ULNRC-06645, ECCS Evaluation Model Revisions

ECCS Evaluation Model Revisions

ML21090A249
Person / Time
Site:	Callaway
Issue date:	03/31/2021
From:	Bianco F Ameren Missouri, Union Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML21090A248	List: ML21090A250 ULNRC-06645, ECCS Evaluation Model Revisions
References
ULNRC-06645
Download: ML21090A249 (4)

Text

Callaway Plant MISSOURI March 31, 2021 ULNRC-06645 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-000 1 10 CfR 50.46 Ladies and Gentlemen:

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

RENEWED FACILITY OPERATING LICENSE NPF-30 ECCS EVALUATION MODEL REVISIONS Ameren Missouri 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 ECCS Large Break and Small Break Loss of Coolant Accident (LOCA) Evaluation Models that have been implemented for Callaway during the time period from March 2020 to March 2021 Attachment 2 provides an ECCS Evaluation Model Margin Assessment which accounts for all peak cladding temperature (PCi) changes resulting from the resolution of prior issues as they apply to Callaway. No new PCi penalties are included in these attachments.

References 1 through 15 (listed on page 2 ofthis letter) provided annual 10 CFR 50.46 reports that were issued after the LOCA analyses were revised to reflect the installation ofthe replacement steam generators in 2005. The PCT values determined in the 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, Ameren Missouri was informed by Westinghouse that the absolute magnitude ofthe Large Break Loss ofCoolant Accident (LBLOCA) penalty assessments that have accumulated since the current analysis of record (replacement steam generator analysis approved in Callaway License Amendment 168) exceeded 50°F. As such, Reference 9 was submitted within the requirements of 10 CFR 50.46(a)(3)(ii), and contains a commitment to reanalyze the Large Break and Small Break Loss of Coolant Accidents using the NRC-approved version of WCAP-16996-P, Realistic LOCA Evaluation Methodology Applied to the Full Spectrum ofBreak Sizes (FULL SPECTRUM LOCA Methodology). This reanalysis will be completed on a schedule to be determined as part ofthe 10 CFR 50.46c rulemaking process.

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

ULNRC-06645 March 31, 2021 Page 2 of 4 This letter does not contain new commitments. for any questions on this report, please contact Mr.

Tom Elwood at (314) 225-1905.

ianco Senior Director, Nuclear Operations JLB/mlp

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 Attachments:

1 Changes to the Westinghouse ECCS Evaluation Model and PCT Penalty Assessments

2. ECCS Evaluation Model Margin Assessment for Callaway

.:::::::..2. ::::::::::: .::::::::::: .2::::: .::::::::: .:::: .::::::::::::::::::::::::::::::::: .:::: .::::::::::::::::::::. ::::::::: .:::: .2:::::.

ULNRC-06645 March 31, 2021 Page 3 of 4 cc: Mr. Scoff A. Morris 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

$201 NRC Road Steedman, MO 65077 Mr. M. Chawla Project Manager, Callaway Plant Office ofNuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0$B1A Washington, DC 20555-0001

ULNRC-06645 March 31, 2021 Page 4 of 4 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 B. L. Cox F. J. Bianco S. P. Banker S. J. Meyer R. C. Wink T. B. Elwood 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)