ML043420075

CFR 50.46 Annual Report

ML043420075
Person / Time
Site:	Limerick
Issue date:	12/03/2004
From:	Gallagher M Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML043420075 (12)

Text

Exelon Nuclear www.exeloncorp.com

,Nuclear 2 0 0 Exelon Way Kennett Square, PA 19348 1 OCFR50.46 December 3,2004 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353

Reference:

10 CFR 50.46 Annual Report

1. Letter from Michael P. Gallagher (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, 1 0 CFR 50.46 Reporting Requirements, dated December 16, 2003

2. GE Letter, 10 CFR 50.46 Notification Letter, 2003-05, May 13, 2004 The purpose of this letter is to submit the 10 CFR 50.46 reporting information for Limerick Generating Station (LGS), Units 1 and 2. The most recent annual 50.46 Report for Limerick Generating Station, Units 1 and 2 (Reference 1) provided the cumulative Peak Cladding Temperature (PCT) errors for the most recent fuel designs through December 16, 2003.

However, this letter did not report all vendor 50.46 notifications to date that resulted in zero (0°F)

PCT impact. These 50.46 notifications are now reported. In addition, GE reported that a new heat source term has been postulated (Reference 2). This heat source involves the recombination of hydrogen and oxygen within the fuel bundle during the core heatup. The additional heat will raise the temperature of the steam heat sink in the bundle, resulting in a potential increase in the peak cladding temperature and local oxidation. The current Loss-of-Coolant Accident (LOCA) evaluation models do not include this new heat source.

Two attachments are included with this letter that provide the current Limerick Generating Station, Units 1 and 2, 10 CFR 50.46 status. Attachments 1 and 2 (Peak Cladding Temperature Rack-Up Sheet) provide updated information regarding the PCT for the limiting

10 CFR 50.46 Annual Report, LGS U1&2 December 3,2004 Page 2 Large Break Loss of Coolant Accident (LOCA) analysis evaluations for Limerick Generating Station, Units 1 and 2, respectively. Attachment 3, Assessment Notes, contains a detailed description for each change or error reported.

If you have any questions, please contact Tom Loomis at 61 0-765-551 0.

Respectfully, Michael P. Gallagher Director, Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments: 1) Peak Cladding Temperature Rack-Up Sheet Limerick Generating Station, Unit 1

2) Peak Cladding Temperature Rack-Up Sheet Limerick Generating Station, Unit 2

3) Assessment Notes cc:

S. J. Collins, USNRC Administrator, Region I T. Tate, USNRC Project Manager, LGS S. Hansell, USNRC Senior Resident Inspector, LGS

ATTACHMENT 1 10 CFR 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of November 4,2004 Peak Cladding Temperature Rack-Up Sheet Limerick Generating Station, Unit 1

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of November 4,2004 Peak Cladding Temperature Rack-Up Sheet, LGS U1 Page 1 of 2 PLANT NAME:

ECCS EVALUATION MODEL:

REPORT REVISION DATE:

Limerick Generatinq Station, Unit 1 SAFERIGESTR-LOCA 11/04/04 11 CURRENT OPERATING CYCLE:

ANALYSIS OF RECORD Evaluation Model:

1. NEDC-23785-1 -PA, Rev. 1, The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume 11, SAFER - Long Term Inventory Model for BW R Loss-Of-Coolant Analysis, October 1 984.

2. NEDC-30996P-A, SAFER Model for Evaluation of Loss-of-Coolant Accidents for Jet Pump and Non-jet Pump Plants, Volume I, SAFER - Long Term Inventory Model for BW R Loss-of-Coolant Analysis, October 1987.

3. NEDC-32950P, Compilation of Improvements to GENES SAFER ECCS-LOCA Evaluation Model, January 2000.

4. NEDC-23785-1-PA, Rev. 1, The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume Ill, SAFEWGESTR Application Methodology, October 1984.

(Jet Pump Plant - SAFER)

Calculations:

1. Limerick Generating Station, Units 1 and 2 SAFEWGESTR-LOCA Loss-of-Coolant Accident Analysis, NEDC-3217OP, May 1995.

2. Limerick Generating Station Units 1 and 2 ECCS-LOCA Evaluation for GE14, GE-NE-J1103793-09-01 P, March 2001.

3. Letter from C. P. Bott to R. M. Butrovich, Limerick Units 1 and 2 SAFEWGESTR Analysis with GE13 Fuel, July 20, 1995.

Fuel Analyzed in Calculations: P8x8R, GE9, GE11/13 and GE14 Limiting Fuel Type: GE14 (note: P8x8R and GE9 are no longer in operation and are not considered for defining the limiting fuel type)

