ML20086H423

AO 50-271/72-03:on 720824,flow for Main Steam Line a Noted Negative When Flow Should Have Been Zero.Caused by Six Mismatched Sensing Lines.Lines Corrected

ML20086H423
Person / Time
Site:	Vermont Yankee
Issue date:	08/25/1972
From:	Rosalyn Jones VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086H406	List: ML20086H414 ML20086H423
References
AO-50-271-72-03, AO-50-271-72-3, VYV-2222, NUDOCS 8401170123
Download: ML20086H423 (2)

Text

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Q g VERMONT YANKEE NUCLEAR POWER CORPORATION aCVENTY SCVCN OROVE STRCCT rut 1,Ano, VEMMONT OG701 REPLY Yoi m -2222 P. o. sox is7 VERNON. VERMONT 0535a August 25, 1972 i

United States Atomic Energy Cormaission Diret.torate of Reaulatory Operations, Region 1 970 Broad Street Newark, New Jersey 07102 REFERE! ICE: Operating License DPR-28 Docket No. 50-271 Abnormal Occurrence No. A0-72-03 Centlement As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.A.c, we are reporting the following Abnormal Occurrence as A0-72-03 and confirming our telephone conversation with your office on this date.

The afternoon of August 24, 1972, a technician, while working in the area of instrument rack 25-26, noticed that the indicated flow for Main Steam Line 'A' was negative when in fact it should have indicated.zero flow. He then prompted an investigation that revealed that the six sensing lines going from instrument rack 25-26 to the drywell through penetration X-30 were ' rolled' within the drywell vall such that the six sensing lines in the drywell were mismatched with their respective instruments on rack 25-26. The result of this mismatch was that the Steam Liue High Flow instrument channels on both steam If nes A and B vere 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 operable.

During the period of time that the Main Steam Line High Flow primary containment isolation instrument channels were inoperable, the reactor pressure had been (bove 600 psig. During this same period of time, however, the Hain Steam Isolation valves were in the closed position as required by Operating License DPR-28.

The Steam Line High Flow sensing lines accounted for four of the six mismatched instrument lines. The remaining two lines are pressure sensing lines that tap into the suction of the Recire 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.

0401170123 721026 PDR ADOCK 05000271 0 PDR ,

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VE7.MONT YANKEE A'UCLEAR POWER CORPORATIC

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United States Atomic Energy Commission . l August 25, 1972 i Page 2 The mismatched sensing lines were corrected on 8/24/72. All other instrument lines that penetrate.the drywell are being visually inspected to ensure that a similar condition does not exist elsewhere.

.Very truly yours. -- -- --

VB YANKEE NU EAR POWBR CORPORATION

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& A Robert F. Jo s ..

Plant Superintendent WPM /rpb e

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