[Federal Register Volume 88, Number 198 (Monday, October 16, 2023)]
[Rules and Regulations]
[Pages 71277-71278]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-22789]


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NUCLEAR REGULATORY COMMISSION

10 CFR Parts 50 and 52

[NRC-2021-0179]


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

AGENCY: Nuclear Regulatory Commission.

ACTION: Final guide; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing 
Revision 1 to Regulatory Guide (RG), 1.183, ``Alternative Radiological 
Source Terms for Evaluating Design Basis Accidents at Nuclear Power 
Reactors.'' This RG 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, nature, and 
documentation of associated analyses and evaluations; consideration of 
impacts on analyzed risk; and content of submittals.

DATES: Revision 1 to RG 1.183 is available on October 16, 2023.

ADDRESSES: Please refer to Docket ID NRC-2021-0179 when contacting the 
NRC about the availability of information regarding this document. You 
may obtain publicly available information related to this document 
using any of the following methods:
     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.

[[Page 71278]]

     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]. 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: The PDR, where you may examine and order copies 
of publicly available documents, is open by appointment. 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 
a.m. and 4 p.m. eastern time (ET), Monday through Friday, except 
Federal holidays.
    Revision 1 to RG 1.183 and the regulatory analysis may be found in 
ADAMS under Accession Nos. ML23082A305 and ML21204A066, respectively.
    Regulatory guides are not copyrighted, and NRC approval is not 
required to reproduce them.

FOR FURTHER INFORMATION CONTACT: Michael Eudy, Office of Nuclear 
Regulatory Research, telephone: 301-415-3104, email: 
[email protected], Mark Blumberg, Office of Nuclear Reactor 
Regulation, telephone: 301-415-1083, email: [email protected], and 
Joseph Messina, Office of Nuclear Reactor Regulation, telephone: 301-
415-4226, email: [email protected]. All are staff of the U.S. 
Nuclear Regulatory Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION: 

I. Discussion

    The NRC is issuing a revision 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 proposed Revision 1 to RG 1.183 was issued with a temporary 
identification of Draft Regulatory Guide, DG-1389. (ADAMS Accession No. 
ML21204A065).
    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 loss-of-coolant accident 
(LOCA) to clarify the accident that the staff finds acceptable to use 
to meet the description in the applicable regulations, identified in 
Section A of RG 1.183, Revision 1, with a clear delineation between 
source term assumptions and plant response; (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 that the RG may provide useful 
information for satisfying the radiological dose analysis requirements 
in parts 50 and 52 of title 10 of the Code of Federal Regulations (10 
CFR), for new LWR applicants, including advanced evolutionary and 
passive LWR design and siting; (5) providing additional guidance for 
modeling boiling-water reactor main steam isolation valve 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 hold-up and retention of main steam 
isolation valve leakage within the main steamlines and condenser for 
boiling-water reactors; and (9) providing additional guidance on 
meteorological assumptions.

II. Additional Information

    The NRC published a notice of the availability of DG-1389 in the 
Federal Register on April 21, 2022 (87 FR 23891) for a 60-day public 
comment period. The public comment period closed on June 21, 2022. 
Public comments on DG-1389 and the staff responses to the public 
comments are available under ADAMS under Accession No. ML23082A309.
    In the notice of availability for DG-1389, Section IV, ``Specific 
Request for Comment,'' the NRC sought specific comments on the 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); the 
NRC staff did not receive any public comments on the draft staff 
technical assessment. At this time, the staff has determined to 
incorporate the supporting technical basis information from that draft 
staff technical assessment into RG 1.183, Revision 1, Appendix A, 
Section A-5.5, rather than finalizing the draft staff technical 
assessment separately for inclusion in this RG. Accordingly, the 
reference to the draft staff technical assessment was deleted from the 
final RG.
    As noted in the Federal Register on December 9, 2022 (87 FR 75671), 
this document is being published in the ``Rules'' section of the 
Federal Register to comply with publication requirements under 1 CFR 
chapter I.

III. Congressional Review Act

    This RG is a rule as defined in the Congressional Review Act (5 
U.S.C. 801-808). However, the Office of Management and Budget has not 
found it to be a major rule as defined in the Congressional Review Act.

IV. Backfitting, Forward Fitting, and Issue Finality

    Issuance of RG 1.183, Revision 1, does not constitute backfitting 
as 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); affect the issue finality of an approval under 10 CFR 
part 52; or constitute forward fitting as defined and described in MD 
8.4 because, as explained in RG 1.183, Revision 1, applicants and 
licensees are not required to comply with the positions set forth in 
this RG.

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: October 11, 2023.

    For the Nuclear Regulatory Commission.
Stephen M. Wyman,
Acting Chief, Regulatory Guide and Programs Management Branch, Division 
of Engineering, Office of Nuclear Regulatory Research.
[FR Doc. 2023-22789 Filed 10-13-23; 8:45 am]
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