Limiting Single Failure: Div 2 DC Power Source Limiting Break Size and Location: Double-Ended Guillotine in a Recirculation Suction Pipe Reference Peak Cladding Temperature (PCT) - GE11/13 Reference Peak Cladding Temperature (PCT) - GE14 PCT = 1605°F PCT = 1670°F

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of November 4,2004 Peak Cladding Temperature Rack-Up Sheet, LGS U1 10 CFR 50.46 Report dated December 16,1996 (See Note 1)

(GE11/13 only) 10 CFR 50.46 Report dated November 4,1998 (See Note 2) (GE11/13 Page 2 of 2 GE11/13 APCT = 45°F GE11/13 APCT = -5°F MARGIN ALLOCATION only) 10 CFR 50.46 Report dated July 22, 1999 (See Note 3) (GEl1/13 only)

(GE11/13 only) 10 CFR 50.46 Report dated June 4,2001 (See Note 5) (GEll/l3 only) 10 CFR 50.46 Report dated December 18,2000 (See Note 4) 10 CFR 50.46 ReDort dated December 18,2002 (See Note 6)

A.

PRIOR LOCA MODEL ASSESSMENTS GEll/l3 APCT = 0°F GEll/l3 APCT = -5°F GEll/l3 APCT = 5°F GE11/13 APCT = -5°F 10 CFR 50.46 Report dated December 16,2003 (See Note 7)

GE14 APCT = 10°F GE11/13 APCT = -5°F Net PCT (GE11113)

Net PCT (GE14)

GE14 APCT = -5°F I

1635 OF 1675 O F GE LOCA Model Change due to GESTR File Interpolation Error (See Note 8) (GEI 1/13 only)

GE LOCA Model Change due to SAFER Computer Platform Change (See Note 9) (GE11/13 only)

GE LOCA Model Change due to WEVOL S1 Volume Error (See Note

10)

GE LOCA Model Change due to SAFER Separator Pressure Drop (See Note 11)

GE LOCA Model Change due to New Heat Source (See Note 12)

Total PCT change from current assessments (GEI 1/13)

Total PCT change from current assessments (GE14)

Cumulative PCT change from current assessments (GEI 1/13)

Cumulative PCT change from current assessments (GE14)

Net PCT (GE11/13)

GE11/13 APCT = 0°F GEll/l3 APCT = 0°F GEI 1/13 APCT = 0°F GEll/l3 APCT = 0°F GE14 APCT = 0°F GEI 1/13 APCT = 0°F GE14 APCT = 0°F GE14 APCT = 0°F D P C T = 0°F CAPCT = 0°F c I APCTI = OOF c I APCT I = OOF 1635 "F

ATTACHMENT 2 10 CFR 50.46 Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of November 4,2004 Peak Cladding Temperature Rack-Up Sheet Limerick Generating Station, Unit 2

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of November 4,2004 Peak Cladding Temperature Rack-Up Sheet, LGS U2 Page 1 of 2 PLANT NAME:

REPORT REVISION DATE:

1 1/04/04 Limerick Generatinq Station, Unit 2 ECCS EVALUATION MODEL:

SAFEWGESTR-LOCA 08 CURRENT OPERATING CYCLE:

ANALYSIS OF RECORD Evaluation Model:

1. NEDC-23785-1 -PA, Rev. 1, The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume 11, SAFER - Long Term Inventory Model for BW R Loss-Of-Coolant Analysis, October 1 984.

2. NEDC-30996P-A, SAFER Model for Evaluation of Loss-of-Coolant Accidents for Jet Pump and Non-jet Pump Plants, Volume I, SAFER - Long Term Inventory Model for BW R Loss-of-Coolant Analysis, October 1987.

3. NEDC-32950P, Compilation of Improvements to GENES SAFER ECCS-LOCA Evaluation Model, January 2000.

4. NEDC-23785-1-PA, Rev. 1, The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume Ill, SAFEWGESTR Application Methodology, October 1984.

(Jet Pump Plant - SAFER)

Calculations:

1. Limerick Generating Station, Units 1 and 2 SAFEWGESTR-LOCA Loss-of-Coolant Accident Analysis, NEDC-3217OP, May 1995.

2. Limerick Generating Station Units 1 and 2 ECCS-LOCA Evaluation for GEl4, GE-NE-J1103793-09-01 P, March 2001.

3. Letter from C. P. Bott to R. M. Butrovich, Limerick Units 1 and 2 SAFEWGESTR Analysis with GE13 Fuel, July 20, 1995.

Fuel Analyzed in Calculations: P8x8R, GE9, GEl 1/13 and GE14 Limiting Fuel Type: GE14 (note: P8x8R and GE9 are no longer in operation and are not considered for defining the limiting fuel type)

