U-601173, Special Rept:On 880329,discovered Failure of Wind Velocity & Direction Sensors on Facility Meteorological Tower.Caused by Inadvertent Exposure of Sensors to Weather.Sensor Assembly, Including Retaining Device Replaced

Special Rept:On 880329,discovered Failure of Wind Velocity & Direction Sensors on Facility Meteorological Tower.Caused by Inadvertent Exposure of Sensors to Weather.Sensor Assembly, Including Retaining Device Replaced

ML20151P570
Person / Time
Site:	Clinton
Issue date:	04/15/1988
From:	Spangenberg F ILLINOIS POWER CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
U-601173, NUDOCS 8804260197
Download: ML20151P570 (2)

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/EICRITY R0'J11N3 10CFR50.36 April 15, 1988

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'1LE A Docket No. 50-461 Mr. A. B. Davis Regional Administrator Region III U.S. Nucleer Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Special Report: Failure of Wind Velocity and Direction Sensors on the CPS Meteorological Tower

Dear Mr. Davis:

CPS Technical Specification 3.3.7.3, ACTION "a", requires all failures of meteorological monitoring instrumentation channels for more than seven days to be reported to the Commission pursuant to Specification 6.9.2, SPECIAL REPORTS, within 10 days. The wind velocity and direction sensors at the 60 meter elevation on the CPS meteorological tower failed as a result of the exposure of the sensors to the weather. Accordingly, this report is submitted to provide the information regarding the cause of the malfunction and plans for restoration to OPERABLE status.

Cause of Malfunction on March 29, 1988, Maintenance Work Request (MWR) C46047 was initiated to determine the cause of the failure of Main Control Roon, recorder IUREM015 which is used to monitor wind velocity and direction at the 60 meter elevation. Investigation rev aled that the wind velocity and direction sensor circuitry (printed circuit board) had been damaged due to inadvertent exposure to the weather. The sensor circuitry is normally environmentally protected with a cylindrical metal cover that has sealing rings at the top and bottom and a single retaining device to hold it in place. This device was found open allowing the shell to be displaced from the normal position and exposing the sensor circuitry to the elements.

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'8804260197 880415 PDR ADOCK 05000461 S APR 191988 DCD _

. U-601173 L30-88 (04 -15 )-LP 1A.120 Plans for Restoration The sensor assembly, including the retaining device, was replaced and the system returned to OPERABLE status on April 5, 1988. Repair of this device was delayed because adverse weather conditions (i.e. high winds) prevented timely troubleshooting of the problem. The manufacturer indicated that they have had no problems with the retaining device. Also, this sensor assembly has been in service at Clinton for over seven years without failure of the the retaining device. In that this is the first such failure CPS has experienced with this component, no further corrective action is warranted.

If you have any questions regarding this event, please contact me.

Sincerely yours,

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2r F. A. Sp en rg, III Manager - iceNsing an Safety KBR/krm cc: NRC Clinton Licensing Project Manager NRC Resident Office Illinois Department of Nuclear Safety