ML25024A012
| ML25024A012 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 01/23/2025 |
| From: | Joel Wiebe NRC/NRR/DORL/LPL3 |
| To: | Brunswick D Exelon Generation Co |
| References | |
| L-2024-LRO-0047 | |
| Download: ML25024A012 (4) | |
Text
From:
Joel Wiebe Sent:
Thursday, January 23, 2025 11:19 AM To:
Brunswick, Dane:(Constellation Nuclear)
Subject:
Multiple Dockets - REQUEST FOR ADDITIONAL INFORMATION RE: [Insert description of request] (EPID L-2024-LRO-0047)
Attachments:
RAI-10494-R1-FINAL.docx By letter dated July 26, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23188A129), the U.S. Nuclear Regulatory Commission (NRC) issued Amendments 233 and 233 for Braidwood Station, Units 1 and 2, respectively, to revise the technical specifications (TS) to adopt Technical Specifications Task Force (TSTF)-577, Revised Frequencies for Steam Generator [SG] Tube Inspections. Constellation Energy Generation, LLC (CEG), stated in the letter dated May 22, 2023, that it will submit, 60 days after implementation of TSTF-577, SG tube inspection reports meeting the revised reporting requirements in TS Section 5.6.9. On December 1, 2023 (ML23313A155), the NRC staff issued its review of the Braidwood Station, Unit 1, fall 2022 SG tube inspection report. By letter dated November 1, 2023 (ML23305A039 (Package)), CEG submitted the updated Braidwood Station, Unit 1, fall 2022 SG tube inspection report and the Braidwood Station, Unit 2, spring 2023 SG tube inspection report meeting the revised TS Section 5.6.9 reporting requirements. The SG tube inspections were performed at Braidwood Station, Units 1 and 2, during refueling outage 23 (A1R23 (Unit 1) and A2R23 (Unit 2)).
TS Section 5.6.9 requires that a report be submitted within 180 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS Section 5.5.9, which requires that a SG Program be established and implemented to ensure SG tube integrity is maintained.
To complete its review of the inspections, the NRC staff requests additional information. The RAI is enclosed. A response is requested within 30 days from the date of this email.
Joel S. Wiebe Senior Project Manager NRC Office of Nuclear Reactor Regulation.
Hearing Identifier:
NRR_DRMA Email Number:
2705 Mail Envelope Properties (MN2PR09MB49712B62E6AA7C666C9CC4868BE02)
Subject:
Multiple Dockets - REQUEST FOR ADDITIONAL INFORMATION RE [Insert description of request] (EPID L-2024-LRO-0047)
Sent Date:
1/23/2025 11:19:27 AM Received Date:
1/23/2025 11:19:00 AM From:
Joel Wiebe Created By:
Joel.Wiebe@nrc.gov Recipients:
"Brunswick, Dane:(Constellation Nuclear)" <Dane.Brunswick@constellation.com>
Tracking Status: None Post Office:
MN2PR09MB4971.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1807 1/23/2025 11:19:00 AM RAI-10494-R1-FINAL.docx 6264 Options Priority:
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1 REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION BRAIDWOOD STATION, UNIT 1 OUTAGE 23 AND UNIT 2 OUTAGE 23 SG TUBE INSPECTION REPORTS TO REFLECT TSTF-577 REPORTING REQUIREMENTS CONSTELLATION ENERGY GENERATION, LLC BRAIDWOOD, UNITS 1, 2 DOCKET NO. 05000456, 05000457 ISSUE DATE: 01/23/2025 Question 1 By letter dated July 26, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23188A129), the U.S. Nuclear Regulatory Commission (NRC) issued Amendments 233 and 233 for Braidwood Station, Units 1 and 2, respectively, to revise the technical specifications (TS) to adopt Technical Specifications Task Force (TSTF)-577, Revised Frequencies for Steam Generator [SG] Tube Inspections. Constellation Energy Generation, LLC (CEG), stated in the letter dated May 22, 2023, that it will submit, 60 days after implementation of TSTF-577, SG tube inspection reports meeting the revised reporting requirements in TS Section 5.6.9. On December 1, 2023 (ML23313A155), the NRC staff issued its review of the Braidwood Station, Unit 1, fall 2022 SG tube inspection report. By letter dated November 1, 2023 (ML23305A039 (Package)), CEG submitted the updated Braidwood Station, Unit 1, fall 2022 SG tube inspection report and the Braidwood Station, Unit 2, spring 2023 SG tube inspection report meeting the revised TS Section 5.6.9 reporting requirements. The SG tube inspections were performed at Braidwood Station, Units 1 and 2, during refueling outage 23 (A1R23 (Unit 1) and A2R23 (Unit 2)).
