ML23135A913
| ML23135A913 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 05/15/2023 |
| From: | Dennis Galvin NRC/NRR/DORL/LPL4 |
| To: | Hicks J Vistra Operations Company |
| References | |
| L-2023-LLA-0057 | |
| Download: ML23135A913 (5) | |
Text
From: Dennis Galvin Sent: Monday, May 15, 2023 5:23 PM To: Jack Hicks (Jack.Hicks@luminant.com)
Cc: Nic Boehmisch (Nicholas.Boehmisch@luminant.com)
Subject:
Comanche Peak - Draft Supplemental Information Request - License Amendment Request to 10 CFR 50.69 (EPID L-2023-LLA-0057)
Attachments: Comanche Peak LAR - 50.69 - Draft Supplemental Request L-2023-LLA-0057 Issued 2023-05-15.pdf
Dear Mr. Hicks,
By letter dated April 19, 2023, Vistra Operations Company LLC (Vistra OpCo, the licensee) submitted a license amendment request (LAR) (ADAMS Accession No. ML23109A333) for Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2 (Comanche Peak or CPNPP). The proposed LAR would allow, by the addition of License Conditions, the implementation of the provisions of Title 10 of the Code of Federal Regulations (10 CFR), Part 50.69, Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors.
To complete its review, the NRC staff has prepared the attached supplemental information request in DRAFT form. To arrange a clarification call and to discuss the due date, please contact me at (301) 415-6256.
Respectfully, Dennis Galvin Project Manager U.S Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Operating Reactor Licensing Licensing Project Branch 4 301-415-6256 Docket Nos. 50-445 and 50-446
Hearing Identifier: NRR_DRMA Email Number: 2097 Mail Envelope Properties (SA1PR09MB8111268A839441E5133DF0A1FB789)
Subject:
Comanche Peak - Draft Supplemental Information Request - License Amendment Request to 10 CFR 50.69 (EPID L-2023-LLA-0057)
Sent Date: 5/15/2023 5:22:51 PM Received Date: 5/15/2023 5:22:00 PM From: Dennis Galvin Created By: Dennis.Galvin@nrc.gov Recipients:
"Nic Boehmisch (Nicholas.Boehmisch@luminant.com)" <Nicholas.Boehmisch@luminant.com>
Tracking Status: None "Jack Hicks (Jack.Hicks@luminant.com)" <Jack.Hicks@luminant.com>
Tracking Status: None Post Office: SA1PR09MB8111.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1022 5/15/2023 5:22:00 PM Comanche Peak LAR - 50.69 - Draft Supplemental Request L-2023-LLA-0057 Issued 2023-05-15.pdf 419143 Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
DRAFT SUPPLEMENTAL INFORMATION NEEDED LICENSE AMENDMENT REQUEST TO ADOPT 10 CFR 50.69, RISK-INFORMED CATEGORIZATION AND TREATMENT OF STRUCTURES, SYSTEMS AND COMPONENTS FOR NUCLEAR POWER REACTORS.
VISTRA OPERATIONS COMPANY LLC COMANCHE PEAK NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-445 AND 50-446 By letter dated April 19, 2023, Vistra Operations Company LLC (Vistra OpCo, the licensee) submitted a license amendment request (LAR) (ADAMS Accession No. ML23109A333) for Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2 (Comanche Peak or CPNPP). The proposed LAR would allow, by the addition of License Conditions, the implementation of the provisions of Title 10 of the Code of Federal Regulations (10 CFR), Part 50.69, Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors. The U.S. Nuclear Regulatory Commission (NRC) staff has identified that the following information is needed to begin its technical review:
Acceptance Review Information Insufficiencies
- 1. The LAR references the approval of the Comanche Peak adoption of Technical Specifications Task Force (TSTF) Traveler TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF [Risk-Informed TSTF] Initiative 4b, dated August 22, 2022 (ML22192A007), as the basis for the probabilistic risk assessment (PRA) technical acceptability. Section 3.2 of the 50.69 LAR indicates that the PRA models credited in this request are the same PRA models credited in the TSTF505 LAR dated May 11, 2021 (ML21131A233), for internal events, internal floods and internal fire. The safety evaluation for the Comanche Peak TSTF505 LAR has a number of items dispositioned specifically for the adoption of TSTF505 at Comanche Peak, such as certain supporting requirements that are met at Capability Category-I, and a number of fire PRA related topics. Those items dispositioned specifically for the TSTF505 LAR do not apply to the 50.69 LAR given the different risk parameters used. For example, for the TSTF505 LAR, the change in core damage frequency (CDF) and large early release frequency (LERF) parameters are used, while importance measures, such as Fussell-Vesely (FV) and risk achievement worth (RAW), are used for the 50.69 LAR.
