ML19326A570

RO NP-33-77-20:on 770707,containment Sump Level & Flow Monitoring Sys of RCS Leakage Detection Sys Determined Inoperable.Caused by Component Failure.Valves Will Be Lined Up When Flow Transmitters Returned to Svc

ML19326A570
Person / Time
Site:	Davis Besse
Issue date:	08/03/1977
From:	Lingenfelter J, Vallade S TOLEDO EDISON CO.
To:
Shared Package
ML19326A525	List: ML19326A524 ML19326A570
References
LER-RO-770803-01, LER-RO-770803-1, NUDOCS 8002040744
Download: ML19326A570 (3)

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t vtut oe scruarioN g ; The Containment Sump Level and Flow Monitoring System, of tihe Reactorj g' Coolant System Leakage Detection System, was inoperable. AIflow trans- g

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' L L M EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-20 DATE OF EVENT: July 7, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: The Containment Sump Level and Flow Monitoring System of the Reactor Coolant System Leakage Detection System, was inoperable.

Condittens Prior to Occurrencei The plant was in Mode 4, with Power (MWI) = 0 and Load (MUE) = 0.

Description of Occurrence: On July 7, 1977, at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, a flow integrating indicator of the Reactor Coolant Detection System registered a flow rate during the Miscellaneous Instrument Shif t Check Surveillance Test. The Containment Normal Sump Pumps, however, were not running. Inspection by station operations personnel revealed that the sump level was normal and there were no leaks. Flow transmitter Foxboro No. FT-2801 was taken out of service for calibration on July 7, 1977 at 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br />, placing the station in the Action Statement of Technical Specification 3.4.6.1.

( The flow transmittar was calibrated and re-installed on hours. The flow monitoring system was still inoperable, July 8,1977 at 0715 however, since the flow monitoring portion of the Miscellaneous Instrument Shift Check Surveillacce Test (ST 5099.01) did not satisfy t.est conditions until 1115 hours on July 9,1977.

Designation of Apparent Cause of Occurrence: The cause of the occurrence is attributed to both instrument failure and personnel error. The transmitter had been transmitting spuriously,necessic2 ting its removal for calibration. It was found to be within tolerances and re-installed on July 8, 1977 at 0715 hours0.00828 days <br />0.199 hours <br />0.00118 weeks <br />2.720575e-4 months <br />.

The flow monitoring system failed to pass the Miscellaneous Instrument Shift Check Surveillance Test (ST 5099.01), however,because the instrument valves had been inadvertently left closed, allowing no pressure differential to reach the transmitter. The flow monitoring system passed ST 5099.01 on July 9, 1977 at 1115 hours0.0129 days <br />0.31 hours <br />0.00184 weeks <br />4.242575e-4 months <br /> removing the station from the Action Statement of Technical Specifi-cation 3.4.6.1 Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. In the event of a reactor coolant system leakage, leakage would have been detected by two other operable systems, the Containment Atmosphere Particulate Radioactivity Monitoring System and the Containment Atmos-phere Gaseous Radioactivity Monitoring System. Containment sump level monitoring was still available.

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, TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-20 PAGE 2 Corrective Action: To prevent recurrence, the Instrument and Control Engineer will specify on Maintenance Work Orders that valves are to be lined up when .

flow transmitters are returned to service.

The Miscellaneous Instrument Shift Check Surveillance Test, through which this flow transmitter was found to be defective, should pinpoint any future devia-tions in instrumentation in the Containment Normal Sump Pump and Flow Monitoring System. ,

Failure Data: No previous similar events have occurred.

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