Notice2026-19217
Draft Interim Staff Guidance: Material Compatibility for Non-Light Water-Reactors
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
September 21, 2026
Issuing agencies
Nuclear Regulatory Commission
Abstract
The U.S. Nuclear Regulatory Commission (NRC) is soliciting public comment on its draft Interim Staff Guidance (ISG), "Material Compatibility for non-Light-Water Reactors, DANU-ISG-2023-01, Revision 1." The purpose of this draft ISG is to assist the NRC staff in reviewing certain applications for non-light water reactor designs, including power and non-power reactors. This ISG has been updated to include an appendix to describe information the NRC staff generally have used to perform the review of materials of construction and passive structures, systems, and components (SSCs) performance for non- light water reactors (non-LWRs), as well as limited updates to technical information in the main body. It has also been updated to make it applicable to certain additional NRC regulations.
Full Text
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<title>Federal Register, Volume 91 Issue 181 (Monday, September 21, 2026)</title>
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[Federal Register Volume 91, Number 181 (Monday, September 21, 2026)]
[Notices]
[Pages 59813-59815]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-19217]
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NUCLEAR REGULATORY COMMISSION
[NRC-2022-0215]
Draft Interim Staff Guidance: Material Compatibility for Non-
Light Water-Reactors
AGENCY: Nuclear Regulatory Commission.
ACTION: Draft guidance; request for comment.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is soliciting
public comment on its draft Interim Staff Guidance (ISG), ``Material
Compatibility for non-Light-Water Reactors, DANU-ISG-2023-01, Revision
1.'' The purpose of this draft ISG is to assist the NRC staff in
reviewing certain applications for non-light water reactor designs,
including power and non-power reactors. This ISG has been updated to
include an appendix to describe information the NRC staff generally
have used to perform the review of materials of construction and
passive structures, systems, and components (SSCs) performance for non-
light water reactors (non-LWRs), as well as limited updates to
technical information in the main body. It has also been updated to
make it applicable to certain additional NRC regulations.
DATES: Submit comments by November 5, 2026. 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
on or before this date.
ADDRESSES: You may submit comments by any of the following methods:
[[Page 59814]]
<bullet> Federal Rulemaking Website: Go to <a href="http://www.regulations.gov">http://www.regulations.gov</a> and search for Docket ID NRC-2022-0215. Address
questions about Docket IDs in <a href="http://Regulations.gov">Regulations.gov</a> to Bridget Curran;
telephone: 301-415-1003; email: <a href="/cdn-cgi/l/email-protection#10526279747775643e53656262717e507e62733e777f66"><span class="__cf_email__" data-cfemail="6426160d000301104a27111616050a240a16074a030b12">[email protected]</span></a>. For technical
questions, contact the individual(s) listed in the FOR FURTHER
INFORMATION CONTACT section of this document.
<bullet> Mail comments to: Office of Nuclear Material Safety and
Safeguards, Mail Stop: TWFN-5-A85, 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: Matthew Hiser, telephone: 301-415-
2454; email: <a href="/cdn-cgi/l/email-protection#216c4055554944560f6948524453614f53420f464e57"><span class="__cf_email__" data-cfemail="b3fed2c7c7dbd6c49dfbdac0d6c1f3ddc1d09dd4dcc5">[email protected]</span></a> and Vincent Voltaggio, telephone:
301-415-3860; email: <a href="/cdn-cgi/l/email-protection#5d0b34333e383329730b3231293c3a3a34321d332f3e733a322b"><span class="__cf_email__" data-cfemail="b8eed1d6dbddd6cc96eed7d4ccd9dfdfd1d7f8d6cadb96dfd7ce">[email protected]</span></a>. Both are staff of the
Office of Advanced Reactors at 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-2022-0215 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:
<bullet> Federal Rulemaking Website: Go to <a href="https://www.regulations.gov">https://www.regulations.gov</a> and search for Docket ID NRC-2022-0215.
<bullet> NRC's Agencywide Documents Access and Management System
(ADAMS): You may obtain publicly available documents online in the
ADAMS Public Documents collection at <a href="https://www.nrc.gov/reading-rm/adams.html">https://www.nrc.gov/reading-rm/adams.html</a>. To begin the search, select ``Begin ADAMS Public 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 <a href="/cdn-cgi/l/email-protection#e8b8acbac6ba8d9b879d9a8b8da8869a8bc68f879e"><span class="__cf_email__" data-cfemail="eebeaabcc0bc8b9d819b9c8d8bae809c8dc0898198">[email protected]</span></a>. 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.
