ML20003H317
| ML20003H317 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/28/1981 |
| 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, SQRD-50-328-81, NUDOCS 8105050542 | |
| Download: ML20003H317 (2) | |
Text
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SORD-50-328/81-28
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Mr. Jamqs P. O'Peilly, Director Office o Inspection and Enforcement U.S. Nucle Regulatory Ca mission Region II -
ite 3100 101 Marietta eet Atlanta, Georgi 30303 Der Mr. O'Reilly:
SR00ZAH NOCLEAR PIAVf INIT 2 - ADDITICNAL LEVEL OF UNDER OR OVER VOLTAGE PFOIII'IIOT - SQRD-50-328/81 FIRST Ihm REPORP Tae subject deficiency was initially reported to NBC-CIE Irwi.Or R. V. Crlenjak on April 3,1981, in accordance with 10 CFR 50.55(e) as NCR SCti EEB8114. Enclosed is our first interim recort. We excect to sutmit our next report by June 2,1981.
If you have any questims, please get in touch with D. L. Lambert at prs 857-2581.
Very truly yours, TH@iE3SEE VALLEY AITIECRITY L. M.. Mills, Manager Nuclear Pegulaticn and Safety Enclosure
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cc: Mr. Victor Stello, Director (Enclosure) V Office of Inscection and Enforcement U.S. Nuclear Pegulatorv Ccmission Washington, DC 20555 Tol9 s
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8105050 5 %
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o-SEQUOYAH NUCLEAR PLANT UNIT 2 ADDITICNAL LEVEL CF UNDER OR OVER VOLTAGE PROTECTICN 10 CFR 50.55(e)
SQRD-50-328/81-28 FIRST INTERIM REPORT
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Descriotion of Deficiency During a design review, it was determined that the present design of the additional level of under or over voltage protection does not fully comply with the time delay selection guidelines as stated in NBC Staff Position 1,
" Degraded Grid Voltage Position." Rese guidelines state that the time delay selected shall:
(1) not exceed the maximum time delay that is assumed in the FSAR accident analysis; and (2) minimize the effect of short duration voltage transients on the availability of the offsite power sources. S e design basis for the present design was that an accident,
would not occur during the time delay. Se time delay of 30 seconds was selected to satisfy item 2 above. Because of this 30 second delay, 'IVA's design exceeds the maximum safety response time of 22 seconds (as stated in the FSAR) required for mitigating an accident.
Interim Prcaress As stated in the Sequoyah Nuclear Plant Safety Evaluation Report, 'IVA has ccanitted to the implementation of degraded voltage relaying on the Class IE ac auxiliary power system by the end of the first unit 1 refueling outage.
TVA is evaluating the present design to determine what nodifications must be made to comply with the time delay selection guidelines.
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