ML19220B256
| ML19220B256 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/04/2019 |
| From: | Justin Poole Plant Licensing Branch 1 |
| To: | Moul D Florida Power & Light Co, NextEra Energy Seabrook |
| Poole J, NRR/DORL/LPLI, 415-2048 | |
| References | |
| EPID L-2019-LRO-0028 | |
| Download: ML19220B256 (4) | |
Text
UNITED STATES WASHINGTON, D.C. 20555-0001 September 4, 2019 Mr. Don Moul Vice President, Nuclear Division and Chief Nuclear Officer Florida Power & Light Company NextEra Energy Seabrook, LLC Mail Stop: NT3/JW 15430 Endeavor Drive Jupiter, FL 33478
SUBJECT:
SEABROOK STATION, UNIT NO. 1 - REVIEW OF THE FALL 2018 STEAM GENERATOR TUBE INSPECTIONS (EPID L-2019-LR0-0028)
Dear Mr. Moul:
By letter dated April 19, 2019 (Agencywide Documents Access and Management System Accession No. ML19109A214), NextEra Energy Seabrook, LLC (NextEra) submitted information summarizing the results of the Fall 2018 steam generator inspections at Seabrook Station, Unit No. 1 (Seabrook). These inspections were performed during the 19th refueling outage.
The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of the information and determined that NextEra provided the information required by the Seabrook technical specifications. In addition, the NRC staff did not identify any technical issues that warrant followup action at this time. A summary of the NRC staff's review is enclosed.
If you have questions, you can contact me at 301-415-2048 and/or via e-mail at Docket No. 50-443
Enclosure:
As stated cc: Listserv Justin C. Poole, Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
REVIEW OF THE FALL 2018 STEAM GENERATOR TUBE INSPECTIONS NEXTERA ENERGY SEABROOK, LLC.
SEABROOK STATION, UNIT NO. 1 DOCKET NO. 50-443 By letter dated April 19, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19109A214), NextEra Energy Seabrook, LLC (the licensee) submitted information summarizing the results of the Fall 2018 steam generator (SG) inspections at Seabrook Station, Unit No. 1 (Seabrook). These inspections were performed during the 19th refueling outage (RFO 19).
Seabrook has four Westinghouse Model F SGs, each of which contains 5,626 thermally-treated Alloy 600 tubes. Each tube has a nominal outside diameter of 0.688 inches and a nominal wall thickness of 0.040 inches. During SG fabrication, the tube ends were hydraulically expanded over the full depth of the tubesheet. Type 405 stainless steel tube support plates, which have broached quatrefoil holes, support the vertical section of the tubes, and anti-vibration bars support the U-bend section of the tubes.
The licensee provided the scope, extent, methods, and results of its SG tube inspections. The licensee also described corrective actions, such as tube plugging, taken in response to the inspection findings.
Based on the U.S. Nuclear Regulatory Commission (NRC) staff's review of the information submitted by the licensee, the NRC staff has the following observations/comments:
One primary water stress corrosion cracking indication was found in the hot leg, top of tubesheet region in the tube located in row 33, column 93 of SG C. This resulted in a scope expansion to 100 percent of the tubes with +PointTM in the hot leg of SG C from 3 inches above the top of tubesheet to the H* depth of 15.21 inches below the top of tubesheet. The maximum +Point' voltage for this indication was 0.58 volts for a crack length of 0.21 inches, which is slightly above the initial in situ pressure test proof screen criteria. The indication was shown to have a 95 percent probability at 50 percent confidence burst pressure greater than three times the normal operating pressure differential. Therefore, the condition monitoring requirements were met, and an in-situ pressure test was not necessary.
No stress corrosion cracking indications were detected during the inspection of high stress tubes at hot leg and cold leg tube support plate locations.
A hollow metal fitting was identified in SG D. The metal object appears to have been in place since the SG was manufactured since it fills the gap between four neighboring tubes and cannot be retrieved. No wear was identified on any of the four bounding tubes during inspection and no tube damage was observed in any SG during Foreign Object Search and Retrieval activities. No tubes were plugged in SG D during RFO 19.
Enclosure A band of discoloration was observed on the wall of the steam drum, just above the feedring. It appears to have been caused by a thin layer of magnetite that had spalled from the wall in this region. The base material appears to be intact. Ultrasonic thickness measurements were taken at select locations on the feedring and not abnormal conditions were noted. No erosion, corrosion, or degradation was noted during visual inspections of the upper steam drum components.
Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by the Seabrook technical specifications. In addition, the NRC staff concludes that there are no technical issues that warrant followup action at this time,
~ince 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.
ML192208256 OFFICE NRR/DORULPL 1/PM NRR/DORULPULA NAME JPoole CSmith DATE 08/20/19 08/19/19 OFFICE NRR/DORULPL 1/BC NRR/DORL/LPL 1/PM NAME JDanna JPoole DATE 08/30/19 09/04/19