ML20009F449

Revised Third Interim Deficiency Rept Re Capacitors on Consolidated Controls Corp Field Buffer Cards,Initially Reported 810123.Failure Caused by Large Inrush Current.Also Reported Under Part 21

ML20009F449
Person / Time
Site:	Bellefonte
Issue date:	07/09/1981
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-PT21- 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8107310164
Download: ML20009F449 (2)

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OFFICIAL COPY

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400 Chestnut Street Tower II e-July 9, 1981 J' BLRD-50-438/81-12 BLRD-50-439/81-12 q'g s@ llhW/

Mr. James P. O'Reilly, Director Office of Inspection and Enforcement

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U.S. Nuclear Regulatory Commission 2 JUL .' O 1981 * -

Regicn II - Suite 3100 s i

{'- vo eucuu * "'55irmwoes 101 Marietta Street s Atlanta, Georgia 30303 y y

Dear Mr. O'Reilly:

• W BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 CAPACITORS ON CONSOLIDATED CONTROL CORPORATION FIELD BUFFER CARDS - BLRD-50-438/81-12, BLRD-50-439/81 REVISED THIRD INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector M. Thomas on January 23, 1981, in accordance with 10 CFR 50.55(e) as NCR 1309 This was followed by our interim reports dated February 23, May 27, and June 19, 1981. As discussed with R. V. Crlenjak by telephone on June 30, 1981, enclosed is our revised third interim report. We expect to submit our next report by January 12, 1982. The reason for the revision is for clarification of the interim p 7gress. We consider 10 CFR Part 21 to be applicable to this deficiency.

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 Comission Washington, DC 20555 m

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8107310164 810709 6 PCR S

ADOCK 05000438 PDR

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o .m o e ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 CAPACITORS ON CONSOLIDATED CONTROL CORPORATION FIELD BUFFER CARDS BLRD-50-438/81-12, BLRD-50-439/81-12 REVISED THIRD INTERIM REPORT Description of Deficiency Field buffer cards (6N193-1) in the Solid-State Control System (SSCS) are vendor supplied by Consolidated Controls Corporation. The card can be used interchangeably in koth safety-related and nonsafety-ralate.d systems. Some field buffer cards have been experiencing railures of the capacitors en the cards, resulting in card failures.

Interim Prograss i Site inspections have been completed and all cards which have discrepancies have been identified.

Although only the 6N193 field bu: cards were cited as possibly deficient, additicnal cards used in the SSCS for Bellefonte units 1 and 2 were analyzed.

The ca]acitor's failure was because of a large inrush current re%1 ting from insertion of a card into a powered cabinet. A different type capacitor (tantalum electrolytic) and a current limiting resistor were added to design drawings. Implementation of these design changes should eliminate further failures.

Capacitors which were evaluated as unnecessary for circuit function shall be removed. This is the case for the 6N191, 6N193, and 6N196 cards.

As a result of their analysis, the vendor is undertaking an extensive rework program on the 6N191, 6N193, and 6N196 cards, and they expect to provide TVA with an engineering report detailing their findings.

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