[Federal Register Volume 84, Number 126 (Monday, July 1, 2019)]
[Notices]
[Pages 31354-31355]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-13928]
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NUCLEAR REGULATORY COMMISSION
[NRC-2019-0119]
Methodology for Modeling Fire Growth and Suppression for
Electrical Cabinet Fires in Nuclear Power Plants
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 Fire
Growth and Suppression for Electrical Cabinet Fires in Nuclear Power
Plants'' (NUREG-2230/EPRI 3002016051). 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.
The purpose of this report is to provide an approach that more closely
models the types of fire progressions and response activities observed
in operating experience. This report provides a revised set of
parameters addressing both the fire growth portion and the suppression
response for electrical cabinet fires.
DATES: Submit comments by July 31, 2019. 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
[[Page 31355]]
for Docket ID NRC-2019-0119. 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-2019-0119 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-2019-0119.
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. ML19163A293.
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-2019-0119 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
Over the past decade, modern fire probabilistic risk assessments
(PRAs) have been developed using NUREG/CR-6850 (EPRI 1011989), EPRI/NRC
Fire PRA Methodology for Nuclear Power Facilities. The results show
that fire can be a significant portion of the overall site risk
profile, however, the methodology was never fully piloted tested before
implementation. As a result, some areas of the fire PRAs have been
found to be overly conservative resulting in potentially unrealistic
results. Additional research is being conducted to improve the tools,
methods, and data used for fire PRAs and refine the estimates of risk
and close technical gaps in the methodology.
Recent research efforts focused on obtaining more detailed
information regarding the fire incidents at nuclear power plants. This
data collection has enabled researchers to obtain more details on the
fire attributes, timeline, and plant impact. This project specifically
reviewed the available electrical cabinet fire incident data in an
effort to update the methodology to better reflect the observed
operating experience. Insights from the data review served as the basis
for amending portions of the fire modeling and suppression response to
more accurately align with operating experience.
Specifically, the methodology described in this report provides:
A conceptual fire event tree progression model developed
through a review of insights from the fire event database. From this
review, guidance was developed to allow for consistent classification
of fire events into two different growth profiles, Interruptible and
Growing.
Split fractions for Interruptible and Growing fires for
use in the revised detection-suppression event tree.
A revised electrical cabinet heat release rate (HRR)
profile for use in the detailed fire modeling of Interruptible Fires.
This revised profile includes a pre-growth period of up to 8 minutes of
negligible HRR. The treatment for the HRR profile for Growing Fires was
not modified in this research.
Revisions to the detection-suppression event tree to
include paths for crediting early intervention by plant personnel as
well as new parameters to facilitate these revisions. These new
parameters include an opportunity to credit detection by general plant
personnel.
An opportunity for main control room (MCR) indications as
a means for fire detection when applicable in the detection-suppression
event tree.
New suppression curves for electrical cabinets (Bin 15)
applicable to Interruptible and Growing electrical cabinet fire
scenarios.
New suppression curves for the MCR.
A new electrical fire suppression curve for use with other
non-cabinet electrical ignition sources (e.g., motors, pumps,
transformers).
A probability of automatic smoke detection effectiveness
for characterizing the ability of spot type smoke detection devices to
operate in a range of geometric conditions and heat release rates. This
is necessary for better alignment with operating experience, which
suggests that the majority of the fires are detected by plant personnel
and MCR indicators instead of automatic smoke detection systems.
An updated Bin 15 fire frequency that makes use of the
fire event data classified in EPRI 3002005302, Fire Events Database
Update for the Period 2010-2014.
Dated at Rockville, Maryland, this 25th day of June 2019.
For the Nuclear Regulatory Commission.
Mark H. Salley,
Branch Chief, Fire and External Hazards Analysis Branch, Division of
Risk Analysis, Office of Nuclear Regulatory Research.
[FR Doc. 2019-13928 Filed 6-28-19; 8:45 am]
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