ML20209C301

Forwards Annual Rept of Corrections to NSP ECCS Evaluation Models,Iaw 10CFR50.46.Since All Analyses Remain in Compliance,No Reanalysis Is Required or Planned

ML20209C301
Person / Time
Site:	Prairie Island
Issue date:	06/29/1999
From:	Richard Anderson NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9907090243
Download: ML20209C301 (10)

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o i Northern States Power Company 414 Nicollet Mall a

, Minneapolis, Minnesota 55401-1927 Telephone (612) 330-5500 June 29,199'. 10 CFR Pad 50 Section 50.46 s

U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 i PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 )

50-306 DPR-60 Annual Report of Corrections to ECCS Evaluation Models Attached is the snnual report of corrections to Northern States Power Company's (NSP)  ;

Emergency Core Cooling System (ECCS) Evaluation Models. This report is being i submitted in accordance with the provisions of 10 CFR 50, Section 50.46.

The applicable corrections noted in Attachment 1 have been applied to Prairie Island's current ECCS analyses of record, and all analyses were found to be in compliance with [

the applicable acceptance criteria (Attachments 2 and 3). Since all analyses remain in compliance, no reanalysis is required or planned. Atd I

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An additional issue relates to the PCT accounting change that Westinghouse performed for the Small Break LOCA Margin Utilization sheets. Between the .

, September 8,1998 submittal to the NRC, of corrections exceeding 50 F, and this 1998 l l Annual submittal, Westinghouse made an accounting change in the margin allontions  !

l under Prior Permanent ECCS Model Assessments (Item B below) and Plant-Specific 1 Assessment to Rebaseline Limiting Case (Item D.3 below). These changes do not I reflect any changes and/or errors to the Evaluation Model, but rather a change in the  !

PCT accounting as discussed below, j NSP had contracted with Westinghouse to perform a sensitivity study on the effects of different Auxiliary Feedwater (AFW) flow rates. The Rebaseline case was utilized in the AFW flow sensitivity study (NSP-98-046) as the starting point for the sensitivity study.

The Rebaselining case is a rerun of the limiting scenario (consistent with the AOR) utilizing the latest version of NOTRUMP - which incorporates corrections for past codin0 errors. The Rebaselining case (Item D.3) incorporates the corrections which 9907090243 990629 PDR P

ADOCK 05000282 PDR

TRANSMITTAL MANIFEST NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT Annual Report of Corrections to ECCS Evaluation Models Correspondence Date: June 29,1999 USNRC: Westinghouse (QCQ2BC2;gdE(ongpnel)1gf W J Orga 1 NRR, Tae Kim 1 S P Swigart 1 Regional Admin 111 1 i

Resident inspector 1 Roger O. Anderson RS-8 1 l Pat Culbert RS-9 1 George Miserendino GO-2 1 State of Minnesota K J Albrecht 1 Steve Minn 1 T E Amundson 1 J E Silberg 1 J O Hill 1 Betty Underwood (SAC) 1 Safety Audit Committee A B CuMer 1 Gerard Goering 1 NL Administrative:

Mike Peckham 1 Gene Eckhc" 1 Wayne Shamla RS-8 1 Joel Sorensen Pl 1 j*,fc e(eme 1 Dale vincent 1 Ken Weinhauer 1 NL File (original) 1 PI Records Mgmt 1 Extra Distribution: Design Cbange No l USAR Yes Tom Breene 1 Commitment No Keith Higar 1 Fire Protection Related No Cliff Bonneau 1

{ Oley Nelson 1 Paras Shah I Comments:

Manifest Date: July 1,1999 RMS. Doc Type:

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USNRC NORTHERN STATES POWER COMPANY June 29,1999 ,

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were previously submitted under item B " Prior Permanent ECCS Model Assessments", item D.1 "Effect of Si in Broken Loop", and item D.2 "Effect of improved Condensation Model". In Westinghouse letter NSP-98-046, the incorrect PCT accounting was alleviated by removing the -19 F allocation from the Margin Utilization sheet, and subtracting the 21 F and 4 *F from the Rebaselining case PCT assessment.

