ML20086H288

AO 50-271/72-06:on 720928,steam Line High Differential Pressure Switch DPIS 13-84 Failed to Operate at Required 180 Inches of Water.Caused by Broken Common Lead.Lead Repaired

ML20086H288
Person / Time
Site:	Vermont Yankee
Issue date:	10/03/1972
From:	Rosalyn Jones VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086H282	List: ML20086H288 ML20086H295 ML20086H300 ML20086H303 ML20086H307 ML20086H309
References
AO-50-271-72-06, AO-50-271-72-6, VYV-2272, NUDOCS 8401160319
Download: ML20086H288 (1)

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L x};Q VElu!oNT Y ANKEM NUCLMAR power Con POR ATION SCVENTY GCVcN OROVE STRCCT l(UTI.AND. VICitMONT 03701 VYV-2272 .

REPLY T O:

P. O. nOX 157 VERNON. VCRMONT 05334 October 3, 1972

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Director /

Directorate of Licensing j 7 , ' .~I U-A U.S. Atomic Enerf;y Conmission jt.7 /

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Wa:;hington, D.C. 20545 l'9 //

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REFERENCE:

Operating License DPR-28 y. ,,._ f Docket No. 50-271 f,. -

Abnornal Occurrence No. A0-72-06 yoh ( [ ,ib -, ';

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Dear Sir:

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As defined by Technical Specifications for the Vernont Yankee Nuclear Power Station, Section 6.7.B d, we are reporting the following Abnorral Occurrence as A0-72-06.

On September 28, during the conduct of the nonthly surveillance on the Reactor Core Icolation Cooling (RCIC) Systcm, the Stean Line Ifigh d/p switch (DPJS 13-S4) for one channel failed to operate at 180 (+ 15) inches of water as required by Table 3.2.2.3 of Technical Specifications. At thin tine the q reactor was operat.ing at approxinately 18% power. Investigation revealed that the switch cornon lead between the conduit and the switch terninal board was broken.

The broken lead was irrediately repaired and the switch was functionally tested and verified to te operable. Further investigation, after restoration of the system to service, yielded the conclusion that this break was apparently j the result of a partial crimping due to an over streso during initial installation.

Li,- Subsequent deterioration of the insulation and uire dt.c to normal vibration caused the wire to fall. The othcr two wires showed no 3vidence of having been

,/ damaged. The Plant Operat' ions Review Conmittee conclude I that a repetition I. of thir. type of occurrence could best be prevented by he ghtened vigilance for g; similar patential failures by instrunent technicians during the course of their

,' activities. This recon =endation has been impleuented.

Very truly yours, VERMONT YANKEE . NUCLEAR POWER CORPORATION

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8401160319 721024

{DRADOCK 05000271 PDR

/t' N/ [i Robert F. Jones Plant Superintendent L*,JE / rpb COPY SENT REGION s9 N b />

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