ML24086A513

CFR 50.46 Annual Report Regarding ECCS Evaluation Model Revisions

ML24086A513
Person / Time
Site:	Callaway
Issue date:	03/26/2024
From:	Witt T Ameren Missouri, Union Electric Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
Shared Package
ML24086A512	List: ML24086A513 ML24086A514 ULNRC-06861, Westinghouse and Framatome, ECCS Evaluation Model Margin Assessments
References
ULNRC-06861
Download: ML24086A513 (1)

Text

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W Ameren Callaway Plant MISSOURI

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March 26, 2024

ULNRC-06861

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

10 CFR 50.46

Ladies and Gentlemen:

DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.

RENEWED FACILITY OPERATING LICENSE NPF-30 10 CFR 50.46 ANNUAL REPORT REGARDING ECCS EVALUATION MODEL REVISIONS

Ameren Missouri (Union Electric) hereby submits the annual report required per 10 CFR 50.46(a)(3) for Callaway Plant.

Attachment 1 to this letter describes those changes to the Westinghouse and Framatome ECCS Large Break and Small Break Loss of Coolant Accident (LOCA) Evaluation Models that have been implemented for Callaway during the March 2023 to March 2024 timeframe. Attachment 2 provides the Westinghouse and Framatome ECCS Evaluation Model Margin Assessments which account for all peak cladding temperature (PCT) changes resulting from the resolution of prior issues as they apply to Callaway. No new PCT penalties are identified in these assessments.

This 10 CFR 50.46(a)(3) report is the first one for Callaway t o include changes and margin assessments to the Framatome ECCS Large Break and Small Break LOCA Evaluation Model. In Reference 16, the 10 CFR 50.46(a)(3) report for Callaway reflected the impact of having four Framatome GAIA lead fuel assemblies in the Callaway core (in non-limiting locations) during operating cycle 25 using only the Westinghouse ECCS Evaluation Model. Subsequently, due to core reload analysis considerations and limitations, no Framatome GAIA fuel was present in the Callaway core during operating cycle 26. In the fall of 2023, however, eight Framatome GAIA fuel assemblies were inserted in the Callaway core for operating cycle 27 as support ed by Framatome's analytical methods, including the Framatome ECCS Evaluation Model, as authorized by License Amendment 235 issued on October 5, 2023 (ML23240A370). Consequently, this 10 CFR 50.46(a)(3) report

.t 8315 County Road 459 : Steedman, MO 65077: AmerenMissouri.com.t

.t ULNRC-06861 March 26, 2024 Page 2 ofS includes changes and margin assessments to both the Westinghouse and Framatome ECCS Evaluation Models.

Reference 1 through 18 (listed on page 3 of this letter) are the annual 10 CFR 50.46 reports that have been submitted since the Westinghouse LOCA analysis was revised to reflect the installation of the replacement steam generators in 2005. As reported in each of these reports, the PCT values determined in the Westinghouse Large Break and Small Break LOCA analyses of record, when combined with all PCT margin allocations, remain below the 2200°F regulatory limit. However, in March 2014, Westinghouse informed Ameren Missouri that the absolute magnitude of the Large Break Loss of Coolant Accident (LBLOCA) penalty assessments accumulated in the analyses of record for Callaway (since replacement of the steam generators) had reached a value that exceeded 50°F. The letter identified as Reference 9 was then submitted pursuant to the requirements of 10 CFR 50.46(a)(3)(ii),

containing a commitment to reanalyze the Large Break and Small Break Loss of Coolant Accidents using the NRC-approved version ofWCAP-16996-P, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology)."

In References 9 through 16, Ameren Missouri noted that the commitment to perform the LOCA reanalysis using the FULL SPECTRUM LOCA (FSLOCA) evaluation methodology was on a schedule to be determined consistent with the proposed 10 CFR 50.46c rulemaking being considered at that time. In Reference 17, Ameren Missouri noted that it was in the process of evaluating a change in fuel vendors for Callaway Plant and that after this determination was made, an appropriate LOCA reanalysis schedule would be established. In Reference 18, Ameren Missouri noted that a fuel contract extension with Westinghouse had been signed which includes performance of a LOCA reanalysis using the FSLOCA methodology. Consequently, Ameren Missouri updated the schedule for performance of the LOCA reanalysis and established a new/revised commitment for submittal of the reanalysis (via a license amendment request), as documented in Attachment 1 to the Reference 18 letter. Per the new/revised commitment, the schedule is to complete the LOCA reanalysis using the FSLOCA methodology and submit the associated license amendment request prior to the Fall of 2025.

This letter does not contain new commitments. If there are any questions, please contact Mr. Tom Elwood at (314) 225-1905.

Sincerely,

Todd A. Witt Manager, Regulatory Affairs

Enclosures:

Attachment 1, Changes to the Westinghouse and Framatome ECCS Evaluation Models and PCT Penalty Assessments Attachment 2, Westinghouse and Framatome ECCS Evaluation Model Margin Assessments

ULNRC-06861 March 26, 2024 Page 3of 5

References:

1) ULNRC-05260 dated 3-9- 06

2) ULNRC-05378 dated 3-7- 07

3) ULNRC-05475 dated 3-4- 08

4) ULNRC-05600 dated 3-4- 09

5) ULNRC-05683 dated 3-1- 10

6) ULNRC-05769 dated 3-1- 11

7) ULNRC-05840 dated 3-1- 12

8) ULNRC -05968 dated 3-6- 13

9) ULNRC-06098 dated 3-25-14

10) ULNRC-06203 dated 3-31-15

11) ULNRC-06292 dated 3-30- 16

12) ULNRC-06361 dated 3-30- 17

13) ULNRC-06428 dated 3-29-18

14) ULNRC-06497 dated 3-28-19

15) ULNRC-06571 dated 3-31-20

16) ULNRC-06645 dated 3-31-21

17) ULNRC-06725 dated 3-22-22

18) ULNRC-06801 dated 3-30- 23

ULNRC-06861 March 26, 2024 Page 4of 5

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 O 8B1A Washington, DC 20555- 0001

ULNRC-06861 March 26, 2024 Page 5of 5 Index and send hardcopy to QA File A160.0761

Hardcopy:

Certrec Corporation 6500 West Freeway, Suite 400 Fort Worth, TX 76116 (Certrec receives ALL attachments as long as they are non -safeguards and may be publicly disclosed.)

Electronic distribution for the following can be made via Other Situations ULNRC Distribution:

F. M. Diya K. C. Scott W. A. Witt J. G. Beck T. A. Witt M. G. Hoehn D. S. Pallardy B. D. Richardson T. B. Elwood J. W. Cordz NSRB Secretary STARS Regulatory Affairs Mr. Jay Silberg ( Pillsbury Winthrop Shaw Pittman LLP)

Ms. Kathleen McNelis (Public Service Commission)

Ms. Claire Eubanks (Public Service Commission)

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