ML22077A373

Review of the Spring 2021 Steam Generator Tube Inspection Report

ML22077A373
Person / Time
Site:	Saint Lucie
Issue date:	03/22/2022
From:	Natreon Jordan Plant Licensing Branch II
To:	Coffey R Florida Power & Light Co
Jordan, N.
References
EPID L-2021-LRO-0061
Download: ML22077A373 (3)

Text

March 22, 2022 Mr. Bob Coffey Executive Vice President, Nuclear and Chief Nuclear Officer Florida Power & Light Company 700 Universe Blvd.

Mail Stop: EX/JB Juno Beach, FL 33408

SUBJECT:

ST. LUCIE NUCLEAR PLANT, UNIT 1 - REVIEW OF THE SPRING 2021 STEAM GENERATOR TUBE INSPECTION REPORT (EPID L-2021-LRO-0061)

Dear Mr. Coffey:

By letter dated November 1, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21305A868), Florida Power & Light Company (the licensee) submitted information summarizing the results of the spring 2021 steam generator (SG) inspections at St. Lucie Nuclear Plant (St. Lucie), Unit 1. These inspections were performed during refueling outage 30.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information referenced above and concludes that the licensee provided the information required by their technical specifications and that no additional follow-up is required at this time. The enclosure contains the NRC staffs review of the submittal.

If you have any questions, please contact me at (301) 415-7410, or via email at Natreon.Jordan@nrc.gov.

Sincerely, Digitally signed by Natreon J. Natreon J. Jordan Date: 2022.03.22 Jordan 17:24:38 -04'00' Natreon (Nate) J. Jordan, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-335

Enclosure:

Review of Steam Generator Tube Inspection Report cc: Listserv

REVIEW OF THE SPRING 2021 STEAM GENERATOR TUBE INSPECTION REPORT FLORIDA POWER AND LIGHT COMPANY ST. LUCIE NUCLEAR PLANT, UNIT 1 DOCKET NO. 50-335 By letter dated November 1, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21305A868), Florida Power & Light Company (the licensee) submitted information summarizing the results of the spring 2021 steam generator (SG) inspections at St. Lucie Nuclear Plant (St. Lucie), Unit 1 (St. Lucie Unit 1). These inspections were performed during refueling outage 30 (RFO 30).

St. Lucie Unit 1 has two replacement SGs designed and fabricated by Babcock and Wilcox International that were installed in 1997. Each SG has 8,523 thermally treated Alloy 690 tubes with a nominal outside diameter of 0.75 inches and a nominal wall thickness of 0.045 inches.

The tubes are arranged in a triangular pattern and were hydraulically expanded at each end for the full depth of the tubesheet. The tubes are supported by horizontal lattice grid tube supports over the straight length of the tubes. In the U-bend region, the tubes are supported by fan bar supports (FBS) and connector bar supports (CBS). All supports are fabricated from stainless steel. The U-bend region of the tubes in rows 1 through 20 was stress relieved after bending.

The tubes with the smallest U-bend radii are in Rows 2 and 3.

The inspection during RFO 30 was the seventh inservice inspection for the replacement SGs.

At the time of the inspection, the replacement SGs had accumulated approximately 246.0 effective full power months of operation. The licensee provided the scope, extent, methods, and results of the SG tube inspections in the document referenced above. In addition, the licensee described corrective actions (e.g., tube plugging) that were taken in response to the inspection findings. Based on the review of the information provided, the NRC staff has made the following observations:

No tube wear exceeded the TS plugging limit of 40 percent through-wall. Five tubes with FBS wear in each SG were preventatively plugged to support the operational assessment until the next planned primary-side inspection.

Based on secondary-side visual inspection, the licensee reported discoloration and scouring on the outer surface of the bundle wrapper in SG-1B where feedwater discharges from the J-tubes. The licensee entered this condition into the corrective action program for monitoring during future SG inspections.

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 additional follow-up action at this time.

This is because 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.

Principal Contributor: G. Makar Enclosure

ML22077A373 OFFICE DORL/LPL2-2/PM DORL/LPL2-2/LA NRR/DNRL/NCSG/BC NAME NJordan RButler SBloom DATE 03/17/2022 03/21/2022 03/17/2022 OFFICE DORL/LPL2-2/BC DORL/LPL2-2/PM NAME DWrona NJordan DATE 03/22/2022 03/22/2022