05000346/LER-1979-070-03, /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

/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: 05000346/LER-1979-070, Forwards LER 79-070/03L-0 05000346/LER-1979-070-03, /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
References
LER-79-070-03L, LER-79-70-3L, NUDOCS 7908070496
Download: ML19242B094 (2)

LER-1979-070, /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

Event date:
Report date:
3461979070R03 - NRC Website

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f4 til DOC A E T P, U'3 E H t2 61 EVENT DATE 14 15 RESORT DAT E 80 EVENT DESCRIPTION AND PROB AULE CONSEQUENCES h 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 j

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40 41 42 43 44 47 CAUSE LESCRIPTION AND CORRECTIVE ACTIONS h lThe cause was a f ailure of the +2' VDC power supply PSO2 in SGLIC Channel 1.

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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 The unit was in Mode 4, with Power (M.n') = 0, and Conditions Prior to Occurrence:

Ihad (Gross T.lE) = 0.

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 Description of Occurrence:

received a one half trip on SFRCS Channels 1 and 3.

This half trip was due to the

' ion Cabinet (SGLIC) 1.

de-energization of half of Steam Generator Level Instrumer ale while the unit is Technicc1 Specification 3.3.2.2 requires the SFRCS to bc <

in Modes 1 through 3.

The station, at the time of occur was in Mode 4, in 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 1-The failed power supply failure of the +24 VDC power supply PSO2 in SOLIC Channel 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