ML12349A295

10 CFR 50.46 30-Day Report

ML12349A295
Person / Time
Site:	Limerick   (NPF-039, NPF-085)
Issue date:	12/12/2012
From:	Jesse M Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML12349A295 (12)

Text

December 12, 2012 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 Subject 10 CFR 50.46 30-Day Report 10 CFR 50.46

References:

1) Letter from Michael D. Jesse (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report,"

dated November 9, 2012

2) Letter from GE Hitachi Nuclear Energy (GEH) to Exelon Generation Company, LLC, "1 0 CFR 50.46 Notification Letter 2012-01, Limerick Generating Station (Unit 1 & 2)," dated November 29, 2012 The purpose of this letter is to submit a 30-day 1 0 CFR 50.46 report for Limerick Generating Station (LGS), Units 1 and 2. The most recent annual 50.46 Report for LGS, Units 1 and 2, (Reference 1) provided the cumulative Peak Cladding Temperature (PCT) errors.

Subsequent to the issuance of Reference 1, GE Hitachi Nuclear Energy (GEH) notified Exelon Generation Company, LLC, (Exelon) of a change to GEH ECCS-LOCA analysis methodology. To address inaccuracies in fuel pellet thermal conductivity as a function of exposure, commonly referred to as thermal conductivity degradation (TCD), GEH replaced the GESTR-LOCA model with a newer model, PRIME. The most dominant effect impacting PCT is from the way the PRIME fuel properties treat thermal conductivity, which results in a higher fuel stored energy. The PCT impact identified in the notification reflects the difference between the existing GESTR analysis PCT and a conservatively postulated PCT if the analysis were performed with the PRIME model. The ECCS-LOCA analysis methodology remains GESTR based and will not be PRIME based until the ECCS-LOCA analysis is re-performed using PRIME.

The total impact of the error reported by GEH increases the calculated peak clad temperature as shown in the attachments. This updated peak clad temperature remains within the 10 CFR 50.46 acceptance criterion of 2200°F with >200°F available margin. All 10 CFR 50.46(b) criteria remain satisfied in the same manner as the analysis of record. The PCT, local oxidation, and core-wide oxidation criteria also meet the requirements to maintain a coolable geometry and supply long-term cooling. Accordingly, no reanalysis will be performed.

U.S. Nuclear Regulatory Commission Limerick Generating Station, Units 1 and 2 1 0 CFR 50.46 Annual Report December 12, 2012 Page 2 As discussed in 10 CFR 50.46(a)(3)(i), this 30-day report is required because the absolute magnitude of the temperature change is greater than 50°F.

Three attachments are included with this letter that provide the LGS, 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 LOCA analysis evaluations for LGS, 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 610-765-5510.

Michael D. Jesse, Director-Licensing crhd 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 (Limerick Generating Station, Units 1 and 2) cc:

USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, LGS USNRC Project Manager, LGS R. R. Janati, Bureau of Radiation Protection

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 December 12, 2012 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 December 12, 2012 Peak Cladding Temperature Rack-Up Sheet, LGS U1 PLANT NAME:

ECCS EVALUATION MODEL:

REPORT REVISION DATE:

CURRENT OPERATING CYCLE:

ANALYSIS OF RECORD Evaluation Model:

Limerick Unit 1 SAFER/GESTR-LOCA 12/12/12 15 Page 1 of 2

1. NEDC-23785-1-PA Rev. 1, "The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume II, SAFER-Long Term Inventory Model for BWR Loss-Of-Coolant Analysis," October 1984.

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 BWR Loss-of-Coolant Analysis," October 1987.

3. NEDC-32950P, "Compilation of Improvements to GENE's 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, SAFER/GESTR Application Methodology,"

October 1984. (Jet Pump Plant-SAFER)

Calculations:

1...Limerick Generating Station, Units 1 and 2 SAFER/GESTR-LOCA Loss-of-Coolant Accident Analysis," NEDC-32170P, Rev. 2, May 1995.

