[Federal Register Volume 87, Number 78 (Friday, April 22, 2022)]
[Notices]
[Pages 24205-24207]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-08617]


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NUCLEAR REGULATORY COMMISSION

[NRC-2022-0085]


Level 3 Probabilistic Risk Assessment Project Documentation 
(Volume 3x)

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 3x: Overview of 
Reactor, At-Power, Level 1, 2, and 3 PRAs for Internal Events and 
Internal Floods.''

DATES: Submit comments by June 21, 2022. Comments received after this 
date

[[Page 24206]]

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-2022-0085. 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-2022-0085 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-2022-0085.
     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, 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: You may examine and purchase copies of public 
documents, by appointment, at the NRC's PDR, Room P1 B35, One White 
Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. 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 
8:00 a.m. and 4:00 p.m. (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-2022-0085 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 PWRs 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 first batch of Level 3 PRA project reports 
provides a high-level discussion of the overall project technical 
approach (Volume 2) and describes the analyses and results for the 
reactor, at-power, Level 1, 2, and 3 PRAs for internal events and 
internal floods (Volume 3). 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.
    The results of the original Level 3 PRA project analyses and the 
reevaluation both show that, when considering internal events and 
floods, 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. Even though these margins can vary for other 
plants due to variations in their design and siting, the estimates 
derived for the reference 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

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interested persons through ADAMS, as indicated.

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                                                               ADAMS
                  Document description                     Accession No.
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SRM-SECY-11-0089, ``Options for Proceeding with Future       ML112640419
 Level 3 Probabilistic Risk Assessment (PRA)
 Activities''...........................................
Level 3 PRA Project, Volume 3x: Overview of Reactor, At-     ML22067A210
 Power, Level 1, 2, and 3 PRAs for Internal Events and
 Internal Floods; Draft Report for Comment..............
Level 3 PRA Project, Volume 3a: Reactor, At-Power, Level     ML22067A211
 1 PRA for Internal Events, Part 1--Main Report.........
Level 3 PRA Project, Volume 3a: Reactor, At-Power, Level     ML22067A212
 1 PRA for Internal Events, Part 2--Appendices..........
Level 3 PRA Project, Volume 3b: Reactor, At-Power, Level     ML22067A213
 1 PRA for Internal Flooding............................
Level 3 PRA Project, Volume 3c: Reactor, At-Power, Level     ML22067A214
 2 PRA for Internal Events and Floods...................
Level 3 PRA Project, Volume 3d: Reactor, At-Power, Level     ML22067A215
 3 PRA for Internal Events and Floods...................
Level 3 PRA Project, Volume 2: Background, Site and          ML22067A232
 Plant Description, and Technical Approach..............
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    Dated: April 19, 2022.

    For the Nuclear Regulatory Commission.
John A. Nakoski,
Chief, Probability Risk Assessment Branch, Division of Risk Analysis, 
Office of Nuclear Regulatory Research.
[FR Doc. 2022-08617 Filed 4-21-22; 8:45 am]
BILLING CODE 7590-01-P