ML19340E250

LER 80-088/03L-0:on 801205,while Troubleshooting for Ground Problems in Safety Features Actuation Sys Channel 3 Cabinet, Station Experienced Channel 1/3 Simultaneous Actuation of Levels 1,2,3 & 5.Caused by Component failure.PS-07 Replaced

ML19340E250
Person / Time
Site:	Davis Besse
Issue date:	01/02/1981
From:	Isley T TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340E245	List: ML19340E244 ML19340E250
References
LER-80-088-03L, LER-80-88-3L, NUDOCS 8101060745
Download: ML19340E250 (3)

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U. S. NUCLE AR REGUL ATORY COMMISSION NRC FORM 366 (7 77)

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? 8 60 61 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h I

I o l 2 l l (NP-33-80-113) on 12/ 5/80 at 2258 hours0.0261 days <br />0.627 hours <br />0.00373 weeks <br />8.59169e-4 months <br /> while I6C personnel were troubleshooting for f7T3, ; ground problems in Saf ety Features Actuation System (SFAS) Channel 3 cabinet, the sta- l l

o . ) tion experienced a channel 1/3 simultaneous actuation of SFAS icvels 1, 2, 3, and 5.

l lol51 lThe inadvertent loss of SFAS Channel 1 entered the station into the action statement Iols]lof T.S. 3.3.2.1, There was no danger to the health and safety of the pub !c or statiop l

j o l 7 l l personnel. The remaining three SFAS channels were available to trip if required.

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_ 22 a 24 HOURS 22 SUH T of 4 UB. St., PP LI E MANLFA TLREA o TH lN lg lS l2 l5 l7 lg TAKE 7 lC jgl34 ACTXl O' g {PLAg l0 l0 l0 lU 40l ]g lY IQ 3J 3s l36Zl@ J/ 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h liloj]The cause was component failure. SFAS Ch. 1 failed when a short occurred between powcq li 11 } l supply common and the cabinet causing a defective power supply in Ch. 1 (PS-07) to fai}.

After re-energizing Ch. 3l i y[-} I s Aa part of troubleshooting, personnel de-energized Ch. 3.

The short occurred when the lampj

,;3, jone of the power "0N" lights was not on as required.

l g,;4, lwas removed from the output module. Under WO IC-807-80, PS-07 was replaced. "

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TOLEDO EDISON COMPANY f LAVIF-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP4 3-80-113

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i DATE OF EVENT: December 5, 1980 t

i FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of power supply PS-07 in Safety Features Actuatioi System (SFAS) Channel l contributing to a levels 1, 2, 3, and 5 actuation

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! Conditions Prior to Occurrence: The unit was in Mode 3 with Power (MWT) = 0 and Load I

(Gross MWE) = 0, r

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Description of Occurrence: On December 5, 1980 at 2258 hours0.0261 days <br />0.627 hours <br />0.00373 weeks <br />8.59169e-4 months <br /> the station-experienced a

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simultaneous actuation of SFAS levels 1, 2, 3, and 5. Control room operators were aware i that Instrument and Centrol (I&C) perconnel were troubleshooting for ground problems in

] the SFAS Channel 3 cabinet. It was immediately confirmed by the IEC personnel that their i work had caused the inadvertent actuation. The station was in Mode 3 at the start of

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the event, and stable hot standby conditions and no Reactor Coolant System (RCS) leakage

- were verified. The reactor operators began restoring systems to pre-SFAS trip status.

The inadvertent loss of SFAS Channel l entered the station into the action statement of Technical Specification 3.3.2.1 which requires the failed SFAS unit to be placed in the tripped condition within one hour. The SFAS event had failed in the tripped condition.

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Designation of Apparent Cause of Occurrence: The cause of the occurrence is component

failure. I&C personnel were trcubleshooting for the cause of the 120 VAC on the common i in SFAS Channels 1 and 3. As part of the process of trying to locate the source of the

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stray voltage, Channel 3 was de-energized. Later, when the channel was re-energized per ,

l SP 1105.03, the SEAS Procedure, it was noted that one of the power "on" lights was not

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on as required. When a lamp was removed from an output module in Channel 3, a short occurred between the power supply common and the cabinet ground. This short caused

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power supply PS-07 in Channel 1 to completely fail. PS-07 was aircady defective caus-

) ing the 120 VAC to be present on the power supply common. The short from common to ground caused complete failure of the power supply. This supply provides power to the following bistables: containment pressure fail, containment pressure high, containment

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i pressure high high, Borated Water Storage Tank level fail, and Borated Water Storage

! Tadk level low. In Channel 3, the containment pressure high and the Borated Water Storage Tank level Jow bistables were still tripped which caused the Channel 1/3 actua-l tion of levels 1, 2. 3, and 5.

Analysis of Occurrence: There was no danger to the health and safety of the public or '

to station personnel.When the power supply failed, the affected bistables tripped plac-ing the system in a 1 out of 3 trip condition for the affected bistables. The remaining three channels were available to trip if required. Even though the high pressure injec-tion and low pressure injection pumps started, there was no injection of water to the RCS since the RCS was at full system pressure prior to the actuation. This was verified by checking the injection flow indication. With the level 5 actuation, the suction for i high pressure injection and low pressure injection pumps switched to the emergency sump.

1 This caused a loss of suction for less than one minute until the pumps were stopped.

This did nor cause any pump damage as verified by the data obtained from the surveillance tests run after the event. Toledo Edison is investigating the consequences of the common between Channel 1 and Channel 3 and between Channel 2 and Channel 4.

LER #80-088

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TOLEDO EDISON COMPANY CAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-80-113 Corrective Action: All output modules for Channels 2, 3, and 4 were reset by 2320 hours0.0269 days <br />0.644 hours <br />0.00384 weeks <br />8.8276e-4 months <br /> on December 5, 1980. Under Maintenance Work Order IC-807-80 the failed power supply PS-07 in Channel 1 was replaced. The SFAS Monthly Test, ST 5031.01 was successfully run on Channels 1 and 3 removing the station from the action statement at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> on December 6, 1980. The high pressure injection pump test, ST 5051.09 run December 6, 1980, verified that there had been no pump damage.

Failure Data: There have been no previous reports of a ground in one channel causing the loss of a power supply in another channel.

LER #80-088

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