ML20086D734

Updated AO 73-14:on 730530,fuse Which Supplies Ac to Main Steam Line Radiation Monitor Drawer 17-251D & High Voltage Power Supply for Reactor Bldg Ventilation Area Monitors Blew.Blown Fuse Replaced & Isolation Cleared

ML20086D734
Person / Time
Site:	Vermont Yankee
Issue date:	06/06/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086D737	List: ML20086D734 ML20086D743
References
AO-73-14, VYV-2698, NUDOCS 8312020479
Download: ML20086D734 (2)

Text

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7 VERMONT YANKEE NUCLEAR POWER CORPORATION SCVENTY SEVEN OROVE STRCCT RUTLANn, VERMONT OG701 VYV-2698 r '$x157 e

VERNON. VERMONT 05354 June 6, 1973 V

- O Director Directorate of Licensing / 4 U.S. Atomic Energy Commission g]} [ l b)37 --"

Washington, D.C. 20545 ), g etcCSM eggd

-p Y MNNa N REFEREUCE: Operating License DPR-28 Docket No. 50-271 Abnormal Occurrence No. A0-73-14 \S A

Dear Sir:

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 A0-73-14.

At approximately 0900 on May 30, a fuse which supplies AC to'17-251D main steam line radiation monitor drawer and 17-451B high voltage power supply for reactor building ventilation area radiation monitors, blew.

The blown fuse caused a group III isolation. All valves functioned properly except FS0-109-75A and 753 (Drywell Oxygen Analyzer Isolation Valves) which indicated that they only traveled to the mid position.

Limiting Condition for Operation as defined by Section 3.7.D.1 of Technical Specifications requires that these valves be operable during power operation. The reactor was at 78% power at the time of the incident.

The blown fuse was immediately replaced, the isolation cleared, and the subject valves were cycled succccsfully several times. The valves were declared operabic by 0930 on May 30, 1973.

Since our 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> report, to the Directorate of Regulatory Operations, Region I, further investigation has indicated that the problem with valves FS0-109-75A and 75B is in the valve position indicating switches' failure 1

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VERMONT YANKEE NUCLEAR POWER ColtPORATION Directorate of Licensing l-June 6, 1973 Page 2 to provide correct remote indication rather than failure of the valves to actually achieve their required closing function. This belief is substantiated by the fact that after replacing the blown fuse the valves were inmediately and successfully cycled several times and further by the fact that in the following seven (7) days these va.1ves were successfully cycled on a daily basis. The Plant Operations Review Committee reviewed and noted these actions and recommended that the Operations Department physically verify the position of the valve solenoid slug if questionable remote indication occurs again on this type of valve.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION O

B.W. Riley Plant Superintendent PET /rpb e