BVY-99-109, Ro:On 990812,stack Ng Effluent Instrumentation for PAM Was Declared Oos.Caused by Instrument Drift Due to Electronic Components Based on Insps by Instrumentation & Controls Dept.Detector & Preamplifier Will Be Replaced on 990831

Ro:On 990812,stack Ng Effluent Instrumentation for PAM Was Declared Oos.Caused by Instrument Drift Due to Electronic Components Based on Insps by Instrumentation & Controls Dept.Detector & Preamplifier Will Be Replaced on 990831

ML20211G593
Person / Time
Site:	Vermont Yankee
Issue date:	08/19/1999
From:	Balduzzi M VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-99-109, NUDOCS 9908310295
Download: ML20211G593 (1)

Text

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V.ER'MONT YANKEE NUCLEAR POWER CORPORATION yN- P.'O, Box 157, Governor Hunt Road Vornon, Vermont 05354-0157 sv

{ (802) 257-7711 August 19,1999.

BVY 99109 U.S. Nuclear. Regulatory Commission ATfN: Document Control Center Washington, D.C. 20555

Subject:

. Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)

Post-Accident Stack Noble Gas Effluent Instrument Out of Service Greater Than 7 Days The Stack Noble Gas Effluent Instrumentation for Post-Accident Monitoring was declared out of service on August 12,1999. The Victoreen Model #945A Wide Range Area Monitoring System was determined to have drifted high (over response) during a scheduled I 8 month calibration surveillance. Local sampling ,

capability for Noble Gas Effluent is available via a routine Chemistry sample point and a Post Accident I sample point.

Vermont Yankee Technical Specification Table 3.2.6 Note 7 indicates that:

"From and after the date that this parameter is unavailable by Control Room indication, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> ensure'that local sampling capability is available. If the Control Room indication is not restored within 7 days, prepare and submit a special report to the NRC within 14 days following the event, outlining the action taken, the cause of the inoperability, and the plans and schedule for restoring the system to operable status."

The apparent cause for the instrument inoperability appears to be instrument drift due of the electronic components based on inspections by the Instrumentation and Controls Department. It's expected that the detector and preamplifier will be replaced, calibrated and returned to service by August 31,1999. 1 This letter is submitted to satisfy the special report requirement of our Technical Specifications for Post-Accident Instrumentation. We trust that you will find this submittal satisfactory. However, should you desire additional information, please feel free to contact :s.

Sincerely, Vermont Yankee Nuclear Power Corporation Y W f t' Michael A.Baldezzi //

, Plant Manager cc: USNRC Region 1 Administrator USNRC Resident Inspector - VYNPS USNRC Project Manager- VYNPS >

Vermont Department of Public Services I

9900310295 990819 ' ') 1 }

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