ML20235X427

Special Rept:On 871010,both Channels of RCS Subcooling Margin Monitor Declared Inoperable.Caused by Suspected Computer Software Calculation Problem.Alternate Monitoring Procedure Established.Followup Rept Expected in 14 Days

ML20235X427
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	10/12/1987
From:	Olmstead C PORTLAND GENERAL ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
CAO-358-87, NUDOCS 8710190358
Download: ML20235X427 (1)

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g-l Portland Gfneral,Eliciric Cornpany 9 Trojan Nuclear Plant

' O m ADM P.O. liox 439 - ' October 12, 1987

. Rainier; Oregon 97048 CAO-358-87

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, '(503)556 3713' d' y USINticlear"Regul'atory. Commission ')'

Document' Control Desk-

. WashingLon,-D.C. 20555 y Gentlemen:

Special Report JLimiting'. Condition'for Operation'(LCO) 3.3.3.9 of the Trojan

-Technical Specifications requires-submittal of a Special Report ~

if -lessi than'. the minimum- number ' of accident monitoring instruments-tionichannels shown in Technical Specification Table 3.3-11 are operable. :On October: 10,~1987, both channels of the Reactor C

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Coolant ' System subcooling margin monitor were declared inoperable due.to-a suspected computer software calculation problem.

.In accordance:with LCO 3.3.3.9, an alternate method of monitoring.

subcooling margin 'has been established by using the P2500 computer (Technica1' Support Center computer) to continuously monitor sub-cooling margin.

As re' quired by LCO'3.3.3.9, a follow-up Special Report will be submi_tted within 14 days outlining the action taken, the cause of the inoperability and the plans for restoring the system to operable' status.

, Sincerely, fh C. A. Olmstead General Manager CAO/ S/ S/ :sg cc: Mr. . David Kish, Director

' State of Oregon Department of Energy Mr. John B. Martin Regional-Administrator i US Nuclear Regulatory Commission l.,

Mr. R. C. Barr USNRC Resident Inspector Trojan Nuclear Plant V

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