[Federal Register Volume 88, Number 204 (Tuesday, October 24, 2023)]
[Notices]
[Pages 73051-73053]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-23426]


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NUCLEAR REGULATORY COMMISSION

[NRC-2023-0181]


Proposed Revision to 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 Safety Systems

AGENCY: Nuclear Regulatory Commission.

ACTION: Standard review plan-draft branch technical position revision; 
request for comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is soliciting 
public comment on draft NUREG-0800, ``Standard Review Plan for the 
Review of Safety Analysis Reports for Nuclear Power Plants: LWR 
Edition,'' Branch Technical Position (BTP) 7-19, Revision 9, ``Guidance 
for Evaluation of Defense In Depth and Diversity To Address Common-
Cause Failure Due to Latent Design Defects in Digital Safety Systems.'' 
The NRC seeks comments on the proposed draft BTP 7-19 revision of the 
Standard Review Plan (SRP) that 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.

DATES: Submit comments by November 24, 2023. Comments received after 
this date will be considered, if it is practical to do so, but the 
Commission is able to ensure consideration only for comments received 
on or before this date.

ADDRESSES: You may submit comments by any of the following methods; 
however, the NRC encourages electronic comment submission through the 
Federal rulemaking website:
     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: 301-415-0624; email: [email protected]. For technical 
questions, contact the individuals listed in the For Further 
Information Contact section of this document.
     Mail comments to: Office of Administration, Mail Stop: 
TWFN-7-A60M, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001, ATTN: Program Management, Announcements and Editing Staff.
    For additional direction on obtaining information and submitting 
comments, see ``Obtaining Information and Submitting Comments'' in the 
SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Ekaterina Lenning, Office of Nuclear 
Reactor Regulation, telephone: 301-415-3151, email: 
[email protected], Brent Ballard, Office of Nuclear Reactor 
Regulation, telephone: 301-415-0680, email: [email protected], and 
Carla Roque-Cruz, Office of Nuclear Reactor Regulation, telephone: 301-
415-1455, email: [email protected]. All are staff of the U.S. 
Nuclear Regulatory Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION:

I. Obtaining Information and Submitting Comments

A. Obtaining Information

    Please refer to Docket ID NRC-2023-0181 when contacting the NRC 
about

[[Page 73052]]

the availability of information for this action. You may obtain 
publicly available information related to this action by any of the 
following methods:
     Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2023-0181.
     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 [email protected]. The draft BTP 7-19, Revision 9, 
``Guidance for Evaluation of Defense In Depth and Diversity to Address 
Common-Cause Failure Due to Latent Design Defects in Digital Safety 
Systems'' is available in ADAMS under Accession No. ML23222A237.
     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 
[email protected] 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.

B. Submitting Comments

    The NRC encourages electronic comment submission through the 
Federal rulemaking website (https://www.regulations.gov). Please 
include Docket ID NRC-2023-0181 in your comment submission.
    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 
https://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 
publicly 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 into ADAMS.

II. Discussion

    The NRC seeks public comment on the draft BTP 7-19 Revision 9, 
``Guidance for Evaluation of Defense In Depth and Diversity to Address 
Common-Cause Failure Due to Latent Design Defects in Digital Safety 
Systems.'' This draft revision BTP 7-19, provides the NRC staff with 
guidance for evaluating an applicant's assessment of the adequacy of D3 
for a proposed DI&C system. The applicant performs this D3 assessment 
to identify and address potential common-cause failures (CCFs) in a 
proposed DI&C system and to evaluate the effects of any unprevented 
CCFs on plant safety.
    The purpose of this proposed update is to implement the expanded 
policy in SRM-SECY-22-0076, ``Expansion of Current Policy on Potential 
Common-Cause Failures in Digital Instrumentation and Control Systems,'' 
(ADAMS Accession Nos. ML23145A181 and ML23145A182) for addressing DI&C 
CCFs. The proposed update provides guidance for the review of risk-
informed D3 assessments, in addition to the existing guidance for 
assessments based on best-estimate methods. The proposed update also 
provides review guidance for design techniques or mitigating measures, 
other than diversity, to address the effects of a DI&C CCF.
    Following NRC staff evaluation of public comments, the NRC intends 
to finalize BTP 7-19, Revision 9 in ADAMS and post it on the NRC's 
public website at https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0800. The SRP is guidance for the NRC staff. The SRP is 
not a substitute for the NRC regulations, and compliance with the SRP 
is not required.

III. Backfitting, Forward Fitting, and Issue Finality

    The guidance in this draft SRP is updated to implement the 
Commission's policies in SRM-SECY-22-0076 for review of applicant 
assessments of defense in depth and diversity to prevent or mitigate 
common-cause failure of digital instrumentation and control systems 
used in light-water nuclear power reactors. Issuance of this draft SRP, 
if finalized, would 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 NRC Management 
Directive (MD) 8.4, ``Management of Backfitting, Forward Fitting, Issue 
Finality, and Information Requests''; would not affect the issue 
finality of an approval under 10 CFR part 52; and would not constitute 
forward fitting as that term is defined and described in MD 8.4. The 
NRC staff's position is based upon the following considerations.
    1. The draft SRP positions, if finalized, would not constitute 
backfitting or forward fitting or affect issue finality, inasmuch as 
the SRP would be internal guidance to the NRC staff.
    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 staff guidance, without further NRC action, are not 
matters that meet the definition of backfitting or forward fitting or 
affect the issue finality of a 10 CFR part 52 approval.
    2. Current or future applicants are not--with limited exceptions 
not applicable here--within the scope of the backfitting and issue 
finality regulations and forward fitting policy.
    Applicants are not, with certain exceptions, within the scope of 
the Backfit Rule or any issue finality provisions under 10 CFR part 52. 
The backfitting and issue finality regulations include language 
delineating when those provisions begin; in general, they begin after 
the issuance of a license, permit, or other approval. Furthermore, 
neither the Backfit Rule nor the issue finality provisions under 10 CFR 
part 52--with certain exclusions discussed further in this notice--were 
intended to apply to NRC actions that substantially change the 
expectations of current and future applicants.
    The exceptions to the general principle are applicable when an 
applicant references a 10 CFR part 52 license (e.g., an early site 
permit) and/or NRC regulatory approval (e.g., a design certification 
rule) with specified issue finality provisions or a construction permit 
under 10 CFR part 50. The NRC staff does not, at this time, intend to 
impose the positions represented in the draft SRP (if finalized) in a 
manner that would constitute backfitting or affect the issue finality 
of a 10 CFR part 52 approval. If, in the future, the staff seeks to 
impose a position in the draft SRP (if finalized) in a manner that 
constitutes backfitting or affects the issue finality of a 10 CFR part 
52 approval, then the staff would need to address the Backfit Rule, or 
the criteria described in the applicable issue finality provision.
    The Commission's forward fitting policy generally does not apply 
when an applicant files an initial licensing action for a new facility. 
Nevertheless, the NRC staff does not, at this time, intend to impose 
the positions represented in the draft SRP (if finalized) in a manner 
that would constitute forward fitting. If, in

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the future, the staff seeks to impose a position in the draft SRP (if 
finalized) in a manner that constitutes forward fitting, then the staff 
would need to address the forward fitting criteria in MD 8.4.

    Dated: October 19, 2023.
    For the Nuclear Regulatory Commission.
Gerond A. George,
Chief, Licensing Project Branch, Division of Operating Reactors, Office 
of Nuclear Reactor Regulation.
[FR Doc. 2023-23426 Filed 10-23-23; 8:45 am]
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