The intent of the accounting change in NSP-98-046 was to have the " Licensing Basis PCT + margin allocations" equal the calculated PCT from the Rebaselining case (1438

• F) which already accounted for the margin allocations under item D explicitly; therefore, these were removed from the Rebaseline APCT to determine the correct allocation for the Rebaselining case.

Then as per the discussion above, the " Licensing Basis PCT + Margin Allocations"in Westinghouse letter, NSP-98-046, was calculated as 1438 *F + 3 F = 1441 F.

Submittal on W - letter This Submittal Sept. 8, NSP-98-046 1998 Annual 1998 A. Analysis of Record 1195 'F 1195 'F i195 *F B. Prior Permanent ECCS Model Assessments " "

-19 *F 0*F 0'F C. 50.59 Safety Evaluations 3 'F 3 'F 3F D.199810 CFR 50.46 Model Assessments

1. Effect of SI in Broken Loop 21 'F 21 'F 21*F

2. Effect of Improved Ccudensation Model 4 'F 4 'F 4 'F

3. Plant-Specific Assessment to Rebaseline Limitmg Case 259 'F 218 'F 218 *F

4. Annular Pellets Misapplicatic, N/A N/A 39'F E. Temporary ECCS ModelIssues 0 'F 0 *F 0 *F F. Other Margin Allocations 0 'F 0 "F 0 *F Licensing Basis PCT + Margin Allocctions 1463 'F 1441 'F 1480 'F l

The Prior Permanent ECCS Model Assessments [-19 'F] are PCT " estimates"

- based on non-Prairie Island specific analyses. These " estimates" are only representative of the anticipated effect upon PCT for each licensee.

Therefore, it was not unexpectod that the PI-specific Rebaselining case that includes the explicit " Prior ECCS. Assessment" corrections did not reproduce the -19 'F effect upon PCT. Hence, simply adjusting the Rebaselining case PCT by the -19 'F would not be appropriate, since the actual PCT impact of those corrections would not equal-19 'F.

In this letter we have made no new Nuclear Regulatory Commission contmitments.

50-46 Annual 1998. DOC

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- USNRC NORTHERN STATES POWER COMPANY June 29,1999 ,

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Please contact Jack Leveille (651-388-1121, Ext. 4142) if you have any questions related to this letter.

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Roger O Anderson Director Nuclear Energy Engineering c: Regional Administrator - Region 111, NRC Senior Resident inspector, NRC NRR Project Manager, NRC J E Silberg Attachments:

1.1997 ECCS Evaluation Model Reportable Changes and Errors

2. Small Break LOCA Peak Clad Temperature (PCT) Margin Utilization Sheets

3. Large Break LOCA Peak Clad Temperature (PCT) Margin Utilization Sheet j l

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50-46 Annual 1998. DOC m-.

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1 ATTACHM~ENT 1 1 l

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l ECCS EVAL'UATION MODE.L j REPORTABLE CHANGES AND ERRORS l

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50 46 Annual 1998. LOC l-

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Prairie Island 1&2, I Annular Pelle~t Misapplication j 10 CFR 50.46 Reporting Information Backaround Analytical results for both solid and annular pellets were presented in the Prairie Island ZIRLO* Fuel  !

!  : Upgrade Small Break LOCA Report, WCAP-13920, Table 3-6, with results as follows:

Annular Pellets 1194.9 (limiting by 38.4 F) l Solid Pellets 1156.5 j j

In 1998, the results of a PCT =1438 F rebaselining analysis performed in 1997 were introduced into the PCT Margin Utilization sheets (letters NSP-98-043, NSP-98-031/SAE-LIS-98-459, SAE-LIS-98-455). The validity of this singular PCT result remains under investigation and the associated conservative PCT penalty was placed on the PCT sheets at Northem States Power request pending results of the continued investigation. During J this investigation, it was observed that the rebaselining analysis PCT change introduced into the PCT sheets was i pertinent to the solid pellet configuration even though the recent reload carrpaigns such as Prairie Island 2 Cycle 19 l included the annular fuel pellet fuel design. Therefore, the PCT results do not reflect the actual plant configuration, l constituting an error in the application of the model as defined in 10 CFR 50.46. I i Estimated Effects This historic plant specific sensitivity study in WCAP-13920 documents a 39 F PCT penalty to annular pellets that will be assigned on the PCT sheet. j i

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Prairie Island The followi' ng is the standardized 10 CFR 50.46 : Reporting page for the Code Uncertainty Investigation discussed in the Surveillance Report SS-97-23 Closeout (NSP-99-015). This page will be included in the 1998 Annual Report that will be transmitted to the NRC.

