ML22208A176

Review of the Fall 2021 Steam Generator Tube Inspection Report

ML22208A176
Person / Time
Site:	Saint Lucie
Issue date:	08/04/2022
From:	Natreon Jordan Plant Licensing Branch II
To:	Coffey B Florida Power & Light Co
Jordan N, NRR/DORL/LPLII-2
References
EPID L-2022-LRO-0026
Download: ML22208A176 (4)

Text

August 4, 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 2 - REVIEW OF THE FALL 2021 STEAM GENERATOR TUBE INSPECTION REPORT (EPID L-2022-LRO-0026)

Dear Mr. Coffey:

By letter dated March 21, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22080A201), Florida Power & Light Company (the licensee) submitted information summarizing the results of the fall 2021 steam generator (SG) inspections at St. Lucie Nuclear Plant, Unit 2. These inspections were performed during refueling outage 26.

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,

/RA/

Natreon (Nate) J. Jordan, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-389

Enclosure:

Review of Steam Generator Tube Inspection Report cc: Listserv

REVIEW OF THE FALL 2021 STEAM GENERATOR TUBE INSPECTION REPORT FLORIDA POWER AND LIGHT COMPANY ST. LUCIE NUCLEAR PLANT, UNIT 2 DOCKET NO. 50-389 By letter dated March 21, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22080A201), Florida Power & Light Company (the licensee) submitted information summarizing the results of the fall 2021 steam generator (SG) inspections at St. Lucie Nuclear Plant (St. Lucie), Unit 2. These inspections were performed during refueling outage 26 (RFO 26).

St. Lucie, Unit 2, has two Model 86/19TI replacement SGs that were manufactured by AREVA and installed in 2007. Each SG has 8,999 thermally treated Alloy 690 tubes with a nominal outside diameter of 0.75 inches and a nominal wall thickness of 0.043 inches. During manufacturing, all tubes were hydraulically expanded at both ends over the full depth of the tubesheet. The tubes are arranged in a triangular pattern with tube center-to-center spacing of 1.0 inch. The radius of the row 1 U-bends is 4.134 inches. The U-bends in rows 1 through 15 were stress relieved after bending. Seven stainless tube steel support plates with broached trefoil holes support the vertical section of the tubes. Four sets of stainless steel anti-vibration bars (AVBs) support the U-bend section of the tubes.

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), if any were taken in response to the inspection findings. After reviewing the information provided by the licensee, the staff has the following observation:

Repairs were performed during RFO 26 on the feedwater ring in SG 2A to install repair ligaments to the support brackets and restore the support gaps. The deformation was a result of water hammer from a pressure transient. Similar repairs were performed previously in both SGs. Redesigned support brackets had been installed during RFO 21 (spring 2014) in response to the first water hammer event causing deformation. The previous repairs on the new brackets were performed on SG 2B in RFO 22 (fall 2015),

and on SG 2A in RFO 24 (fall 2018). As noted in a previous licensee response (ML19233A273), the feedring support system was designed to plastically deform during certain loading conditions and still maintain allowable stress limits. No loose parts have been generated by these water hammer events, and the plant has fine mesh debris screens designed to prevent loose parts from entering the tube bundle.

Enclosure

Based on a review of the information provided, the staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff concludes 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. Although the number of wear indications is greater than the number of wear indications found in other AREVA SGs of similar age, the depths of these indications (i.e., the severity) are comparable to those observed at other plants.

Principal Contributor: G. Makar Date of issuance: August 4, 2022

ML22208A176 OFFICE DORL/LPL2-2/PM DORL/LPL2-2/LA NRR/DNRL/NCSG/BC NAME NJordan RButler SBloom DATE 07/27/2022 07/28/2022 07/11/2022 OFFICE DORL/LPL2-2/BC DORL/LPL2-2/PM NAME DWrona NJordan DATE 08/02/2022 08/04/2022