ML20236C593
| ML20236C593 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/23/1987 |
| From: | Olmstead C PORTLAND GENERAL ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CAO-381-87, NUDOCS 8710270261 | |
| Download: ML20236C593 (2) | |
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. Portland Genera'l Electric Company
~ Trojan Nuclear Plant October 2I'r 1987
'o 71760 Columbia River liwy CAO-581-87 M
~ Rainier. Oregon 97048 (503) 556-3713 i
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Nuclear Regulatory Commission tj Washington, D.
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Gentlemen:-
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93 Special Report A
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Limiting. Condition' for Operation (LCO) 3.3.3.9'cf;the'. Trojan Technical Specifications requires submittal of.6/ follow-up Special Report: within 14 days if less than. the @inimum number of (j,b accident. monitoring instrumentation-channels shdwn in Technical Specification Table 3.3-11 are operable.
On Oct'ooe'r 10, 1987, both! channels.of the Reactor Coolant System subcoolirs parpin
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monitor.(SMM) were declared inoperable.
The source'of triQ problem was a failed high Reactor Coolant SystemJ.60p[esistance temperature detector (RTD) input to the SMM.
Thidv ivasulted in an apparent failure of the SMM and it was declared ihoperab]p'.-
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i In accordance with LCO 3.3.3.9, an alternate method dfjr.onitoring d
subcooling margin was established by using the P2500 cctlsuter
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(Technical Support Center. computer) to continuously ihonitor 4
subcooling margin.
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After defeating the failed input to the SMM, N.riodic Engineering Test (PET) 7-5,
" Reactor Core Subcooling Margi ionitor 4
Operability Check," was performed to confirm tila the SMM was operable.. This PET includes a hand calculatied of subcooling margin using'incore thermocouple-and primary prdssure measurements from other instrumentation and compare;,this
.T 3 calculation with the value indicated by the SMM.
This PET indicated that the
'B' train of SMM was apparoyitly not operating l
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properly, but the
'A' train was operable.
Further investigation determined that the input to thb' data logger, which displays incore thermocouple temperatures, had drifted out of adjustment by 17'F high.
The data loggpr' display f
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8710270261 871023
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PDR ADOCK 05000344-"
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CAO-381-87
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'I is useJ fort comparison purposes to determine if the SMM is g
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6,'ince the subcooling margin calculated using the data
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log'Jer display of thermocouple temperatures was substantially
' ksh dif f arent than the value displayed by t 'ie SMM, it had been 0
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ihiitie.lly conservatively assumed that the SMM was inoperable, i
when in fact, the data logger display was incorrect.
The data logger display was incorrect for some time, and the unrelated failure of the RTD and consequent performance of PET 7-5 resulted 3
in discovery of the data logger problem.
The SMM was never s i ',[
inoperable and no subcooling problem existed in the core.
i Sincerely,
,b i
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A.
Olmstead
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General Manager CAO/PPS/ WS/BLK:sg 4
c's i Mr. David Kish, Director State of Oregon
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' Department of Energy r
t Mr. JoP3 B. Martin Regional' Administrator US Nuclear Regulatory Commission Mr.
R.
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Dirr USNRC Resiq'ert Inspector s
Trojarf'Nucdeat Plant f;
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