ML20127G202
| 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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LF CREEK W@) NUCLEAR OPERATING 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 cc:
A. T.
Howell (NRC), w/a 4
J.
L. Milhoan (NRC), w/a G. A.
Pick (NRC), w/a W.
D.
Reckley (N RC), w/a 190b,.Q
~
9301210185 930112
-' ' 004 411/ Burlingt n KS 66839 / Phone (310) 364-6831 '
S PDR
\\ _
PDR AbOCK OS000482 An Equal Opportunity Employer M/F/HCA'ET i
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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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