ULNRC-06947, Request for ASME Code Relief Regarding 48-Hour Hold Time When Performing Repairs Using Ambient Temperature GTAW Temper Bead Method Per ASME Code Case N-638-11 (Relief Request I5R-01)
| ML25142A386 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 05/22/2025 |
| From: | Elwood T Ameren Missouri, Union Electric Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| Shared Package | |
| ML25142A385 | List: |
| References | |
| ULNRC-06947 | |
| Download: ML25142A386 (1) | |
Text
2rAI118refl Callaway Plant MISSOURI May 22, 2025 ULNRC-06947 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 10 CFR 50.55a Ladies and Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
RENEWED FACILITY OPERATING LICENSE NPF-30 REQUEST FOR ASME CODE RELIEF REGARDING 48-HOUR HOLD TIME WHEN PERFORMING REPAIRS USING AMBIENT TEMPERATURE GTAW TEMPER BEAD METHOD PER ASME CODE CASE N-638-11 (RELIEF REQUEST I5R-01)
Reference 1 : NRC Public Meeting: Teleconference with Union Electric Company Regarding Reactor Vessel Bottom Mounted Instrument Nozzle Repair for Callaway Plant, Unit No. 1 (ADAMS Accession No. ML25140A089)
During the current refueling outage at the Callaway plant (i.e., Refuel 27), under-vessel and subsequent, additional non-destructive examinations led to the identification of indications in the J groove welds for several reactor vessel bottom-mounted instrument (BMI) nozzle penetrations, on the inside of the reactor vessel. A repair plan has been developed to address the indications, which involves the application of a weld pad to each nozzle penetration on the outside of the reactor vessel, using the Gas Temperature Arc Welding (GTAW) temper bead technique in accordance with ASME Code Case N-638-1 1, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique Section XI, Division 1.
As the repairs involve the need for relief from ASME Code requirements, the repair plan was discussed with the NRC in the Reference 1 meeting/teleconference on May 21, 2025.
For similar and dissimilar metal welding using the GTAW temper bead method, Code Case N-638-11 allows such repairs to be done without the applying the preheat and postweld heat treatment requirements of IWA-44 11. When austenitic materials are used, the Code Case requires the completed weld to be nondestructively examined after the three tempering layers have been in place for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. In the Reference 1 meeting, Ameren Missouri described its plan to perform liquid penetrant 8315 County Road 459 Steedman, MO 65077 AmerenMissouri.com
ULNRC-06947 May 22, 2025 Page 2 of 4 surface and UT volumetric examinations of the completed weld pads in accordance with ASME Section III acceptance criteria (after the weld pad has been prepared for NDE and dimensionally inspected). However, in lieu of performing the required NDE at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the three tempering layers have been installed, Ameren Missouri noted that it proposes to perform the NDE methods after completion of the weld pad. This proposed alternative to the Code Case requirement is the basis of Ameren Missouris Relief Request, as further described and explained in the Relief Request document itself, provided via the enclosure to this letter. The attachment to the enclosure provides additional technical justification for the proposed alternative of foregoing the 48-hour hold time.
It should be noted that Callaways Inservice Inspection (151) Program complies with the 2019 Edition of the ASME Boiler and Pressure Vessel Code (BPVC),Section XI. Callaways fifth 1ST interval began December 19, 2024, and ends on December 18, 2036, as a result of Callaway moving from the ten-year to the twelve-year 151 interval as allowed by ASME Code Case N-92 1.
In regard to Ameren Missouris request for approval of the enclosed relief request, it was discussed in the Reference 1 meeting that verbal approval of the request is desired ahead of reaching a certain point in the repair plan for the three affected BMI nozzles, specifically, before applying the first of the noted weldpads. As that activity is projected to begin on May 25 or 26, verbal approval of Relief Request 15R-01 is respectfully requested on or before Saturday, May 24.
Lastly, and as also discussed in the Reference 1 meeting, there are other aspects of the repair plan for the three affected BMI nozzles that require Code relief. A separate Code Relief Request is being developed for that, i.e., Relief Request 15R-02, and will be submitted as soon as possible. Verbal approval of that request will be sought prior to heat-up and pressurization of the reactor in preparation for restart from the current outage.
For any questions concerning this submittal, please contact the undersigned at (314) 225-1905.
This letter does not contain new commitments.
Sincerely, Thomas B. Elwood Regulatory Affairs Manager ESS, Relief Request 15R-0 1 to Enclosure 1
ULNRC-06947 May 22, 2025 Page 3 of 4 cc:
Mr. John Monninger Regional Administrator U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. M. Chawla Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop O8B1A Washington, DC 20555-000 1
ULNRC-06947 May 22, 2025 Page 4 of 4 Index and send hardcopy to QA File A160.0761 Hardcopy:
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