NRC-2007-0055, Error Identified in ECCS Evaluation Model 30-Day Report Required by 10 CFR 50.46
| ML071860067 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 07/03/2007 |
| From: | Koehl D Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-2007-0055 | |
| Download: ML071860067 (6) | |
Text
July 3, 2007 NRC 2007-0055 10 CFR 50.46 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units 1 and 2 Docket 50-266 and 50-301 Renewed License No. DPR-24 and DPR-27 Error Identified in ECCS Evaluation Model 30-Day Re~ort Required by 10 CFR 50.46 As required by 10 CFR 50.46(a)(3)(ii), Nuclear Management Company, LLC (NMC), is submitting this 30-day report of an error discovered in an emergency core cooling system (ECCS) evaluation model for Point Beach Nuclear Plant (PBNP), Units 1 and 2.
The HOTSPOT corrected code was used to reanalyze peak center-line temperature (PCT) for the large break loss-of-coolant-accident. The plant-specific PCT penalty is 5OF for blowdown and 45OF for Reflood 1. The resultant estimated PCT, including all assessments, is 213I0F, which is within 3OF of the analysis of record PCT of 2128 OF. Therefore, PBNP continues to comply with the requirements of 10 CFR 50.46. Enclosure 1 provides the revised PCT summary. Enclosure 2 provides the rack-up sheets supporting this PCT change. This issue has been entered into the PBNP Corrective Action Program.
In accordance with a discussion held on July 2, 2007, between the PBNP Regulatory Affairs Supervisor and the PBNP Nuclear Reactor Regulation Project Manager, the proposed schedule for reanalysis of the ECCS Evaluation Model will be submitted by September 14, 2007.
Summary of Commitments The proposed schedule for reanalysis of the PBNP ECCS Evaluation Model will be submitted by September 14, 2007.
1 Dennis L. Koehl
/
Site Vice-President, Point Beach Nuclear Plant Nuclear Management Company, LLC Enclosures (2) cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC 661 0 Nuclear Road Two Rivers, Wisconsin 54241-951 6 Telephone: 920.755.2321
ENCLOSURE I PCT
SUMMARY
POINT BEACH NUCLEAR PLANT, UNITS I AND 2 Larae Break Peak Claddina Temperature Marain Utilization for BELOCA Analysis of Record (November 2000)
PCT =
A.
Prior Permanent ECCS Model Assessments
- 1. MONTECF Decay Heat Uncertainty Error APCT =
- 2. Revised Blowdown Heatup Uncertainty Distribution APCT =
- 3. Revised Downcomer Gap Inputs APCT =
B.
Planned Plant Change Evaluations I.
1.4% Uprate Evaluation APCT =
C.
2007 ECCS Model Assessments
- 1. HOTSPOT Fuel Relocation Error APCT =
D. Other
- 1. None APCT =
Licensing Basis PCT + Margin Allocations PCT =
Small Break Peak Claddina Temperature Margin Utilization
/Three-Inch Cold Leg Analysis of Record (November 2000)
PCT =
A.
Prior Permanent ECCS Model Assessments
- 1. NOTRUMP Mixture Level TrackingIRegion Depletion APCT =
- 2. NOTRUMP Bubble RiseIDrift Flux Model Inconsistency APCT =
B.
Planned Plant Change Evaluations
- 1. None APCT =
C.
Permanent ECCS Model Evaluations
- 1. None APCT =
D. Temporary ECCS Model Issues
- 1. None APCT =
E.
Other
- 1. None APCT =
Licensing Basis PCT + Margin Allocations APCT =
Page 1 of 2
HOTSPOT Fuel Relocation
{Non-Discretionarv Chansre)
Backqround In the axial node where burst is predicted to occur, a fuel relocation model in HOTSPOT is used to account for the likelihood that additional fuel pellet fragments above that elevation may settle into the burst region. It was discovered that the effect of the fuel relocation on local linear heat rate was being calculated, but then canceled out later in the coding. This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.
Affected Evaluation ModeMs) 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model 1999 Westinghouse Best Estimate Large Break LOCA Evaluation Model, Application to pressurized water reactors with upper plenum injection 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM Estimated Effect 1996 and 1999 BELOCA EMS analyses were assessed on a plant-specific basis, via the HOTSPOT reanalysis of a representative of WCOBRA/TRAC case using the corrected code version at the burst elevationlburst model enabled sub-case. The HOTSPOT 95% probability PCT results were used to establish the plant-specific PCT penalty.
2004 ASTRUM EM analyses were assessed on a plant-specific basis, via the reanalysis of all of the burst cases from the original HOTSPOT calculations using the corrected HOTSPOT code version.
Plant-S~ecific Text The plant-specific PCT penalty was 5°F for Blowdown and 45°F for Reflood 1.
