[Federal Register Volume 90, Number 142 (Monday, July 28, 2025)]
[Proposed Rules]
[Pages 35445-35449]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-14215]
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NUCLEAR REGULATORY COMMISSION
10 CFR Part 50
[Docket No. PRM-50-124; NRC-2022-0178]
Licensing Safety Analysis for Loss-of-Coolant Accidents
AGENCY: Nuclear Regulatory Commission.
ACTION: Petition for rulemaking; denial.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is denying a
petition for rulemaking (PRM), dated August 1, 2022, submitted by Ralph
O. Meyer. The petition requested that the NRC amend its regulations
regarding the licensing safety analysis for loss-of-coolant accidents.
The petition was docketed on August 1, 2022, and was assigned Docket
No. PRM-50-124. The NRC is denying the petition because the NRC is
addressing emergency core cooling system performance with a risk-
informed and performance-based regulatory approach rather than a
deterministic approach as suggested by the petitioner.
DATES: The docket for the petition for rulemaking, PRM-50-124, is
closed on July 28, 2025.
ADDRESSES: Please refer to Docket ID NRC-2022-0178 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-2022-0178. Address
questions about NRC dockets to Helen Chang; telephone: 301-415-3228;
email: [email protected]. For technical 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, at 301-415-4737,
or by email to [email protected]. For the convenience of the reader,
instructions about obtaining materials referenced in this document are
provided in the ``Availability of Documents'' section.
NRC's PDR: The NRC 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, Monday through Friday, except Federal
holidays.
FOR FURTHER INFORMATION CONTACT: Denise Edwards, Office of Nuclear
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission,
Washington, DC 20555-0001; telephone: 301-415-7204, email:
[email protected].
SUPPLEMENTARY INFORMATION:
Table of Contents
I. The Petition
II. Public Comments on the Petition
III. Evaluation of the Petition
IV. Reasons for Denial
V. Availability of Documents
VI. Conclusion
I. The Petition
Section 2.802 of title 10 of the Code of Federal Regulations (10
CFR), ``Petition for rulemaking,'' provides an opportunity for any
interested person to petition the Commission to issue, amend, or
rescind any regulation. On August 1, 2022, the NRC received and
docketed a PRM filed by Ralph O. Meyer. On November 23, 2022, the NRC
published a notice of docketing requesting comment on the petition in
the Federal Register (87 FR 71531). The petition requested that the NRC
amend its regulations in 10 CFR 50.46, ``Acceptance criteria for
emergency core cooling systems for light-water nuclear power
reactors.'' The regulations in 10 CFR 50.46 require the calculation of
emergency core cooling system (ECCS) performance following postulated
loss-of-coolant accidents (LOCAs) to demonstrate that the acceptance
criteria in 10 CFR 50.46(b) are met. The petition requested the
elimination of the acceptance criteria for peak cladding temperature
(PCT) and maximum cladding oxidation (commonly referred to as maximum
local oxidation, or MLO) in 10 CFR 50.46(b). As a replacement for these
criteria, the petition requested that the NRC regulations be revised to
limit the number of fuel rod ruptures to 1 percent for small-break
LOCAs and 10 percent for large-break LOCAs. The petition stated that
nuclear power reactors in Germany must show that the proposed fuel rod
rupture limits are met.
The NRC identified two issues in the petition, as follows:
Issue 1: The petition asserted that the current acceptance criteria
for the calculated PCT and MLO in 10 CFR 50.46(b) do not ensure an
easily coolable geometry at moderate and higher fuel burnups due to
fuel dispersal.
Issue 2: The petition asserted that the calculations of temperature
and oxidation within the burst region of a fuel rod are prone to large
uncertainties, and the technical bases for the acceptance criteria on
these two parameters are complex and misunderstood. Specifically, the
petition stated that the beliefs that the temperature limit prevents
autocatalytic oxidation and that a reduction in cladding thickness
causes embrittlement are incorrect.
