ML20003G494

Final Rept Re Error in Tpipe Program,Initially Reported on 810327.Corrected Version of Tpipe Program Verified & Put Into Production.Poll Showed No Incorrect Design Info Issued from Using Error

ML20003G494
Person / Time
Site:	Yellow Creek
Issue date:	04/23/1981
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, YCRD-50-566-81, YCRD-50-567-81, NUDOCS 8104290669
Download: ML20003G494 (2)

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Dear Mr. O'Reilly:

YELLOW CREEK NUCLEAR PLANT UNITS 1 AND 2 - TPIPE PROGRAM ERROR -

YCRD-50-566/81-09, YCRD-50-567/81 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector J. Celenjak on March 27, 1981, in accordance with 10 CFR 50.55(e) as NCR YCN CEB 8104 Enclosed is our final report.

If you have any questions concerning this matter, please get in touch with D. L. Lambert at FTS 857-2581.

Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure cc: Mr. Victor Stello, Jr., Director (Enclosure)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 -

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ENCLOSURE YELLOW CREEK NUCLEAR PLANT UNITS 1 AND 2 TPIPE PROGRAM ERROR 10 CFR 50.55(e)

YCRD-50-566/81-09 AND YCRD-50-567/81-07 FINAL REPORT Description of Deficiency The TVA.TPIPE computer program was producing erroneous results when runnihg a modal superposition time history analysis on a problem with multiple arrival times and multiple zones. TPIPE versions 4 3 and 4.3A were in error. The TPIPE program was being reviewed for another type of problem when this error was discovered. An analysis of the error showed that the program could have potentially generated bad design information if the error had not been found and corrected.

Safety Implications The magnitude of any deficiency in analyzed piping systems caused by the error in the TPIPE code is a function of the given piping system and is impossible to evaluate without running each problem in question. This condition of erroneous results when running a modal superposition time history.. analysis with multiple arrival times and multiple zones could have potentially jeopardized the safe operation of the plant had it remained uncorrected in that the piping systems affected would not have been analytically verified as required.

Corrective Action To correct the described deficiency, a new corrected version of the TPIPE program was verified and put into production in place of the version in error. The verification benchmark problems are being reviewed and modified to help locatt .11s type of problem area. Also, all users which were using or had used the erroneous TPIPE versions were polled to determine if any incorrect design information had been issued. The results of this poll showed that no incorrect design data had been issued.

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