RS-12-192, Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Dresden Nuclear Power Station, Units 2 and 3

Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Dresden Nuclear Power Station, Units 2 and 3

ML12300A416
Person / Time
Site:	Dresden
Issue date:	10/26/2012
From:	Simpson P Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-12-192
Download: ML12300A416 (7)

Text

RS-12-192 10 CFR 50.46 October 26, 2012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249

Subject:

Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Dresden Nuclear Power Station, Units 2 and 3 In accordance with 10 CFR 50.46, "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors," paragraph (a)(3)(ii), Exelon Generation Company, LLC (EGC) is submitting this letter and its attachments to meet the annual reporting requirements of the Emergency Core Cooling System (ECCS) Evaluation Model changes and errors for Dresden Nuclear Power Station, Units 2 and 3. This report covers the period from October 29,2011, through October 26,2012.

There are no regulatory commitments contained in this letter. If there are any questions concerning this letter, please contact Mr. Mitchel A Mathews at (630) 657-2819.

Patrick R. Simpson Manager - Licensing Attachments:

1. Dresden Nuclear Power Station Unit 2 - 10 CFR 50.46 Report (Westinghouse Fuel)

2. Dresden Nuclear Power Station Unit 3 - 10 CFR 50.46 Report (Westinghouse Fuel)

3. Dresden Nuclear Power Station Units 2 and 3 - 10 CFR 50.46 Report Assessment Notes

Attachment 1 Dresden Nuclear Power Station, Unit 2 10 CFR 50.46 Report (Westinghouse Fuel)

PLANT NAME: Dresden Nuclear Power Station, Unit 2 ECCS EVALUATION MODEL: USA5 REPORT REVISION DATE: 10/26/2012 CURRENT OPERATING CYCLE: 23 ANALYSIS OF RECORD Evaluation Model: "Westinghouse BWR ECCS Evaluation Model:

Supplement 3 to Code Description, Qualification and Application to SVEA-96 Optima2 Fuel," WCAP-16078-P-A, November 2004.

Calculations: "Dresden 2 & 3 LOCA Analysis for SVEA-96 Optima2 Fuel," OPTIMA2-TR021 DR-LOCA, Revision 6, Westinghouse Electric Company, LLC. September 2010.

Fuel Analyzed in Calculation: SVEA-96 Optima2 Limiting Fuel Type: SVEA-96 Optima2 Limiting Single Failure: Low Pressure Coolant Injection system injection valve Limiting Break Size and Location: 1.0 Double-Ended Guillotine Break in the Recirculation Pump Suction Line Reference Peak Cladding Temperature (PCT)

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Attachment 1 Dresden Nuclear Power Station, Unit 2 10 CFR 50.46 Report (Westinghouse Fuel)

MARGIN ALLOCATION A PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated October 30,2009 (See Note 1) L1PCT =2°F 10 CFR 50.46 report dated October 29, 2010 (See Note 2) L1PCT =12°F 10 CFR 50.46 report dated October 28,2011 (See Note 3) L1PCT =18°F Net PCT 2182°F B. CURRENT LOCA MODEL ASSESSMENTS None (see Note 4) L1PCT =OaF Total PCT change from current assessments IL1PCT =OaF Cumulative PCT change from current assessments I IL1PCT I =OaF Net PCT 2182°F Page 2 of 2

Attachment 2 Dresden Nuclear Power Station, Unit 3 10 CFR 50.46 Report (Westinghouse Fuel)

PLANT NAME: Dresden Nuclear Power Station, Unit 3 ECCS EVALUATION MODEL: USA5 REPORT REVISION DATE: 10/26/2012 CURRENT OPERATING CYCLE: 22 ANALYSIS OF RECORD "Westinghouse BWR ECCS Evaluation Model:

Supplement 3 to Code Description, Qualification and Evaluation Model:

Application to SVEA-96 Optima2 Fuel," WCAP-16078-P-A, November 2004.

Calculations: "Dresden 2 & 3 LOCA Analysis for SVEA-96 Optima2 Fuel," OPTIMA2-TR021 DR-LOCA, Revision 6, Westinghouse Electric Company, LLC.

September 2010.

