolidates predecessor industry PRA peer review guidance for different hazard groups

- PWROG-19027-NP, Revision 2 (ML20213C660)

• Includes requirements for determining acceptability of newly developed methods (NDMs) and necessary submittal documentation

• Includes process for differentiating between PRA maintenance and a PRA upgrade

- ASME/ANS RA-S Case 1 (i.e., the seismic code case)

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 7

Changes incorporated into RG 1.200, Revision 3 (cont)

• Provides a new glossary of terms

- Some terms adopted directly from PWROG-19027-NP

• Provides descriptions of hazards to be considered in the development of a PRA RG 1.200, Revision 3, retains the staff endorsement of ASME/ANS RA-Sa-2009 with an exception for terms and definitions endorsed from PWROG-19027-NP, Revision 2 RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 8

ACRS Subcommittee Members Feedback

• The staff briefed the ACRS Subcommittee on Reliability and PRA on February 5, 2020

• The staff did not identify changes based on views expressed by committee members RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 9

Primary Regulatory Driver for RG 1.200, Revision 3

• Evolution of the peer review process

- Gap in Rev. 2 of RG 1.200 with respect to peer review of NDMs

- Significance of closing this gap, specifically for (Risk-Informed Technical Specification (RITS)-4b)

- Strategy to close this gap using PWROG-19027-NP and NEI 17-07 RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 10

A Gap in RG 1.200 and the ASME/ANS Level 1/LERF PRA Standard

• For each technical element, the ASME/ANS Level 1/LERF PRA standard provides high-level requirements (HLRs) and supporting requirements (SRs).

• 2009 version of the ASME/ANS Level 1/LERF PRA standard endorsed via Revision 2 to RG 1.200 does not provide HLRs or SRs for NDMs; Furthermore, there is no definition of what constitutes an NDM.

• This gap resulted in inefficiencies in the staffs review of NFPA 805 applications and loss of confidence of the peer review method to adequately peer review NDMs.

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 11

Importance of Closing the Gap; Base PRA Acceptability for an Application RITS-4b, Risk-Informed Completion Times NFPA-805, Risk-Informed

• Greater reliance Required scope, Fire Protection on PRA level of detail, technical robustness, and

• More flexibility 50.69 SSC Categorization plant for licensee representation TSTF-425, Surveillance

• More complex Frequency Control Prgm. staff review Risk-Informed Inservice Inspection RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 12

Current Solution to the Gap

• For RITS-4b applications, staff has imposed the following Administrative Technical Specification (TS)/License Condition:

...and any change in the PRA methods to assess risk that are outside these approval boundaries require prior NRC approval.

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 13

Leveraging the Commission Endorsed Peer Review Process to Close Gap

• SECY-99-256: Rulemaking Plan for Risk-Informing Special Treatment Requirements, October 29, 1999

• COMNJD-03-0002, Stabilizing the PRA Quality Expectations and Requirements, September 8, 2003

• SECY-04-0118, Plan for the Implementation of the Commissions Phased Approach to Probabilistic Risk Assessment Quality, July 13, 2004

• SRM-SECY-04-0118, Plan for the Implementation of the Commissions Phased Approach to Probabilistic Risk Assessment Quality, October 6, 2004.

• Establishment of the peer review process using RG 1.200 and consensus standards

• Peer review process acknowledged in regulations (10 CFR 50.69, November 2004)

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 14

Approach to Close the Gap in RG 1.200, Revision 3

• PWROG-19027-NP, Revision 2:

- Provides definitions related to NDMs, PRA maintenance, and PRA upgrade.

- Provides 6 HLRs and 21 SRs for peer review of NDMs (Are being considered for inclusion in the next edition of the ASME/ANS Level 1/LERF PRA Standard)

• NEI 17-07, Revision 2:

- Delineates the process that peer reviewers must use to peer review NDMs in addition to other technical elements of the PRA.

• Emphasis has been added to close as opposed to disposition peer review finding relating to NDMs prior to using them in PRA models.

