ML20199B460

Special Rept:On 980105,meteorological Monnitoring Instrumentation for Air Temp Delta T Inoperable for More than 7 Days.Caused by Breakdown in Wiring Between Junction Box at 199 Foot Level.Wiring Replaced

ML20199B460
Person / Time
Site:	Yankee Rowe
Issue date:	01/20/1998
From:	Williams F YANKEE ATOMIC ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TSD-98-01, TSD-98-1, NUDOCS 9801280283
Download: ML20199B460 (2)

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L2MKEE ATOMIC ELECTRIC COMPANY r. . . ,,,,,,,...,,,

w/ s g*& 49 Yankee Road, Rowe, Massachusetts 01367

.Y. Auxst .-

January 20, 1998 TSD 98-01 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Subject Special Report Meteorological Monitoring In'2rumentation ~ Air Temperature Delta T Inoperable For More Than 7 Days Dear Sir In accordanco with Yankee Nuclear Power Station of f-Site Dose Calculation H nual Section 5.5 Action Statement a, the attached 10 day Special Report outlining the action taken, the cause of the inoperability at.d the plans and schedule for restoring the instrument to operable status is hereby submitted.

Very truly yours, M lbu4 Frederick N. Williams Plant Superintendent

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~Jt2x ELH\ elm Enclosures con (3) NSARC Chairman (7AEC)

(1) USNRC. Region I (1) Resident Inspector

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YANKEE ATOHIC ELECTRIC COMPANY Page 1 TSD 98-01 DME9ROUND At 0700 houre, on January 5,1998, the Meteorological Instrumentation channel for 197-33 leet Delta T was declared inoperable due to apparent inaccurate readings indicated on the computer output trending display. This condition was found during performance of a routine meteorological data evaluation. The channel was declared operational at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on January 14, 1998. The Off-Site Dose Calculation Manual Action Statement requires the inoperable channel to be restored to operable status within 7 days.

ACTION TAKEF The meteorological monitoring instrumentation service contractor, TRC Environmental Corporation (TRC), was contacted to troubleshoot the channel on January 5th and were informed that the indication was consistent with that of an upper aspirator f ailure. Arrangements were made for TRC to provide technicians to investigate the problem the morning of January 7th. On the morning of January 7, TRC arrived and began to troubleshoot the channel. Curing the investigation the upper aspirator was found to be functioning properly. Continued troubleshooting indicated that the reference ternparature sensor was not providing the proper input to the channel. Replacement lower and upper sensors were ordered and arrangements were made to have TRC return as soon as the new sensors arrived (January 8th or 9th).

On January 9, TRC technicians arrived with the new s. The lower sensor, which supplies the reference input, was replaced. A .ibration of the channel was attempted without success. The upper sensor was s..en replaced and again the channel could not be calibrated. Troubleshooting continued until dark without finding the cause of the problem. The TRC technicians indicated that the earliest they would be available to continue work on the problem would be January 13th. On January 13, TRC called to postpone their arrival until January 14, due to existing weather conditions and the forecast for freezing rain and snow tor the remainder of the day which made the tower unsafe to climb. On the morning of January 14, TRC arrived and continued troubleshooting the wiring for the channel between the translator card and the temperature sensors. The wire between the top and bottom of the tower for the upper temperature sensor was replaced with a spare pair. The channel was calibrated and declared operational.

pMIE OF THE INOPERMMidII The root cause of the inoperability was attributed a breakdown in the wiring between the junction box at the 199 f oot level and the junction box at the base of the tower.

Jf1EDULE FOR RESTORATIQJ{

The wiring was replaced in kind using a spare pair of wires in the existing cable. The channel was declared operational at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on January 14, 1998, during the report preparation period.