ML23122A317

Review of the Spring 2022 Steam Generator Tube Inservice Inspections

ML23122A317
Person / Time
Site:	Callaway
Issue date:	05/08/2023
From:	Mahesh Chawla NRC/NRR/DORL/LPL4
To:	Diya F Callaway Energy Center
References
EPID L-2022-LRO-0143
Download: ML23122A317 (1)

Text

May 8, 2023 Mr. Fadi Diya Senior Vice President and Chief Nuclear Officer Ameren Missouri Callaway Energy Center 8315 County Road 459 Fulton, MO 65077

SUBJECT:

CALLAWAY PLANT, UNIT NO. 1 - REVIEW OF THE SPRING 2022 STEAM GENERATOR TUBE INSPECTION REPORT (EPID L-2022-LRO-0143)

Dear Mr. Diya:

By letter dated November 1, 2022 (Agencywide Documents Access and Management System Accession No. ML22305A679), as supplemented by letter dated March 29, 2023 (ML23088A130), Union Electric Company, doing business as Ameren Missouri (the licensee),

submitted information summarizing the results of the spring 2022 steam generator inservice inspections performed at Callaway Plant, Unit No. 1 (Callaway) during Refueling Outage 25.

The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of the submittal as supplemented, and concludes that the licensee provided the information required by Callaway TS 5.6.10, Steam Generator Tube Inspection Report. In addition, the NRC staff concludes that there are no technical issues that warrant follow-up actions at this time. Enclosed is the NRC staffs review of the Callaway Steam Generator Tube Inspection Report.

If you have any questions, please contact me at 301-415-8371 or via email to Mahesh.Chawla@nrc.gov.

Sincerely,

/RA/

Mahesh L. Chawla, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-483

Enclosure:

Review of the Steam Generator Tube Inspection Report cc: Listserv

REVIEW OF THE SPRING 2022 STEAM GENERATOR TUBE INSPECTION REPORT UNION ELECTRIC COMPANY CALLAWAY PLANT, UNIT NO. 1 DOCKET NO. 50-483 By letter dated November 1, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22305A679), as supplemented by letter dated March 29, 2023 (ML23088A130), Union Electric Company, doing business as Ameren Missouri (the licensee),

submitted information summarizing the results of the spring 2022 steam generator (SG) inservice inspections performed at Callaway Plant Unit No. 1 (Callaway) during Refueling Outage 25 (1R25).

Callaway has four Framatome-designed model 73/19T SGs installed at the plant in 2005. Each SG has 5872 thermally treated Alloy 690 tubes, which have a nominal outside diameter of 0.75 inches and a nominal wall thickness of 0.043 inches. The tubes are hydraulically expanded throughout the entirety of the tubesheet. The U-bend region of the tubes in rows 1 through 18 was stress relieved after bending. The tubes are supported by eight stainless steel tube support plates and anti-vibration bars. The holes in the tube support plates are trefoil shaped.

The licensee provided the scope, extent, methods, and results of the SG tube inspections in the letters referenced above. In addition, the licensee described corrective actions (e.g., tube plugging), if any were 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 licensee performed visual inspections of the steam drums in three SGs. The original steam drum inspection scope was for SG-B and SG-C, but the scope was expanded to include SG-A when foreign objects were found on the loose parts trapping system (LPTS) screens. The foreign objects were bolts and washers from the feedwater isolation valves (FWIVs) upstream of the three SGs. All bolts and washers from the three FWIVs were accounted for except for one washer from FWIV A. The one washer was evaluated as a potential loose part for the upcoming operating cycles and found to be acceptable. Minor damage to the LPTS screens was noted and evaluated for replacement during a future outage.

All hot-leg tubes with sludge indications from the sludge analysis performed in 1R21 were inspected with the 610XP array probe.

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 follow-up action currently, 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.

Enclosure

ML23122A317 *concurrence via email NRR-106 OFFICE NRR/DORL/LPL4/PM* NRR/DORL/LPL4/LA* NRR/DNRL/NCSG/BC*

NAME MChawla PBlechman SBloom DATE 5/1/2023 5/3/2023 5/1/2023 OFFICE NRR/DORL/LPL4/BC* NRR/DORL/LPL4/PM*

NAME JDixon-Herrity MChawla DATE 5/8/2023 5/8/2023