ML20004F758

Second Interim Deficiency Rept Re Addl Level of Under or Over Voltage Protection,Initially Reported on 810403.New Design Will Be Finalized & Tech Spec Changes Will Be Submitted by Late 1981.Next Rept by 811117

ML20004F758
Person / Time
Site:	Sequoyah
Issue date:	06/03/1981
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, NUDOCS 8106220289
Download: ML20004F758 (2)

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TENNESSEE V ALLEY AUTHORITV cwAmacocA. ENNEsste 3 4ct 400 Chestnut Street Tower II 4i d ja June 3, 1981

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JU,y I g ]ggj m Mr. James P. O'Reilly, Director Office of Inspecticn and Enforcement

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4 U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303 Qp

Dear Mr. O'Reilly:

SEQUOYAH NUCLEAR PLANT UNIT 2 - ADDITIONAL MVEL CF UNDER CR CVER VOLTAGE PROTECTION - SQRD-50-328/81 SECOND INTERIM REPORT The subject deficiency was initially reported to NRC-OIE Inspector R. V. Celenjak en April 3,1981, in accordance with 10 CFR 50.55(e) as NCR SQN EEB 8114. An interim report was submitted on April 28, 1981. Enclosed is cur second interim repert. We expect to submit our next report by November 17, 1981.

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

Very truly yours, TENNESSEE VALLE! AUTHORITY cy,

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L. M. Mills, Manager Nuclear Regulation and Safety Enclosure-cc:

Mr. Victor Stello, Director (Enclosure)

Office of Inspection and. Enforcement U.S. Nuclear Regulatory Consnission Washington, DC 20555 sn11 J i

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ENCLOSURE SEQUOYAH NUCLEAR PLANI UNIT 2 ADDITIONAL LEVEL OF UNDER CR CVER VOLTAGE PROTECTION SCRD-50-328/81-28 10 CFR 50.55(e)

SECOND INTERIM REPORT Descriction of Deficierx /

During a design review, it was determined that the present design of the additional level of under or over voltage protection does not fully em: ply with the time delay selection guidelines as stated in NFC Staff Position 1,

" Degraded Grid Voltage Position." nese guidelines state that the time delay selected shall:

(1) not exceed the maxim, time delay that is assumed in the FSAR accident analysis; and (2) minimize the effect of short duration voltage transients en the availability of the offsite power sources. The design basis for the present design was that an accident would not occur during the time delay. Se time delay of 30 se<: ends was

s. elected to satisfy item 2 above. Because of this 30 second delay, TVA's design exceeds the maximm safety response time of 22 seconds (as stated in the FSAR) recuired for mitigating an accident.

Interim Progress As stated in the terms of the unit 1 operating license, T7A has

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cc==itted to the imi.? e=entation of degraded voltage relaying on the Class IE ac auxiliary power system by the end of unit 1 refueling outage.

TVA hasi completed its evaluation of the present design to. determine-what modifications are. *cea-a v to comply with NRC Staff Position 1.

TVA expects to finalize the nsa des gn and submit technical specification changes incorporating the degrac.3d volts ' relaying design to NRC-NRR for-review by late 1981.

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