ML20138H747
| ML20138H747 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 04/30/1997 |
| From: | Gambhir S OMAHA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LIC-97-064, LIC-97-64, NUDOCS 9705070263 | |
| Download: ML20138H747 (8) | |
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Omaha PublicPowDistrict 444 South 16th StreetMall Omaha NE68102-2247 l
April 30, 1997 LIC-97-064 l
U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Wa1.ngton, D.C.
20555
References:
1.
Docket No. 50-285 2.
WCAP-13027-P. ' Westinghouse ECCS Evaluation Model for Analysis of CE-NSSS." dated July lo91 3.
WCAP-13451, "Westinghws Mcthodology for Implementation of 10 CFR 50.46 Reporting." da ec October 1992 l
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Letter from OPPD (T. L. Patterson) to NRC (Document Control Desk),
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dated August 21, 1996 (LIC-96-0119)
SUBJECT:
Annual Report for 1996 Loss of Coolant Accident (LOCA)/ Emergency Core Cooling System (ECCS) Models Pursuant to 10 CFR 50.46 l
In accordance with 10 CFR 50.46(a)(3)(ii), the Omaha Public Power District (OPPD) is submitting the annual 10 CFR 50.46 summary report for 1996. This summary report updates all identified changes or errors in the LOCA/ECCS codes and methods used by Westinghouse Electric Corporation (W) to model Fort Calhoun Station (FCS) Unit No.1. Reference 2 describes the methodology utilized by W to model Combustion Engineering plants, such as FCS.
In Reference 4, OPPD provided notification of significant changes / errors as defined in 10 CFR 50.46(a)(3)(11).
- contains the one error and change identified using the NOTRUMP code for the small break Loss of Coolant Accident (SBLOCA) analysis. contains the one error and change identified related to translation of fluid conditions between the SATAN blowdown hydraulits code and the LOCTA fuel rod j
subchannel analysis code for the large break Loss of Coolant Accident (LBLOCA) analysis. summarizes the small break LOCA/ECCS peak c1 i temperature (PCT) margin utilization and the large break LOCA/ECCS PCT margin utilization.
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U. S. Nuclear Regulatory Commission LIC-97-064 Page 2 includes the Reference 4 significant change / error associated with modeling of the steam generator orifice plates, subsequent to transmittal of Reference 4, a more detailed assessment of the orifice plate effects was completed and the very conservative estimate of +112*F penalty for PCT previously reported in Page 2 of Reference 4 was revised to +100 F for the SBLOCA and +98 F for the LBLOCA.
The revised values correspond tc 20% steam generator (SG) tube plugging, while une actual Cycle 17 tube plugging levels are 15.6% for the A SG and 15.3% for the B SG. Thus, use of the 100*F and 98*F PCT increases are conservative. OPPD currently plans to remove the SG orifice plates following completion of Cycle 17 oDeration and restore the plant to a configuration which is bounded by the previous LOCA/ECCS analysis assumption of 6% SG tube plugging. Thus, it is OPPD's position that operation for the remainder of Cycle 17 (before removing the SG orifice plates) is conservatively analyzed and no further analysis is required.
1 In conclusion, the non-significant cumulative errors / changes identified or implemented through 1996 result in a net increase of 10"F PCT for the SBLOCA analysis and a net i
decrease of 5*F PCT for the large break LOCA (LBLOCA) analysis.
Combined with the revised estimates of the SG orifice plate effects previously noted, the resultant "'.0CA and LBLOCA PCT values continue to re%. less than the 10 CFR 50.46(b)(1) acceptance criteria of 2200*F.
Please contact me if,
ave any questions.