II. Public Comments on the Petition
The NRC invited interested persons to submit comments on the
petition (87 FR 71531; November 23, 2022). In response to a request by
the Nuclear Energy Institute (NEI), the comment period was extended to
March 8, 2023 (88 FR 7012; February 2, 2023). The NRC received 12
[[Page 35446]]
comment submissions on the petition. The petitioner submitted eight
comment submissions in support of the petition, including submittals
after the closure of the public comment period. Westinghouse Electric
Company LLC (Westinghouse), Framatome Inc., the Pressurized Water
Reactors Owners Group (PWROG), and NEI each provided a comment
submission opposing the petition. A summary of the significant comments
and NRC responses is provided below. The NRC evaluation of the petition
is provided in Section III, ``Evaluation of the Petition.''
Several comments on the petition mentioned the then-pending draft
final rule commonly referred to as ``10 CFR 50.46c.'' This draft final
rule was provided to the Commission in SECY-16-0033, ``Draft Final
Rule--Performance-Based Emergency Core Cooling System Requirements and
Related Fuel Cladding Acceptance Criteria (RIN 3150-AH42),'' dated
March 16, 2016. On April 11, 2024, the Commission returned the 10 CFR
50.46c draft final rule to the staff in a staff requirements memorandum
(SRM) for SECY-16-0033, ``Staff Requirements--SECY-16-0033--Draft Final
Rule--Performance-Based Emergency Core Cooling System Requirements and
Related Fuel Cladding Acceptance Criteria.'' The NRC comment responses
below include responses to the comments on the petition that mentioned
the 10 CFR 50.46c draft final rule.
Comment: The petitioner stated that it is appropriate to consider
fuel fragmentation, relocation, and dispersal (FFRD) as part of the
rulemaking for ``Increased Enrichment of Conventional and Accident
Tolerant Fuel Designs for Light-Water Reactors'' (Increased Enrichment
rulemaking).
NRC Response: The NRC agrees with this comment. The Increased
Enrichment rulemaking plan was provided to the Commission in SECY-21-
0109, ``Rulemaking Plan on Use of Increased Enrichment of Conventional
and Accident Tolerant Fuel Designs for Light-Water Reactors,'' dated
December 20, 2021. In an SRM dated March 16, 2022, SRM-SECY-21-0109,
``Staff Requirements--SECY-21-0109--Rulemaking Plan on Use of Increased
Enrichment of Conventional and Accident Tolerant Fuel Designs for
Light-Water Reactors,'' the Commission approved this plan and further
directed the staff to consider FFRD issues relevant to higher
enrichment and fuel burnup levels as part of the rulemaking.
Comment: Framatome stated that the range of burnups meant by
``moderate fuel burnup'' in the petition is not clear.
NRC Response: The NRC agrees with this comment. The term ``moderate
fuel burnup'' lacks specificity. The NRC interpreted ``moderate fuel
burnup'' to encompass currently authorized fuel burnups above which
FFRD could potentially occur.
Comment: The petitioner stated that licensees should report the
number of fuel rod ruptures during a LOCA so the NRC may determine if
near-term action is needed to limit the amount of loose material in the
core.
NRC Response: The NRC disagrees with this comment. The NRC has
reasonable assurance that the extent and consequences of fuel dispersal
during a LOCA, for currently authorized fuel burnup levels, would be
limited such that core coolability would not be challenged on a large
scale. This conclusion is based on research and analyses summarized in
SECY-15-0148, ``Evaluation of Fuel Fragmentation, Relocation and
Dispersal Under Loss-Of-Coolant Accident (LOCA) Conditions Relative to
the Draft Final Rule on Emergency Core Cooling System Performance
During a LOCA (50.46c),'' dated November 30, 2015.
Comment: The petitioner stated that, based on engineering judgment,
setting rod rupture limits to 1 percent of the core for a small-break
LOCA and 10 percent of the core for a large-break LOCA is reasonable
and practical. The petitioner stated that FFRD research should focus on
establishing a technical basis for these limits and refine these limits
as needed.
