[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]


=======================================================================
-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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.

------------------------------------------------------------------------
                                                 ADAMS Accession No./
                  Document                     Federal Register citation
------------------------------------------------------------------------
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.
------------------------------------------------------------------------


    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]
BILLING CODE 7590-01-P