TS Section 5.6.9 requires that a report be submitted within 180 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS Section 5.5.9, which requires that a SG Program be established and implemented to ensure SG tube integrity is maintained. To complete its review of the inspections, the NRC staff requests the following additional information:
Braidwood Station, Unit 1, Updated Fall 2022 SG Tube Inspection Report
- 1. In the discussion of the forward-looking tube integrity assessment in the updated fall 2022 Braidwood Station, Unit 1, SG tube inspection report, there are some inconsistencies with regards to the values for total Effective Full Power Years (EFPY) in five fuel cycles (7.3 or 7.5 EFPY), the growth rate per EFPY for fan bar wear (1.0 percent through wall (TW) per EFPY or 1.5 percent TW per EFPY), and the maximum depth predicted at the next inspection for fan bar and lattice grid wear. For example, The updated report states that the operational assessment for wear at support structures was evaluated for five fuel cycles of 1.5 EFPY each (1.5 x 5 = 7.5 EFPY). However, for both fan bar and lattice grid wear, it appears that 7.3 EFPY was used.
The updated report states that a growth rate of 1.5 percent TW per EFPY was used for fan bar wear. However, the report appears to use a growth rate of 1.0 percent TW per EFPY (Applying a growth rate of 7.3%TW (1.0 x 7.3)).
For fan bar wear, the updated report states, Applying a growth of 7.3% TW (1.0 x 7.3) gives a bounding real depth at the end of the upcoming inspection interval of 34.1% TW (23.1 + 7.3). However, a projected depth of 30.4 percent TW is reported elsewhere in the report, consistent with the (23.1 + 7.3) value.
2 Please clarify which values were used in the degradation projections for the following:
- 1. The total EFPY used for five fuel cycles.
- a. The growth rate per EFPY for fan bar wear.
- b. Based on the total EFPY in five cycles and the growth rate per EFPY, please confirm the maximum depths predicted at the next inspection for fan bar wear and lattice grid wear.
- 2. The updated fall 2022 Braidwood Station, Unit 1, SG tube inspection report states 14 foreign objects in SGs A, B, and C were not removed during A1R23 and are included in Table 10. However, Table 10 appears to only include 13 foreign objects with a status of Remains. Therefore, it is unclear how many total foreign objects remain in the three SGs. Please confirm how many total foreign objects remain in SGs A, B, and C.
Braidwood Station, Unit 2, Spring 2023 SG Tube Inspection Report
- 1. Table 1 in the spring 2023 Braidwood Station, Unit 2, SG tube inspection report states, A sub-population of 14 potentially high residual stress tubes has been identified from eddy current U-bend offset signals and are currently designated as a sub population potentially more susceptible to ODSCC [outside diameter stress corrosion cracking] in the A2R23 degradation assessment [DA]. In addition, the report states, During A2R23, all tube-to-TSP intersections received a bobbin and array exam, so tubes with potentially higher residual stresses no longer need to be treated differently for OA [Operational Assessment] purposes since all tube-to-TSP intersections received the same baseline examinations. Please clarify if the 14 potentially high residual stress tubes will be treated as a sub-population in subsequent DAs such that they will be more likely to be inspected with enhanced probes in subsequent SG inspections.
OFFICE NRR/DORL/LLPB/PM NRR/DORL/LPL3/BC NRR/DNRL/NCSG/BC NAME JWiebe IBerrios SBloom DATE 01/23/2025 01/21/2025 01/07/2025