ML20086H414

AO 50-271/72-03:on 720824,six Sensing Lines in Drywell Mismatched W/Respective Instruments on Racks 25-26. Mismatched Lines Corrected & Other Lines Visually Inspected

ML20086H414
Person / Time
Site:	Vermont Yankee
Issue date:	09/01/1972
From:	Rosalyn Jones VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086H406	List: ML20086H414 ML20086H423
References
AO-50-271-72-03, AO-50-271-72-3, VYV-2228, NUDOCS 8401170110
Download: ML20086H414 (2)

Text

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2 . O O VicRMONT YANKElc NUCLEAR POWER CORPORATION SEVENTY GCVCid OROVC GTRCCT l(tJTLAND, VEliMONT 03701 ftEPLY 701 VYV-2228 c. o. Box 157 VERNON, VERMONT 05354 September 1, 1972 Director i . ?x Directorate of Licensing United States Atomic Energy Commission .

Washington, D.C. 20545 I

Reference:

Operating License DPR-28 , ,

} ..

Docket No. 50-271 ?l Abnormal Occurrence No. A0-72-03 f, ,s i ./'

Dear Sir i N/

As defined by Technical Specifications for the Vermont Yankee  ;

Nuclear Power Station, Section 6.7.B.d, we are reporting the following i o A ust , 1972, a technician, while working in thn area of instrument rack 25-26, noticed that the indicated flow for Main d  %

Steam Line 'A' was negative when in fact it should have indicated zero :g f.)

flow. lie then prompted an investigation that revealed that the six j W t. ;i sensing lines going from instrument rack 25-26 to the drywell through g 7.Q e f penetration X-30 were ' rolled' within the dryuell wall 3enetration such that the six sensing _ lines _in_the drywell were mismatched with their S McL.

f;

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respective instruments on rack 25-26. The result of this mismatch was

_ i.h that the Stedm Line High Flow instrument channels on both stean lines A and B uere inoperable. Technical Specifications table 3.2.2.1 and associated Note 2 require that a minimum of two channels per steamline per Trip System be operabic.

During the period of time that the Main Steam Line High Flow prinary containment isolation instrument channels were inoperable, the reactor pressure had been above 600 psig. During this sane period of time, however, the Main Steam Isolation Valves were in the closed position as required by Operating License DPR-28.

The Steam Line High Flou sensing lines accounted t'or four of the six nismatched instrument lines. The remaining two lines are pressure sensing lines that tap into the suction of the Recirc lines and provide the reactor pressure permissive signal for the injection of LPCI. The LPCI system was not required to be operable at anytime while these sensors were inoperable, ,

8401170110 721026 PDR ADOCK 05000271

• G PDR

__. /l091

-* VERMONT YANKEE LEAR POWER CORPORATION United States Atomic Energy Commission September 1, 1972 Page 2 The mismatched sensing lines were corrected on 8/24/72. All other instrunent lines that penetrate the drywell have been visually inspected and it has been verified that the sane condition does not exist in any other drywell penetration.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION o' - . -

.,'. . s.

Robert F. Jones Plant Superintendent WPM /rpb s

' hC_____.