ML24135A228
| ML24135A228 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/29/2024 |
| From: | V Sreenivas Plant Licensing Branch 1 |
| To: | Blair B Vistra Operations Company |
| Sreenivas, V | |
| References | |
| EPID L-2023-LRO-0058 | |
| Download: ML24135A228 (5) | |
Text
May 29, 2024 Barry N. Blair Vistra Operations Company LLC Beaver Valley Power Station Mail Stop P-BV-SSB P.O. Box 4, Route 168 Shippingport, PA 15077-0004
SUBJECT:
BEAVER VALLEY POWER STATION, UNIT 2 - REVIEW OF THE SPRING 2023 OUTAGE GENERIC LETTER 95-05 VOLTAGE-BASED ALTERNATE REPAIR CRITERIA AND STEAM GENERATOR F STAR REPORTS (EPID L-2023-LRO-0058)
Dear Barry Blair:
By letter dated August 7, 2023 (Agencywide Documents Access and Management System Accession No. ML23219A059), Energy Harbor Nuclear Corp. submitted the spring 2023 Generic Letter 95-05 Voltage-Based Alternate Repair Criteria (ARC) and Steam Generator (SG)
F Star (F*) Reports for Beaver Valley Power Station, Unit 2. The SG tube inspections were performed during refueling outage 23. The licensee provided additional information in a letter dated November 29, 2023 (ML23333A208). When the voltage-based ARC and the F*
methodology have been applied, Technical Specification (TS) Sections 5.6.6.2.2 and 5.6.6.2.4, respectively, require that a report be submitted within 90 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS Section 5.5.5.2.
Effective March 1, 2024, the facility operating license for Beaver Valley was transferred from Energy Harbor Nuclear Generation LLC (owner) and Energy Harbor Nuclear Corp. (operator) to Energy Harbor Nuclear Generation LLC (owner) and Vistra Operations Company LLC (operator)
(ML24057A092). Upon completion of this license transfer, it was reported by the licensee that VistraOps assumed the responsibility for all licensing actions under the U.S. Nuclear Regulatory Commission (NRC) review at the time of the transfer and requested that the NRC continue its review of these actions (ML24054A498).
The NRC staff has completed its review of the information provided and concludes that the licensee provided the information required by its technical specifications. The staffs review summary is enclosed.
B. Blair If you have any questions, please contact me at 301-415-2597 or by email to V.Sreenivas@nrc.gov Sincerely,
/RA/
V. Sreenivas, Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-412
Enclosure:
Steam Generator Inspection Report Summary cc: Listserv
Enclosure BEAVER VALLEY POWER STATION, UNIT 2 REVIEW OF THE REFUELING OUTAGE 21 GENERIC LETTER 95-05 VOLTAGE-BASED ALTERNATE REPAIR CRITERIA AND F STAR REPORTS DOCKET NO. 50-412 By letter dated August 7, 2023 (Agencywide Documents Access and Management System Accession No. ML23219A059), Energy Harbor Nuclear Corp. submitted the spring 2023 Generic Letter (GL) 95-05 Voltage-Based Alternate Repair Criteria (ARC) and Steam Generator (SG) F Star (F*) Reports for Beaver Valley Power Station, Unit 2. The SG tube inspections were performed during refueling outage 23 (2R23). The licensee provided additional information in a letter dated November 29, 2023 (ML23333A208). When the voltage-based ARC and the F*
methodology have been applied, Technical Specification (TS) Sections 5.6.6.2.2 and 5.6.6.2.4, respectively, require that a report be submitted within 90 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS Section 5.5.5.2.
Based on the review of the information provided, the U.S. Nuclear Regulatory Commission (NRC) staff has the following observations:
The 2R23 outage is the seventh application of the GL 95-05 voltage-based ARC to the Beaver Valley Unit 2 Model 51M SGs.
Beginning in 2R22, Unit 2 has been implementing a tube recovery program to improve the thermal performance of the SGs. A total of 77 tubes that were previously plugged, many due to indications at the hot leg top of tubesheet expansion transition, were de-plugged and returned to service during 2R23 by installing a tube sleeve. The NRC staff has previously reviewed and approved an amendment to permit use of SG tube sleeves at this location. After the tubes in the cold leg top of tubesheet region were de-plugged during 2R23, +PointTM inspections found two indications of circumferential cracking. Both tubes were in SG B and had been originally plugged for hot leg indications in 2008 and 2014. Once the cold leg indications were detected, the
+Point' tubesheet inspection scope was expanded to include all previously de-plugged tubes that were in service through Cycle 23, plus 2100 other tubes within the cold leg critical area in SG A and SG B. During the expansion scope inspection, circumferential outside diameter stress corrosion cracking (ODSCC) was detected in one additional tube in SG A that had been de-plugged and returned to service after Cycle 22. No tubes in SG C have been de-plugged and returned to service. In addition, no cold leg top of tubesheet indications were detected in SG C during the two 33-percent sample inspections of the critical area performed in 2R22 and 2R23. In response to an NRC staff question, the licensee indicated that the cold leg expansion region of all tubes returned to service will be inspected each outage with a +Point' probe.
In response to an NRC staff request for additional information, the licensee provided a summary of a simplistic stress analysis of a plugged tube at the cold leg top of tubesheet region. The analysis assumed that the plugged tube (before plugging) and surrounding tubes become locked at the first carbon steel drilled support plate. Although the plugged tube would have a lower operating temperature, the stress evaluation determined the axial stress in a locked plugged tube is up to 2 times higher than an adjacent, in-service locked tube. This analysis is consistent with the outage inspection results that circumferential ODSCC was only detected in three previously plugged tubes within the expanded cold leg top of tubesheet inspection scope.
Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their TS. In addition, the staff concludes that there are no technical issues that warrant additional follow-up action at this time, since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.
ML24135A228 OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DNRL/NCSG/BC NAME VSreenivas KZeleznock SBloom DATE 05/13/2024 05/14/2024 12/14/2023 OFFICE NRR/DORL/LPL1/BC NRR/DORL/LPL1/PM NAME HGonzález VSreenivas DATE 05/24/2024 05/29/2024