ML20086D935

AO 73-28:on 730910,microswitch Installed in Differential Pressure Indicating Switch 2-129B Failed to Actuate at Required Setpoint.Sensor Rendered Operable by Replacing Microswitch Assembly

ML20086D935
Person / Time
Site:	Vermont Yankee
Issue date:	09/11/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086D933	List: ML20086D932 ML20086D935
References
AO-73-28, VYV-3021, NUDOCS 8312050683
Download: ML20086D935 (1)

Text

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. O O r s VEIN 10NT YANKEE NUCLEAR POwEn CORPOR ATION i W

SCVCNTY GCVEN OROVC STRCCT Ru rl. ann, VIMD10NT 05701 VYV-3021 , *h g m VCRNON. VCRMONT 05354 September 11, 1973 D beb gg ,

United States Atomic Energy Commission Directorate of Regulatory Operations, Region I

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REFERENCE:

Operating License DPR-28 g., \

Nf Docket No. 50-271 P, /

Abnormal occurrence No. A0-73-28 s J Gentlemen:

As defined by Technical Specificctions for the Vermont Yankee u... i o - u n. .a * < r n H nn Section 6.7.B.I. we are reporting che following nonot um veuut te.n e ao Ag 7 2 2 ....' --..firnin g :- - * * ' a""

a"^ # a "" " 'n" with your office. ,

At approximately 1330 on September 10, 1973, while performing a monthly functional test on the Lou Pressure Coolant Injection System (LPCI) break detection logic (i.e. , A>B d/p across risers) , a microswitch installed in DPIS 2-1293 f ailed to actuate at the required setpoint of 1 (-1,0.5) psid as specified in Tabic 3.2.1 of the Technical Specifications.

The microsuitch actuating arm was mechanica1'ly bound and failed to drop into the can valley. Functionally, this switch operates in conjunction with DPI^ 2-129D to actuate a relay in their respective logic st' rings to close the Loop "d" LPCI valves and actuate the Loop "A" Recirculation valves.

The reactor was shutdown at the time of this incident.

The sensor waa made operable by replacing the microswitch assembly which includes the switch, the switch actuating arm and backplate assembly.

Operation uas satisf actory af ter repeated actuations and the instrument channel uas declared operabic at 1619 on' September 10, 1973. .

Very truly yours, khD g

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VERMONT YANREE. NUCLEAR POWER CORPORATION g -

bk s-Bradford W. Riley

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Plant Superintendent gW~, , '}.Q -

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Cwi DEN 1' REGION

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