NRC 2007-0017, ECCS Evaluation Model Changes

ECCS Evaluation Model Changes

ML071800510
Person / Time
Site:	Point Beach
Issue date:	06/27/2007
From:	Koehl D Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC 2007-0017
Download: ML071800510 (10)

Text

Committed to Nuclear Excellence Point Beach Nuclear Plant Operated by Nuclear Management Company, LLC June 27,2007 NRC 2007-0017 10 CFR 50.46 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 ECCS Evaluation Model Chan~es As required by 10 CFR 50.46(a)(3)(ii), Nuclear Management Company, LLC (NMC), is submitting this annual report of changes to, and errors discovered in, emergency core cooling system (ECCS) evaluation models for Point Beach Nuclear Plant (PBNP),

Units 1 and 2. This letter provides a summary of ECCS evaluation model changes and errors identified since the previous annual report NRC 2006-0047 dated May 5,2006.

For PBNP Units 1 and 2 in 2006 there were two non-discretionary changes and one discretionary change to the peak cladding temperature (PCT) assessment for the best estimate large break loss-of-coolant (BELBLOCA) analysis, and one discretionary change for the small break LOCA analysis. These changes are summarized in Enclosures 1 and 2, respectively. PCT margin utilization data is provided in Enclosure 3. PCT rackup sheets for the large break and small break LOCA analyses are provided in Enclosure 4. This issue has been entered into the site Corrective Action Program.

On August 4,2006, NMC submitted a 30-day report (NRC 2006-0068), documenting an error that Westinghouse discovered in the downcomer gap inputs. The error in the gap inputs resulted in a PCT change of -5g°F. Since this error increased margin to the PCT limit relative to the analysis of record, and demonstrated that the PCT limit continued to be met, no schedule for re-analysis was submitted.

This s u m 1 contains no new commitments or revisions to existing commitments.

&*Koe:y/ "

Site Vice-president. Point B ach Nuclear Plant Nuclear ~ a n a ~ e m ecomp;ny, nt LLC Enclosures (4) cc: Regional Administrator, Region III, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC 6610 Nuclear Road Two Rivers, Wisconsin 54241-9516 Telephone: 920.755.2321

ENCLOSURE I LBLOCA ECCS EVALUATION MODEL CHANGES AND ERRORS Inconsistent Vertical Levels in Vessel

/Nan-Discretionarv Chanae)

Backqround A discrepancy was identified during the course of a Best Estimate Large Break LOCA (BELBLOCA) Analysis whereby the number of vertical levels in the vessel are modeled inconsistent with the analysis input guidelines. An assessment was performed to estimate the impact of these differences on the BELBLOCA results for the affected plants. These changes represent a closely-related group of Non-Discretionary changes in accordance with Section 4.1.2 of WCAP-13451.

Affected Evaluation Model 1999 Westinghouse BELBLOCA Evaluation Model, Application to PWRs with Upper Plenum Injection.

Estimated Effect An assessment was performed with consideration of all the affected plants. This assessment concluded that there is no significant impact on the BELBLOCA analysis results due to the inconsistent modeling of the vessel vertical levels, leading to an estimated zero degree PCT impact.

Revised Downcomer Gap Inputs

/Nan-Discretionarv Change)

An error was identified during the course of a BELBLOCA analysis. A factor of W had been missed from the downcomer nominal gap width (GAPN) calculations from the Point Beach Nuclear Plant (PBNP) Units 1 and 2 analyses, resulting in downcomer GAPN values twice as big as they should be. The error has been corrected and the effect on PCT was evaluated. This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

Affected Evaluation Modells):

1999 Westinghouse BELBLOCA Evaluation Model, Application to PWRs with Upper Plenum Injection.

Page 1 of 2

Estimated Effect:

A representative reference transient was rerun using WCOBRAITRAC to establish an estimated effect on the PCT. The estimated effect is -3°F for Reflood 1 for PBNP Units 1 and 2.

