[Federal Register Volume 86, Number 150 (Monday, August 9, 2021)]
[Notices]
[Pages 43567-43570]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-16899]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-424 and 50-425; NRC-2021-0086]
Southern Nuclear Operating Company, Inc; Vogtle Electric
Generating Plant, Units 1 and 2
AGENCY: Nuclear Regulatory Commission.
ACTION: Exemptions; issuance.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) has issued
exemptions from certain portions of the acceptance criteria for
emergency core cooling systems to allow the use of a risk-informed
methodology in lieu of a deterministic methodology to evaluate the
effects of debris in containment following a loss-of-coolant accident
for the Vogtle Electric Generating Plant, Units 1 and 2 (Vogtle),
located in Burke County, Georgia. The exemptions are in response to a
request dated August 17, 2020, as supplemented by letters dated
December 17, 2020, and February 15, 2021, from the Southern Nuclear
Operating Company, Inc. (SNC, the licensee).
DATES: The exemptions were issued on July 30, 2021.
ADDRESSES: Please refer to Docket ID NRC-2021-0086 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-2021-0086. Address
questions about Docket IDs in Regulations.gov to Stacy Schumann;
telephone: 301-415-0624; 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, 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.
Attention: The PDR, where you may examine and order copies
of public documents, is currently closed. You may submit your request
to the PDR via email at [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.
FOR FURTHER INFORMATION CONTACT: John G. Lamb, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001; telephone: 301-415-3100, email: [email protected].
SUPPLEMENTARY INFORMATION: The text of the exemptions is attached.
Dated: August 3, 2021.
For the Nuclear Regulatory Commission.
John G. Lamb,
Senior Project Manager, Plant Licensing Branch 2-1, Division of
Operating Reactor Licensing, Office of Nuclear Reactor Regulation.
Attachment--Exemption
NUCLEAR REGULATORY COMMISSION
Docket Nos. 50-424 and 50-425
Southern Nuclear Operating Company, Inc. Vogtle Electric Generating
Plant, Units 1 and 2 Exemptions
I. Background
Southern Nuclear Operating Company, Inc. (SNC, the licensee) is the
holder of Renewed Facility Operating License Nos. NPF-68 and NPF-81,
which authorize operation of Vogtle Electric Generating Plant (Vogtle),
Units 1 and 2, respectively. The licenses provide, among other things,
that the facility is subject to all applicable rules, regulations, and
orders of the U.S. Nuclear Regulatory Commission (NRC, the Commission)
now or hereafter in effect. The facility consists of two pressurized-
water reactors (PWRs) located in Burke County, Georgia.
In 1996, the NRC identified Generic Safety Issue (GSl)-191
associated with the effects of debris accumulation on PWR sump
performance during design-basis accidents (Agencywide Documents Access
and Management System (ADAMS) Accession No. ML030160807). As part of
the actions to resolve GSl-191, the NRC issued Generic Letter (GL)
2004-02, ``Potential Impact of Debris Blockage on Emergency
Recirculation during Design Basis Accidents at Pressurized-Water
Reactors,'' dated September 13, 2004 (ADAMS Accession No. ML042360586),
to holders of operating licenses for PWRs. In GL 2004-02, the NRC staff
requested that these licensees perform an evaluation of the emergency
core cooling system (ECCS) and the containment spray system (CSS)
recirculation functions considering the potential for debris-laden
coolant to be circulated by the ECCS and the CSS after a loss-of-
coolant accident (LOCA) or high-energy line break inside containment
and, if appropriate, take additional actions to ensure system function.
The GL required that these licensees provide a written response to the
NRC, pursuant to title 10 of the Code of Federal Regulations (10 CFR)
section 50.54(f), describing the results of their evaluation and any
modifications made, or planned, to ensure that the ECCS and the CSS
remain functional.
[[Page 43568]]
II. Request/Action
By letter dated August 17, 2020 (ADAMS Accession No. ML20230A346),
as supplemented by letters dated December 17, 2020, and February 15,
2021 (ADAMS Accession Nos. ML20352A228 and ML21046A094, respectively),
SNC requested for the NRC to grant exemptions under 10 CFR 50.12,
``Specific exemptions,'' from certain requirements in 10 CFR 50.46,
``Acceptance criteria for emergency core cooling systems for light-
water nuclear power reactors,'' for Vogtle, Units 1 and 2. The request
for exemptions from SNC relates to using a specific risk-informed
methodology to evaluate the effects of debris on long-term core cooling
in lieu of a deterministic methodology.
