ML20217Q888
| ML20217Q888 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 04/06/1998 |
| From: | Sorensen J NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9804130219 | |
| Download: ML20217Q888 (10) | |
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i Northern States Power Company Prairio Island Nuclear Generating Plant 1717 Wakonada Dr. East Welch. Minnesota 55089 April 6,1998 10 CFR Part 50 Section 50.46 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Report of Corrections to ECCS Evaluation Modeis Attached is the 30-day report (data was received frorn Westinghouse March G,1998) of j
corrections to Northern States Power Company's (NSP) Emergency Core Cooling System (ECCS) Evaluation Models. This report is being submitted in accoldance with the provisions of 10 CFR 50, Section 50.46.
The apolicable corrections noted in Attachment 1 have been applied to Prairie lafand's 'f current ECCS analyses of record, and all analyses were found to be in compliance with the applicable acceptance criteria (Attachment 2).
In this letter we have made no new Nuclear Regulatory Commission commitments.
i Please contact Jack Leveille (612-388-1121, Ext. 4662) if you have any questions MY relat d to this letter.
2 Joel P Sorensen Plant Manager i
Prairie Island Nuclear Generating Plant c: (see next page) i 9801130219 980406 PDR ADOCK 05000282 PDR
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USNRC NORTHERN STATES POWER COMPANY April 6,1998 page 2 c: Regional Administrator - Region ill, NRC Senior Resident inspector, NRC NRR Project Manager, NRC l
J E Silberg I
A.ttachments:
1.1997 ECCS Evaluation Model Reportable Changes and Errors
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$0-44-01 DOC
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D ATTACHMENT 1 1997 ECCS EVALUATION MODEL REPORTABLE CHANGES AND ERRORS
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1-D TRANSITION BOILINO HEAT TRANSFER ERROR j
Background:
i The transition boiling heat flux in ID components double accounts for the contribution to the heat flux by the vapor phase. This heat transfer regime occurs only briefly in the steam generator component during a large break transient. The vapor phase contribution to the overall heat flux in this regime is very small compared to the liquid phase contribution, which l
is calculated correctly.
This was dete:Tnined to be a Non-discretionary change as described in Section 4.1.2 of WCAP 13451.
Affected Evaluation Models SECY UPI WCOBRA/ TRAC Large Break LOCA Evaluation Model I
Estimated Effect For the SECY UPI Evaluation model, plant specific PCT assessments of the impact of this change have been generated.
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O VESSEL CHANNEL DX ERROR
Background:
Incorrect cell height is used in calculating gap flow wall friction and interfacial drag coefficients at gap level J. The cell height, DX, is a function of the continuity / gap level J in the section. The error is that only cell 1 DX value is used, rather than cell heights specific to each level, I through J.
This was determined to be a Non-discretionary change as described in Section 4.1.2 of WCAP 13451.
Affected Evaluation Models SECY UPI WCOBRA/ TRAC Large Break LOCA Evaluation Model Estimated Effect Plant specific PCT impacts have been determined and assessed for all SECY UPI WCOBRA/ TRAC Evaluation model analyses.
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INPUT CONSISTENCY
Background:
A general review of all SECY UPI WCOBRA/ TRAC analyses was conducted in 1997. A list 1
of recommended procedures was generated and all plant calculations were reviewed for their compliance. This review revealed that input methods and input data transfer were not done consistently in all of the plant analyses. A decision was made to incorporate these changes
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into all SECY UPI Appendix K analyses along with the implementation of other code corrections, since the effect was estimated to be small. In all cases, these consistency refinements represent details not explicitly called out in the licensed methodology and therefore had been left to analyst discretion.
These changes were determined to be a Discretionary change as described in Section 4.1.1 of WCAP-13451.
Affected Evaluation Models 4
SECY UPI WCOBRA/ TRAC Large Break LOCA Evaluation Model l
i Estimated Effeel i
All Appendix K calculations of UPI plants with the SECY UPI WCOBRAfrRAC Evaluation Model have been re analyzed with the 1997 recommended input procedures. The PCT impact of these changes has been calculated for each plant and assessed.