INVESTIGATION OF CODE UNCERTAINTIES FOR SECY UPI HCOBRA/ TRAC i

Background:

A subset of the test simulations used to determine the code uncertainty for the SECY UPI ECOBRA/ TRAC Large Break LOCA Evaluation Model were reanalyzed utilizing the latest code version (Revision 12) consistent with the current methodology used in plant calculations. The results were used to recalculate the code bias, X, and I uncertainty,6, for the blowdown and reflood peaks. These new values, in tum, were used to recalculate the EC/T j code uncertainty for blowdown, Swen30, and reflood, Sacn.r# The code uncertainties were used to recalculate the l

95* perecntile ECOBRA/ TRAC SECY UPI code uncertainty for blowdown,6 95 mso, and reflood,6 95 mu. These values are used to demonstrate compliance with the SER for SECY Appendix K calculations and to determine the licensing basis PCT for Superbounded calculations.

These changes were determined to be a Non-Discretionary change as described in Section 4.1.2 of WCAP-13451. I I

Affected Evaluation Modgls SECY UPI ECOBRA/ TRAC Large Break LOCA Evaluation Model Estimated Effect l

Recalculation of the 95* percentile ECOBRA/ TRAC SECY UPI code uncertainty for blowdown and reflood for l the current code version (Revision 12) using a subset of the test simulations used in the original detenrunation of code uncertainty showed a negligible change in values. This recalculation has shown that the original 95* percentile code uncertainty for blowdown and reflood for the ECOBRA/ TRAC SECY UPI Evaluation Model remains valid for the current code version (Revision 12) and there is no PCT impact on plant results.

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ATTACHMENT 2 Small Break LOCA Peak Clad I mPerature (PCT) .

Margin Utih.zation Sheets l i

l 50-46 Annual 1998.Mc

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• Wcstlighouse LOCA Peck Clad Tempertture Summ:ry F:r Sm'll BreIk Plant Name: Prairie Island Units 1 & 2 Utility Name: Northern States Power Revision Date 3/ 4/99 Auslysis lafonnstion EM: NOTRUMP Analysis Date: 07/93 Limiting Break Size: 6 inch FQ: 2.8 FdH: 2 Fuel: OFA SGTP (%): 25 Notes: Zirlo (14X14)

Clad Temp ( *F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 88'5 8 (*)

MARGIN ALLOCATIONS (Delta PCT)

A. PRIOR PERMANENT ECCS MODEL ASSESSMENTS 1, Total 0 2,6 (f)

B.10 CFR 50.59 SAFETY EVALUATIONS I. MFW Temperature 3 3

2. AFW Flow Reduction to 180 spm 0 5 C.199810 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT N!argin) l . Effect of Siin Broken Loop (Plant Specific) 21 4 (b,c)

2. Effect ofimproved Condensation Model(Plara Specifu:) 4 4 (b)

3. Plant-Specific Assessment to Rehaseline Limiting Case 218 4,7 (d,e,f)

4. Annular Pellets Misapplication 39 1,7 l

D. TEMPORA.RY ECCS MODEL ISSUES *

1. None 0 l E.OTHER

1. None 0  !

l . _ . .. -. .. . _ . - . . . . . . _ . - ~ .. .. .. . . . . . . . . . _

LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT = 1480

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It is .=- ------'--4 that these temporary PCT allocations which address curnmt LOCA model issues not be considered I with respect to 10 CFR 50,46 reporting requirements.