The LAR also states that with regards to PRA assumptions and sources of uncertainty:
Key CPNPP PRA model specific assumptions and sources of uncertainty were identified and dispositioned for the RICT [risk-informed completion time] calculation as identified in Section 3.2.4.1.5 in Reference 1. The conclusion of this review was that no additional sensitivity analyses are required to address CPNPP PRA model specific assumptions or sources of uncertainty.
DRAFT
However, the staff noted that disposition of impact of PRA uncertainty to in the TSTF505 LAR does not apply to the 50.69 LAR given the different risk metrics used.
Therefore, provide the following information to allow staff to review the PRA technical acceptability for the 50.69 LAR:
a) Discuss any updates for the PRA models since the submittal of the TSTF505 LAR.
b) Discuss how the assessment of the PRA assumptions and sources of uncertainty for the 50.69 LAR was performed and provide the results of the assessment.
c) Provide an assessment of the impact of the two supporting requirements that were assessed as Capability Category-I in the TSTF505 LAR on the 50.69 LAR.
d) Provide an assessment of the impact of any fire PRA related items that were dispositioned in the TSTF505 LAR on the 50.69 LAR.
- 2. LIC109, Acceptance Review Procedures, (ML20036C829) states that (1) lacking an analysis necessary for the NRC staffs review should be considered unacceptable, (2) simply referencing unapproved guidance may not be acceptable, and (3) deviations from guidance should not be considered acceptable unless fully justified. The LAR states To address seismic hazard in the Structures, Systems and Components (SSC) categorization process, an alternative method to NEI 00-04 [10 CFR 50.69 SSC Categorization Guideline, (ML052900163)], has been implemented consistent with the Electric Power Research Institute (EPRI) alternative seismic approach described in EPRI Report 3002022453
[Alternate Approaches for Addressing Seismic Risk in 10 CFR 50.69 Risk-Informed Categorization]. Further, Section 3.1.1 of the enclosure to the LAR states evaluation of impact of the seismic hazard, which will use the EPRI Alternative Tier 1 Seismic Approach described in EPRI Report 3002022453. The staff has not reviewed EPRI Report 3002022453. The report has not been submitted by the licensee as part of the LAR and it is currently unavailable in ADAMS. Further, EPRI Report 3002022453 includes changes beyond technical updates compared to prior EPRI reports reviewed by the staff. Review of these changes can increase the staffs resources and schedule for this LAR. The NRC staff has communicated issues resulting from the use of EPRI Report 3002022453 to licensees and EPRI.
EPRI Report 3002017583, "Alternative Approaches for Addressing Seismic Risk in 10 CFR 50.69 Risk-Informed Categorization," is available in ADAMS (ML21082A170) and has been used by several licensees to support their approved Tier 1 alternative seismic approach.
EPRI Report 3002017583 includes the updates to the Tier 1 approach resulting from the staff's review of the Calvert Cliffs LAR (ML19330D909).
Provide EPRI Report 3002022453 for the staff's review as a supplement to the LAR.
Alternately, the licensee can choose to support its proposed alternative seismic approach by using and citing an approach previously accepted by the NRC, such as EPRI Report 3002017583.
- 3. LIC109, Acceptance Review Procedures, states that the staff should determine if there are significant, obvious problems with the information and analyses provided. Section 3.2.4 of the enclosure to the LAR references the screening performed in the licensee's TSTF505 LAR. However, information specific to the 50.69 LAR on categorization of SSCs considering other external hazards is not included in the LAR. Specifically, there is no discussion on whether any SSCs are credited in the screening of other external hazards and if yes, how
those SSCs will be categorized, including justification for any deviations from the guidance in NEI 00-04 for the categorization of these SSCs.
Describe how SSCs that are credited for screening of other external hazards will be categorized consistent with the guidance in NEI 00-04. Identify and justify any deviations from relevant guidance in NEI 00-04 for the categorization of such SSCs.
- 4. Section 2.3 of the enclosure to the LAR proposes a condition on the licensee's operating license which states, in part, Vistra OpCo is approved to implement 10 CFR 50.69 using the EPRI alternative Tier 1 seismic approach for active categorization of RISC-1, RISC-2, RISC-3, and RISC-4 SSCs, and as specified in License Amendment No. [XXX] dated
[DATE]." The staff has not reviewed and approved the EPRI report(s) documenting the so-called Tier 1 process as generic topical reports. Therefore, the proposed license condition needs to reflect the fact that the alternative seismic approach is proposed by the licensee.
Several precedents are available where the NRC staff has approved proposed license conditions stating simply "the proposed alternative seismic approach Justify the use of "the EPRI alternative Tier 1 seismic approach" in the proposed license condition when the licensee is requesting the methodology on a plant-specific basis and the NRC staff has not approved the approach or the EPRI report(s) as a generic methodology.
Alternately, the licensee can choose to propose a condition which identifies the alternative seismic approach as the licensee's proposed approach.