General Code Maintenance lDiscretionarv Channe No PCT Impact)

Backaround A number of coding changes were made as part of normal code maintenance. Examples include additional information in code outputs, improved automation in the ASTRUM codes, increased W C O B M R A C code dimensions, and general code cleanup. All of these changes are considered to be Discretionary Changes in accordance with Section 4.1 .Iof WCAP-13451.

Affected Evaluation Models 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model 1999 Westinghouse Best Estimate Large Break LOCA Evaluation Model, Application to PWRs with Upper Plenum Injection 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM Estimated Effect The nature of these changes leads to an estimated PCT impact of 0°F.

Page 2 of 2

ENCLOSURE 2 SBLOCA ECCS EVALUATION MODEL CHANGES AND ERRORS General Code Maintenance

/Enhancements/Forward-Fit Discretionary Change)

Backqround Various changes in code input and output format have been made to enhance usability and help preclude errors in analyses. This includes both input changes (e.g., more relevant input variables defined and more common input values used as defaults) and input diagnostics designed to preclude unreasonable values from being used, as well as various changes to code output which have no effect on calculated results. In addition, various updates were made to eliminate inactive coding, improve active coding, and enhance commenting, both for enhanced usability and to facilitate code debugging when necessary.

These changes represent Discretionary changes that will be implemented on a forward-fit basis in accordance with Section 4.1 .Iof WCAP-13451.

Affected Evaluation Models 1981 Westinghouse Large Break LOCA Evaluation Model with BASH 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The nature of these changes leads to an estimated PCT impact of 0°F.

Page 1 of 1

ENCLOSURE 3 LARGE BREAK PEAK CLADDING TEMPERATURE MARGIN UTILIZATION FOR BELBLOCA Point Beach Nuclear Plant Units 1 and 2:

Analysis of Record (1112000) PCT =

Prior Permanent ECCS Model Assessments

1. MONTECF Decay Heat Uncertainty Factor APCT =

2. Revised Blowdown Heatup Uncertainty Distribution APCT =

Planned Plant Change Evaluations

1. Measurement Uncertainty Recapture Power Uprate APCT =

2006 10 CFR 50.46 Model Assessments APCT =

1. Inconsistent Vessel Vertical Level Modeling APCT =

2. Revised Downcomer Gap Inputs APCT =

Temporary ECCS Model Issues (none) APCT =

Other Margin Allocations (none) APCT =

Licensing Basis PCT + Margin Allocations PCT =

SMALL BREAK PEAK CLADDING TEMPERATURE MARGIN UTILIZATION

/Three Inch Cold Leg)

Unit 1 1 Unit 2 A. Analysis of Record (1112000) PCT= 1157"FI 1046°F B. Prior Permanent ECCS Model Assessments

1. NOTRUMP Mixture Level TrackinglRegion Depletion APCT = 13°F

2. NOTRUMP Bubble RiselDrift Flux Model Inconsistency APCT = 35"F C. 10 CFR 50.59 Safety Evaluations (none) APCT = 0°F D. 2005 10 CFR 50.46 Model Assessments (none) APCT = 0°F E. Temporary ECCS Model Issues (none) APCT = 0°F F. Other Margin Allocations (none) APCT = 0°F Licensing Basis PCT + Margin Allocations PCT = 1205°F 1 1094°F Page 1 of 1