2... Limerick Generating Station Units 1 and 2 ECCS-LOCA Evaluation for GE14,..

GE-NE-J1103793-09-01 P, March 2001.

3. "Limerick Generating Station Units 1 and 2 GNF2 ECCS-LOCA Evaluation,"

0000-0111-9078-RO, February 2011 Fuels Analyzed in Calculations and in Operation: GE14 and GNF2 Limiting Fuel Type: GNF2 Limiting Single Failure (GE14/GNF2): Battery Failure Limiting Break Size and Location (GE14/GNF2): Double-Ended Guillotine in a Recirculation Suction Pipe Reference Peak Cladding Temperature (PCT)- GE14: 1670°F Reference Peak Cladding Temperature (PCT)- GNF2: 1880°F

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of December 12, 2012 Peak Cladding Temperature Rack-Up Sheet, LGS U1 MARGIN ALLOCATION A.

PRIOR LOCA MODEL ASSESSMENTS 1 0 CFR 50.46 Report dated December 18, 2002 (See Note 1) 1 0 CFR 50.46 Report dated December 16, 2003 (See Note 2) 1 0 CFR 50.46 Report dated December 3, 2004 (See Note 3) 10 CFR 50.46 Report dated December 1, 2005 (See Note 4) 1 o CFR 50.46 Report dated December 1, 2006 (See Note 5) 10 CFR 50.46 Report dated November 30, 2007 (See Note 6) 1 0 CFR 50.46 Report dated November 24, 2008 (See Note 7) 1 0 CFR 50.46 Report dated November 24, 2009 (See Note 8) 1 0 CFR 50.46 Report dated November 24, 201 0 (See Note 9) 1 0 CFR 50.46 Report dated November 23, 2011 (See Note 1 0) 1 0 CFR 50.46 Report dated November 9, 2012 (See Note 11)

Net PCT {GE14)

Net PCT {GNF2)

B.

CURRENT LOCA MODEL ASSESSMENTS Impact of PRIME Implementation (See Note 12)

Total PCT change from current assessments (GE14)

Total PCT change from current assessments (GNF2)

Cumulative PCT change from current assessments (GE14)

Cumulative PCT change from current assessments (GNF2)

Net PCT lGE14}

Net PCT lGNF2}

Page 2 of 2 GE14 ~PCT = 10°F GE14 ~PCT = -5°F GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = 50°F GNF2 ~PCT = 50°F GE14 ~PCT = ooF GNF2 ~PCT = ooF 1725°F 1930°F GE14 ~PCT = 65°F GNF2 ~PCT = 45°F

L~PCT = 65°F

L~PCT = 45°F

L I ~PCT I = 65°F

L I~PCTI =45°F 1790°F 1975°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 December 12,2012 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 December 12, 2012 Peak Cladding Temperature Rack-Up Sheet, LGS U2 PLANT NAME:

ECCS EVALUATION MODEL:

REPORT REVISION DATE:

CURRENT OPERATING CYCLE:

ANAL VSIS OF RECORD Evaluation Model:

Limerick Unit 2 SAFER/GESTR-LOCA 12/12/12 12 Page 1 of 2

1. NEDC-23785-1-PA Rev. 1, The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume II, SAFER-Long Term Inventory Model for BWR Loss-Of-Coolant Analysis," October 1984.

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 BWR Loss-of-Coolant Analysis," October 1987.

3. NEDC-32950P, "Compilation of Improvements to GENE's 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, SAFER/GESTR Application Methodology,"

October 1984. (Jet Pump Plant-SAFER)

Calculations:

1. "Limerick Generating Station, Units 1 and 2 SAFER/GESTR-LOCA Loss-of-Coolant Accident Analysis," NEDC-32170P, Rev. 2, May 1995.

2... Limerick Generating Station Units 1 and 2 ECCS-LOCA Evaluation for GE14,..