NRC Response: The NRC agrees, in part, with this comment. The NRC
agrees that research would be needed to establish the technical basis
for any fuel rod rupture limits that may be imposed. However, the NRC
disagrees with the statement that the petition's proposed limits are
reasonable and practical because there currently is not sufficient
evidence to support this assertion.
Comment: The petitioner stated that current thermal-hydraulic codes
can predict cladding rupture with enough accuracy such that built-in
conservatisms are not needed to calculate the number of fuel rod
bursts.
NRC Response: The NRC agrees, in part, with this comment. The NRC
agrees that current thermal-hydraulic codes can predict fuel rod
rupture with reasonable accuracy, such that best-estimate plus
uncertainty models may be used. However, current LOCA analyses are not
focused on fuel rod rupture. The conservatisms in current LOCA analyses
are necessary to ensure that the PCT and MLO acceptance criteria are
met.
Comment: The petitioner stated that, based on analyses and
international experience, fuel rod ruptures can be limited to 1 percent
for small-break LOCAs and 10 percent for large-break LOCAs. However,
this may require some alteration in reactor core design or adjustment
of power level to achieve.
NRC Response: The NRC disagrees with this comment. The NRC
determined that more research and analysis would be needed to
demonstrate that the proposed fuel rod rupture limits could be met,
under which operating conditions, and whether such limits are
appropriate to ensure a reasonable level of safety.
Comment: The petitioner stated that current LOCA analyses do not
address fuel dispersal, and that they assume it does not occur. In
reality, fuel dispersal is expected to occur during LOCA.
NRC Response: The NRC agrees with this comment. The NRC
acknowledges that fuel dispersal is not accounted for in current LOCA
analyses and agrees that fuel dispersal is expected to occur during a
LOCA. However, the NRC has reasonable assurance that the extent and
consequences of fuel dispersal during a LOCA, for currently authorized
fuel burnup levels, would be limited such that core coolability would
not be challenged on a large scale.
Comment: The petitioner stated that increased enrichment and burnup
could become an issue for long-term core cooling during large-break
LOCAs.
NRC Response: The NRC agrees with this comment. The NRC agrees that
the higher enrichment and higher burnups that are being considered in
the future could increase the magnitude of fuel dispersal and thus it
could become challenging to demonstrate long-term cooling. As noted in
other comment responses, the Commission has directed the staff to
consider FFRD issues relevant to higher enrichment and fuel burnup
levels as part of the Increased Enrichment rulemaking.
Comment: The petitioner stated that high burnup fuel is more likely
to pulverize than low burnup fuel and is thus a greater threat to long-
term core cooling.
NRC Response: The NRC agrees, in part, with this comment. The NRC
agrees that high burnup fuel is more likely to pulverize than low
burnup fuel, which would very likely result in higher amounts of fuel
dispersal. However, the impact of fuel dispersal and particle size on
long-term core cooling requires additional research.
Comment: NEI, Westinghouse, Framatome, and the PWROG recommend
rejection of the PRM but support rulemaking to address FFRD in
[[Page 35447]]
a holistic manner that considers industry initiatives including
accident tolerant fuel, increased fuel enrichment, and higher fuel
burnups. Several commenters requested that the NRC revise the pending
draft final rule for 10 CFR 50.46c to address FFRD issues and industry
fuel design initiatives. Framatome indicated that the petition could be
considered as part of an update to the draft final rule for 10 CFR
50.46c.
NRC Response: The NRC agrees, in part, with these comments. As
discussed in Section IV, ``Reasons for Denial,'' the NRC plans to
address regulatory issues related to accident tolerant fuel, increased
fuel enrichment, higher fuel burnups, and FFRD in the Increased
Enrichment rulemaking. However, consistent with SRM-SECY-16-0033, the
NRC plans to assess the need for further action on the 10 CFR 50.46c
rulemaking after the conclusion of the Increased Enrichment rulemaking.
