ML19275A591

RO NP-09-79-05:on 790831,during Review of Station Vent Data, Physicist Determined That Vent Recorder Was Inoperable. Caused by Inoperable Computer Point.Recorder Recalibr & Computer Input Card Changed

ML19275A591
Person / Time
Site:	Davis Besse
Issue date:	09/27/1979
From:	TOLEDO EDISON CO.
To:
Shared Package
ML19275A588	List: ML19275A587 ML19275A591
References
NUDOCS 7910050561
Download: ML19275A591 (2)

Text

s so TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE REPORTABLE CCCURRENCE NP-09-79-05 DATE OF EVENT: August 31, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of continuous recording of station vent airborne activity and flow Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2772, and Load (Gross MWE) = 906.

Descrintion of Occurrence: On August 31, 1979 during the review of station vent data, the Chemist and Health Physicist determined that station vent recorder UJR 5023 was giving faulty information. It was declared inoperable. The other source of recording station vent flow is by computer point F885, which was also inoperable, waiting further changes created when the vent probes were changed (the flow transnitter and local flow indicator were changed as a set) . This made the unit in violation of Environmental Technical Specification (ETS) 2.4.4.b, uhich requires a continuous recording of airborne activity and vent flow. Operations personnel did set up an hourly reading of station vent flow indicator FI-5090A until the recorder or computer point was repaired.

FI-5090A and flow transmitter FT-5090A were changed as a set on August 22, 1979.

Designation of Apoarent Cause of Occurrence: Computer point F885 (station vent flow) was still inoperable due to additional changes required when the range of the flow detector was expanded on June 29, 1979 to read a full range of 0-5000 feet / minute (vent velocity). This also required the calibration of the integrating flow indicator FQI-2024. The repair was also complicated by repeated failures of the radiation moni-tor system RE-2024A, B, and C. When RE-2024 is off for repairs, there is no power to computer point FS85.

Station vent recorder UJR-5023 plots several items associated with the station vent.

It receives these values through radiation momitor system RE-2025A, B, and C which powers the detector f rom the second set of probes which feed flow information to UJR-5023. The recorder itself also f ails intermittently, and this was the case on August 31, 1979. This recorder is slated for replacement. An improved recorder will be installed per Facility Change Request 79-217.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. An hourly reading of the vent flow was established to record FI-5090A. The local monitors from the areas that exhaust into the station vent were operable and would have alarmed if there had been unusual radiation levels in the r eleases. .

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE REPORTABLE OCCURRENCE NP-09-79-05 PAGE 2 0F 2 _

Carrective Action: Under Maintenance Work Order IC-079-101-79, FQI-2024 was recali-brated and a computer input card changed. Thia made F885 operable on Septenber 21, 1979 with the station recovering its continuous r: cording of station vent flow, and therefore, the station no longer violated ETS 2.4.4.b.

IC-079-105-79 Pas been issued to recalibrate FQI-2025 which feeds UJR-5023, and this will make UJR-5023 operable also.

Failure Data: F885 is inoperable for at least three days each quarter while Instru-ment and Control personnel are recalibrating vent monitors RE-2024A, B, and C (which power FS85). UJR-5023 is also inoperable three days each quarter while RE-2025A, B_

and C is being recalibrated. Reportable Occurrence NP-09-77-02 reported RE-2024 inoperable on September 30, 1977. This was the only occurrence which resulted in a reportable occurrence.

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