[Federal Register Volume 85, Number 119 (Friday, June 19, 2020)]
[Notices]
[Pages 37115-37116]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-13254]


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NUCLEAR REGULATORY COMMISSION

[NRC-2016-0233]


Pressurized-Water Reactor Control Rod Ejection and Boiling-Water 
Reactor Control Rod Drop Accidents

AGENCY: Nuclear Regulatory Commission.

ACTION: Regulatory guide; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing 
regulatory guide (RG) 1.236, ``Pressurized-Water Reactor Control Rod 
Ejection and Boiling-Water Reactor Control Rod Drop Accidents.'' This 
is a new RG that provides guidance for analyzing control rod accidents. 
It defines fuel cladding failure thresholds for ductile failure, 
brittle failure, and pellet-clad mechanical interaction. It also 
describes analytical limits and guidance for demonstrating compliance 
with regulations governing reactivity limits. RG 1.236 supersedes the 
guidance for control rod ejection accidents in RG 1.77, ``Assumptions 
Used for Evaluation a Control Rod Ejection Accident for Pressurized 
Water Reactors,'' which is being withdrawn in conjunction with the 
issuance of RG 1.236.

DATES: RG 1.236 is available on June 19, 2020.

ADDRESSES: Please refer to Docket ID NRC-2016-0233 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-2016-0233. Address 
questions about NRC dockets IDs in Regulations.gov to Jennifer Borges; 
telephone: 301-287-9127; email: [email protected]. For technical

[[Page 37116]]

questions, contact the individual listed in the FOR FURTHER INFORMATION 
CONTACT section of this document.
     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]. RG 1.236 and the regulatory analysis 
may be found in ADAMS under Accession Nos. ML20055F490 and ML16124A198, 
respectively.
    Regulatory guides are not copyrighted, and NRC approval is not 
required to reproduce them.

FOR FURTHER INFORMATION CONTACT: Paul Clifford, Office of Nuclear 
Reactor Regulation, telephone: 301-415-4043, email: 
[email protected] and Edward O'Donnell, Office of Nuclear 
Regulatory Research, telephone: 301-415-3317, email: 
[email protected]. Both are staff of the U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION: 

I. Discussion

    The NRC is issuing a new guide in the NRC's ``Regulatory Guide'' 
series. This series was developed to describe and make available to the 
public information regarding methods that are acceptable to the NRC 
staff for implementing specific parts of the NRC's regulations, 
techniques that the staff uses in evaluating specific issues or 
postulated events, and information that the staff needs in its review 
of applications for permits and licenses.
    The RG, titled ``Pressurized-Water Reactor Control Rod Ejection and 
Boiling-Water Reactor Control Rod Drop Accidents,'' describes one 
acceptable method for demonstrating compliance with appendix A of part 
50 of title 10 of the Code of Federal Regulations (10 CFR), General 
Design Criteria (GDC) 28, ``Reactivity Limit,'' with respect to control 
rod ejection (CRE) accidents for pressurized-water reactors and control 
rod drop (CRD) accidents for boiling-water reactors. RG 1.236 provides 
guidance for analyzing these reactivity-initiated accidents. It defines 
fuel cladding failure thresholds for ductile failure, brittle failure, 
and pellet-clad mechanical interaction. It also describes analytical 
limits and guidance for demonstrating compliance with regulations 
governing reactivity limits.
    The guide incorporates new empirical data from in-pile, prompt 
power pulse test programs and analyses from several international 
publications that examine fuel rod performance under reactivity-
initiated accident conditions to provide guidance on acceptable 
analytical methods, assumptions, and limits for evaluating a CRE and 
CRD accidents. The guide supersedes the guidance for control rod 
ejection accidents in RG 1.77, ``Assumptions Used for Evaluation a 
Control Rod Ejection Accident for Pressurized Water Reactors,'' which 
is being withdrawn in conjunction with the issuance of RG 1.236.

II. Additional Information

    The NRC issued RG 1.236 as Draft Guide (DG)-1327 for public comment 
on November 21, 2016 (81 FR 83288), with a 60 day comment period that 
expired on February 21, 2017. A public meeting was held at NRC 
Headquarters on January 25, 2017, while the guide was issued for public 
comment. During the meeting NRC made a commitment to hold a second 
public meeting to discuss the staff's proposed resolution of key 
comments prior to finalization of the guide. Following the public 
meeting the NRC extended the comment period to April 21, 2017 (82 FR 
8998), to allow more time for comment. A second public meeting was held 
at NRC Headquarters on June 5, 2018, to discuss resolution of the 
public comments. To facilitate discussion at the meeting, drafts of the 
guide (ADAMS Accession No. ML18138A459) and a table showing resolution 
of the public comments (ADAMS Accession No. ML18138A458) were made 
publicly available.
    As a result of the written public comments and discussion at the 
two public meetings, the NRC made several changes to the draft guide 
and it was released a second time for public comment on July 30, 2019 
(84 FR 36961). That comment period ended November 18, 2019. The guide 
was further revised to address the second round of public comments. The 
response to this second round of public comments is located in ADAMS 
under Accession No. ML20055F489. Among the changes resulting from the 
two public meetings and the two rounds of public comments were: (1) The 
pellet-clad mechanical interaction cladding failure thresholds were 
revised; (2) the appendix that provided acceptable steady-state and 
transient fission product releases was removed; and (3) the 
implementation section was revised to be consistent with recent 
Commission direction on backfitting and forward fitting as found in 
Management Directive 8.4 ``Management of Backfitting, Forward Fitting, 
Issue Finality, and Information Requests.''

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

    RG 1.236 describes one acceptable method for demonstrating 
compliance with 10 CFR part 50, appendix A, GDC 28 with respect to CRE 
accidents for pressurized-water reactors and CRD accidents for boiling-
water reactors. In general, issuance of this RG does not constitute 
backfitting as defined in 10 CFR 50.109, ``Backfitting,'' and as 
described in NRC Management Directive 8.4; does not constitute forward 
fitting as that term is defined and described in Management Directive 
8.4; and does not affect the issue finality of any approval issued 
under 10 CFR part 52, ``Licenses, Certificates, and Approvals for 
Nuclear Power Plants.'' As explained in this regulatory guide, 
applicants and licensees are not required to comply with the positions 
set forth in this RG. Licensees using RG 1.77 may continue using that 
RG. In future requests or applications for NRC licensing actions 
related to the guidance in RG 1.77, those licensees should use RG 
1.236, which contains the guidance in RG 1.77. Further information on 
the staff's use of the RG is contained in the RG under Section D., 
``Implementation.''

    Dated: June 16, 2020.

    For the Nuclear Regulatory Commission.
Meraj Rahimi,
Chief, Regulatory Guidance and Generic Issues Branch, Division of 
Engineering, Office of Nuclear Regulatory Research.
[FR Doc. 2020-13254 Filed 6-18-20; 8:45 am]
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