Fuel Analyzed in Calculation: SVEA-960ptima2 Limiting Fuel Type: SVEA-96 Optima2 Limiting Single Failure: Low Pressure Coolant Injection system injection valve Limiting Break Size and Location: 1.0 Double-Ended Guillotine Break in the Recirculation Pump Suction Line Reference Peak Cladding Temperature (PCT)

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Attachment 2 Dresden Nuclear Power Station, Unit 3 10 CFR 50.46 Report (Westinghouse Fuel)

MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated October 30,2009 (See Note 1) ~PCT =2°F 10 CFR 50.46 report dated October 29, 2010 (See Note 2) ~PCT = 12°F 10 CFR 50.46 report dated October 28,2011 (See Note 3) llPCT =18°F Net PCT 2182°F B. CURRENT LOCA MODEL ASSESSMENTS None (See Note 4) ~PCT = O°F Total PCT change from current assessments L~PCT = O°F Cumulative PCT change from current assessments L IllPCT I =O°F Net PCT 2182°F Page 2 of 2

Attachment 3 Dresden Nuclear Power Station, Units 2 and 3 10 CFR 50.46 Report Assessment Notes Assessment Notes

1. Prior Loss of Coolant Accident (LOCA) Model Assessment The referenced letter provided the annual 10 CFR 50.46, "Acceptance criteria for emergency core cooling systems [ECCS] for light-water nuclear power reactors," report for Dresden Nuclear Power Station (DNPS), Units 2 and 3. The letter updated the vessel leakage between the lower shroud and the downcomer. Westinghouse evaluated this change and demonstrated that all 10 CFR 50.46 criteria were satisfied. This evaluation resulted in maximum peak cladding temperature (PCT) impact due to the change in vessel leakage of 2°F for Optima2 fuel with the licensing basis PCT of 2152°F.

This PCT update will remain in effect only until the maximum average planar linear heat generation rate (MAPLHGR) limits for all bundles in future DNPS, Unit 2 and Unit 3 cores are evaluated for this change.

[

Reference:

Letter from Timothy Hanley (SVPLTR: #09-0052, Exelon Generation Company, LLC (EGC)) to NRC, "Plant Specific ECCS Evaluation Changes - 10 CFR 50.46 Report," dated October 30,2009.]

2. Prior LOCA Model Assessment The referenced letter provided the annual 10 CFR 50.46 report for DNPS Units 2 and 3.

The letter reported the replacement of core spray lower sectional piping in DNPS, Unit 2 during DNPS, Unit 2 Refueling Outage No. 21. Westinghouse evaluated the core spray leakage due to this modification and concluded that the PCT impact was O°F. The letter also identified a change in input for modeling bypass hole flow coefficient in the Westinghouse LOCA analysis. The impact on PCT due to this change was determined by Westinghouse to be 12°F. Westinghouse established a MAPLHGR limit for the fresh bundles to accommodate the change. For 10 CFR 50.46 reporting purposes, the PCT impact is conservatively applied to all bundle types in the core including the fresh bundles. This PCT update will remain in effect only until the MAPLHGR limits for all bundles in future DNPS, Unit 2 and Unit 3 cores are evaluated for the change in bypass hole flow coefficient.

[

Reference:

Letter from Jeffrey Hansen (RS-1 0-191, EGG) to NRC, "Plant Specific ECCS Evaluation Changes -10 CFR 50.46 Report," dated October 29,2010.]

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Attachment 3 Dresden Nuclear Power Station, Units 2 and 3 10 CFR 50.46 Report Assessment Notes

3. Prior LOCA Model Assessment The referenced letter provided the annual 10 CFR 50.46 report for DNPS, Units 2 and 3.

The letter reported errors in the current Westinghouse Dresden LOCA analysis associated with the use of incorrect R-factors. The impact due to this change was determined to be 18°F in PCT update. For 10 CFR 50.46 reporting purposes, the PCT update is conservatively applied to all bundle types including the fresh bundles. This PCT update will remain in effect only until the MAPLHGR limits for all bundles in future DNPS, Unit 2 and Unit 3 cores are evaluated with the correct R-factors.

[

Reference:

Letter from David M. Gullott (RS-11-171, EGC) to NRC, "Plant Specific ECCS Evaluation Changes - 10 CFR 50.46 Report," dated October 28, 2011.]

4. Current LOCA Model Assessment No new changes, error corrections, or enhancements have been report for the current DNPS LOCA analysis. No ECCS-related changes or modifications have occurred at DNPS that affect the assumptions in the DNPS LOCA analysis of record. The Analysis of Record was updated to Revision 6, but did not result in a change to the analysis results previously reported.

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