Comment: NEI, Framatome, Westinghouse, and the PWROG stated that
revising the ECCS acceptance criteria would require a large amount of
effort and resources for industry to comply with them, and this would
divert resources from industry's work on accident tolerant fuel and
FFRD research. One commenter noted that criteria similar to the
petition's proposed criteria could be valuable as an alternative or
supplemental criteria to demonstrate core coolability, but this would
still require significant time and effort to develop and implement.
NRC Response: The NRC agrees, in part, with these comments. Any
changes to the ECCS acceptance criteria would require significant
effort from the NRC and industry. To the extent that the Increased
Enrichment rulemaking would include amendments or alternatives to the
ECCS acceptance criteria, the NRC would perform a regulatory analysis
to consider the costs and benefits of these approaches. In addition,
the cumulative effects of regulations would be considered as part of
the rulemaking process to identify and resolve issues that could lead
to implementation challenges.
Comment: NEI and the PWROG stated that current ECCS performance
criteria in 10 CFR 50.46 remain adequate for the protection of public
health and safety. The PWROG noted that the adequacy of the PCT and MLO
acceptance criteria was supported by original testing, and subsequent
testing to account for changes in plant operations continues to support
the basic nature of these acceptance criteria. NEI and the PWROG also
noted that industry and NRC analyses performed since 2012 have
confirmed the safe operations of the commercial nuclear fleet.
NRC Response: The NRC agrees with the comments. The current
acceptance criteria in 10 CFR 50.46 provide for adequate protection of
public health and safety. The NRC agrees that industry and NRC analyses
have confirmed the safe operations of the commercial nuclear fleet. As
documented in a February 10, 2012, memorandum titled ``ECCS Performance
Safety Assessment and Audit Report,'' the staff completed an ECCS
performance safety assessment in 2011 which confirmed, on a plant-
specific basis, the safe operation of the commercial nuclear fleet
following the identification of concerns with the current acceptance
criteria in 10 CFR 50.46. The staff updates this assessment annually to
verify the continued safe operation of the fleet. Therefore, with
respect to ECCS performance, adequate protection of public health and
safety is provided by the current acceptance criteria in 10 CFR 50.46
in conjunction with the annual NRC assessments.
Comment: Westinghouse disagreed with the statement in the petition
that the current acceptance criteria become ineffective at moderate
fuel burnups because burst fuel rods experience massive fuel loss and
do not retain fuel pellets in the fuel rods. The commenter stated that
the petition lacks information to support this statement.
NRC Response: The NRC agrees, in part, with the comment. NRC
studies to-date predict that 1 to 3 percent of the fuel in the core
might be dispersed during a large-break LOCA, using conservative
dispersal thresholds, for currently authorized burnup levels. The NRC
considers this to be a limited amount of dispersed fuel. The
consequences of fuel dispersal at higher burnups are still the topic of
ongoing research by the international community.
Comment: Westinghouse and NEI stated that current methods to
calculate the MLO and PCT are sufficiently detailed and conservative to
demonstrate compliance with 10 CFR 50.46 with a high probability.
NRC Response: The NRC agrees with these comments for currently
authorized fuel burnup levels and fuel designs.
Comment: Westinghouse stated that calculations of MLO and PCT using
NRC-approved methods support the demonstration of a coolable core
geometry and continued safe operation under postulated LOCA conditions.
NRC Response: The NRC agrees with this comment for currently
authorized fuel burnup levels and fuel designs. This was documented in
SECY-15-0148 and is supported by the NRC staff's annual updates to the
ECCS performance safety assessment.
Comment: Westinghouse stated that the petition contains a quoted
statement from a paper by the German Reactor Safety Commission (RSK)
that was taken out of context. The commenter stated that the RSK
determined that the criteria in the proposed 10 CFR 50.46c rule are
adequate to prevent cladding fragmentation during quench, contrary to
what the petition implies.
NRC Response: The NRC agrees with this comment. The petition
implied that RSK stated that cladding temperature and oxidation cannot
be used in a safety demonstration to comply with regulations. The NRC
does not agree with the petition's assertions about the German
regulations. In fact, the NRC confirmed that cladding temperature and
oxidation are used to demonstrate compliance with RSK regulations.
