ML20086D784

Updated AO 73-08:on 730307,time Delay Relay Failed to Actuate Isolation of Sys within Specified Time.Check of Timer Will Be Conducted After 3 Months to Confirm Reliability of Timer.Relay Replaced & Bench Tested

ML20086D784
Person / Time
Site:	Vermont Yankee
Issue date:	03/08/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086D786	List: ML20086D784 ML20086D792
References
AO-73-08, AO-73-8, VYV-2505, NUDOCS 8312050115
Download: ML20086D784 (2)

Text

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, VERMONT YANKEE NUCLEAR POWER CORPORATION SEVENTY SEVEN OROVE STRECT RUTLAND, VF.MMONT OG701 VYV-2505 P. O. BOX 157 i VERNON, VERMONT C5354 March 8, 1973 tD l\

Director @ .g Directorate of Licensing f U.S. Atomic Energy Commission &

Washington, D.C. 20545 "-f kg ~

REFERC;CE: Operating License DPR-28 ,

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h [0 Docket No. 50-271 Abnormal Occurrence No. A0-73-08

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Dear Sir:

1 As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.B d, we are reporting the following Abnormal Occurrence as A0-73-08. ~

At .approximately 1420 on March 7,1973 while performing routine surveillance on the RCIC system, a time delay relay failed to actuate  :/

an isolation of the system within the 30 +5 minutes specified by Table 3.2.2.3 of the Technical Specifications. The time delay relay, -

13A-K41, which initiates an isolation of the RCIC system upon receipt I of a high temperature signal in the Main Stean Line Tunnel, did not I operate untild0~minUtieJ af ter a simulated high temperature was induced on the logic. The reactor was operating at approximately 75% at the time of this incident.

pp,. ./ -g, 7 The RCIC isolation valves were closed as specified by Note 3 of Table 3.2.2.3 of the Technical Specifications and testing of the HPCI system was started as specified in Section 3.5.G.2. A new relay was bench tested for the correct time delay . and installed in the RCIC system. The RCIC system logic test was then conducted and the new relay uas verified to operate properly and the system was back'in-service at 1725 on March 7, 1973.

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VERMONT Y NKEE NUCLEAR POWER CORPORATION l

Directorate of Licensing March 0, 1973 Page 2 The Plant Operations Review Committee concluded that although this was probably an isolated incident, a check of the timer would be conducted three nonths after the incident to confirm the reliability of the timer.

Very truly yours, VERf!ONT YANKEE NUCLEAR POWER CORPORATION B.W. Riley Plant Superintendent WPM /rph l

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