Limiting Single Failure: Div 2 DC Power Source Limiting Break Size and Location: Double-Ended Guillotine in a Recirculation Suction Pipe Reference Peak Cladding Temperature (PCT) - GE11/13 Reference Peak Cladding Temperature (PCT) - GE14 PCT = 1605°F PCT = 1670°F

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of November 4,2004 Peak Cladding Temperature Rack-Up Sheet, LGS U2 (GEll/l3 only) 10 CFR 50.46 Report dated November 4, 1998 (See Note 2) (GE11/13 Page 2 of 2 GE11/13 APCT = -5°F MARGIN ALLOCATION only) 10 CFR 50.46 Report dated July 22, 1999 (See Note 3) (GE11/13 only)

(GE11/13 only) 10 CFR 50.46 Report dated June 4,2001 (See Note 5) (GE11/13 only) 10 CFR 50.46 Report dated December 18,2000 (See Note 4) 10 CFR 50.46 Report dated December 18,2002 (See Note 6) 10 CFR 50.46 Report dated December 16,2003 (See Note 7)

A.

PRIOR LOCA MODEL ASSESSMENTS GEl1/13 APCT = 0°F GE11/13 APCT = -5°F GE11/13 APCT = 5°F GE11/13 APCT = -5°F GE14 APCT = 10°F GE11/13 APCT = -5°F GE14 APCT = -5°F I 10 CFR 50.46 Report dated December 16, 1996 (See Note 1)

I G E l l / l 3 APCT = 45°F I Net PCT (GEI 1/13)

Net PCT (GE14) 1635 "F 1675 O F (See Note 9) (GE11/13 only)

GE LOCA Model Change due to WEVOL S1 Volume Error (See Note GE11/13 APCT = 0°F B.

CURRENT LOCA MODEL ASSESSMENTS

10)

GE LOCA Model Change due to SAFER Separator Pressure Drop (See Note 11)

GE LOCA Model Change due to New Heat Source (See Note 12)

I GE LOCA Model Change due to GESTR File Interpolation Error (See I GE11/13 APCT = 0°F GE14 APCT = 0°F GE14 APCT = 0°F G E l l / l 3 APCT = 0°F GE14 APCT = 0°F GE11/13 APCT = 0°F Note 8) (GE11/13 only)

I GE LOCA Model Change due to SAFER Computer Platform Change I GE11/13 APCT = 0°F Total PCT change from current assessments (GE11/13)

Total PCT change from current assessments (GE14)

Cumulative PCT change from current assessments (GEll/l3)

Cumulative PCT change from current assessments (GE14)

CAPCT = 0°F CAPCT = 0°F c I APCT I = OOF c I APCT 1 = OOF Net PCT (GEllA3)

Net PCT (GEI 4) 1635 "F 1675 O F 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessment Notes

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments Notes Page 1 of 3

1.

Prior LOCA Assessment The referenced letter provided the total accumulation of peak clad temperature (PCT) changes or errors determined since the original 1995 SAFER analysis for Limerick Generating Station, Units 1 and 2. This letter reported that since 1988, GE had been compiling changes and errors and provided that information to the NRC and licensees on an annual basis. The PCT impact for these errors for GE11/13 fuel was determined to be 45OF.

[

Reference:

Letter from G. A. Hunger (PECO Nuclear) to U.S. NRC, Limerick Generating Station, Units 1 and 2 10 CFR 50.46 Reporting Requirements, dated December 16, 1996.1

2.

Prior LOCA Assessment The referenced letter provided clarification of the previous Limerick 50.46 report (see Note 1). This letter reported the previous GE LOCA errors to be related to SAFER omission of the bottom head drain and incorrect number of fuel rods error. This letter also reported that one of the errors contributing to the reported 45OF PCT impact in the previous Limerick Generating Station, Units 1 and 2 50.46 report (see Note 1) was actually corrected in the base analysis and identified a correction of -5OF PCT. This letter constituted a 30 day report. The PCT impact for the correction for GEl 1/13 fuel was determined to be -5 F.

[

Reference:

Letter from G. D. Edwards (PECO Nuclear) to U.S. NRC, Limerick Generating Station, Units 1 and 2 10 CFR 50.46 Reporting Requirements, dated November 4, 1998.1

3.

Prior LOCA Assessment The referenced letter reported a GE LOCA error related to SAFER CCFL at the upper spacer. This error was reported to be not applicable to GE11 and later fuel types. This letter constituted a 30 day report. The PCT impact for the new error for GEl1/13 fuel was determined to be O°F.

[

Reference:

Letter from J. A. Hutton (PECO Nuclear) to U.S. NRC, Limerick Generating Station, Units 1 and 2 - Peach Bottom Atomic Power Station, Units 2 and 3 10 CFR 50.46 Reporting Requirements, dated July 22, 1999.1

4.