GE-NE-J11 03793-09-01 P, March 2001.

3. "Limerick Generating Station Units 1 and 2 GNF2 ECCS-LOCA Evaluation,"

0000-0111-9078-RO, February 2011.

Fuels Analyzed in Calculations and in Operation: GE14 and GNF2 Limiting Fuel Type: GNF2 Limiting Single Failure (GE14/GNF2): Battery Failure Limiting Break Size and Location (GE14/GNF2): Double-Ended Guillotine in a Recirculation Suction Pipe Reference Peak Cladding Temperature (PCT)- GE14: 1670°F Reference Peak Cladding Temperature (PCT)- GNF2: 1880°F

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of December 12, 2012 Peak Cladding Temperature Rack-Up Sheet, LGS U2 MARGIN ALLOCATION A.

PRIOR LOCA MODEL ASSESSMENTS 1 0 CFR 50.46 Report dated December 18, 2002 (See Note 1) 1 0 CFR 50.46 Report dated December 16, 2003 (See Note 2) 1 0 CFR 50.46 Report dated December 3, 2004 (See Note 3) 10 CFR 50.46 Report dated December 1, 2005 (See Note 4) 1 0 CFR 50.46 Report dated December 1, 2006 (See Note 5) 1 0 CFR 50.46 Report dated November 30, 2007 (See Note 6) 10 CFR 50.46 Report dated November 24, 2008 (See Note 7) 1 0 CFR 50.46 Report dated November 24, 2009 (See Note 8) 10 CFR 50.46 Report dated November 24, 2010 (See Note 9) 1 0 CFR 50.46 Report dated November 23, 2011 (See Note 1 0) 1 0 CFR 50.46 Report dated November 9, 2012 (See Note 11)

Net PCT {GE14}

Net PCT {GNF2}

B.

CURRENT LOCA MODEL ASSESSMENTS Impact of PRIME Implementation (See Note 12)

Total PCT change from current assessments (GE14)

Total PCT change from current assessments (GNF2)

Cumulative PCT change from current assessments (GE14)

Cumulative PCT change from current assessments (GNF2)

Net PCT CGE14l Net PCT CGNF2l Page 2 of 2 GE14 ~PCT = 10°F GE14 ~PCT = -5°F GE14 ~PCT = ooF GE14 ~PCT = 0°F GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = ooF GE14 ~PCT = 50°F GNF2 ~PCT = 50°F GE14 ~PCT = 0°F GNF2 ~PCT = ooF 1725°F 1930°F GE14 ~PCT = 65°F GNF2 ~PCT = 45°F I~PCT = 65°F I~PCT = 45°F L I~PCTI =65°F L I ~PCT I = 45°F 1790°F 1975°F

ATTACHMENT 3 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 Limerick Generating Station, Units 1 and 2

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of December 12, 2012 Assessment Notes LGS, U1 and U2

1.

Prior LOCA Assessment Page 1 of 3 The referenced letter provided an annual 50.46 report for 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 15°F and -5°F, respectively, for GE14 fuel. The total PCT impact of these errors was determined to be 10°F for GE14 fuel.

[

Reference:

Letter from Michael P. Gallagher (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Reporting Requirements," dated December 18, 2002.]

2.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. This letter reported aGE LOCA error related to a SAFER LeveiNolume Table error. The PCT impact for the new error was determined to be -5°F for GE14 fuel.

[

Reference:

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.]

3.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. This letter reported GE LOCA errors related to a GESTR file interpolation error, a SAFER computer platform change, a WEVOL S1 volume error, a SAFER separator pressure drop error and a new heat source. The PCT impact for the new errors was determined to be ooF for each error. The total PCT impact of these errors on GE14 fuel was determined to be 0°F.

[

Reference:

Letter from Michael P. Gallagher (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated December 3, 2004.]

4.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. There were no errors reported for the 2005 reporting period.

