ML20086E473

AO 74-09:on 740625,movements of LPCI Loop Break Detection Logic Differential Pressure Indicating Switches 2-129B & 2-129C Sluggish,Causing Pointer to Lag Input Pressure.Switch 2-129B Replaced & 2-129C Placed in Trip Condition

ML20086E473
Person / Time
Site:	Vermont Yankee
Issue date:	06/26/1974
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086E468	List: ML20086E460 ML20086E473
References
AO-74-09, AO-74-9, VYV-3314, NUDOCS 8312070323
Download: ML20086E473 (1)

Text

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. . O O J VERMONT YANKEE NUCLEAR POWER CORPORATION

'v SCVcNTY GeVcN OROVc STRCCT RuTLAxn, Venotoxr osToi -

3M "]'$xis7 p o VERNON. VERMONT oS354 June 26, 1974

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Director Directorate of Regulatory Operations, Region I g { ,,L y

United States Atomic Energy Commission -

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REFERENCE:

Operating License DPR-28 [y .

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Docket No. 50-271 l__b</' ~

, Abnormal Occurrence No. AO-74-09 (24 Ilour Report)

Dear Sir:

As defined by Technical Specifications for the Vermont Yankee Nuclear Tower Otati-... :kction 0.7, we oa wartio;. the ivile in( Abuurral Occurrence as A0-74-09 and confirming our telephone conversation with your office.

At approximately 1200 on June 25, 1974, plant personnel who were performing routine instrument surveillance testing on the Riser d/p LPCI Loop Break Detection Logic discovered that the movements of DPIS 2-1293 and C uere sticking to the extent that the pointer would lag the input pressure by approximately 0.5 psid on increasing and decreasing pressure. This condition was determined to be in violation of Technical Specifications, Section 3.2, Tabic 3.2.1, in that the requirement for the minimum number of operable trip channels per trip system for the A>B d/p Across Risers trip functica was not satisfied. The plant was operating.

at 80% power at the time of this discovery.

Switch DPIS 2-129B was replaced with an operable spare and. switch DPIS 2-129C was placed in the tripped' condition and will remain that way until another operable spare can be obtained.

8312070323 740703 Very truly yours, PDR ADOCK 05000271 S

PDR VERMONT YANKEE NUCLEAR POWER CORPORATION M SENT M : 3 NS lC_.~

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U B.W. Riley g.c , Plant Superintendent Mdh '

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