U-602311, Special Rept:On 940624,inoperabilities of Meteorological Monitoring Instrumentation Channels for More than 7 Days Identified.Personnel Worked Expeditiously to Return Meteorological Instrumentation to Operable Status

Special Rept:On 940624,inoperabilities of Meteorological Monitoring Instrumentation Channels for More than 7 Days Identified.Personnel Worked Expeditiously to Return Meteorological Instrumentation to Operable Status

ML20071H562
Person / Time
Site:	Clinton
Issue date:	07/12/1994
From:	Phares R ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
U-602311, NUDOCS 9407190319
Download: ML20071H562 (3)

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liknois Power Company Chnton Power Station P.O Box 678

, Chnton. IL 61727 Tel 217 935-8881 ILLIN9IS 2 P44WER E29$(7 12>te 8E.100c July 12, 1994 Docket No. 50-461 10CFR50.36 Document Control Desk Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Special Report: Failure to Return Clinton Power Station I

Meteorological Tower Instrumentation to Service Within Allowed Out of Service Time

Dear Sir:

Clinton Power Station (CPS) Technical Specification 3.3.7.3, Action "a," requires inoperabilities of meteorological monitoring instrumentation channels for more than 7 days be reported to the Nuclear Regulatory Commission (NRC) within the next 10 days pursuant to Specification 6.9.2, SPECIAL REPORTS. The difTerential air temperature monitoring instrumentation was declared inoperable at 0315 hours0.00365 days <br />0.0875 hours <br />5.208333e-4 weeks <br />1.198575e-4 months <br /> on June 26,1994 and was not declared operable again until 2245 hours0.026 days <br />0.624 hours <br />0.00371 weeks <br />8.542225e-4 months <br /> on July 8,1994. This Special Report is therefore being submitted in accordance with the CPS Technical Specifications to provide information regarding the extended inoperability of the meteorological monitoring instrumentation.

The CPS Environmental Monitoring system utilizes a 199 foot high tower equipped with two levels ofinstrumentation to monitor the meteorological conditions at the plant. The toweris instrumented with wind direction, wind speed, temperature, and dewpoint (10-meter elevation only) sensors at the 10-meter and 60-meter levels. A delta temperature is taken between the 10-meter and 60-meter levels and a rain sensor is set on a mounting stand adjacent to the meteorological tower. The temperature is sensed by an aspirated dual temperature sensor at the 60-meter level and an aspirated dual temperature sensor at the 10-meter level. One half of the dual sensor at each elevation is used for ,

ambient temperature. The second half of each sensor is used to provide a differential l temperature between the 10-meter and 60-meter elevation. It is this difTerential temperature instrumentation in addition to the wind speed and direction instrumentation which is required to be operable in accordance with CPS Technical Specification 3.3.7 3.

On June 24,1994, the 60-meter temperature indication was observed to be indicating a saw tooth pattern with a magnitude of variation of approximately three degrees every 15 minutes on the associated recorder. The difTerential air temperature 9407190319 94o71, i 'D DR ADOCK 05000$61 PDR h7

U-602311 Page 2 instrumentation was declared inoperable and a maintenance work request (MWR) was initiated and worked. All as-found data was satisfactory and the instrumentation was declared operable again on June 25,1994. Ilowever, the problem occurred again, and at 0315 hours0.00365 days <br />0.0875 hours <br />5.208333e-4 weeks <br />1.198575e-4 months <br /> on June 26,1994, the differential air temperature instrumentation was declared inoperable due to the inoperability of the 60-meter temperature indication. Control and Instrumentation (C&I) personnel installed continuous recorders to aid in localizing the problem and worked on correcting the problem which was intermittent in nature. Several times it was thought that the problem was resolved only to discover that the same erratic indications would again occur. As a result of the time needed to identify the cause of the intermittent problem and the desire to ensure the problem had been fixed prior to returning the equipment to operation, C&I personnel were not able to restore the instrumentation to operable status within seven days.

Subsequent to exceeding the allowed out-of-sersice time it was determined that the problems being experienced were associated only with the 60-meter temperature indication and that these problems actually had no effect on the differential air temperature indication. It was initially thought by Operations personnel that the 60-meter temperature indication provides input to the difTerential temperature indication. As a result, when the 60-meter temperature indication was determined to be inoperable the differential air  :

temperature indication was also declared inoperable thus requiring entry into the Action statement. It has since been verified that the problem was in fact only associated with the .

60-meter ambient temperature instrumeritation A review of the recorder traces indicates ,

that the difTerential air temperature indication was functioning properly during this period.

Illinois Power believes that calling the differential temperature instrumentation inoperable was a conservative decision to make since the problem had been difficult to troubleshoot and the differential temperature is used as input to emergency plan decisions.

C&l personnel worked expeditiously to return the meteorological tower instrumentation to serice. llowever, because of the intermittent nature of the problems troubleshooting was difTicult. It was finally determined that the 60-meter transmutter card had degraded. In fact, the card eventually failed upscale. The faulty transmutter card was replaced, calibrations were performed and the instmmentation was declared operable at 2245 hours0.026 days <br />0.624 hours <br />0.00371 weeks <br />8.542225e-4 months <br /> on July 8,1994.

Submittal of this letter satisfies the requirem.mts of CPS Technical Specifications 3.3.7.3, Action "a" and 6.9.2 for submitting a Special Report for meteorological tower  ;

inoperabilities.

Sincerely,  ;

.Q Richard F. Phares  !

Director, Licensing TAB /csm i

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U-602311 Page 3 l

1 cc: NRC Clinton Licensing Project Manager l NRC Resident Office, V-690 J Regional Administrator, Region Ill, USNRC lllinois Department ofNuclear Safety f

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