05000346/LER-1980-065-03, /03L-0:on 800826,loss of Position Indication Light Caused Loss of Control Power to Breakers Rendering Emergency Diesel Generator 1-1 Inoperable.Caused by Human Error.Switch Reclosed & Breaker Position Indication Returned

/03L-0:on 800826,loss of Position Indication Light Caused Loss of Control Power to Breakers Rendering Emergency Diesel Generator 1-1 Inoperable.Caused by Human Error.Switch Reclosed & Breaker Position Indication Returned

ML19337A648
Person / Time
Site:	Davis Besse
Issue date:	09/23/1980
From:	Matheny D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19337A640	List: 05000346/LER-1980-065, Forwards LER 80-065/03L-0 05000346/LER-1980-065-03, /03L-0:on 800826,loss of Position Indication Light Caused Loss of Control Power to Breakers Rendering Emergency Diesel Generator 1-1 Inoperable.Caused by Human Error.Switch Reclosed & Breaker Position Indication Returned
References
LER-80-065-03L, LER-80-65-3L, NUDOCS 8009290370
Download: ML19337A648 (3)

LER-1980-065, /03L-0:on 800826,loss of Position Indication Light Caused Loss of Control Power to Breakers Rendering Emergency Diesel Generator 1-1 Inoperable.Caused by Human Error.Switch Reclosed & Breaker Position Indication Returned

Event date:
Report date:
3461980065R03 - NRC Website

text

U. S. NUCLE AR REGUL ATORY COMMISSION NRC FORM 366 LICENSEE EVENT REPORT CONTROL BLOCK: l l

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8 60 61 DOCKET NUMBER bd 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h the breakeil ITlT! l (NP-33-80-77) On 8/26/80 at 1055 hours0.0122 days <br />0.293 hours <br />0.00174 weeks <br />4.014275e-4 months <br />, Control Room operators noticed that The loss ]

lo la l l position indication lights of C1, the 4160 VAC Essential Bus, had gone out.

the 1 lof position indication caused the loss of control power to the breakers rendering lo l4 l lOlsl l Emergency Diesel Generator (EDG) 1-1 inoperable. The station entered the accion stated l o l6 l l ment of T.S. 3.8.1.2 since neither EDG was operable..There was no danger to the publid lcl7l lor station personnel. Being in Mode 5, the station was already in compliance with thel I

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DVR 80-143 Dennis Matheny PHONE:

NAME OF PHEPAHER L

r TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-77 4

DATE OF EVENT: August 26, 1980 FACILITY: Davis-Besse Unit l'

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IDENTIFICATION OF OCCURRENCE:

Loss of Control Power on a 4160 VAC Essential Bus, Cl s

s Conditions Prior to Occurrence: The unit was in Mode 5, with Power (MWT) = 0 and 1

Load (Gross MWE) = 0.

Description of Occurrence: On August 26.1980 at 1055 hours0.0122 days <br />0.293 hours <br />0.00174 weeks <br />4.014275e-4 months <br />, control room operators noticed that the breaker position indication lights on Cl, the 4160 VAC Essential Bus, had gone out.

The loss of position indication (open or closed) of the breakers on the bus meant that control power to the breakers had been lost. This meant that had Emergency Diesel Generator (EDG) 1-1 been needed, it would not have been able to close in on C1.

The loads that would have been shedded with an undervoltage condi-tion at the bus (due to a loss of off-site power) could not have been reloaded.

In addition, EDG l-2 had been previously removed from service for maintenance work.

Therefore, during these eight minutes in which control power was off the bus, the station did not have an operable EDG.

Being in Mode 5, the station had entered the action statement of Technical Specifica-tion 3.8.1.2.

The technical specification requires a minimum of one operable EDG in Modes 5 and 6.

The action statement requires a suspension of operations involving core alterations or positive reactivity changes until the minimum required electrical power sources are restored to operable status. No such operations were being con-ducted during this time. Therefore, the conditions of the action statement were met.

Designation of Apparent Cause of Occurrence: The cause of the occurrence was the failure of the service representative to stay within the limits of his responsibility and authority. His services had been retained for technical direction and to certify various maintenance functions being performed on certain buses. The error was made while working on breaker ACll3 on bus C1.

During the course of the work on this breaker, it was necessary to de-energize all power to the female secondary block mounted inside the cubicle (this block was to be replaced). To accomplish this, all the control' power fuses in the cubicle were removed. His mistake in attempting to assure all control power was off the block was to open the knife switch inside the cubicle. However, this knife switch is for control power for the entire Cl bus and co-incidentally was located in the cubicle being worked on.

When the switch was opened,= it removed control power from the C1 bus breakers which would have prevented EDG 1-1 from automatically starting.

LER #80-065

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O TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-80-77 Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The problem was detected immediately and corrected within eight minutes. During this time, tl re were no core alterations or positive reacti-vity changes in progress.

Corrective Action

At 1103 hours0.0128 days <br />0.306 hours <br />0.00182 weeks <br />4.196915e-4 months <br /> ou August 26, 1980, the Shift Supervisor arrived at the switchgear room, determined the cause of the problem, and reclosed the knife switch. This restored control power to the bus and removed the station from the

. ction statement of Technical Specification 3.8.1.2.

At 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br /> the same day, a meeting was conducted by the Maintenance Engineer with all parties involved. The contractor was directed to insure that they conducted proper planning and had proper authorization and tagging for any work being performed.

The service representative was informed of the gravity of his action. A formal letter 9

was sent to the representative's company protesting his actions and insisting that he not be allowed to return to the site.

Failure Data: There have been no previous repcrted similar occurrences.

LER #80-065 4

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