ML20100B720

Part 21 Rept Re Error in TOODEE2 Code Used in LOCA-ECCS Analysis for DC Cook Unit 1.Initially Reported on 850315. Analysis Affected by Coding Error Reperformed Using Corrected Version of TOODEE2

ML20100B720
Person / Time
Site:	Cook
Issue date:	03/22/1985
From:	Owsley G SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:	Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-85, REF-PT21-85-169-000 GFO:85:010, GFO:85:10, PT21-85-169, PT21-85-169-000, NUDOCS 8503280536
Download: ML20100B720 (2)

Text

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g0gNUE NE, PO DOX 90m BELLEVUE,WA 98009 March 22, 1985 GF0:85:010 Mr. Richard DeYoung, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

Error in the T00DEE2 Code Used in the Evaluation Model for PWR's Ref.: G.F. Owsley (ENC) letter to Mr. H. Denton (NRC);

Subject:

Error in the 48,000 MWD /MTU LOCA-ECCS Analysis for D.C. Cook Unit 1, dated March 21, 1985

Dear Mr. DeYoung:

As has been reported to the Office of Nuclear Reactor Regub tion in a telephone call from Mr. James Morgan of our organization on March 15,1985 and by the reference letter, an error was discovered in the Evaluation Model used by Exxon Nuclear which affected the LOCA-ECCS analyses for some PWRs. This error was identified by Exxon Nuclear on March 15, 1985. The error was in an expression for a multiplier on the heat transfer coefficient used in T00DEE2, which was incorrectly programmed into the code.

T00DEE2 calculates the thermal response (heatup) of the hot fuel rod following the end of the blowdown transient until the core tcmperature transient is terminated. The incorrect coding caused the heat transfer coefficient multiplier in T00DEE2 to be 1.045, when it was intended to be 1.0 based on input to the code.

This notification is provided following the procedures identified in Part 21.21(b)(3). However, Exxon Nuclear does not believe this error could create a substantial safety hazard. Exxon Nuclear has now evaluated the impact of the error on all affected reactors and has concluded that the error would not_ result in exceeding the criteria of Part 50.46 during operation at the Technical Specification limits.

The reactors which were reanalysed by Exxon Nuclear with the error corrected were D. C. Cook Unit 1, Fort Calhoun, and St. Lucie Unit 1. The licensees operating each of these plants were notified of the error on March 15, 1985 and have been advised of the impact of the error on the analysis performed by Exxon Nuclear for their reactors.

The error effecting D. C. Cook Unit I was in the analyses to support increased burnup from 42.2 MWD /kg to 48.0 MWD /kg as reparted in Exxon Nuclear document XN-NF-83-tA. The analyses to support burnup points up to 42.2 MWD /kg were previously repcrted in XN-NF-81-07 and were done with a version of T00DEE2 which did not contain the error.

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. 2 Mr. Richard DeYoung March 22, 1985 U.S. Nuclear Regulatory Commission Page 2 ENC has reperformed the 48 MWD /kg exposure analysis which was affected by the coding error. The peak clad temperature calculated with this analysis using the corrected version of T000EE2 at 48 MWD /kg is 1785 F versus the previous value of 1736gF for operation with a single LPSI pump. Using the same sensitivity study applied in XN-NF-83-61 the PCTincreasefrgmtheanalysis for maximum rather than minimum (single pump) LPSI flog is 42 F' Therefore, the PCT reported in XN-NF-83-61 was increased from 1736 F to 1778 F to account for maximum LPSI Thus flgw.F to increased from 1785 1827[n F. the Thecorrected analysis the upward adjustment calculated in PCT PCTfor to account is maximum LPSI flow was not reported in the reference letter.

If there are questions, or if I can be of further help, please contact me.

Sin erely G. F. Owsley, anager Reload Licensing Liaison GF0:lco cc: Mr. J.G. Feinstein (AEP)

Mr. D. L. Wigginton (NRC)

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