III. Discussion
Pursuant to 10 CFR 50.12, the Commission may, upon application by
any interested person or upon its own initiative, grant exemptions from
the requirements of 10 CFR part 50 when (1) the exemptions are
authorized by law, will not present an undue risk to the public health
and safety, and are consistent with the common defense and security and
(2) special circumstances are present. Under 10 CFR 50.12(a)(2)(ii),
special circumstances are present when application of the regulation in
the particular circumstances would not serve the underlying purpose of
the rule or is not necessary to achieve the underlying purpose of the
rule. Under 10 CFR 50.12(a)(2)(iii), special circumstances are present
when compliance would result in undue hardship or other costs that are
significantly in excess of those contemplated when the regulation was
adopted, or that are significantly in excess of those incurred by
others similarly situated.
SNC submitted a request for exemptions under 10 CFR 50.12 for
Vogtle, Units 1 and 2 from certain requirements of 10 CFR 50.46(a)(1)
as it relates to using specific deterministic methodology to evaluate
the effects of debris generated from breaks on long-term core cooling.
SNC stated that the scope of the requested exemptions applies to all
debris effects addressed in the risk-informed element of the Vogtle
methodology described in SNC's July 2018 submittal responding to GL
2004-02 (ADAMS Accession Nos. ML18193B163 and ML18193B165). SNC stated
that the addressed debris effects are those associated with breaks that
potentially generate and transport debris amounts that exceed the
Vogtle-specific analyzed debris limit.
SNC is requesting exemptions related to these breaks to allow
evaluation of the debris effects using a risk-informed methodology in
lieu of a deterministic methodology. The licensee stated that the key
elements of the exemption request are that (1) the exemptions will
apply only to the effects of debris as described in Enclosures 2 and 3
of the submittal dated July 2018 and (2) the exemptions will apply to
any breaks that can generate and transport debris that is not bounded
by Vogtle-specific analyzed debris limits, provided that the delta core
damage frequency ([Delta]CDF) and delta large early release frequency
([Delta]LERF) remain within the acceptance guidelines identified as
Region III in Regulatory Guide (RG) 1.174, ``An Approach for Using
Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-
Specific Changes to the Licensing Basis,'' Revision 3, dated January
2018 (ADAMS Accession No. ML17317A256).
By letter dated September 30, 2019, ``Final Staff Evaluation for
Vogtle Electric Generating Plant, Units 1 and 2, Systematic Risk-
Informed Assessment of Debris Technical Report'' (ADAMS Accession No.
ML19120A469), the NRC staff found that the subject technical report
enclosed with SNC's July 2018 submittal was acceptable for use in
plant-specific licensing applications for Vogtle in accordance with the
limitations and conditions section and applicability provided in the
enclosed NRC staff evaluation. Except for downstream effects--fuel and
vessel, and licensing basis, the NRC staff concluded that the technical
report contained sufficient information to address the information
requested in GL 2004-02.
The NRC staff performed an integrated review of the risk-informed
approach proposed to be used in lieu of a deterministic methodology by
the requested exemptions, considering the five key principles of risk-
informed decision-making set forth in RG 1.174. The five key principles
are: (1) The proposed change meets the current regulations unless it is
explicitly relates to a requested exemption; (2) the proposed change is
consistent with the defense-in-depth philosophy; (3) the proposed
change maintains sufficient safety margins; (4) when proposed changes
result in an increase in risk, the increases should be small and
consistent with the intent of the Commission's policy statement on
safety goals for the operations of nuclear power plants (51 FR 30028);
and (5) the impact of the proposed change should be monitored using
performance measurement strategies.
The NRC staff finds that the proposed risk-informed approach meets
the five key principles in RG 1.174. The proposed risk-informed
approach is consistent with the defense-in-depth philosophy, maintains
sufficient safety margins, and is monitored using performance
measurement strategies. The proposed risk-informed approach also
explicitly relates to a requested exemption. Finally, the Vogtle risk
evaluation results show that the risk associated with post-accident
debris effects is within RG 1.174, Region Ill acceptance guidelines as
a ``Very Small Change,'' and, therefore, is consistent with the intent
of the Commission's policy statement on safety goals for the operations
of nuclear power plants.
A. The Exemptions Are Authorized by Law
The exemptions to use a risk-informed methodology would allow SNC
to show compliance with 10 CFR 50.46(a)(1) when considering debris in
containment generated and transported during a postulated LOCA. This
regulation was promulgated under Section 161 of the Atomic Energy Act
of 1954, as amended (AEA), and this regulation is consistent with the
Commission's authority under Section 161 of the AEA. Because the
application of a risk-informed methodology to show compliance with 10
CFR 50.46 would not violate the AEA or the Commission's regulations,
the exemptions are authorized by law.