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References:

1. WCAP 13920,"Small Break Imf Coolant Accident Engineering Report for the Prairie Island ZlRLO Fuel Upgrade."

November 1993 (Includes Update NSD SAE.ESI-97 522)

2. Annual Reports for 1993 through 1997 (NSP-94 204. NSP-95-202, NSP-96-202, NSP-97-201, NSP 98 012).

3. NSP 97-504," Northern States Power Corr:pany Prairie Island Unas I and 2, Feedwater Temperature increase / Net RCS Heat input Addition Program. Tranraruttal of Final Safety Evaluation." September 23,1997.

4. NSP-98-031 " SBLOCA Evaluation for Elimination of AFW Flow for Prairic Island Units I and 2," September 8,1998.

5 NSP-98-043, " SDLOCA Evaluation for AFW Flow Reduction for Prairie Island Units 1 and 2," October 27,1998.

6. NSP-98-012 " Northern States Power Company Prairie Island Uruts I and 210 CFR 50.46 Annual Notification and Reporting for 1997." February 27,1998.

Friday. March 12.1999 Page 1 of 2

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• Wcstirghouse LOCA Peak Clad Tcmper:ture S:mm:ry F:r Smill Bre-k Plant Name: Prairic Island Units 1 & 2 Utility Name: Northern States Power Revision Date: 3/4/99

7. 1998 Annual Report.

Notes:

! (a) Annular pellet sensitivity study result (b) Plant-specific assessments for the effects that were originally estimated for these two items in NSP-93-222.

(c) Also includes die effect of relocation of the break location to the midplane of the cold leg (see WCAP 10054-P-A, Addendum 2.

Revision 1). The original estimate (NSP-93-222) did not include this effect.

(d) Value requested by customer pending completion of Westinghouse investigation Rebaseline study includes newer code versions, COSI condensation model and select input changes (e.g. more conservative power shape, solid fuel pellas).

(e) At the request of NSP, this line item was included under Section C, and represents a deviation from Westinghouse's normal approach.

(f) The estimated effects of previous code changes (through the .19 *F accumulated as of 1997 Annual Report NSP-98-012) are superceded by the 1998 Report items C.I. C.2 & C.3 plant specific calculations performed to rebanline the limiting case (1438 1195 = 21 + 4 + 218).

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Friday, March 12,1999 Page 2 of 2

ATTACHMENT 3 Large Break LOCA Peak Clad Temperature (PCT)

Margin Utilization Sheet l

l 50-46 Annual 1998. DOC

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[ Westinghouse LOCA Peak Clad Temperature Summary For SECY UPI Large Break Plant Ncme: Prairie Island Units 1 & 2 Utility Name: Northern States Power I

Revisi,on Dat,e: 3/4/99 A n alysis Infonnation P

EM: UPI WCOBRNTR Anslysis Date: 03 95 Limiting Break Size: Cd = 0.4 FQ: 24 FdH: 1.77 Fuel: OFA SGTP(%): 15 Notes: Zirlo LICENSING BASIS Analysis-Of-Record PCT 2180 1.2 (a)

MARGIN ALLOCATIONS (Delta PCT)

A. PRIOR PERMANENT ECCS MODEL ASSESSMENTS

1. Total 196 3,4 B.10 CFR 50.59 SAFETY EVALUATIONS I. None O

C.1998 to CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin) 1

1. None 0

D. TEMPORARY ECCS MODEL ISSUES

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1. None O

E. OTIIER

1. None 0

LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT = 1984 p

• It is recommended that these temporary PCT allocations u hich address current LOCA model issues not be considered with respect to 10 CFR 50 46 reporting requirements.

References:

1. 95 NS-G-0021, " Updated UPI LHlDCA." March 24.1995.

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2. WCAP-13919, Addendum I,"Praine Island Units 1 and 2 WCOBRATR AC Best Esttmate UPI Large Break LOCA Analysis Engineenng Report Addendum 1: Updated Results." December 1996

3. Annual Reports for 1995 through 1997 (NSP-96-202, NSP-97 201, NSP-98 012).

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NSP-98 012. "Northem States Power Cornpany Praine Island Units I and 210 CFR 50.46 Annual Notdication and Reportmg for j 1997." February 27,1998.

I Notes:

(a) P-bar HA increased from 1.57 to 1.59 Thursday, March 04,1999 Page1ofI A

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