ML19242B094

LER 79-070/03L-0 on 790705:1/2 Trip Occurred on Channels 1 & 3 of Steam & Feedwater Rupture Control Sys. Caused by Failure of +24 Volt Dc Power Supply PS02 in Steam Generator Level Instrumentation Cabinet Channel 1

ML19242B094
Person / Time
Site:	Davis Besse
Issue date:	08/01/1979
From:	Hitchens D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242B087	List: ML19242B086 ML19242B094
References
LER-79-070-03L, LER-79-70-3L, NUDOCS 7908070496
Download: ML19242B094 (2)

Text

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8 f4 til DOC A E T P, U'3 E H EVENT DESCRIPTION AND PROB AULE CONSEQUENCES h j io 2 [At 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on July 5, 1979, a one half trip occurred on Channels 1 and 3 of the jo 3 l Steam and Feedw-ter Rupture Control Systen (SFRCS). This one half trip was due to tej o 4 l de-energi:ation of half of Stena Generator Level Instrumentation Cabinet (SCLIC). As o s lthe unit was in Mode 4 throughout this occurrence, the action scatement of T.S. 3.3.2.]

o c l vas not applicable. This report is being submitted to document a conponent failure. l SGLIg

[TJT] l There was no danger to the health and safety of the public or station personnel.

s l Channel 1 and consequently SFRCS Channel 1 actuated as designed. (NP-33-79-79) ]

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33 3 CAUSE LESCRIPTION AND CORRECTIVE ACTIONS h

1. The i o lThe cause was a f ailure of the +2' VDC power supply PSO2 in SGLIC Channel [

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jigi] l power supply vendor is investigating to deternine the root cause.

On July 5,1979, j

, , , ,,, l supply was replaced unC _r Maintenance Work Order (K.:0) IC-333-79.

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o-TOLEDO EDISON CO:tPANY DAVIS-BESSE NUCLEAR P0bER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-79 DATE OF EVENT: July 5, 1979 FACILITY: E avis-Besse Unit 1 IDENTIrICATIO:I 0F OCCUPRENCE: Partial de-energi ation of Steam and Feedwater Rupture Cantrol Systen (SERCS) Channel 1 Conditions Prior to Occurrence: The unit was in Mode 4, with Power (M.n') = 0, and Ihad (Gross T.lE) = 0.

Description of Occurrence: At 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on July 5, 1979, operations personnel received a one half trip on SFRCS Channels 1 and 3. This half trip was due to the de-energization of half of Steam Generator Level Instrumer ' ion Cabinet (SGLIC) 1.

Technicc1 Specification 3.3.2.2 requires the SFRCS to bc < ale while the unit is The station, at the time of occur .,

was in Mode 4, in in Modes 1 through 3.

which SFRCS is not required to be operable. This incident .s being reported as docu-mentation of a component failure.

Dcsignation of Anparant Cause of Occurrence: The cause of this nccurrence was a failure of the +24 VDC power supply PSO2 in SOLIC Channel 1- The failed power supply has been returned to the canufacturer, Sorenson (a division of Raytheon) for repair and analysis of the f ailure to de terninm the root cause of the event.

Analysis of Occurrence: There war- no danger to the health and safety of the public or to station personnel. The SCLIC Channel 1, and consequently SFRCS Channel 1, actuated as designed when the power supply was lost. In addition, the unit was in Mode 4 throughout the occutrence during which SFRCS is .iot required.

Corrective Action: The def ective power supply was replaced under Maintenance k'ork Order IC-333-79 on Jr.ly 5, 1979. The SCLIC Channel 1 was declared operable af t er performance of ST 5099.01, "'Tiscellaneous Instrument Shift t,n ec t " , the same day of the occurrence, July 5, 1979 Failure Data: A +24 VDC power supply failure was previously reported in Licensee Lvent Report NP-33-77-24, however, that failure was due to a design deficiency which was corrected at Sorenson.

LER #79-070

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