2024-09323. Final Revision to Branch Technical Position 7-19, Guidance for Evaluation of Defense in Depth and Diversity To Address Common-Cause Failure Due to Latent Design Defects in Digital Instrumentation and Control Systems

AGENCY:

Nuclear Regulatory Commission.

ACTION:

Standard review plan-final section revision; issuance.

SUMMARY:

The U.S. Nuclear Regulatory Commission (NRC) is issuing a final revision to the following section of NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plans: LWR Edition”: Branch Technical Position (BTP) 7-19, “Guidance for Evaluation of Defense in Depth and Diversity to Address Common-Cause Failure Due to Latent Design Defects in Digital Instrumentation and Control Systems.”

DATES:

The Standard Review Plan update is effective on May 31, 2024.

ADDRESSES:

Please refer to Docket ID NRC-2023-0181 when contacting the NRC about the availability of information regarding this document. You may obtain publicly available information related to this document using any of the following methods:

• Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2023-0181. Address questions about Docket IDs in Regulations.gov to Stacy Schumann; telephone: [phone]; email: [e-mail]. For technical questions, contact the individual listed in the FOR FURTHER INFORMATION CONTACT section of this document.

• NRC's Agencywide Documents Access and Management System (ADAMS): You may obtain publicly available documents online in the ADAMS Public Documents collection at https://www.nrc.gov/​reading-rm/​adams.html. To begin the search, 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, at 301-415-4737, or by email to [e-mail]. The ADAMS accession number for each document referenced (if it is available in ADAMS) is provided the first time that it is mentioned in this document.

• NRC's PDR: The PDR, where you may examine and order copies of publicly available documents, is open by appointment. To make an appointment to visit the PDR, please send an email to [e-mail] or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. eastern time (ET), Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Carla P. Roque-Cruz, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, telephone: [phone]; email: [e-mail].

• The NRC posts its issued staff guidance on the NRC's public website at https://www.nrc.gov/​reading-rm/​doc-collections/​nuregs/​staff/​sr0800.

SUPPLEMENTARY INFORMATION:

I. Background

This BTP provides the NRC staff with guidance for evaluating an applicant's assessment of the adequacy of defense in depth and diversity (D3) for a proposed digital instrumentation and control (DI&C) system. On October 24, 2023 (88 FR 73051), the NRC published for public comment a proposed revision to BTP 7-19, “Guidance for Evaluation of Defense in Depth and Diversity to Address Common-Cause Failure Due to Latent Design Defects in Digital Instrumentation and Control Systems” of NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition.” The public comment period closed on November 24, 2023. Thirty-five public comments were received regarding draft Revision 9 of BTP 7-19. The final Revision 9 to NUREG-0800, BTP 7-19, “Guidance for Evaluation of Defense in Depth and Diversity to Address Common-Cause Failure Due to Latent Design Defects in Digital Instrumentation and Control Systems” is available in ADAMS under Accession No. ML24005A077.

A summary of the public comments and the NRC staff's disposition of the comments are available in a separate document, “Response to Public Comments on Draft Standard Review Plan Branch Technical Position 7-19, `Guidance for Evaluation of Defense in Depth and Diversity to Address Common-Cause Failure Due to Latent Design Defects in Digital Instrumentation and Control Systems' ” (ADAMS Accession No. ML24005A115).

II. Backfitting, Forward Fitting, and Issue Finality

Chapter 7 of the SRP provides guidance to the staff for reviewing instrumentation and controls information provided in applications for licensing actions. Part of Chapter 7 provides guidance for the evaluation of defense-in-depth and diversity in digital computer-based instrumentation and control systems. Issuance of this BTP revision does not constitute backfitting as defined in section 50.109 of title 10 of the Code of Federal Regulations (10 CFR), “Backfitting” (the Backfit Rule), and as described in Management Directive (MD) 8.4, “Management of Backfitting, Forward Fitting, Issue Finality, and Information Requests”; does not constitute forward fitting as that term is defined and described in MD 8.4; and does not affect the issue finality of any approval issued under 10 CFR part 52, “Licenses, Certificates, and Approvals for Nuclear Power Plants.” The NRC staff's position is based upon the following considerations.

First, the SRP provides guidance to the NRC staff on how to review an application for NRC regulatory approval in the form of licensing. Changes in internal guidance intended for use by only the staff are not matters that constitute backfitting as that term is defined in 10 CFR 50.109(a)(1); does not constitute forward fitting as that term is defined and described in MD 8.4; and does not affect the issue finality of any approval issued under 10 CFR part 52, “Licenses, Certificates, and Approvals for Nuclear Power Plants.”

Second, the NRC staff does not intend to use the guidance in this SRP section to support NRC staff actions in a manner that would constitute backfitting or forward fitting. If, in the future, the NRC seeks to impose a position in this SRP section in a manner that constitutes backfitting, forward fitting, or affects the issue finality for a 10 CFR part 52 approval, then the NRC will address the Backfit Rule, the forward fitting provision of MD 8.4, or the applicable issue finality provision in 10 CFR part 52, respectively.

III. Congressional Review Act

This standard review plan section is a rule as defined in the Congressional Review Act (5 U.S.C. 801-808). However, the Office of Management and Budget has not found it to be a major rule as defined in the Congressional Review Act.

Dated: April 25, 2024.

For the Nuclear Regulatory Commission.

Undine Shoop,

Chief, Integrated Program Management and Beyond Design Basis Branch, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation.