05000346/LER-1978-073-03, /03L-0:on 780620,relay Wiring Error Found in Logic to Channel 2 Safety Features Actuation Sys.Caused by Mfg Defect:Relay Incorrectly Wired to Socket.Wiring Corrected & Verified by Surveillance Test 5031.07

/03L-0:on 780620,relay Wiring Error Found in Logic to Channel 2 Safety Features Actuation Sys.Caused by Mfg Defect:Relay Incorrectly Wired to Socket.Wiring Corrected & Verified by Surveillance Test 5031.07

ML19326A080
Person / Time
Site:	Davis Besse
Issue date:	07/18/1978
From:	Albert J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A078	List: 05000346/LER-1978-073, Forwards LER 78-073/03L-0 05000346/LER-1978-073-03, /03L-0:on 780620,relay Wiring Error Found in Logic to Channel 2 Safety Features Actuation Sys.Caused by Mfg Defect:Relay Incorrectly Wired to Socket.Wiring Corrected & Verified by Surveillance Test 5031.07
References
LER-78-073-03L, LER-78-73-3L, NUDOCS 8001310650
Download: ML19326A080 (3)

LER-1978-073, /03L-0:on 780620,relay Wiring Error Found in Logic to Channel 2 Safety Features Actuation Sys.Caused by Mfg Defect:Relay Incorrectly Wired to Socket.Wiring Corrected & Verified by Surveillance Test 5031.07

Event date:
Report date:
3461978073R03 - NRC Website

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8 EVENT OESCRIPTION AND PROB A8tE CONSEQUENCES h I

l Safety Features Actuation System (SFAS) Channel 2 logic to the secuencer was found to I o 12 l i o,3 g l have a wiring error. This was discovered at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on June 20, 1978 while running 1 lo y ; lthe'"SFAS 18 Month Test", ST 5031.07. This incident is being reoorted in accordance I

l o I s l l with Technical Specification 3.9.1.9.

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i l o t s ! l Properly for every condition except if an SFAS actuatiLon occurred while the emereency (NP-33-78-87) 1 I o I 7 l [ diesel generator was supplying essential bus Dl.

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4i 42 as 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l 3 g o l lThe relay in question (SEQX Relay - E64B Drawing) was incorrectly wired to the relay i

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Since the viring of this socket is factory wiring, this incident was caused I

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TOLEDO EDISON CCHPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION

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f SUFPLEMENTAL INFORMATION FOR LER NP-33-78-87 V

DATE OF EVENT: June 20, 1978 FACILITY: ' Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: A relay viring error in the logic to Channel 2 Safety Features Actuation System Conditions Prior to Occurrence: The unit was in Mode 6, with Power (ET) = 0, and Load (WE) = 0.

Safety Features Actuation System (SFAS) Channel 2 logic Description of Occurrence:

to the sequencer was found to have a viring error. This was discovered at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on June 20, 1978 while running the "SFAS 18 Month Test", ST 5031.07.

This relay -(SEQX - see Drawing E64B) is part of the circuit which starts the sequencer if offsite power is lost (Emergency Diesel Generator 1-2 supplying D1 essential bus), prior to an SFAS actuation. The wiring was done in such a way as to make the relay contacts for tbd.] circuit always open, or taking this function out of the circuit.

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Designation of' Apparent Cause of Occurrence: The relay in question was incorrectly

- wired to th.e relay socket. Since the viring of this socket is factory viring, this incident was caused by a manufacturing defect.

Analysis of Occurrence:

During the time in which this error existed, there was a coincident problem which is documented in Licensee Event Report NP-32-78-05.

The analysis below will consider both items as the relay problem was actually found in doing the testing of the coincident problem. This relay problem was corrected and retested along with the other problem.

The circuit containing the ' improper wiring provides a' memory logic which starts the sequencer if an SFAS actuation occurs while the diesel generator is supplying the bus. With the open circuit condition existing, the Channel 2 sequencer would function properly for every condition except the one which requires this memory.

The sequencer would not have sequenced any loads. Under these conditions, the SFAS loads would come on simultaneously.

As, electrically, Channel 4 (which is complementary to Channel 2) was in the same open-circuit condition due to open slide links (Licensee Event Report NP-32-78-05), actuation Channel 2 would have operated as described above.

Sequencers would have perfor=ed, except for the case of an SFAS actuation following a loss of offsite power. In this case, essential leads would have i==ediately loaded onto' the bus.

LER #78-073 l

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3 TOLEDO' EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-78-87 PAGE 2 0F 2

Corrective Action

At approrimately 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on June 20, 1978, viring was corrected and verified by satisfactory completion of Surveillance Test ST 5031.07.

Fa' l'ure' Data: This is not a repetitive occurrence.

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LER #78-073 e

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