[Federal Register Volume 90, Number 147 (Monday, August 4, 2025)]
[Notices]
[Pages 36454-36455]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-14701]
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NUCLEAR REGULATORY COMMISSION
[NRC-2025-0098]
Level 3 Probabilistic Risk Assessment Project Documentation
(Volume 8)
AGENCY: Nuclear Regulatory Commission.
ACTION: Draft report; request for comment.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing for
public comment a draft report on the Level 3 Probabilistic Risk
Assessment (PRA) project; specifically, ``Volume 8: Integrated Site
Risk, All Hazards, Level 1, Level 2, and Level 3 PRA.''
DATES: Submit comments by October 3, 2025. 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-2025-0098. Address
questions about Docket IDs in Regulations.gov to Bridget Curran;
telephone: 301-415-1003; email: [email protected]. For technical
questions, contact the individual 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: Alan Kuritzky, Office of Nuclear
Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001; telephone: 301-415-1552; email: [email protected].
SUPPLEMENTARY INFORMATION:
I. Obtaining Information and Submitting Comments
A. Obtaining Information
Please refer to Docket ID NRC-2025-0098 when contacting the NRC
about 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-2025-0098.
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]. For the convenience of the reader,
instructions about obtaining materials referenced in this document are
provided in the ``Availability of Documents'' section.
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-2025-0098 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
As directed in SRM-SECY-11-0089, ``Options for Proceeding with
Future Level 3 Probabilistic Risk Assessment (PRA) Activities,'' the
staff is conducting a full-scope multi-unit site Level 3 PRA (Level 3
PRA project) that addresses all internal and external hazards; all
plant operating modes; and all reactor units, spent fuel pools (SFPs),
and dry cask storage. The reference site for this study contains 2
four-loop Westinghouse pressurized water reactors with large dry
containments. The objectives of the Level 3 PRA project are to (1)
develop a Level 3 PRA, generally based on current state-of-practice
methods, tools, and data, that (a) reflects technical advances since
the last NRC-sponsored Level 3 PRAs (NUREG-1150), which were completed
over 30 years ago, and (b) addresses scope considerations that were not
previously considered (e.g., low-power and shutdown risk, multi-unit
risk, other radiological sources); (2) extract new insights to enhance
regulatory decision making and to help focus limited NRC resources on
issues most directly related to the agency's mission to protect public
health and safety; (3) enhance PRA staff capability and expertise and
improve documentation practices to make PRA information more
accessible, retrievable, and understandable; and (4) demonstrate
technical feasibility and evaluate the realistic cost of developing new
Level 3 PRAs.
The work performed under this project is being documented as a
multi-volume report. The current Level 3 PRA project report (Volume 8)
describes the analyses and results for the integrated site risk (ISR)
task. The Level 3 PRA project ISR task is a site-specific analysis that
consists of the following high-level steps: sitewide dependency
assessment; multi-unit (MU) Level 1, Level 2, and Level 3 PRA; and ISR
analysis. Multi-unit core damage frequencies (MUCDFs) were developed
for all identified multi-unit initiating events (MUIEs). The total
MUCDF was approximately 10 percent of the total single-unit core damage
frequency, with seismic events being the largest
[[Page 36455]]
contributors to MU risk. Due to computational challenges, MU Level 2
and Level 3 analyses were limited to two MUIEs: weather-related losses
of offsite power and a large seismic event. The study found that MU
consequences for these MUIEs were small compared to the single-unit
results. For the final ISR step, a single illustrative scenario was
identified that involved potential sitewide dependencies between the
reactors and the spent fuel pools and was risk-significant to both the
spent fuel pools and the reactors: a large seismic event. Risk results
for the illustrative ISR scenario are reported for several consequence
metrics, including individual latent cancer fatality risk, collective
total effective dose risk, and economic cost. Regardless of the
consequence metric, the risk estimated for the illustrative ISR
scenario was calculated to be low as compared to the MU and single-
source (i.e., single-unit reactor or SFP) results.
III. Availability of Documents
The documents identified in the following table are available to
interested persons through ADAMS, as indicated.
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Document description ADAMS accession No.
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SRM-SECY-11-0089, ``Options for Proceeding ML112640419
with Future Level 3 Probabilistic Risk
Assessment (PRA) Activities,'' dated
September 21, 2011.
Level 3 PRA Project, Volume 8: Integrated ML25149A043
Site Risk, All Hazards, Level 1, Level 2,
and Level 3 PRA (draft for public comment),
published August 2025.
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Dated: July 31, 2025.
For the Nuclear Regulatory Commission.
Latonia Enos-Sylla,
Acting Chief, Probability Risk Assessment Branch, Division of Risk
Analysis, Office of Nuclear Regulatory Research.
[FR Doc. 2025-14701 Filed 8-1-25; 8:45 am]
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