Comment: Westinghouse and Framatome stated that the fact that the
PCT and MLO criteria in 10 CFR 50.46 are surrogates for the
demonstration of the post-quench coolability of the core is well
understood and well documented. In addition, the proposed surrogate
criteria in 10 CFR 50.46c would maintain the coolability goal and thus
maintain plant safety.
NRC Response: The NRC agrees with these comments. Extensive
technical bases for 10 CFR 50.46 have been developed and describe the
rationale for the surrogate criteria, as summarized by G. Hache and
H.M. Chung in ``The History of LOCA Embrittlement Criteria,'' NUREG/CP-
0172, May 2001, pp. 205-237.
Comment: Westinghouse stated that the petition does not provide
evidence to support the limits on the percentage of fuel rod bursts
proposed in the petition as being appropriate to ensure core
coolability. Westinghouse and Framatome stated that the proposed rod
burst criteria in the petition do not account for important differences
between the various plant designs operating in the United States. These
differences could be particularly important when assessing fuel
dispersal and its consequences. Framatome stated that using a core-wide
burst limit does not make sense given that only high burnup rods are
susceptible to fuel dispersal.
NRC Response: The NRC agrees with these comments. The petition does
not provide evidence showing that the proposed fuel rod rupture limits
would ensure core coolability and the petition does not account for
differences in plant designs. As noted in other comment responses,
research would be needed to establish the technical basis for any fuel
[[Page 35448]]
rod rupture limits that would be imposed.
Comment: NEI, Westinghouse, and Framatome responded to the
petition's statement that the proposed fuel rod rupture limits are used
in Germany. The German regulatory limits on the percentage of fuel rod
ruptures are related to radiological consequences and not used for core
coolability assessments. The historical ECCS acceptance criteria for
MLO and PCT remain in German regulations.
NRC Response: The NRC agrees with these comments. The NRC does not
agree with the petition's assertions about the German regulations.
Comment: Westinghouse, Framatome, and the PWROG stated that, as
described in SECY-15-0148, plants continue to operate safely with
existing burnup limits and current styles of operation. Any increases
above currently licensed fuel burnup levels would require NRC approval.
The NRC Research Information Letter 2021-13, ``Interpretation of
Research on Fuel Fragmentation, Relocation, and Dispersal at High
Burnup,'' dated December 2021, concluded that significant fine
fragmentation begins above a fuel burnup threshold of 55 gigawatt days
per metric ton uranium, which is conservative.
NRC Response: The NRC agrees with these comments. Today's plants,
operating within their burnup limits, are safe.
Comment: Framatome stated that general aspects of FFRD have been
known since the 1980s and widespread dispersal that would impact
coolability was not expected to be significant.
NRC Response: The NRC agrees, in part, with the comment. The NRC
agrees that fuel dispersal would be limited under current licensed
burnups and operating practices. However, for higher fuel burnup
levels, the NRC recognizes that fuel dispersal could challenge core
coolability.
Comment: Westinghouse stated that conclusions from a Westinghouse
paper cited in the petition have been superseded by new research and
are not appropriate to support the suggested criteria in the petition.
NRC Response: The NRC agrees with this comment. The Westinghouse
paper, as explained by the commenter, did not consider fuel pellet
thermal conductivity degradation and other material high burnup
phenomena.
Comment: One commenter stated that the distribution of ruptured
rods in the core is important, and clusters of ruptured rods are more
detrimental than more evenly distributed ruptures.
NRC Response: The NRC agrees with this comment based on engineering
judgment.
III. Evaluation of the Petition
The petition states that the PCT and MLO acceptance criteria in 10
CFR 50.46(b) would not ensure adequate core cooling during a LOCA
because these criteria do not prevent significant fuel dispersal at
currently authorized fuel burnup levels and higher.
The PCT and MLO acceptance criteria in 10 CFR 50.46 are important
to preventing gross fuel rod failure via a brittle failure mechanism.
