[Federal Register Volume 85, Number 1 (Thursday, January 2, 2020)]
[Notices]
[Pages 143-144]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-28323]



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NUCLEAR REGULATORY COMMISSION

[NRC-2019-0229]


Methodology for Modeling Transient Fires in Nuclear Power Plant 
Fire Probabilistic Risk Assessments

AGENCY: Nuclear Regulatory Commission.

ACTION: Draft NUREG; request for comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing for 
public comment a draft NUREG entitled, ``Methodology for Modeling 
Transient Fires in Nuclear Power Plant Fire Probabilistic Risk 
Assessments'' (NUREG-2233/EPRI 3002016054). This report is a joint 
product of the NRC and the Electric Power Research Institute (EPRI) 
collaborating under a memorandum of understanding for fire research. 
This report contains a methodology to increase the realism in the 
modeling of transient ignition sources in fire probabilistic risk 
assessment (FPRA). Additionally, the report develops a method for the 
detailed modeling of transient fires that includes fire growth and 
decay parameters, yields of minor products of combustion, heat of 
combustion, and the physical size and effective elevation of the fire.

DATES: Submit comments by February 18, 2020. 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 
before this date.

ADDRESSES: You may submit comments by any of the following methods:
     Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2019-0229. Address 
questions about Docket IDs in Regulations.gov to Jennifer Borges; 
telephone: 301-287-9127; 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: David W. Stroup, Office of Nuclear 
Regulatory Research, telephone: 301-415-1649, email: 
[email protected]; or Nicholas Melly, Office of Nuclear Regulatory 
Research, telephone: 301-415-2392, email: [email protected]. Both 
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-2019-0229 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-2019-0229.
     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]. The draft NUREG on ``Methodology for 
Modeling Fire Growth and Suppression Response of Electrical Cabinet 
Fires in Nuclear Power Plants'' is available in ADAMS under Accession 
No. ML19357A270.
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

B. Submitting Comments

    Please include Docket ID NRC-2019-0229 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

    In 2005, the Electric Power Research Institute (EPRI) and the NRC's 
Office of Nuclear Regulatory Research (RES) issued a joint technical 
report titled, EPRI/NRC-RES, Fire PRA Methodology for Nuclear Power 
Facilities, EPRI 1011989, NUREG/CR-6850. This publication documented 
state-of-the-art methods, tools, and data for conducting a fire 
probabilistic risk assessment (FPRA) for a commercial nuclear power 
plant (NPP) application. Following this publication, many utilities 
developed FPRAs using the guidance in NUREG/CR-6850 to support risk 
informed applications, including the transition to an NFPA 805 
licensing basis, among others. The results obtained from the FPRA 
models have suggested specific elements in the fire scenario analysis 
where improved methods and/or guidance could reduce conservatism and 
increase realism in the risk estimates. Consequently, over the past 
fifteen years, FPRA research covering the areas of fire ignition 
frequencies, fire modeling, human reliability analysis and spurious 
operations have been published. These research results have improved 
realism for the ignition sources identified in NUREG/CR-6850 except for 
transient combustibles. The research in this report addresses that gap.
    The research documented in this report was developed by a working 
group that included members of both the regulator and the nuclear power 
industry and consisted of two phases. For the first phase, an extensive 
set of experiments measuring the heat release rate and other fire 
characteristics of transient fires was conducted to supplement the 
existing data in NUREG/CR-6850/EPRI 1011989. The test report for this 
set of experiments, NUREG-2232/EPRI 3002015997, ``Heat Release Rate and 
Fire Characteristics of Fuels Representative of Typical Transient Fire 
Events in Nuclear Power Plants,'' contains details on all the fuel 
packages tested; the test method including selection of fuel packages 
and ignition sources; the methods used to process the collected test 
data; and the collected and derived data including heat release rate, 
fire diameter, zones of influence, fire growth and decay parameters, 
and the combustion properties of the fuel packages. The test report is 
available from EPRI at https://www.epri.com/#/pages/product/

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3002015997/. The second phase, documented in this report, combined the 
data collected in the first phase with data from previous experimental 
programs, developed a methodology for weighting the combined dataset 
based on industry experience with transient fires, and used the 
weighted combined dataset to create improved probabilistic 
distributions for use in modeling transient fires in FPRA. 
Additionally, this report presents detailed guidance for modeling the 
time-dependence and defining the combustion characteristics of 
transient fires.

    Dated at Rockville, Maryland, this 27th day of December 2019.

    For the Nuclear Regulatory Commission.
David W. Stroup,
Acting Branch Chief, Fire and External Hazards Branch, Division of Risk 
Analysis, Office of Nuclear Regulatory Research.
[FR Doc. 2019-28323 Filed 12-31-19; 8:45 am]
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