Prior LOCA Assessment The referenced letter reported a GE LOCA error related to SAFER time steps. The PCT impact for the new error was determined to be -5OF for GE11/13 fuel.

[

Reference:

Letter from J. A. Hutton (PECO Nuclear) to U.S. NRC, Limerick Generating Station, Units 1 and 2 Peach Bottom Atomic Power Station, Units 2 and 3 10 CFR 50.46 Reporting Requirements, dated December 18, 2000.1

5.

Prior LOCA Assessment The referenced letter reported the introduction of GE14 fuel at Limerick and the associated GE14 baseline PCT. The GE14 PCT (1 67OoF) bounds the GE11/13 fuel.

The referenced letter also reported a GE LOCA error related to a SAFER pressure rate

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments Notes Page 2 of 3 error. The PCT impact for this new error was determined to be 5OF. This PCT error applied only to the GE11/13 fuel types. This letter constituted a 30 day report. The total PCT impact of this error on GEll/l3 fuel was determined to be 5OF.

[

Reference:

Letter from J. A. Hutton (PECO Nuclear) to US. NRC, Limerick Generating Station, Units 1 and 2 10 CFR 50.46 Reporting Requirements, dated June 4, 2001.]

6.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Limerick Generating Station, Units 1 and 2. This letter reported GE LOCA errors related to a SAFER core spray sparger elevation error and a SAFER bulk water level error. The PCT impact for the new errors was determined to be O°F and -5OF, respectively, for GE11/13 fuel and 15OF and -5OF, respectively, for GE14 fuel. The total PCT impact of these errors was determined to be -5OF for GE11/13 fuel and 1 O°F for GE14 fuel. The GE14 PCT continues to bound the GE11/13 PCT.

[

Reference:

Letter from Michael P. Gallagher (Exelon Generation Company, LLC) to U.S. NRC, 1 0 CFR 50.46 Reporting Requirements, dated December 18, 2002.1

7.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Limerick Generating Station, Units 1 and 2. This letter reported a GE LOCA error related to a SAFER LevelNolume Table error. The PCT impact for the new error was determined to be -5OF for both GE11/13 fuel and GE14 fuel. The GE14 PCT continues to bound the GE11/13 PCT.

[

Reference:

Letter from Michael P. Gallagher (Exelon Exelon Generation Company, LLC) to U.S. NRC, 1 0 CFR 50.46 Reporting Requirements, dated December 16, 2003.1

a.

Current LOCA Assessment GE reported a GESTR Input File Interpolation Error. This results in an error in the initial gap conductance for cases at or beyond the knee in the LHGR curve. Due to this error, the initial gap conductance used in the SAFER calculations was slightly lower than it should have been. GE determined the PCT impact of this error to be negligible for GE11/13 fuel and not applicable to GE14 fuel.

[

Reference:

GE 10 CFR 50.46 Notification Letter, 2002-03, August 26, 2002.1

9.

Current LOCA Assessment GE reported that the LOCA evaluation code SAFER04 has been migrated from the VAX computer platform (SAFER04V) to the Alpha computer platform (SAFER04A). The change in computer platform may result in a change in the calculated peak cladding temperature (PCT) due to changes in the processor word size and FORTRAN compiler characteristics. GE determined that the PCT impact of this error to be negligible for GE11/13 fuel and not applicable to GE14 fuel.

[

Reference:

GE 10 CFR 50.46 Notification Letter, 2002-04, August 26, 2002.1

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments Notes Page 3 of 3

10.

Current LOCA Assessment GE reported that an error was found in the WEVOL code, which affects the calculated vessel volume in the downcomer region. The free volume in the region of the shroud head is calculated incorrectly. The code did not properly account for the volume of the standpipes inside the shroud head thickness. This resulted in the value for the free volume in the downcomer being too small by 4-1 0 ft3. GE determined that the PCT impact of this error to be negligible for GEll/l3 fuel and GE14 fuel.

[

Reference:

GE 10 CFR 50.46 Notification Letter, 2002-05, August 26, 2002.1

11.

Current LOCA Assessment GE reported that an error was found in the SAFER Initial Separator Pressure Drop due to an error in the specified separator loss coefficient. GE determined that the PCT impact of this error to be negligible for GE11/13 fuel and GE14 fuel.

[

Reference:

GE 10 CFR 50.46 Notification Letter, 2003-03, May 6, 2003.1

12.

Current LOCA Assessment GE has postulated a new heat source applicable to 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-condensible 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 similar to Limerick Generating Station, Units 1 and 2 and determined that the impact is insignificant, because the 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 10 CR 50.46 Notification Letter, 2003-05, May 13, 2004.1