ML20127G202

Special Rept 93-001:on 921229,10-60 Meter Elevation Delta Temp Indication for Meteorological Tower Declared Inoperable Due to Erratic Indications.Ice Shields Installed to Minimize Recurrence

ML20127G202
Person / Time
Site:	Wolf Creek
Issue date:	01/12/1993
From:	Maynard O WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
93-001, 93-1, WO-93-0005, WO-93-5, NUDOCS 9301210185
Download: ML20127G202 (2)

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W@) LF CREEKOPERATING NUCLEAR Otto L Maynard vge bes+nt Plant Opetutvans January 12, 1993-WO 93-0005 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station F1-137 Washington, D. C. 20555

Subject:

Docket No. 50-482: Special Report 93-001 Gentlemen:

The attached Special' Report is .being submitted in accordance with_

Technical Specification 3.3.3.4 concerning the inoperability of the 10-60 meter elevation delta temperature indication for the meteorological -

tower.

Very truly yours,

/(ifj'NI^&

Otto L. Maynard Vice President'-

Plant operations OLM/jan 4 cc: A. T. Howell (NRC), w/a J. L. Milhoan (NRC) , w/a G. A. Pick (NRC), w/a W. D. Reckley (N RC) , w/a -

190b,.Q ~

-' ' 004 411/ Burlingt n KS 66839 / Phone (310) 364-6831 '

9301210185 930112 PDR AbOCK OS000482 An Equal Opportunity Employer M/F/HCA'ET

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-6 i Attachment to WO 93-0005 4 Page 1 of 1 Special Report 93-001  : )

Inocerable Meteorological Tower Instrumentation- l; tl l

On December 29, 1992, at approximately 0120 CST, the 10-60 meter elevation delta temperature (AT) indication -for the meteorological-tower was declared inoperable. . Because this inoperability extended beyond a 7 day period, this Special Report is being submitted pursuant-to Technical Specifications 3.3.3.4 and 6.9.2.

On December 29, 1992,. at approximately 0120 CST, operations personnel ,

identified that the 10-60 meter elevation -AT indication for the meteorological tower was reading significantly higher than the 10-35 and 10-85 meter elevation AT indications. Work Request 06435-92 was initiated and Technical Specification 3.3.3.4, Action a, was entered for inoperability of a meteorological monitoring instrumentation channel. Technical Specification 3.3.3.4, Action a, requires that the instrumentation be returned to operable status within 7 days, or that a Special Report be submitted within tho following 10 days.

A review of historical data for the 10-60 meter elevation AT indication revealed that erratic indications occur during high humidity conditions .,

(i.e., rain, fog). The electronic circuitry for the 10-60 meter elevation AT loop was verified using procedure, STS IC-890C, " Channel Calibration of Air Temperature Differential Meteorological-Instrumeatation," that simulates Resistance Temperature Detector. .(RTD).

inputs with known resistance values. Ohmic values taken between the shield and the individual conductors of'the RTD cables indicated an '

insulation breakdown in the 60 meter elevation cable. It was determined' that this breakdown is causing the erratic readings during high' humidity conditions. Since the 10-60 meter elevation AT indication cannot be considered operable during all weather conditions and.was not-able-tos be repaired within 7 days, this special report is being submitted to satisfy Technical Specification 3.3.3.4.

The 10-60 meter elevation AT indication can be considered operable f during ef fectively dry weather conditions based on a review of trend data from the plant computer on the response of the indication. . - Thus, .

useful information is available depending on weather conditions. DuringL high humidity weather conditions- the erratic 11ndication variesE from = an . ,

occasional spiking to a' continuous high reading. However, the ,10-35 and 10-85 meter elevation AT indications are available for back-up data when the 10-60 mater elevation AT indication - is inoperable. On the~

basis of the current work schedule, the cabling for the 10, 35,-60,,and-

. 85 meter elevations of the meteorological tower will be: replaced following the sixth refueling outage, but no later than Augu:t-31, 1993.

This is the first event in which the- 10-60 meter elevation AT=

indication was inoperable for more than.7 days! because of the . weather

- conditions. Special-Report 91-001 discusses inoperability of the 10 and!

t 60 meter'elevatton-wind speed indicators for more than 7 days because of-inclement weather. However, in.the case of-the wind'apeed indicators, freezing precipitationJeaused the bearings'of-the transmitter to freeze to their housing,1 thereby-restricting free-movement of the transmitter ,

, due to the formation of an ' ice bridge. between the rotating- and stationary shaft. - Plant Modification 1 Request 03363 installed - *1ce shields" to minimize the occurrence of this previous problem.

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