05000346/LER-1980-011-03, /03L-0:on 800131,during Normal Operation, Operations Personnel Received Half Trip on Steam & Feedwater Rupture Control Sys Channels 1/3.Caused by Spurious Trip from +25 Volt Dc Power Supply PS03 in Sglic Channel 1

/03L-0:on 800131,during Normal Operation, Operations Personnel Received Half Trip on Steam & Feedwater Rupture Control Sys Channels 1/3.Caused by Spurious Trip from +25 Volt Dc Power Supply PS03 in Sglic Channel 1

ML19296D450
Person / Time
Site:	Davis Besse
Issue date:	02/28/1980
From:	Trautman D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19296D446	List: 05000346/LER-1980-011, Forwards LER 80-011/03L-0 05000346/LER-1980-011-03, /03L-0:on 800131,during Normal Operation, Operations Personnel Received Half Trip on Steam & Feedwater Rupture Control Sys Channels 1/3.Caused by Spurious Trip from +25 Volt Dc Power Supply PS03 in Sglic Channel 1
References
LER-80-011-03L, LER-80-11-3L, NUDOCS 8003040605
Download: ML19296D450 (2)

LER-1980-011, /03L-0:on 800131,during Normal Operation, Operations Personnel Received Half Trip on Steam & Feedwater Rupture Control Sys Channels 1/3.Caused by Spurious Trip from +25 Volt Dc Power Supply PS03 in Sglic Channel 1

Event date:
Report date:
3461980011R03 - NRC Website

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FA EN T C A T E 14 15 RiPUR T DATE 8J EVEP.T DESCRIPTION AND PROBABLE CONSECUENCES h l On January 31, 1980 at 1307 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.973135e-4 months <br /> during normal plant operation, operations personnelg a

2 received a half trip on Steam and Feedwater Rupture Control System (SFRCS) Channels g,; ;

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This placed the unit in the action statement.of T.S. 3.3.2.2 which requires the; inoperable section of the channel be placed in the tripped condition within one hour.;

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3 is l There was no danger to the health and safety of the public or station personnel. The j and SFRCS Channel 1 failed in the saf e direction

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Ii o i l Yhe cause of the occurrence was determined to be a spurious trip from the +15 volt DC l li i

l power supply PS03 in SCLIC Channel 1.

The fuses on the input to the supply were i

_ I, l 71 l removed, cleaned, and reinstalled, and the supply was restored to normal. The output l l voltage was checked and found to be normal.

The channel was declared operable on l

_ i, i14 1 January 31, 19S0.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-15 DATE OF EVENT: January 31, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF GCCURRENCE:

Steam and Feedwater Rupture Control System (SFRCS)

Channel I half trip due to loss of +15 volt DC power from steam generator level cabinet #1.

Conditions Prior to Occurrence: The unit was ir Mode 1, with Power (MNT) = 2764, and Load (Gross MWE) = 920.

Description of Occurrence: On January 31, 1980 at 1307 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.973135e-4 months <br /> during normal plant operations, operations personnel received a half trip on SFRCS Channels 1/3. The half trip was caused by partial de-energization of SGLIC (steam generator level in-strumentation cabinet) Channel 1. This placed the unit in the action statement of Technical Specification 3.3.2.2 which requires that the inoperable section of the channel be placed in the tripped condition within one hour during Modes 1, 2, and 3.

The inoperable portion of the channel was already in the tripped condition.

Startup feedwater control valve SP7B closed as designed.

Designation of Apparent Cause of Occurrence: The apparent cause of the occurrence was determined to be a spurious trip f rom the +15 volt DC power supply PS03 in SCLIC Cpannel 1.

Analysts yf Occurrence: There was no danger to the health and safety of the public or to station personnel. The other SERCS channel was operable during the time that SFRCS Channel 1 was inoperable. The SFRCS Channel 1 failed in the safe direction as designed.

Corrective Action

In-cabinet troubleshooting was performed under Maintenance Work Order IC-246-80.

The fuses on the input to the supply were cleaned and reinstalled, and the supply was restored to normal.

The output voltage from the supply was checked and the overvoltage trip setting was checked and found to be normal.

Visual inspection in the cabinet revealed no probicas.

The supply output is presently being monitored to determine if spurious channel difficulties are being encountered.

The channel was declared operable on January 31, 1980, and the unit removed from the action statement.

Consolidated Controls and Sorenson are continuing their investiga-tions. Their findings are expected soon.

Failure Data:

For information concerning previous +15 volt DC power supplies (Sorenson), see Licensee Event Reports NP-33-79-ll3 and NP-33-79-148.

LER #80-011