B. The Exemptions Present No Undue Risk to the Public Health and Safety
The provisions of 10 CFR 50.46 establish criteria for the ECCS
performance. SNC submitted a request for exemptions under 10 CFR 50.12
for Vogtle, Units 1 and 2 from certain requirements of 10 CFR
50.46(a)(1) as it relates to using specific deterministic methodology
to evaluate the effects of debris generated from breaks on long-term
core cooling. The licensee justified its requested exemptions by
stating that they are consistent with the purpose of the requirements
in that the use of the proposed risk-informed approach would account
for the effects of debris on the ECCS cooling performance and would
support a high probability of successful ECCS performance, based on the
risk results meeting the acceptance guidelines of RG 1.174.
Additionally, the licensee stated that the Vogtle, Units 1 and 2 risk
quantification showed that the changes in [Delta]CDF and [Delta]LERF
are below the threshold for RG 1.174, Region Ill, ``Very Small
Changes,'' without significant plant modifications. The licensee stated
that the proposed
[[Page 43569]]
risk-informed approach would provide an equivalent level of assurance
for sump performance without incurring significant cost and
occupational dose associated with removing, replacing, or reinforcing
insulation in containment.
The NRC staff finds that the risk associated with the requested
exemptions is consistent with the guidance in RG 1.174 for the use of
probabilistic risk assessment and with the Commission's policy
statement on safety goals for the operations of nuclear power plants;
therefore, the requested exemptions present no undue risk to the public
health and safety.
C. The Exemptions Are Consistent With the Common Defense and Security
The requested exemptions would allow the use of a risk-informed
methodology to allow SNC to resolve a generic safety concern for PWRs
associated with the potential clogging of the ECCS and CSS strainers
during certain design-basis events. The proposed change would be
adequately controlled by safety acceptance criteria and technical
specification requirements and is not related to security issues.
Because the common defense and security is not impacted by the
requested exemptions, the requested exemptions are consistent with the
common defense and security.
D. Special Circumstances Are Present
The requested exemptions from 10 CFR 50.46(a)(1) would allow SNC to
use a risk-informed methodology in lieu of a deterministic methodology
to show conformance with the ECCS and CSS performance criteria
accounting for debris in containment for LOCAs. In its request, SNC
cited the special circumstances criteria of 10 CFR 50.12(a)(2)(ii) and
(iii) and stated that application of the regulation in the particular
circumstances would not serve the underlying purpose of the rule or is
not necessary to achieve the underlying purpose of the rule and that
compliance would result in undue hardship or other costs that are
significantly in excess of those contemplated when the regulation was
adopted, or that are significantly in excess of those incurred by
others similarly situated.
The licensee stated that the intent of 10 CFR 50.46(a)(1) is to
ensure that ECCS cooling performance design requirements imposed by 10
CFR 50.46 are determined by a rigorous method that provides a high
level of confidence in ECCS performance. SNC stated that its proposed
risk-informed approach accounts for the effects of debris on the ECCS
cooling performance and supports a high probability of successful ECCS
performance based on the risk results meeting the acceptance guidelines
of RG 1.174.
The licensee also stated that in order to meet a deterministic
threshold value for sump debris loads, the debris sources in
containment would need to be significantly reduced. SNC stated that the
amount of radiological exposure received during the removal and/or
modification of insulation from the Vogtle, Units 1 and 2 containments
is dependent on the scope of the changes. The licensee stated that the
expected total dose for replacing insulation in Vogtle, Units 1 and 2
is estimated generically to be about 200 roentgen equivalent man (rem)
(100 rem per unit) based on the South Texas Project pilot submittal.
The licensee concluded that the special circumstances described in
10 CFR 50.12(a)(2)(ii) and (iii) would apply to its requested
exemptions.
The NRC staff evaluated the exemption request and summarized its
evaluation of the proposed risk-informed approach in a safety
evaluation (ADAMS Accession No. ML20268A070). Since 10 CFR 50.46(a)(1)
requires a deterministic approach, an exemption is an appropriate means
to grant the licensee relief to use an alternative, risk-informed
approach. The underlying purpose of the regulation is to protect the
public health and safety in the event of a LOCA by establishing
criteria for the ECCS. In its safety evaluation, the NRC staff
concluded, in part, that the licensee adequately demonstrated that the
change in risk attributable to debris in postulated LOCAs is very
small. The NRC staff also concluded that the licensee's proposal for
demonstrating compliance with the ECCS and the CSS performance
requirements meets the risk acceptance guidelines in RG 1.174, because
the approach is related to a permissible exemption request, is
consistent with defense-in-depth philosophy, maintains sufficient
safety margins, results in a small increase in risk, and the impact of
the approach is monitored by the licensee using performance measurement
strategies. Therefore, the NRC staff finds that the licensee's use of
the proposed risk-informed approach to consider the impacts of debris
meets the underlying intent of 10 CFR 50.46 to ensure that a licensee
demonstrates that the ECCS and the CSS will provide adequate cooling
for the reactor core and containment, as well as containment atmosphere
cleanup, following postulated design-basis accidents.
