[Federal Register Volume 85, Number 249 (Tuesday, December 29, 2020)]
[Notices]
[Pages 85683-85685]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-28708]
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NUCLEAR REGULATORY COMMISSION
[NRC-2020-0237]
Considerations for Estimating Site-Specific Probable Maximum
Precipitation at Nuclear Power Plants in the United States of America
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, knowledge management NUREG, NUREG/KM-
0015, ``Considerations for Estimating Site-Specific Probable Maximum
Precipitation at Nuclear Power Plants in the United States of
America.'' The NRC Staff and Oak Ridge National Laboratory have
prepared a reference document summarizing recent lessons-learned in
connection with a review of the site-specific probable maximum
precipitation (SSPMP) estimates used by some nuclear power plant owners
and operators in connection with a recent re-evaluation of external
flooding at their respective project sites.
DATES: Submit comments by March 1, 2021. 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.
[[Page 85684]]
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-2020-0237. Address
questions about Docket IDs in Regulations.gov to Jennifer Borges;
telephone: 301-287-9127; 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: Kevin Quinlan, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001; telephone: 301-415-6809, email: [email protected].
SUPPLEMENTARY INFORMATION:
I. Obtaining Information and Submitting Comments
A. Obtaining Information
Please refer to Docket ID NRC-2020-0237 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-2020-0237.
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]. NUREG/KM-0015, ``Considerations
for Estimating Site-Specific Probable Maximum Precipitation at Nuclear
Power Plants in the United States of America'' is available in ADAMS
under Accession No. ML20356A293.
Attention: The PDR, where you may examine and order copies
of public documents is currently closed. You may submit your request to
the PDR via email at [email protected] or call 1-800-397-4209
between 8:00 a.m. and 4:00 p.m. (EST), 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-2020-0237 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. Background
By letter dated March 12, 2012, the NRC issued a request for
information to all power reactor licensees and holders of construction
permits in active or deferred status licensees to reevaluate seismic
and external flooding for their sites against current Commission
requirements and guidance. This request was made consistent with
section 50.54(f)--``Conditions of Licenses''--of the Commission's
regulations found at part 50 of title of the Code of Federal
Regulations (10 CFR). The request was issued in connection with
implementing lessons-learned identified by the staff, and described in
their Near-Term Task Force Report, following the 2011 accident at the
Fukushima Dai-ichi nuclear power plant. In connection with this
request, owners and operators were to re-evaluate flood hazards at
their respective sites using present-day methods and regulatory
guidance used by the NRC staff when reviewing 10 CFR part 52
applications for Early Site Permits and Combined Operating Licenses.
In response to the staff's 2012 Sec. 50.54(f) information request,
owners and licensees submitted about 60 external flood hazard re-
evaluation reports (FHRRs) corresponding to the operating fleet of
power reactors. In the matter of the probable maximum precipitation
(PMP) value used for some of the flood-hazard re-evaluations (primarily
the estimation of local intense precipitation and riverine-based
floods), current NRC guidance documents recommend the use of the PMP
estimation methods described in a series of Hydrometeorological Reports
(HMRs) developed by the National Oceanographic and Atmospheric
Administration (NOAA). The PMP event itself is generally defined as the
greatest depth of precipitation for a given duration meteorologically
possible for a design watershed or a given storm area at a particular
time of year. The estimated PMP over a particular watershed or basin
results in a flood magnitude for which there is virtually no risk of
exceeding. The challenge, however, is that HMR-derived PMP estimates
are based on methodologies and data which have not been updated with
rainfall and storm events which have occurred in the decades since the
HMRs were last published.
Upon review of the FHRRs, the staff found that about 26 project
sites responding to the Sec. 50.54(f) information request submitted
PMP estimates that were not based on NOAA HMRs but were developed by a
commercial interest. As part of the FHRR process, the staff conducted
an audit of the commercial vendor who developed the site-specific PMP
estimates to better-understand the technical basis underlying the
approach. In all cases, these SSPMP estimates were less than those
obtained from the applicable HMR. Although the development and
estimation of the SSPMP studies reviewed by the staff generally
followed processes similar to those described in the existing guidance,
several different methods, data sources, assumptions, and procedures
were used to obtain site specific results other than those found using
the HMR methodology.
Based on the staff's Sec. 50.54(f) review experience and in
anticipation of its continued use, this NUREG summarizes the lessons-
learned concerning the review and application of a SSPMP. To that end,
this NUREG addresses the following topics:
Storm Selection
Storm Reconstruction
Storm Transposition
Storm Representative Dew Point Selection
[[Page 85685]]
Precipitable Water Estimation
Dew Point Climatology, Moisture Maximization, and Moisture
Transposition
Terrain Adjustment
Envelopment and Probable Maximum Precipitation Determination
Spatial and Temporal Distributions for SSPMP Applications
This reference document describes the technical theory, data
sources, and analysis methodology that could be used to derive a SSPMP
estimate. Certain new terms are also introduced and defined. This
reference document also identifies key technical (meteorological)
considerations when reviewing a SSPMP estimate.
To date, there is no clear NRC guidance on this topic or a commonly
agreed-to approach on the estimation of SSPMP. As the staff may be
reviewing additional SSPMP estimates in the future in connection with
its regulatory responsibilities, it was decided to elicit stakeholder
views on the matters and approaches discussed in this draft document.
This document contains no regulatory guidance or regulatory
positions.
III. Knowledge Management
Since its inception, the Atomic Energy Commission and its
successor, the NRC, have focused on preserving the (explicit)
documentary record of its decision-making in the form of NUREGs, SECY
Papers, Regulatory Guides, and other documents. However, in 2006, the
agency recognized that there was a need to engage in a more-formal
program of knowledge management that also reflects the less-tangible
(implicit) human capital aspect of the agencies' knowledge base. This
feature was particularly important as the agency enters its fifth
decade of operation--a period characterized by an increasing number of
retirements among long-serving staff involved in many of the agencies'
early regulatory programs and associated licensing actions. Staff
efforts thus far in preserving this legacy of experience that describe
important historical events, facts, and research that were instrumental
in shaping NRC's regulatory programs, can be found at https://www.nrc.gov/reading-rm/doc-collections/nuregs/knowledge/.
The purpose of this knowledge management NUREG (or NUREG/KM) is
intended to satisfy an NRC goal of maintaining and preserving knowledge
concerning the lessons-learned from the recent flood hazard re-
evaluations at current and planned nuclear power plant sites performed
most recently in connection with the staff 2012 Sec. 50.54(f) reviews.
Dated: December 22, 2020.
For the Nuclear Regulatory Commission.
Luissette Candelario,
Project Manager, External Hazards Branch, Division of Engineering and
External Hazards, Office of Nuclear Reactor Regulation.
[FR Doc. 2020-28708 Filed 12-28-20; 8:45 am]
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