Page 2 of 2
ENCLOSURE 2 PCT RACKUP SHEETS FOR POINT BEACH NUCLEAR PLANT, UNITS I AND 2 2 Pages Follow
Attachment to LTR-LIS-07-381 June 4,2007 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:
6/4/2007 Composite Analysis Information EM:
UP1 ( 1999)
Analysis Date:
91111997 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 PCT ASSESSMENTS (Delta PCT)
A. PRIOR ECCS MODEL ASSESSMENTS 1. MON'I'ECF Decay Heat Uncerta~nty Error 2. Revised Blowdown Heatup Uncertainty Distribution 5
4 3. Inconsistent Vessel Vertical Level Modeling 0
5 4. Revised Downcomer Gap Inputs
-59 6
B. PLANNED PLANT MODIFICATION EVALUATIONS I. 1.4% Uprate Evaluation C. 2007 ECCS MODEL ASSESSMENTS I
HOTSPOT Fuel Relocation Error D. OTHER*
I. None LICENSING BASIS PCT + PCT ASSESSMENTS PCT-2131 I t is reco~n~nentled that the licensee determine if these PCT allocnuons be conaidrreil with teapect to I0 CFR 50.46 reporting requirements.
References:
I 09WE-(i-0034. "Wisconsin Electric Power Company. Point Bcllch Units I and 2. Finiil BE UP1 LBLOCA Engineering Report (WC1ZI'-l5220) for Point Beach Un~ta I and 2 (WkP'WIS)." June 24. 1999.
2. WEP-01 -008, "I0 CFR 50.46 Annual Notification and Repotling for 2000," March 2001 3. OC-WES-BI-29-2003-006. "Point Beach Unit I. Cycle 29; Final Kelood Safety & Licensing Checkliar," November 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 Po~nt Beach Units I (WEP) and 2 (WIS)," July 2006.
7. LTR-LIS-07-381. "10 CFK 50.46 Reporting Text for HOTSPOT Fuel Relocation Error and Revised PCT Rackup Sheets for Po~nt Beach Un~ts 1 and 2." June 2007.
Notes:
None
Attachment to LTR-LIS-07-381 June 4,2007 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:
6/4/2007 Composite Analysis Information EM:
UP1 (1999)
Analysis Date:
9/1/1997 Limiting Break Size:
Split FQ:
2.6 FdH:
1.8 Fuel:
422 Vantage +
SGTP (7'0):
25 Notes:
Uprate LICENSING BASIS Analysis-Of-Record PCT PCT ASSESSMENTS (Delta PCT)
A. PRIOR ECCS MODEL ASSESSMENTS I. MONTECF Decay Heat Uncertainty Error Clad Temp (OF)
Ref.
Notes 2128 1
2. Revised Blowdown Heatup Uncerta~nty Distribution 5
4 3. lncons~stent Vessel Vertlcal Level Modellng 0
5 4. Revised Downcomer Gap Inputs
-59 6
B. PLANNED PLANT MODIFICATION EVALUATIONS I. 1.4% Uprate Evaluetion C. 2007 ECCS MODEL ASSESSMENTS I. HOTSPOT Fuel Relocation Error D. OTHER*
1. None LICENSING BASIS PCT + PCT ASSESSMENTS PCT=
2131 It is reco~nlnended that the llcensee determlnc ~f these PC1 allocat~ons be considered wlth respect to 10 CFR 50.46 reporting requirements.
References:
I. 99WE-G-0034. "Wiscons~n Electric Powcl-<:ompany. Point Beach Urilta I and 2. Final BE UP1 LBLOCA Engineering Rep011 (WCAP-15220) for Point Beach Uniis I and 2 (WEP!WIS)." June 24. 1999.
2. WEP-01-008. "10 CFR 50.46 Annual Notification and Reporting for 2000." Malrh 2001.
3. NPL 2003-0071. "Final RS&LC Point Beach Nuclear Plant. Unit 2 Cyclc 27". Feb~ua~y 2003 4. WEP-05-84. "10 CFR 50.46 Annual Not~ficatlon and Reporting for 2004." April 2005.
5. LTR-LIS-06-209. "Plant Specific Reporting Text for Various Errors for IR-04-337-MOI2.08." Aprll2006.
6. LTR-LIS-06-334. "Updates to the Bcst Estimate Large Break LOCA PCI Rackup Sheets for Kewaunee (WPS) and Point Beach Unita I (WEP) and 2 (WIS)." July 2006.
7. LTR-LIS-07-381, "10 CFR 50 46 Reporting Text for HOTSPOI Fuel Relocation Emor and Revlaed I'CT Rackup Sheets f o ~
Point Beach Units 1 and 2." June 2007.
Notes:
None