ULNRC-05600, 10 CFR 50.46 Annual Report ECCS Evaluation Model Revisions

10 CFR 50.46 Annual Report ECCS Evaluation Model Revisions

ML090720162
Person / Time
Site:	Callaway
Issue date:	03/04/2009
From:	Sandbothe S AmerenUE
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ULNRC-05600
Download: ML090720162 (10)

Text

AmerenUE PO Box 620 Cal/awayPlant Fulton, MO 65251 March 4, 2009 ULNRC-05600 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001

"'Ameren 10 CFR 50.46 JF Ladies and Gentlemen:

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

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

References:

1) LTLNRC-05260 dated 3-9-06

2) ULNRC-05378 dated 3-7-07

3) ULNRC-05475 dated 3-4-08 Attachment 1 to this letter describes changes to the Westinghouse ECCS Large Break and Small Break Loss of Coolant Accident (LOCA) Evaluation Models which have been implemented for Callaway during the time period from March 2008 to March 2009. Attachment 2 provides an ECCS Evaluation Model Margin Assessment which accounts for all peak cladding temperature (PCT) changes resulting from the resolution of prior issues as they apply to Callaway. No new PCT penalties are included in these attachments. References 1 through 3 below provided annual 10 CFR 50.46 reports that were issued after the LOCA analyses were revised to reflect the installation of the 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. As such, no reanalysis is planned by AmerenUE.

a subsidiary of Amoren Corporation

ULNRC-05600 March 4, 2009 Page 2 This letter does not contain any new commitments. If you have any questions on this report, please contact Mr. Scott Maglio at (573) 676-8719.

Sincerely, Scott Sandbothe Manager - Regulatory Affairs GGY/nls Attachments

ULNRC-05600 March 4, 2009 Page 3 cc: Mr. Elmo E. Collins, Jr.

Regional Administrator U.S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Mohan C. Thadani (2 copies)

Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop O-8G14 Washington, DC 20555-2738

ULNRC-05600 March 4, 2009 Page 4 Index and send hardcopy to QA File A160.0761 Hardcopy:

Certrec Corporation 4200 South Hulen, Suite 630 Fort Worth, TX 76109 (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 Responses and Reports ULNRC Distribution:

A. C. Heflin F. M. Diya T. E. Herrmann S. M. Maglio T. B. Elwood L. S. Sandbothe S. L. Gallagher T. L. Woodward (NSRB)

Mr. Ron Reynolds, Director (SEMA)

Mr. Edward Gray, Senior REP Planner (SEMA)

Mr. John Campbell, REP Planner (SEMA)

Ms. Diane M. Hooper (WCNOC)

Mr. Dennis Buschbaum (TXU)

Mr. Scott Bauer (Palo Verde)

Mr. Stan Ketelsen (PG&E)

Mr. Wayne Harrison (STPNOC)

Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)

Mr. Floyd Gilzow (DNR)

ATTACHMENT ONE CHANGES TO THE WESTINGHOUSE ECCS EVALUATION MODEL AND PCT PENALTY ASSESSMENTS 1

TABLE OF CONTENTS

1. ERRORS IN REACTOR VESSEL LOWER PLENUM SURFACE AREA CALCULATIONS

2. DISCREPANCY IN METAL MASSES USED FROM DRAWINGS

3. GENERAL CODE MAINTENANCE 2

1. ERRORS IN REACTOR VESSEL LOWER PLENUM SURFACE AREA CALCULATIONS Two errors were discovered in the calculations of reactor vessel lower plenum surface area. The corrected values have been evaluated for impact on current licensing-basis analysis results and will be incorporated on a forward-fit basis. These changes represent a closely-related group of Non-Discretionary Changes in accordance with Section 4.1.2 of WCAP- 13451.

The differences in vessel lower plenum surface area are relatively minor and would be expected to produce a negligible effect on large and small break LOCA analysis results, leading to an estimated PCT impact of 0°F for 10 CFR 50.46 reporting purposes.

2. DISCREPANCY IN METAL MASSES USED FROM DRAWINGS Discrepancies were discovered in the use of metal masses from drawings. The updated reactor vessel metal masses and fluid volumes have been evaluated for impact on current licensing-basis analysis results and will be incorporated on a forward-fit basis. These changes represent a closely-related group of Non-Discretionary Changes in accordance with Section 4.1.2 of WCAP-13451.

The differences in the reactor vessel metal mass and fluid volume are relatively minor and would be expected to produce a negligible effect on large and small break LOCA analysis results, leading to an estimated PCT impact of 0OF for 10 CFR 50.46 reporting purposes.

3. GENERAL CODE MAINTENANCE Various changes have been made to enhance the usability of the codes and to help preclude errors in analyses. This includes items such as modifying input variable definitions, units, and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. These changes represent Discretionary Changes that will be implemented on a forward-fit basis in accordance with Section 4.1.1 of WCAP- 13451.

The nature of these changes leads to an estimated PCT impact of 0°F on the LBLOCA and SBLOCA analyses of record for Callaway.

3 ATTACHMENT TWO ECCS EVALUATION MODEL MARGIN ASSESSMENT FOR CALLAWAY I

LARGE BREAK LOCA A. ANALYSIS OF RECORD (AOR) PCT = 1939'F B. PRIOR ECCS MODEL ASSESSMENTS + 17 0 F C. CURRENT LOCA MODEL ASSESSMENTS - + 0°F March 2009 LICENSING BASIS PCT + MARGIN ALLOCATIONS 1956 0 F ABSOLUTE MAGNITUDE OF MARGIN ALLOCATIONS 170 F SINCE LAST LBLOCA 30-DAY REPORT 2

SMALL BREAK LOCA A. ANALYSIS OF RECORD (AOR)

PCT = 1043 0 F B. PRIOR ECCS MODEL ASSESSMENTS

+ 0°F C. CURRENT ECCS MODEL ASSESSMENTS -

+ 0°F March 2009 LICENSING BASIS PCT + MARGIN ALLOCATIONS 1043 0 F ABSOLUTE MAGNITUDE OF MARGIN ALLOCATIONS 0OF SINCE LAST SBLOCA 30-DAY REPORT 3