ML23313A155

Review of the Fall 2022 Steam Generator Tube Inspection Report

ML23313A155
Person / Time
Site:	Braidwood
Issue date:	12/01/2023
From:	Joel Wiebe Plant Licensing Branch III
To:	Rhoades D Constellation Energy Generation, Constellation Nuclear
Wiebe J
References
EPID L-2023-LRO-0034
Download: ML23313A155 (4)

Text

December 1, 2023 Mr. David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BRAIDWOOD NUCLEAR POWER STATION, UNIT 1 - REVIEW OF THE FALL 2022 STEAM GENERATOR TUBE INSPECTION REPORT (EPID L-2023-LRO-0034)

Dear Mr. Rhoades:

By letter dated April 5, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23095A128), Constellation Energy Generation, LLC (the licensee),

submitted information summarizing the results of the fall 2022 steam generator (SG) inspections performed at Braidwood Station, Unit 1. The inspections were performed during refueling outage 23. The SG tube inspection report was submitted in accordance with Technical Specification (TS) 5.6.9, Steam Generator (SG) Tube Inspection Report.

Based on its review, the U.S. Nuclear Regulatory Commission (NRC) staff concludes that the licensee has provided the information required by TS 5.6.9, and that no follow-up is required at this time. A summary of the NRC staffs review is enclosed.

If you have any questions, please contact me at 301-415-6606 or via email at Joel.Wiebe@nrc.gov.

Sincerely,

/RA/

Joel S. Wiebe, Senior Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No.: STN 50-456

Enclosure:

Review of the Braidwood Station, Unit 1, Steam Generator Tube Inspection Report cc: Listserv

REVIEW OF THE FALL 2022 STEAM GENERATOR TUBE INSPECTION REPORT CONSTELLATION ENERGY GENERATION, LLC BRAIDWOOD STATION, UNIT NO. 1 DOCKET NO. STN 50-456 By letter April 5, 2023 (Agencywide Documents Analysis and Management System (ADAMS)

Accession No. ML23095A128), Constellation Energy Generation, LLC (the licensee), submitted information summarizing the results of the fall 2022 steam generator (SG) tube inspections performed at Braidwood Station (Braidwood), Unit No. 1, during refueling outage 23 (A1R23).

Technical Specification (TS), section 5.6.9, requires that a report be submitted within 180 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS, section 5.5.9, which requires that a SG program be established and implemented to ensure SG tube integrity is maintained.

Braidwood, Unit 1, is a 4-loop plant with Babcock and Wilcox Model 7720 replacement SGs.

These SGs had been in service for approximately 22 effective full-power years of operation through the end of cycle 23. Each SG contains 6633 thermally treated Alloy 690 tubes with a nominal outside diameter of 0.6875 inches and a nominal wall thickness of 0.040 inches. The tubes are supported by stainless steel lattice grid structures and fan bars (U-bend). The tubes were hydraulically expanded at both ends for the full depth of the tubesheet. The U-bend region of tube rows 1 to 21 received a thermal stress relief prior to operation.

The licensee provided the scope, extent, methods, and results, of its SG tube inspections in its April 5, 2023, letter. In addition, the licensee described corrective actions, such as tube plugging 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 A1R23 SG inspections was the seventh outage and last inspection for Braidwood, Unit 1, in the 120 effective full-power month period of Technical Specifications Task Force (TSTF)-510. The licensee is planning to adopt TSTF-577, which was approved by letter dated July 26, 2023 (ML23188A129), before the next SG inspection.

The licensee inspected 100 percent of the tubes in service and identified a total of 86 fan bar wear indications, 11 lattice grid wear indications, and 16 foreign object wear indications.

The deepest fan bar wear indication measured 16 percent through-wall (TW) and the deepest lattice grid wear indication measured 11 percent TW. The licensee plugged 14 tubes due to foreign objects (FO) in SG 1C. One tube was plugged for FO wear greater than the 40 percent TS plugging criterion. An additional tube was plugged that had FO wear with a potential loose part present; however, the tube could not be visually inspected. Twelve additional tubes had no FO wear but were preventively plugged when the foreign object could not be removed or properly characterized by visual inspection.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by the TSs. In addition, the staff concludes that there are no current technical issues that warrant follow-up action. The inspections appear to be consistent Enclosure

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.

Reviewer: P. Klein, NRR Date: December 1, 2023

ML23313A155 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DNRL/NCSG NAME JWiebe SRohrer SBloom DATE 11/9/2023 11/14 /2023 8/23/2023 OFFICE NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME JWhited JWiebe DATE 11/30/2023 12/1/2023