Sincerely, l
l W q
S. K. Gambhir Divisiun Manager i
Engineering and Operations Support SKG/tcm l
l Attachments l
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c:
Winston & Strawn l
E. W. Merschoff, NRC Regional Administrator, Region IV i
L. R Wharton. NRC Project Manager W. C. Walker, NRC Senior Resident Inspector
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LIC-97-064 Page 1 l
FORT CALHOUN STATION SMALL BREAK LOCA ANALYSIS NOTRUMP/SBLOCTA FUEL R0D INITIALIZATION ERROR l
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LIC-97-064 Page 2 NOTRUMP/SBLOCTA FUEL R0D INITIALIZATION Affected_Evahiationliodel 1985 Westinghouse Small Break Loss-of-Coolant-Accident (LOCA) Evaluation Model Using NOTRUMP I
Backgrouna An error was discovered in the SBLOCTA code related to adjustments which are made as part of the fuel rod initialization process used to obtain agreement between the SBLOCTA model and the fuel data supplied from the fuel thermal-hydraulic design calculations at full power, steady-state conditions. Specifically, an adjustment to the power, which is made to compensate for adjustments to the assumed pellet diameter, was incorrect.
Additionally, updates were made to the fuel rod clad creep anc strain model to correct logic errors that could occur in certain transient conditions. These model revisions also had a small effect on the fuel rod initialization process, and can produce small effects during the t.ransient. Due to the small magnitude and the interaction between L
the two items, they are being evaluated as a single, closely related effect.
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correction is a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.
i Estimated _Effect Representative plant calculations have led to an estimated effect of +10*F for this error correction.
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l FORT CALHOUN STATIO!1 i
i LARGE BREAK LOCA ANALYSIS I
IRANSLATION OF FLUID CONDITIONS ERROR i
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l LIC-97-064 Page 2 TRANSLATION OF FLUID CONDITIONS FROM SATAN TO LOCTA Affected_EvaluatjorLEodels 1981 Westinghouse large Break LOCA Evaluation Model
Background
An error was discovered in the coding related to the transic+ ion of fluid conditions between the SATAN blowdown hydraulics code and the LOCTA cou used for subchannel analysis of the fuel rods. In performing axial interpolations to translate the SATAN fluid conditions onto the mesh nodalization used by the LOCTA code, the length of the lower core channel fluid connection to the lower plenum node was incorrectly calculated.
This correction is a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.
Estimated _ Effects Renresentative plant calculations have lead to an estimated effect of -5'F for this error correction.
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LIC-97-064 i
Page 1 FORT CALHOUN STATION LOCA PEAK CLAD TEMPERATURE (PCT)
MARGIN UTILIZATION SHEETS i
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i LIC-97-064 Page 2 1996_ SMALL. BREAK 1EAK_ C LAD _ TEMPERATURE. MARGIN _ UTI LIZATION FORT _CALH0VN3TATION_ UNIT _NO._1 CLAD _IEMEERATURE A.
Analysis of Record (8/91)
PCT - 1444*F B.
Prior Permanent ECCS Model Assessments APCT - -14*F C.
10 CFR 50.59 Safety Evaluations -SG Orifice Plates APCT - 100* F D.
1996 10 CFR 50.46 Model Assessments this Update (Permanent Assessment of PCT Margin) -
A P.T -
10*F SBLOCTA Fuel Rod Initialization Error E
Temporary ECCS Model Issues - None APCT -
0*F F.
Other Margin Allocations - None APCT -
0F LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT - 1540*F i
1996_LARGE_ BREAK _PEAKILAD_ TEMPERATURE _ MARGIN _ UTI LIZATION FORT _CAli 00N_ STATION _UNILN0.._1 l
CLAD _ TEMPERATURE l
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Analysis of Record (8/91)
PCT - 2066*F j
B.
Prior Permanent ECCS Model Assessments APCT - -25'F 1
C.
10 CFR 50.59 Safety Evaluations - SG Orifice Plates APCT -
98'F l
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1996 10 CFR 50.46 Model Assessments APCT -
-5 F (Permanent Assessment of PCT Margin) -
Translation of Fluid Conditions From SATAN ta LOCTA l
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Temporary ECCS Model Issues - None APCT -
0F F.
Other Margin Allocations - None APCT -
0* F LICENSING GASIS PCT + MARGIN ALLOCATIONS PCT - 2134*F i
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