This ensures that fuel assemblies will remain in a rod-like array
within the reactor core that is easier to cool than a rubble pile of
fuel and cladding. However, research has shown that the PCT and MLO
acceptance criteria do not prevent ductile failure of the cladding
(ballooning and rupture), which could lead to fuel dispersal in the
reactor core through a rupture in the fuel cladding at higher fuel
burnups. Therefore, while the NRC considers the PCT and MLO to be
appropriate surrogate metrics for cladding embrittlement, the NRC
agrees with the petition's assertion that the acceptance criteria for
the calculated PCT and MLO in 10 CFR 50.46(b) do not prevent fuel
dispersal due to ductile failures at higher fuel burnup.
For currently authorized fuel burnup levels, the NRC has
determined, based on research and analyses, that the extent and
consequences of fuel dispersal during a LOCA would be limited such that
core coolability would not be challenged on a large scale. However, for
higher fuel burnup levels, the NRC recognizes that fuel dispersal could
challenge core coolability. The Commission has directed the staff to
consider FFRD issues relevant to higher enrichment and fuel burnup
levels as part of the Increased Enrichment rulemaking.
The NRC disagrees with the petition's assertion that the technical
bases for the PCT and MLO acceptance criteria in 10 CFR 50.46(b) are
complex and misunderstood. The calculated PCT and MLO typically occur
in the ballooned region of a fuel rod during a LOCA. The NRC
acknowledges that the calculation of these parameters is complex and
subject to large uncertainties but has found that these calculations
can be performed in an appropriately conservative manner. It is well
understood by the NRC and experts that perform such calculations that
the PCT and MLO acceptance criteria are relatively simple surrogate
metrics that correlate with the phenomena leading to an autocatalytic
reaction and to embrittlement, respectively. In addition, the
rulemaking record for 10 CFR 50.46 adequately describes the basis for
the acceptance criteria.
As a solution to the issues raised in the petition, the petition
requested that the NRC regulations be revised to limit the number of
fuel rod ruptures to 1 percent for a small-break LOCA and 10 percent
for a large-break LOCA. The petition also requested that the PCT and
MLO acceptance criteria be eliminated from the NRC regulations. The
petition indicates that German nuclear reactors were subject to the
fuel rod rupture limits proposed in the petition.
The NRC agrees with several commenters that the petition does not
provide an adequate technical basis to support the specific limits on
the number of fuel rod ruptures. The German regulations include limits
on the PCT and MLO during a LOCA to ensure core coolability that are
similar to the acceptance criteria in the NRC regulations. The German
regulations also include limits on the number of fuel rod ruptures as
indicated in the petition, but these limits are related to the
confinement of radioactive materials and not related to core
coolability. In addition, the NRC found that the petition does not
provide a technical basis to support eliminating the PCT and MLO
acceptance criteria from the regulations. Specifically, the petition
does not explain how limiting the number of fuel rod ruptures would
prevent gross fuel rod failure via a brittle failure mechanism.
IV. Reasons for Denial
The NRC is denying PRM-50-124 because the NRC is addressing
emergency core cooling system performance with a risk-informed and
performance-based regulatory approach rather than a deterministic
approach as suggested by the petitioner. The Commission directed the
staff to use a risk-informed and performance-based approach in SRM-
SECY-16-0033 and SRM-SECY-21-0109. Under this direction, the staff has
begun the Increased Enrichment rulemaking, and the petitioner will have
an opportunity to comment on that rulemaking.
V. Availability of Documents
The documents identified in the following table are available to
interested persons through one or more of the following methods, as
indicated.
[[Page 35449]]
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ADAMS Accession No./
Document FEDERAL REGISTER Citation
------------------------------------------------------------------------
PRM-50-124, Ralph O. Meyer, Petition for ML22284A087
Rulemaking, dated August 1, 2022.
PRM-50-124, ``Licensing Safety Analysis for 87 FR 71531
Loss-of-Coolant Accidents,'' notice of
docketing and request for comments, dated
November 23, 2022.
PRM-50-124, ``Licensing Safety Analysis for 88 FR 7012
Loss-of-Coolant Accidents,'' extension of
comment period, dated February 2, 2023.