<bullet> 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
<a href="/cdn-cgi/l/email-protection#8edecadca0dcebfde1fbfcedebcee0fceda0e9e1f8"><span class="__cf_email__" data-cfemail="174753453945726478626574725779657439707861">[email protected]</span></a> 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.
B. Submitting Comments
The NRC encourages electronic comment submission through the
Federal rulemaking website (<a href="https://www.regulations.gov">https://www.regulations.gov</a>). Please
include Docket ID NRC-2022-0215 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
<a href="https://www.regulations.gov">https://www.regulations.gov</a> 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
As part of its review of advanced non-light water reactor
applications, the NRC staff evaluates materials performance to ensure
passive components fulfill design requirements for the design life, and
that adequate surveillance and monitoring programs are in place. NRC
regulations in parts 50, 52, and 53 of title 10 of the Code of Federal
Regulations (10 CFR) describe the information applicants must include
in applications for construction permits, operating licenses, combined
operating licenses, standard design approvals, standard design
certifications, and manufacturing licenses. This includes information
related to requirements to ensure passive materials performance and
performance monitoring. The NRC endorsed, with exceptions and
limitations, American Society of Mechanical Engineers (ASME) Code
Section III, Division 5, ``High Temperature Reactors'' (III-5), with
conditions, in Revision 3 of Regulatory Guide (RG) 1.87,
``Acceptability of ASME Code, Section III, Division 5, `High
Temperature Reactors,''' (ADAMS Accession No. ML25176A084) for use by
non-LWR applicants and licensees subject to 10 CFR parts 50 and 52. The
NRC staff has not endorsed this document for use by applicants and
licensees subject to 10 CFR part 53. The NRC staff is currently
considering whether to endorse both III-5 for applicants and licensees
subject to 10 CFR part 53. If, based on the NRC staff's review, the NRC
staff determines that it cannot endorse either III-5 for use by
applicants and licensees subject to 10 CFR part 53, it will revise this
ISG accordingly before issuing it for use.
This revision to DANU-ISG-2023-01 adds an appendix providing risk-
informed guidance on information related to materials performance that
applicants should include in various applications. It also updates
miscellaneous information and extends the ISG's applicability to
applications under 10 CFR part 53.
III. Discussion
The purpose of this draft ISG, ``Material Compatibility for non-
Light-Water Reactors, DANU-ISG-2023-01, Revision 1'' (ADAMS Accession
No. ML26155A114), is to aid the NRC staff reviewing non-light water
reactor applications for permits, licenses, certifications, and
approvals under 10 CFR parts 50, 52 and 53. III-5 and other codes and
standards used for the design and construction of mechanical components
specify the mechanical properties and allowable stresses for design of
components in high temperature reactors. Because III-5 and other design
and construction codes and standards do not provide methods to evaluate
deterioration that may occur in service as a result of corrosion, mass
transfer phenomena, radiation effects, or other material instabilities,
this draft ISG revision identifies information that the staff should
consider as part of its evaluation of a non-light water reactor
application with respect to applicable design requirements including
materials performance, environmental compatibility, and performance
monitoring programs for safety-significant SSCs.
This revision of DANU-ISG-2023-01 adds an appendix to provide
guidance related to information the NRC staff generally have used to
perform the review of materials of construction and passive SSC
performance for non-LWRs. This appendix provides guidance across key
application content areas for materials performance, including
description of the design and operating environment as well as
performance evaluation and monitoring. Description of the design and
operating environment includes identification of materials of
construction, identification of
[[Page 59815]]
environmental conditions, and use of codes and standards. Performance
evaluation and monitoring covers primarily an environmental
compatibility assessment and performance monitoring. The appendix
concludes with tables providing guidance on what information is
acceptable at the preliminary and final design stages across these key
application content areas as a function of safety significance.
In addition to adding the appendix, this revision also makes the
ISG applicable to applications under 10 CFR part 53 and makes other
miscellaneous changes to the ISG.
(Authority: 42 U.S.C. 2011 et seq.)
Dated: September 16, 2026.
For the Nuclear Regulatory Commission.
Mehdi Reisi Fard,
Director, Division of Advanced Reactor Engineering, Office of Advanced
Reactors.
[FR Doc. 2026-19217 Filed 9-18-26; 8:45 am]
BILLING CODE 7590-01-P
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