ENCLOSURE 4 PCT RACKUP SHEETS FOR LBLOCA AND SBLOCA 4 Pages Follow

Attachment 2 - PCT Rackup Sheets Our ref: LTR-LIS 194 Apn1 13,2007 Westinghouse LOCA Peak Clad Temperature Summary for Best Estimate Large Break Plant Name: Point Beach Unit 1 Utility Name: Nuclear Management Company, LLC Revision Date: 7110106 Composite Analvsis Information EM: UP1 ( 1 999) Analysis Date: 9/1/97 Limiting Break Size: Split FQ: 2.6 FdH: 1.8 Fuel: 422 Vantage + SGTP (%): 25 Notes: Uprate Clad Temp (OF) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 2128 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS I . MONTECF Decay Heat Uncertainty Error 2 . Revised Blowdown Heatup Uncertainty Distribution B. PLANNED PLANT MODIFICATION EVALUATIONS I . 1.4% Uprate Evaluation C. 2006 ECCS MODEL ASSESSMENTS I . Inconsistent Vessel Vertical Level Modeling 2 . Revised Downcomer Gap Inputs D. OTHER*

1 . None LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 2086

• It is recommended that the licensee determine if these PCT allocations be considered with respect to 10 CFR 50.46 reporting requirements.

References:

I . 99WE-(3-0034, "Wisconsin Electric Power Company, Point Beach Units I and 2, Final BE UP1 LBLOCA Engineering Report (WCAP-15220) for Point Beach Units 1 and 2 (WEPiWIS)," June 24, 1999.

2 . WEP-01-008, "I 0 Ct'K 50.46 Annual Notification and Reporting for 2000," March 2001.

3 . OC-WES-BI-29-2003-006, "Point Beach Unit I, Cycle 29; Final Reload Safety & Licensing Checklist," November 2003 4 . WEP-05-84, "I0 CFR 50.46 Annual Notification and Reporting for 2004," April 2005 5 . LTR-LIS-06-209, "Plant Specific Reporting Text for Various Errors for IR-04-337-M012.08," April 2006.

6 . LTR-LIS-06-334, "Updates to the Best Estimate Large Break LOCA PCT Rackup Sheets for Kewaunee (WPS) and Point Beach Units 1 (WEP) and 2 (WIS)," July 2006.

Notes:

None

Attachment 2 - PCT Rackup Sheets Our ref LTR-LIS-07-194 April 13,2007 Westinghouse LOCA Peak Clad Temperature Summary for Best Estimate Large Break Plant Name: Point Beach Unit 2 Utility Name: Nuclear Management Company, LLC Revision Date: 7110106 Composite Analvsis Information EM: UP1 (1 999) Analysis Date: 9/1/97 Limiting Break Size: Split FQ: 2.6 FdH: 1.8 Fuel: 422 Vantage + SGTP (%): 25 Notes: Uprate Clad Temp ( O F ) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 2128 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS 1 . MONTECF Decay Heat Uncertainty Error 2 . Revised Blowdown Heahlp Uncertainty Distribution 5 4 B. PLANNED PLANT MODIFICATION EVALUATIONS 1 . 1.4% Uprate Evaluation C. 2006 ECCS MODEL ASSESSMENTS 1 . Inconsistent Vessel Vertical Level Modeling 2 . Revised Downcomer Gap Inputs D. OTHER*

1 . None LICENSING BASIS PCT + PCT ASSESSMENTS PCT= 2086

• It is recommended that the licensee determine if these PCT allocations be considered with respect to 10 CFR 50.46 reporting requirements.

References:

1 . 99WE-G-0034, "Wisconsin Electric Power Company, Point Beach Units 1 and 2, Final BE UP1 LBLOCA Engineering Report (WCAP-15220) for Point Beach Units 1 and 2 (WEPIWIS)," June 24, 1999.

2 . WEP-01-008, " 10 CFR 50.46 Annual Notification and Reporting for 2000," March 2001 3 . NPL 2003-0071, "Final RS&LC Point Beach Nuclear Plant, Unit 2 Cycle 27", February 2003 4 . WEP-05-84, "10 CFR 50.46 Annual Notification and Reporting for 2004," April 2005.

5 . LTR-LIS-06-209, "Plant Specific Reporting Text for Various Errors for IR-04-337-M012.08," April 2006 6 . LTR-LIS-06-334, "Updates to the Best Estimate Large Break LOCA PCT Rackup Sheets for Kewaunee (WPS) and Point Beach Units 1 (WEP) and 2 (WIS)," July 2006.