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J ATTACHMENT 2 LOCA Peak Clad Temperature (PCT)
Margin Utilization Sheets
Smell Break Peak Clad Temperature Margin Utilization Revision Date: 02/18/98 Plant Name: Prairie Island Units I and 2 Eval.Model: NOTRUMP Utility Name: Northern States Power Fuel: 14x14 OFA ZlRLO(TM)
FQ=2.80 FAH=2.00 SGTP=25%
Reference
- Clad Temperature Notes A. ANALYSIS OF RECORD (7/93) 1 PCT =
1195 'F 1
B, PRIOR PERMANENT ECCS MODEL ASSESSMENTS 2
APCT=
-19'F C. 10 CFR 50.59 SAFETY EVALUATIONS Table A APCT=
3 'F D.199710 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin)
- 1. None APCT=
0 'F E. TEMPORARY ECCS MODEL ISSUES"
- 1. None APCT=
0 'F F. OTHER MARGIN ALLOCATIONS
- l. None APCT=
0 'F LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT =
1179 'F
- References for the Peak Clad Temperature Margin Utilization summary can be found in Table B.
" It is recommended that these temporary PCT allocations which address current LOCA model issues not be considered with respect to 10 CFR 50.46 reporting requirements.
Notes:
- 1. Includes annular pelkt evaluation.
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Large Break Peak Clad Temperature Margin Utilization Revision Date: 02/18/98 Plant Name: Prairie Island Units I and 2 Eval.Model: SECY UPI Utility Name: Northern States Power Fuel: 14x14 OFA ZlRLO(TM)
FQ=2.40 FAH= l.77 SGTP=15%
Reference
- Clad Temperature Notes A. ANALYSIS OF RECORD (3/95) 3.4 PCT = 2180 #F 1
B. PRIOR PERMANENT ECCS MODEL ASSESSMENTS 2
APCT=
-175 'F C. 10 CFR 50.59 SAFETY EVALUATIONS Table A APCT=
0 'F D.199710 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin) 1.1 D Transition Boiling Heat Transfer Error APCT=
59 'F
- 2. Vessel Channel DX Error APCT=
14 'F
- 3. Input Consistancy APCT=
-66 'F E. TEMPORARY ECCS MODEL ISSUES"
- 1. None APCT=
0 'F F. OTHER MARGIN ALLOCATIONS
- 1. None APCT=
0 'F LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT =
1984 'F
- References for the Peak Clad Temperature Margin Utilization summaries can be found in Table B.
" It is recommended that these temporary PCT allocations which address current LOCA model issues not be considered with respect to 10 CFR 50.46 reporting requirements.
Notes:
- 1. P-bar HA increased from 1.57 to 1.59
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Table A 10 CFR 50.59 Safety Evaluations Revision Date: 02/18/98 Plant'Name: 'Prairic Island Units I and 2 Utility Name: Northern States Power Refem.u nd Temperature Notes 1.
SMALL BREAK ECCS SAFETY EVALUATIONS A. MFW Temperature 5
APCT=
3 'F TOTAL 10 CFR 50.59 SMALL BP,EAK ASSESSMENTS PCT =
3 'F
!!. LARGE BREAK ECCS SAFETY EVALUATIONS A. None APCT=
0 'F TOTAL 10 CFR 50.59 LARGE BREAK ASSESSMENTS PCT =
0 'F Notes:
None Table B References
- 1. NSP 93 521," Northern Power Company Prairie Island Units I and 2 Small Break Loss-of Coolant Accident Final Engineering Report for the ZIRLO(TM) Fuel Upgrade," July 30,1993.
- 2. NSP-97 201," Northern Power Company Prairie Island Units I and 210 CFR 50.46 Annual Notification and Reporting " April 17,1997, 3, 95NS-G-0021. " Updated UPI LBLOCA." March 24,1995.
- 4. WCAP 13919, Addendum I," Prairie Island Units I and 2 WCOBRAfrRAC Eest Estimate UPI Large Break LOCA Analysis Engineering Report Addendum 1: Updated Results." December 1996.
- 5. NSP-97-5(M," Northern States Power Company Prairie Islant Units 1 and 2, Feedwater Temperature Increase /
Net RCS Heat Input Addition Program, Transmittal of Final Safety Evaluation," September 23,1997.
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