ML25052A059
| ML25052A059 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/28/2025 |
| From: | William Orders Plant Licensing Branch IV |
| To: | Heflin A Arizona Public Service Co |
| Orders, William | |
| References | |
| EPID L-2024-LRO-0052 | |
| Download: ML25052A059 (4) | |
Text
February 28, 2025 Adam C. Heflin Executive Vice President/
Chief Nuclear Officer Mail Station 7605 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 - REVIEW OF THE SPRING 2024 STEAM GENERATOR TUBE INSPECTION REPORT (EPID L-2024-LRO-0052)
Dear Adam Heflin:
By letter dated October 17, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24292A032), Arizona Public Service Company (the licensee) submitted information summarizing the results of the spring 2024 steam generator (SG) inspections performed at Palo Verde Nuclear Generating Station (Palo Verde), Unit 3. These inspections were performed during refueling outage 24. The SG tube inspection report was submitted in accordance with Technical Specification (TS) 5.6.8, Steam Generator Tube Inspection Report.
The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of the submittal and concludes that the licensee provided the information required by Palo Verde, Unit 3, TS 5.6.8. In addition, the staff concludes that there are no technical issues that warrant follow-up actions at this time. Enclosed is the NRC staffs review of the Palo Verde, Unit 3 SG tube inspection report.
A. Heflin If you have any questions, please contact me at (301) 415-3329 or via email at William.Orders@nrc.gov.
Sincerely,
/RA/
William Orders, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. STN 50-530
Enclosure:
Review of SG Tube Inspection Report cc: Listserv
Enclosure REVIEW OF THE SPRING 2024 STEAM GENERATOR TUBE INSPECTION REPORT ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 DOCKET NO. STN 50-530 By letter dated October 17, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24292A032), Arizona Public Service Company (the licensee) submitted information summarizing the results of the spring 2024 steam generator (SG) inspections performed at Palo Verde Nuclear Generating Station (Palo Verde), Unit 3. These inspections were performed during Unit 3 refueling outage 24 (U3R24).
Palo Verde, Unit 3 has two replacement SGs manufactured by Ansaldo. Each SG has 12,580 thermally treated Alloy 690 tubes with an outside diameter of 0.75 inches and a nominal wall thickness of 0.042 inches. The straight portion of the SG tubes are supported by a series of stainless steel eggcrate tube supports. Diagonal bars (batwings), and vertical straps support the U-bend portion of the SG tubes.
The licensee provided the scope, extent, methods, and results of the SG tube inspections in the letter dated October 17, 2024. In addition, the licensee described corrective actions (e.g., tube plugging), if any were taken in response to the inspection findings.
Based on the review of the information provided, the U.S. Nuclear Regulatory Commission (NRC) staff has the following observations:
The only degradation mechanism detected during the U3R24 outage was tube wear.
The chemical cleaning and sludge lancing of both SGs removed approximately 8,000 pounds of sludge, which was similar to the amount of sludge removed from Palo Verde, Unit 1 in 2022 and Palo Verde, Unit 2 in 2023.
A foreign object was detected in U3R20 and U3R22 in SG 32, just above the flow distribution plate and in contact with a tube that had no detected tube wear, so the foreign object was classified as a possible loose part (PLP). In U3R24, the foreign object was found in the same location and determined to be associated with a new tube wear indication, so it was classified as a possible loose part with indication. The PLP was also detected from the three adjacent tubes, but they did not have wear indications. Because the foreign object was not able to be retrieved, the four tubes adjacent to the loose part were stabilized and plugged.
Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff concludes that there are no technical issues that warrant 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.
- by email OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA*
NRR/DNRL/NCSG/BC*
NAME WOrders PBlechman SBloom DATE 2/21/2025 2/24/2025 2/25/2025 OFFICE NRR/DORL/LPL/BC*
NRR/DORL/LPL4/PM*
NAME TNakanishi WOrders DATE 2/28/2025 2/28/2025