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 15

Public Comments on DG-1362: Summary

• DG-1362 issued for public comment on 07/01/2020 day comment period ending 07/31/2020

• Received 19 public comments

- Nuclear Energy Institute (NEI; 15 comments including text in transmittal letter)

- Pressurized Water Reactor Owners Group (PWROG; 3 comments)

- Individual (1 comment)

• Public comments included responses to two questions in Federal Register notice (FRN) on the closure of peer review findings using an NRC-endorsed approach

• PWROG submitted updated report PWROG-19027-NP, Revision 2, with its public comments RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 16

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Peer review of PRAs Added guidance for PRAs of operating that credit planned plants that credit planned modifications modifications - Considered as a special circumstance

- Staff will address on case-by-case basis

- Peer review and submittal documentation should clearly identify and describe such modifications and design changes RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 17

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Correcting the Added context to the definition of PRA definition of PRA acceptability acceptability - Determined for each risk-informed application

- Considers staff positions in RG 1.200, in application-specific regulatory guidance, and any related requirements RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 18

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Clarification of peer Added guidance for peer review of PRA review of PRA upgrade(s) upgrade(s) - Performed prior to using the upgraded PRA model in support of a PRA application

- Either for an approved risk-informed program or in the submittal of a risk-informed PRA application for NRC review

- Use of a newly developed method (NDM) in a PRA is considered a PRA upgrade RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 19

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Clarifying when Clarified that differences between the 2005 and differences between 2009 version of the Level 1/LERF PRA Standard the 2005 and 2009 need to be addressed only if 2005 version used version of the to demonstrate base PRA acceptability Level 1/LERF PRA standard should be identified in support of a license amendment request RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 20

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Ensuring consistency Revised Appendix D, Other Hazards to be of Appendix D to RG consistent with Part 6 of the 2009 version of 1.200, Revision 3, Level 1/LERF PRA Standard (ASME/ANS RA-Sa-Other Hazards, with 2009)

Part 6 of the 2009 version of Level 1/LERF PRA Standard (ASME/ANS RA-Sa-2009)

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 21

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Removal of a Public comment identified guidance in NEI 17-07, clarification to Revision 2, that addressed a clarification in the NEI 17-07, Revision 2, public release version of DG-1362 on the documentation of the resolution of peer review findings Submission of Removal of clarification regarding PRA upgrade PWROG-19027-NP, determination process because PWROG-19027-NP, Revision 2 Revision 2, addressed the clarification RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 22

Changes to DG-1362 Based on Public Comments Synopsis of Synopsis of Change to DG-1362 Comment Closure of peer Agreed that the F&O closure decisions should be review findings based on cost and benefit for licensee (answers to FRN F&O closure helps ensure PRA acceptability and reduces resources for licensee as well as staff questions)

Added guidance for disposition of peer review findings from any peer reviews

- Findings should be evaluated for their impact on risk-informed application

- Addressed with documented justification and necessary changes to the PRA

- Prior to use of PRA in risk-informed application RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 23

Public Comments Resulting in No Changes to DG-1362 Synopsis of Synopsis of Change to DG-1362 Comment Availability of RG 1.200, - Comment was addressed via publicly available NRC Revision 2 for use after staff response; It explicitly states that Revision 2 is not issuance of Revision 3 being withdrawn and, therefore, there is no need to modify DG.

- This practice is consistent with other RG revisions

- Staff, however, anticipates one revision of RG 1.200 to be followed for a given PRA application

- Deviations from the referenced revision of RG 1.200 used in an application submitted to the NRC, including alternatives from other revisions of RG 1.200, should be identified and justified RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 24

Public Comments Resulting in No Changes to DG-1362 Synopsis of Synopsis of Change to DG-1362 Comment Change use of the term - The term application is used in RG 1.200 application to consistent with the definition of the term PRA narrower application from ASME/ANS RA-Sa-2009, as term "licensing endorsed by the NRC application" throughout - Application-specific staff positions on PRA DG-1362 acceptability exists in corresponding guidance (e.g.,

Integrated Leak Rate Test)

RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 25

Path Forward

• Staff considers ACRS Full Committee feedback

• Final reviews and concurrence

• Final publication late-2020/early-2021 RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 26

Path Forward (cont)

• Revision 4 of RG 1.200 expected to include endorsement of the following LWR PRA standards:

- Next edition of the ASME/ANS Level 1/LERF PRA standard; and

- ASME/ANS Level 2 PRA standard

- Advanced LWR PRA standard

• Advanced non-LWR PRA standard to be endorsed in a new RG RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 27

Path Forward (cont)

• Considerations for update of guidance on the treatment of uncertainty in PRA:

- Update to reflect references to the next edition of the ASME/ANS Level 1/LERF LWR PRA standard

- Consideration of application-specific guidance

- Expansion of guidance on uncertainty in risk-informed decisionmaking

- Uncertainty issues related to PRA for advanced reactor designs RG 1.200, Revision 3 Briefing for the ACRS Full Committee 11/5/20 28