[Federal Register Volume 88, Number 160 (Monday, August 21, 2023)]
[Notices]
[Pages 56885-56887]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-17401]


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NUCLEAR REGULATORY COMMISSION

[NRC-2023-0140]


Level 3 Probabilistic Risk Assessment Project Documentation 
(Volume 4)

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 4:

[[Page 56886]]

Overview of Reactor, At-Power, Level 1, 2, and 3 PRAs for Internal 
Fires, Seismic Events, and High Winds.''

DATES: Submit comments by October 20, 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-2023-0140. Address 
questions about Docket IDs in Regulations.gov to Stacy Schumann; 
telephone: 301-415-0624; 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-2023-0140 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-2023-0140.
     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-2023-0140 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, and dry 
cask storage. The reference site for this study contains two 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. This second batch of Level 3 PRA project reports 
describes the analyses and results for the reactor, at-power, Level 1, 
2, and 3 PRAs for internal fires, seismic events, and high winds 
(Volume 4). Each set of Level 3 PRA project reports covering the Level 
1, 2, and 3 PRAs for a specific site radiological source, plant 
operating state, and hazard group (or groups) is accompanied by an 
overview report. The overview reports summarize the results and 
insights from all three PRA levels.
    The Level 3 PRA project analyses reflect the reference plant as it 
was designed and operated as of 2012. To provide results and insights 
better aligned with the current design and operation of the reference 
plant, the overview reports also provide a reevaluation of the plant 
risk based on a set of new plant equipment and PRA model assumptions 
and compare the results of the reevaluation to the original study 
results. This reevaluation reflects the current reactor coolant pump 
shutdown seal design at the reference plant, as well as the potential 
impact of FLEX strategies, both of which reduce the risk to the public.
    As documented in Section 2 of the Volume 4 overview report, the 
results of the original Level 3 PRA project analyses and the 
reevaluation both show that, when considering all hazards combined for 
the reactor at power, the combination of this plant design and site 
location has substantial margin to the quantitative health objectives 
related to the NRC's safety goal policy, though the margins are 
noticeably less for the surrogate risk metrics of core damage frequency 
and large, early release frequency. Even though these margins can vary 
for other plants due to variations in their design and siting, the 
estimates derived for the reference

[[Page 56887]]

plant, when adjusted for siting and design variations, would provide 
useful qualitative risk insights for other U.S. operating plants.

III. Availability of Documents

    The documents identified in the following table are available to 
interested persons through ADAMS, as indicated.

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                                                        ADAMS accession
                 Document description                         No.
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SRM-SECY-11-0089, ``Options for Proceeding with              ML112640419
 Future Level 3 Probabilistic Risk Assessment (PRA)
 Activities''........................................
Level 3 PRA Project, Volume 4: Overview of Reactor,          ML23194A015
 At-Power, Level 1, 2, and 3 PRAs for Internal Fires,
 Seismic Events, and High Winds; Draft Report for
 Comment.............................................
Level 3 PRA Project, Volume 4a: Reactor, At-Power,           ML23194A016
 Level 1 PRA for Internal Fires......................
Level 3 PRA Project, Volume 4b: Reactor, At-Power,           ML23194A017
 Level 1 PRA for Seismic Events......................
Level 3 PRA Project, Volume 4c: Reactor, At-Power,           ML23194A012
 Level 1 PRA High Winds and Other Hazards............
Level 3 PRA Project, Volume 4d: Reactor, At-Power,           ML23194A013
 Level 2 PRA for Internal Fires, Seismic Events, and
 High Winds..........................................
Level 3 PRA Project, Volume 4e: Reactor, At-Power,           ML23194A014
 Level 3 PRA for Internal Fires, Seismic Events, and
 High Winds..........................................
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    Dated: August 9, 2023.

    For the Nuclear Regulatory Commission.
Jonathan E. Evans,
Chief, Probability Risk Assessment Branch, Division of Risk Analysis, 
Office of Nuclear Regulatory Research.
[FR Doc. 2023-17401 Filed 8-18-23; 8:45 am]
BILLING CODE 7590-01-P