ML20015A012
| ML20015A012 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 01/16/2020 |
| From: | Siva Lingam Plant Licensing Branch IV |
| To: | Bement R Arizona Public Service Co |
| Lingam S, 301-415-1564 | |
| References | |
| EPID L-2019-LRO-0083 | |
| Download: ML20015A012 (5) | |
Text
January 16, 2020 Mr. Robert S. Bement Executive Vice President Nuclear/
Chief Nuclear Officer Mail Station 7602 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNIT 1 - REVIEW OF THE 2019 STEAM GENERATOR TUBE INSPECTIONS DURING REFUELING OUTAGE 21 (EPID L-2019-LRO-0083)
Dear Mr. Bement:
By letter dated October 18, 2019, as supplemented by letter dated December 6, 2019, Arizona Public Service Company (the licensee) submitted information summarizing the results of the spring 2019 steam generator tube inspections performed at Palo Verde Nuclear Generating Station (Palo Verde), Unit 1. These inspections were performed during Refueling Outage 21.
The steam generator 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 1, TS 5.6.8. In addition, the NRC staff concludes that there are no technical issues that warrant followup actions at this time. Enclosed is the NRC staffs review of the Palo Verde, Unit 1, steam generator tube inspection report.
If you have any questions, please contact me at (301) 415-1564 or via e-mail at Siva.Lingam@nrc.gov.
Sincerely,
/RA/
Siva P. Lingam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. STN 50-528
Enclosure:
Review of SG Tube Inspection Report cc: Listserv
Enclosure REVIEW OF THE SPRING 2019 STEAM GENERATOR TUBE INSPECTIONS PERFORMED DURING REFUELING OUTAGE 21 ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION, UNIT 1 DOCKET NO. STN 50-528 By letter dated October 18, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19291F576), as supplemented by letter dated December 6, 2019 (ADAMS Accession No. ML19340B214), Arizona Public Service Company (the licensee) submitted information summarizing the results of the spring 2019 steam generator (SG) tube inspections performed at Palo Verde Nuclear Generating Station (Palo Verde), Unit 1. These inspections were performed during Refueling Outage 21. The NRC held a clarification call on the additional information with the licensee on January 7, 2020.
Palo Verde, Unit 1, has two replacement SGs designed by Combustion Engineering and manufactured by Ansaldo. Each SG contains 12,580 thermally treated Alloy 690 tubes with an outside diameter of 0.750 inches and a wall thickness of 0.042 inches. Ferritic stainless steel eggcrate tube supports, diagonal bars, and vertical straps support the tubes at various locations.
The licensee provided the scope, extent, methods, and results of its SG tube inspections in the above referenced letters. In addition, the licensee described corrective actions (e.g., tube plugging) taken in response to the inspection findings. After reviewing the information provided by the licensee, the U.S. Nuclear Regulatory Commission (NRC) staff has the following observations and comments:
The licensee performed an inspection of the blowdown patch plate welds in SGs 11 and 12 as part of the foreign object search and retrieval effort. The inspections confirmed that the weld material near the cracked welds on the four patch plates (two per SG) is intact, and a loose parts concern is not being created. The licensee initially found these patch plate welds to be cracked during Refueling Outage 15.
The licensee confirmed that there was a typographical error in Table 2, Indication Summary, of the spring 2019 SG tube inspection report. The licensee confirmed, consistent with the Plug Map for SG 12 in Appendix E of the spring 2019 SG tube inspection report, that a total of 183 tubes have been plugged in SG 12.
The licensee clarified that the three-letter code RLW, used in the spring 2019 SG tube inspection report, stands for Retest Large Wear Standard and is typically used on bobbin or rotating coil wear indications that are greater than 50 percent. During the clarification call on January 7, 2020, the licensee discussed the use of the calibration standard for large wear indications.
The licensee clarified during the January 7, 2020, call that the SG tube in Row 41, Column 88 that contained a 65 percent wear indication exceeded the condition
monitoring limit when initially evaluated. Therefore, the licensee performed eddy current flaw profiling to more accurately calculate the burst pressure, which demonstrated that the structural integrity performance criterion was met. The licensee clarified that the 65 percent wear indication was within the previous operational assessment predictions and no changes were needed to the future operational assessment. The SG tube in Row 41, Column 88 was plugged.
Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by its technical specifications. In addition, the NRC staff concludes that there are no technical issues that warrant followup 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.
- SE memorandum by email OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DNRL/NCSG/BC*
NAME SLingam PBlechman SBloom DATE 1/15/20 1/15/20 01/14/20 OFFICE NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME JDixon-Herrity SLingam DATE 1/16/20 1/16/20