The NRC staff also finds that the licensee demonstrated that using
the required deterministic approach as opposed to the proposed risk-
informed approach would result in undue hardship or other costs that
are significantly in excess of those contemplated when the regulation
was adopted, or that are significantly in excess of those incurred by
others similarly situated.
Based on the above, the NRC staff concludes that the special
circumstances described in 10 CFR 50.12(a)(2)(ii) and (iii) are present
for the requested exemptions.
E. Environmental Considerations
The regulations in 10 CFR 51.21, ``Criteria for and identification
of licensing and regulatory actions requiring environmental
assessments,'' generally provide that NRC licensing and regulatory
actions require an environmental assessment (EA) except those
identified in 10 CFR 51.20(b) as requiring an environmental impact
statement, those identified in 10 CFR 51.22(c) as categorical
exclusions, and those identified in 10 CFR 51.22(d) as other actions
not requiring environmental review. These regulations also provide that
the NRC may, in special circumstances, prepare an EA on an action
covered by a categorical exclusion. Typically, exemptions are
identified in 10 CFR 51.22(c) as categorical exclusions; however,
because the requested exemptions propose a novel risk-informed approach
to the requirements in 10 CFR 50.46(a)(1), the NRC staff determined
that special circumstances were present and prepared an EA. As
discussed in the EA and the associated Finding of No Significant Impact
published in the Federal Register on April 7, 2021, 2021 (86 FR 18076)
and in accordance with 10 CFR 51.31(a), the Commission has determined
that granting the requested exemptions will not have a significant
effect on the quality of the human environment.
IV. Conclusion
Accordingly, the Commission has determined, pursuant to 10 CFR
50.12, that the requested exemptions are authorized by law, will not
present an undue risk to the public health and safety, and are
consistent with the common defense and security and that special
circumstances are present. Therefore, the Commission hereby grants
SNC's request for exemptions under 10 CFR 50.12 for Vogtle, Units 1 and
2, from 10 CFR 50.46(a)(1) to allow the use of a risk-informed
methodology in lieu of a deterministic methodology
[[Page 43570]]
to show conformance with the ECCS and CSS performance criteria
accounting for debris in containment for LOCAs.
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.
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ADAMS Accession No./
Document Federal Register citation
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SNC letter, ``Exemption Request and License ML20230A346
Amendment Request for a Risk-Informed
Resolution to GSI-191,'' dated August 17,
2020.
SNC letter, ``Response to Request for ML20352A228
Additional Information Regarding Risk-
Informed Resolution to GSI-191,'' dated
December 17, 2020.
SNC letter, ``Supplement to Request for ML21046A094
Exemption to Support Risk-Informed
Resolution to Generic Letter 2004-02,''
dated February 15, 2021.
NRC Generic Letter 2004-02, ``Potential ML042360586
Impact of Debris Blockage on Emergency
Recirculation During Design Basis Accidents
at Pressurized-Water Reactors,'' dated
September 13, 2004.
Regulatory Guide 1.174, Revision 3, ``An ML17317A256
Approach for Using Probabilistic Risk
Assessment in Risk-Informed Decisions on
Plant-Specific Changes to the Licensing
Basis,'' dated January 2018.
NRC Safety Evaluation, Vogtle, Units 1 and ML20268A070
2--Amendments for a Risk-Informed
Resolution to GSI-191, dated July 30, 2021.
SNC Letter ``Vogtle Electric Generating ML18193B163 and
Plant--Units 1 & 2, Supplemental Response ML18193B165
to NRC Generic Letter 2004-02,'' dated July
10, 2018.
NRC letter, ``Final Staff Evaluation for ML19120A469
Gotle Electric Generating Plant, Units 1
and 2, Systematic Risk-Informed Assessment
of Debris Tenical Report,'' dated September
30, 2019.
NRC, ``Safety Goals for the Operations of 51 FR 30028
Nuclear Power Plants; Policy Statement;
Republication,'' dated August 21, 1986.
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Dated: July 30, 2021.
For the Nuclear Regulatory Commission.
/RA/
Caroline L. Carusone,
Deputy Director, Division of Operating Reactor Licensing, Office of
Nuclear Reactor Regulation.
[FR Doc. 2021-16899 Filed 8-6-21; 8:45 am]
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