[

Reference:

Letter from Pamela B. Cowan (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated December 1, 2005.]

5.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. This letter reported a newly discovered sensitivity to the assumed axial power shape for small break LOCA cases. This sensitivity may result in higher calculated PCT values for top-peaked axial power shapes. Due to this sensitivity, the calculated small break PCT for Limerick was higher than the previously calculated value. However, the Licensing Basis PCT

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of December 12, 2012 Assessment Notes LGS, U1 and U2 Page 2 of 3 (based on large break) remained the same. Therefore the PCT impact of the new power shape sensitivity was determined to be ooF for GE14 fuel.

[

Reference:

Letter from David P. Helker (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated December 1, 2006.]

6.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. There were no errors reported for the 2007 reporting period.

[

Reference:

Letter from David P. Helker (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated November 30, 2007.]

7.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. There were no errors reported for the 2008 reporting period.

[

Reference:

Letter from David P. Helker (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated November 24, 2008.]

8.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. There were no errors reported for the 2009 reporting period.

[

Reference:

Letter from David P. Helker (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated November 24, 2009.]

9.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. There were no errors reported for the 2010 reporting period.

[

Reference:

Letter from David P. Helker (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated November 24, 201 0.]

1 0.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. The referenced letter discussed the introduction of the GNF2 fuel design to the Limerick Unit 2 core. The assessment notes above (Notes 1-9) are not applicable to GNF2 fuel. Subsequent to the referenced letter, the GNF2 fuel design was introduced to the Unit 1 core and the errors discussed in this note also apply to Unit 1 (See Note 11 ).

Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of December 12, 2012 Assessment Notes LGS, U1 and U2 Page 3 of 3 Also discussed in the referenced letter are two vendor notifications of Emergency Core Cooling System (ECCS) model error/changes for GE14 and GNF2 fuel applicable to Limerick. The errors/changes are summarized below.

The first error involved the way input coefficients were used to direct the deposition of gamma radiation energy produced by the fuel. Correction of this error resulted in a PCT increase of 45°F for both the GE14 fuel and GNF2 fuel.

The second error involved the contribution of heat from gamma ray absorption by the channel. The gamma ray absorption by the channel was found to have been minimized.

Correction of this error resulted in a PCT increase of 5°F for both the GE14 fuel and GNF2 fuel.

[

Reference:

Letter from Michael D. Jesse (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated November 23, 2011.]

11.

Prior LOCA Assessment The referenced letter provided an annual 50.46 report for Units 1 and 2. There were no errors reported for the 2012 reporting period.

GNF2 fuel was introduced into the Unit 1 core during Reload 14 (Cycle 15) outage. The ECCS model error/changes discussed in Note 10 were applied to Unit 1 as Prior LOCA Model Assessments.

[

Reference:

Letter from Michael D. Jesse (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "1 0 CFR 50.46 Annual Report," dated November 9, 2012.]

12.

Current LOCA Assessment Subsequent to the 2012 Annual 50.46 Report (see Note 11 ), one vendor notification was received (Reference). To address inaccuracies in fuel pellet thermal conductivity as a function of exposure, commonly referred to as thermal conductivity degradation (TCD),

GEH replaced the GESTR-LOCA model with a newer model, PRIME. The most dominant effect impacting PCT is from the way the PRIME fuel properties treat thermal conductivity, which results in a higher fuel stored energy. The PCT impact identified in the notification reflects the difference between the existing GESTR analysis PCT and a conservatively postulated PCT if the analysis were performed with the PRIME model. The ECCS-LOCA analysis methodology remains GESTR based and will not be PRIME based until the ECCS-LOCA analysis is re-performed using PRIME.

[

Reference:

Letter from GE Hitachi Nuclear Energy (GEH) to Exelon Generation Company, LLC, "1 0 CFR 50.46 Notification Letter 2012-01, Limerick Generating Station (Unit 1 & 2)," dated November 29, 2012.]