Nuclear Energy Institute, Request for ML23023A275
Extension of the Comment Period for PRM-50-
124, dated January 23, 2023.
Comment (001) from Ralph Meyer on PRM-50-124, ML23009B712
dated October 12, 2022.
Comment (002) from Ralph Meyer on PRM-50-124, ML23031A196
dated January 12, 2023.
Comment (003) from Zachary Harper of ML23058A228
Westinghouse on PRM-50-124, dated February
2, 2023.
Comment (004) from Gayle Elliott on behalf of ML23061A128
Framatome Inc., dated February 23, 2023.
Comment (005) from Mike Powell on behalf of ML23062A715
Pressurized Water Reactors Owners Group on
PRM-50-124, dated March 1, 2023.
Comment (006) from Frances Pimentel on Behalf ML23062A716
of Nuclear Energy Institute on PRM-50-124,
dated March 3, 2023.
Comment (007) from Ralph Meyer on PRM-50-124, ML23074A071
dated March 14, 2023.
Comment (008) from Ralph Meyer on PRM-50-124, ML23209A607
dated July 26, 2023.
Comment (009) from Ralph Meyer on PRM-50-124, ML23254A398
dated September 11, 2023.
Comment (010) from Ralph Meyer and Wolfgang ML24024A061
Wiesenack on PRM-50-124--Licensing Safety
Analysis for Loss-of-Coolant Accidents,
dated January 18, 2024.
Comment (011) from Ralph Meyer on PRM-50-124-- ML24100A815
Licensing Safety Analysis for Loss-of-
Coolant Accidents.
Comment (012) Ralph Meyer on PRM-50-124-- ML24239A784
Licensing Safety Analysis for Loss-of-
Coolant Accidents.
SECY-21-0109, ``Rulemaking Plan on Use of ML21232A237
Increased Enrichment of Conventional and
Accident Tolerant Fuel Designs for Light-
Water Reactors,'' dated December 20, 2021.
SRM-SECY-21-0109, ``Staff Requirements--SECY- ML22075A103
21-0109--Rulemaking Plan on Use of Increased
Enrichment of Conventional and Accident
Tolerant Fuels Designs for Light-Water
Reactors,'' dated March 16, 2022.
SECY-16-0033, ``Draft Final Rule--Performance- ML15238A947 (Package)
Based Emergency Core Cooling System
Requirements and Related Fuel Cladding
Acceptance Criteria (RIN 3150-AH42),'' dated
March 16, 2016.
SRM-SECY-16-0033, ``Staff Requirements--SECY- ML24102A281
16-0033--Draft Final Rule--Performance-Based
Emergency Core Cooling System Requirements
and Related Fuel Cladding Acceptance
Criteria (RIN 3150-AH42).
SECY-15-0148, ``Evaluation of Fuel ML15230A200
Fragmentation, Relocation and Dispersal
Under Loss-Of-Coolant Accident (LOCA)
Conditions Relative to the Draft Final Rule
on Emergency Core Cooling System Performance
During a LOCA (50.46c),'' dated November 30,
2015.
NRC Research Information Letter 2021-13, ML21313A145
``Interpretation of Research on Fuel
Fragmentation, Relocation, and Dispersal at
High Burnup,'' dated December 2021.
NRC Memorandum from Paul M. Clifford to ML12041A078
William H. Ruland, ``ECCS Performance Safety
Assessment and Audit Report,'' dated
February 10, 2012.
G. Hache and H.M. Chung, ``The History of ML011370559
LOCA Embrittlement Criteria,'' NUREG/CP-
0172, May 2001, pp. 205-237.
------------------------------------------------------------------------
VI. Conclusion
For the reasons cited in this document, the NRC is denying PRM-50-
124. The petition did not present any significant new information or
arguments that would warrant the requested amendment.
Dated: July 24, 2025.
For the Nuclear Regulatory Commission.
Carrie Safford,
Secretary of the Commission.
[FR Doc. 2025-14215 Filed 7-25-25; 8:45 am]
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