Notes:

None

Attachment 2 - PCT Rackup Sheets Our ref: LTR-LIS-07-194 April 13,2007 Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Small Break Plant Name: Point Beach Unit 1 Utility Name: Nuclear Management Company, LLC Revision Date: 2/23/2006 Analysis Information EM: NOTRUMP Analysis Date: 6/1/1999 Limiting Break Size: 3 inch CL Hi T a v g FQ: 2.6 FdH: 1.8 Fuel: Vantage + SGTP (%): 25 Notes: 422 Vantage +

Clad Temp (OF) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1157 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS 1 . NOTRUMP Mixture Level Tracking / Region Depletion Errors 13 3 2 . NOTRUMP Bubble Rise I Drift Flux Model Inconsistency Corrections 35 4 B. PLANNED PLANT MODIFICATION EVALUATIONS 1 . None C. 2007 ECCS MODEL ASSESSMENTS 1 . None D. OTHER*

I .None LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 1205

• It is recommended that the licensee determine if these PCT allocations be considered with respect to 10 CFR 50.46 reporting requirements.

References:

1 . CAB-99-226, Rev. 1, "Fuel Upgrade 1 Power Uprating Reload Transition Safety Report for Point Beach Units I and 2 Revision 1," July 13, 1999.

2 . WEP-00-009, "Wisconsin Electric Power Company, Point Beach Units 1 and 2, 10 CFR 50.46 Annual Notification and Reporting for 1999." February 23,2000.

3 . WEP-00-027, "Wisconsin Electric Power Company, Point Beach Units 1 and 2, 10 CFR 50.46 Appendix K (BARTIBASHNOTRUMP) Evaluation Model Mid-Year Notification and Reporting for 2000," June 30,2000 4 . WEP-05-84, "10 CFR 50.46 Annual Notification and Reporting for 2004," April 2005.

Notes:

None

Attachment 2 - PCT Rackup Sheets Our refi LTR-LIS-07-194 April 13,2007 Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Small Break Plant Name: Point Beach Unit 2 Utility Name: Nuclear Management Company, LLC Revision Date: 2/23/2006 Analysis Information EM: NOTRUMP Analysis Date: 6/1/1999 Limiting Break Size: 3 inch CL Lo Tavg FQ: 2.6 FdH: 1.8 Fuel: Vantage + SGTP (%): 25 Notes: 422 Vantage +

Clad Temp (OF) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1046 I PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS 1 . NOTRUMP Mixture Level Tracking I Region Depletion Errors 13 3 2 . NOTRUMP Bubble Rise 1 Drifi Flux Model Inconsistency Corrections 35 4 B. PLANNED PLANT MODIFICATION EVALUATIONS I . None C. 2007 ECCS MODEL ASSESSMENTS 1 . None D. OTHER*

I .None LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 1094

• It is recommended that the licensee determine if these PCT allocations be considered with respect to 10 CFR 50.46 reporting requirements.

References:

1 . CAB-99-226, Rev. 1, "Fuel Upgrade I Power Uprating Reload Transition Safety Report for Point Beach Units 1 and 2 Revision I," July 13, 1999.

2 . WEP-00-009, "Wisconsin Electric Power Company, Point Beach Units 1 and 2, 10 CFR 50.46 Annual Notification and Reporting for 1999," February 23,2000.

3 . WEr-00-027, "Wisconsin Electric Power Company, Point Beach U~litr1 and 2, 10 CFR 50.46 Appendix K (BARTIBASHMOTRUMP) Evaluation Model Mid-Year Notification and Reporting for 2000," June 30,2000 4 . WEP-03-142, "10 CFR 50.46 Mid-Year Notification and Reporting for 2003," November 2003.

Notes:

None