RS-04-170, Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors

Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors

ML043200162
Person / Time
Site:	Clinton
Issue date:	11/05/2004
From:	Simpson P AmerGen Energy Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-04-170
Download: ML043200162 (5)

Text

AmerGen Energy Company, LLC www.exeloncorp.com AmerGen An Exelon Company SM 4300 Winfield Road Warrenville, IL 60555 RS-04-170 November 5, 2004 10 CFR 50.46 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461

Subject:

Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Clinton Power Station In accordance with 10 CFR 50.46, "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors," paragraph (a)(3)(ii), AmerGen Energy Company (AmerGen), LLC is submitting the annual report of the Emergency Core Cooling System (ECCS) Evaluation Model changes and errors for Clinton Power Station (CPS), Unit 1. This report covers the period from November 6, 2003 through November 5, 2004.

Should you have any questions concerning this letter, please contact Mr. Timothy A. Byam at (630) 657-2804.

Respectfully, Patrick R. Simpson Manager - Licensing Attachments:

1. 10 CFR 50.46 Report

2. 10 CFR 50.46 Report Assessment Notes cc: Regional Administrator - NRC Region IlIl NRC Senior Resident Inspector - Clinton Power Station froI-- C

Attachment I Clinton Power Station Unit I 10 CFR 50.46 Report Page 1 of 2 PLANT NAME: Clinton Power Station, Unit 1 ECCS EVALUATION MODEL: SAFER/GESTR - LOCA REPORT REVISION DATE: 11/05/04 CURRENT OPERATING CYCLE: 10 ANALYSIS OF RECORD Evaluation Model Methodology: The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-of-Coolant Accident; Volume l1l, SAFER/GESTR Application Methodology, NEDC-23785-1-PA, Revision 1, General Electric Company, October 1984.

Calculation: Clinton Power Station, SAFER/GESTR-LOCA Analysis Basis Documentation, NEDC-32974P, GE Nuclear Energy, October 2000.

Fuel: GE 10 and GE 14 Limiting Fuel: GE 14 Limiting Single Failure: High Pressure Core Spray (HPCS) Diesel Generator Limiting Break Size and Location: 1.0 Double Ended Guillotine of Recirculation Pump Suction Piping Reference Peak Cladding Temperature (PCT): 1550°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated November 13, 2000 (See Note 1) APCT = 00F 10 CFR 50.46 report dated November 08, 2001 (See Note 2) APCT = 50F 10 CFR 50.46 report dated November 05, 2002 (See Note 3) APCT = 350 F 10 CFR 50.46 report dated November 05, 2003 (See Note 4) APCT = 50F Net PCT 15950F

Attachment I Clinton Power Station Unit I 10 CFR 50.46 Report Page 2 of 2 B. CURRENT LOCA MODEL ASSESSMENTS GE LOCA Model Change due to New Heat Source (See Note 5) APCT = 00 F Reload and Equipment Out of Service Assessment (See Note 6) D APCT = 00F Net PCT 15950 F

Attachment 2 Clinton Power Station Unit I 10 CFR 50.46 Report Assessment Notes Page 1 of 2 NOTES:

1. Prior LOCA Model Assessments The referenced letter reported a new analysis of record for Clinton Power Station.

[

Reference:

Letter from M. A. Reandeau (AmerGen Energy Company) to U.S.

NRC, "Report of a Change to the ECCS Evaluation Model Used for Clinton Power Station (CPS)," November 13, 2000.]

2. Prior LOCA Model Assessments An inconsistent core exit steam flow was used in the pressure calculation in the SAFER code when there is a change in the two-phase level. The incorrect calculated pressure may result in premature termination of ECCS condensation and will impact the second PCT. GE evaluated the impact of this error and determined that the impact is an increase of 5YF in the PCT. This error was reported to the NRC in the referenced letter.

[

Reference:

Letter from K. A. Ainger (Exelon Generation Company) to U.S. NRC, "Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Clinton Power Station," November 8, 2001.]

3. Prior LOCA Model Assessments In the referenced letter to the NRC, the impact of the Low Pressure Coolant Injection (LPCI) and Low Pressure Core Spray (LPCS) minimum flow valve flow diversion was reported and was found to have a 00F impact. Also in the referenced letter GE LOCA errors were reported all of which had a 00F PCT increase except for the SAFER Core Spray sparger injection elevation error that resulted in a 150F increase in the PCT. The Extended Power Uprate (EPU) has resulted in an increase of 20'F in the PCT. The EPU was implemented in Cycle 9 Reload.

[

Reference:

Letter from Patrick R. Simpson (Exelon Generation Company) to U.S. NRC, "Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Clinton Power Station," November 5, 2002.]

4. Prior LOCA Assessment In the referenced letter to the NRC, the impact of an error found in the initial level/volume table for SAFER was reported. This resulted in an incorrect volume split in the nodes above and below the water surface, and incorrect initial liquid mass. This error resulted in a 5VF increase in the PCT for all fuel types (i.e., GE 10 & GE14).

[

Reference:

Letter from Patrick R. Simpson (Exelon Generation Company) to U.S. NRC, "Annual Report of Emergency Core Cooling System Evaluation Model Changes and Errors for Clinton Power Station," November 5, 2003.3

Attachment 2 Clinton Power Station Unit i 10 CFR 50.46 Report Assessment Notes Page 2 of 2

5. Current LOCA Model Assessment GE has postulated a new heat source applicable to the LOCA event. This heat source is due to recombination of hydrogen and excess oxygen drawn into the vessel from containment during core heatup. The oxygen enters the vessel either as a dissolved gas in the ECCS water or through the break when the vessel fully depressurizes and draws the containment non-condensable gases back into the vessel. The current LOCA evaluation model does not account for the effect of this heat source, which has potential to raise the steam temperature while leading to an increase in PCT and local oxidation.

GE has evaluated the effect of this additional heat source for the jet pump plants like CPS and determined that the impact is insignificant. This is because of the fact that oxygen from containment enters the vessel after the core is reflooded for the jet pump plants. Therefore, the PCT impact for all fuel types is zero and the effect on local oxidation is negligible.

[

Reference:

GE Letter 2003-05, "10 CFR 50.46 Notification Letter," dated May 13, 2004.]

6. Current LOCA Model Assessment For Reload 9, 312 new GE14 fuel bundles were introduced into the CPS Unit 1 Cycle 10 Core. GE evaluated this change and determined that the impact on the licensing basis PCT is 00 F (Reference 1). Evaluation was also performed to support several equipment out-of-service options and this evaluation is documented in Reference 2. GE determined that the LOCA analyses are not impacted by these options.

[

References:

(1) Supplemental Reload Licensing Report for Clinton Power Station, Unit 1, Reload 9 Cycle 10, 0000-0016-5277 SRLR, Revision 0, December 2003.

(2) Evaluation of Operation With Equipment Out-of-Service for the Clinton Power Station, GE-NE-0000-0026-1857-Rl, June 2004.]