[Federal Register Volume 87, Number 77 (Thursday, April 21, 2022)]
[Notices]
[Pages 23891-23892]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-08519]


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NUCLEAR REGULATORY COMMISSION

[NRC-2021-0179]


Alternative Radiological Source Terms for Evaluating Design Basis 
Accidents at Nuclear Power Reactors

AGENCY: Nuclear Regulatory Commission.

ACTION: Draft regulatory guide; request for comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing for 
public comment a draft regulatory guide (DG), DG-1389, ``Alternative 
Radiological Source Terms for Evaluating Design Basis Accidents at 
Nuclear Power Reactors.'' This DG is proposed Revision 1 to Regulatory 
Guide (RG) 1.183 which describes a method that the NRC staff considers 
acceptable in complying with regulations for design basis accident dose 
consequence analysis using an Alternative Source Term. This guidance 
for light-water reactor (LWR) designs includes the scope, and 
documentation of associated analyses and evaluations; consideration of 
impacts on analyzed risk; and content of submittals.

DATES: Submit comments by June 21, 2022. Comments received after this 
date will be considered if it is practical to do so, but the NRC 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-2021-0179. Address 
questions about Docket IDs in Regulations.gov to Stacy Schumann; 
telephone: 301-415-0624; 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: Michael Eudy, Office of Nuclear 
Regulatory Research, telephone: 301-415-3104, email: 
[email protected]; and Mark Blumberg, Office of Nuclear Reactor 
Regulation, telephone: 301-415-1083, 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-2021-0179 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-2021-0179.
     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 ADAMS accession number for each 
document referenced (if it is available in ADAMS) is provided the first 
time that it is mentioned in this document.
     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-2021-0179 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. Additional Information

    The NRC is issuing for public comment a DG in the NRC's 
``Regulatory Guide'' series. This series was developed to describe 
methods that are acceptable to the NRC staff for implementing specific 
parts of the agency's regulations, to explain techniques that the staff 
uses in evaluating specific issues or postulated events, and to 
describe information that the staff needs in its review of applications 
for permits and licenses.
    The DG, entitled ``Alternative Radiological Source Terms for 
Evaluating Design Basis Accidents at Nuclear Power Reactors,'' (ADAMS 
Accession No. ML21204A065) is temporarily identified by its task 
number, DG-1389 which is proposed

[[Page 23892]]

Revision 1 of RG 1.183 of the same name. This revision of the guide 
(Revision 1) addresses new issues identified since the guide was 
originally issued. These include (1) using the term maximum 
hypothetical accident (MHA) loss-of-coolant accident (LOCA) to define 
the accident described in regulation, (2) adding transient release 
fractions from empirical data from in-pile, prompt power pulse test 
programs and analyses from several international publications of fuel 
rod performance under prompt power excursion conditions, (3) revising 
steady-state release fractions for accidents other than the LOCA based 
on a revision to the American National Standards Institute/American 
Nuclear Society Standard 5.4, ``Method for Calculating the Fractional 
Release of Volatile Fission Products from Oxide Fuel,'' (4) adding 
information to acknowledge the proposed Revision 1 may provide useful 
information for satisfying the radiological dose analysis requirements 
in part 50 of title 10 of the Code of Federal Regulations (10 CFR), 
``Domestic Licensing of Production and Utilization Facilities'' and 10 
CFR part 52, ``Licenses, Certifications, and Approvals for Nuclear 
Power Plants,'' for advanced LWR design and siting, (5) providing 
additional guidance for modeling boiling-water reactor (BWR) main steam 
isolation valve (MSIV) leakage, (6) adding guidance for accident 
tolerant fuel, high-burnup fuel, and increased enrichment source term 
analyses, (7) revising transport and decontamination models for the 
fuel handling design basis accident, (8) adding guidance for crediting 
holdup and retention of MSIV leakage within the main steam lines and 
condenser for BWRs, and (9) providing additional meteorological 
assumption guidance.
    On October 14, 2009, the NRC staff issued DG-1199, ``Alternative 
Radiological Source Terms for Evaluating Design Basis Accidents at 
Nuclear Power Reactors,'' (ADAMS Accession No. ML090960464), for public 
comment (74 FR 52822). DG-1199 was a proposed Revision 1 to RG 1.183. 
The NRC staff has elected not to finalize DG-1199 and is issuing DG-
1389 as a replacement. The staff notes that DG-1389 addresses technical 
issues and considered public comments related to the issuance of DG-
1199.
    The staff is also issuing for public comment a draft regulatory 
analysis (ADAMS Accession No. ML21204A066). The staff developed a 
regulatory analysis to assess the value of issuing or revising a 
regulatory guide as well as alternative courses of action.

III. Backfitting, Forward Fitting, and Issue Finality

    The NRC staff may use this RG, if finalized, as a reference in its 
regulatory processes, such as licensing, inspection, or enforcement. 
However, the NRC staff does not intend to use the guidance in this RG 
to support NRC staff actions in a manner that would constitute 
backfitting as that term is defined in 10 CFR 50.109, ``Backfitting,'' 
and as described in NRC Management Directive (MD) 8.4, ``Management of 
Backfitting, Forward Fitting, Issue Finality, and Information 
Requests'' (ADAMS Accession No. ML18093B087), nor does the NRC staff 
intend to use the guidance to affect the issue finality of an approval 
under 10 CFR part 52. The staff also does not intend to use the 
guidance to support NRC staff actions in a manner that constitutes 
forward fitting as that term is defined and described in MD 8.4. If a 
licensee believes that the NRC is using this RG in a manner 
inconsistent with the discussion in this Implementation section, then 
the licensee may file a backfitting or forward fitting appeal with the 
NRC in accordance with the process in MD 8.4.

IV. Specific Request for Comment

    In addition to the general request for comments on DG-1389, the NRC 
is also seeking specific comments on a draft staff technical assessment 
titled, ``Technical Assessment of Hold-up and Retention of Main Steam 
Isolation Valve Leakage within the Main Steam Lines and Main 
Condenser'' (ADAMS Accession No. ML20085J042) that is referenced in the 
draft revised guidance. The technical assessment provides the proposed 
technical basis for the low risk of gross failure of the alternate 
pathway to the condenser at seismic accelerations at or below a plant's 
design basis safe shutdown earthquake, as described in DG-1389. The 
technical assessment also supports a proposed streamlined approach in 
DG-1389 for demonstrating the seismic capacity of structures, systems, 
and components in the alternate pathway, compared to the approach in RG 
1.183, Revision 0 (ADAMS Accession No. ML003716792).

V. Submitting Suggestions for Improvement of Regulatory Guides

    A member of the public may, at any time, submit suggestions to the 
NRC for improvement of existing RGs or for the development of new RGs. 
Suggestions can be submitted on the NRC's public website at https://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.html. 
Suggestions will be considered in future updates and enhancements to 
the ``Regulatory Guide'' series.

    Dated: April 18, 2022.

    For the Nuclear Regulatory Commission.
Meraj Rahimi,
Chief, Regulatory Guide and Programs Management Branch, Division of 
Engineering, Office of Nuclear Regulatory Research.
[FR Doc. 2022-08519 Filed 4-20-22; 8:45 am]
BILLING CODE 7590-01-P