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Federal Register / Vol. 86, No. 150 / Monday, August 9, 2021 / Notices
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.

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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 50.12a2ii, 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 50.12a2iii, 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 50.46a1 as it relates to using specific deterministic methodology to evaluate the effects of debris generated from breaks on longterm 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 SNCs 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.

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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 DCDF and delta large early release frequency DLERF 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 SNCs 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 effectsfuel and vessel, and licensing basis, the NRC staff concluded that the technical report contained sufficient information to address the information requested in GL
200402.
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 Commissions 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.

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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 Commissions policy statement on safety goals for the operations of nuclear power plants.
A. The Exemptions Are Authorized by Law The exemptions to use a riskinformed methodology would allow SNC to show compliance with 10 CFR
50.46a1 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 Commissions 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 Commissions 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 50.46a1 as it relates to using specific deterministic methodology to evaluate the effects of debris generated from breaks on longterm 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 DCDF and DLERF are below the threshold for RG 1.174, Region Ill, Very Small Changes, without significant plant modifications.
The licensee stated that the proposed
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