05000346/LER-1980-054-01, /01T-0:on 800724,loss of Decay Heat Flow Found Due to DH12 Closing.Decay Heat Pump 1-2 Halted.Bypass Valves DH21 & DH23 Opened & Pump Restarted.Caused by Shorted Fuse Clip Due to Personnel Pulling Wires

/01T-0:on 800724,loss of Decay Heat Flow Found Due to DH12 Closing.Decay Heat Pump 1-2 Halted.Bypass Valves DH21 & DH23 Opened & Pump Restarted.Caused by Shorted Fuse Clip Due to Personnel Pulling Wires

ML19331B668
Person / Time
Site:	Davis Besse
Issue date:	08/07/1980
From:	Frohne R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19331B663	List: 05000346/LER-1980-054, Forwards LER 80-054/01T-0 05000346/LER-1980-054-01, /01T-0:on 800724,loss of Decay Heat Flow Found Due to DH12 Closing.Decay Heat Pump 1-2 Halted.Bypass Valves DH21 & DH23 Opened & Pump Restarted.Caused by Shorted Fuse Clip Due to Personnel Pulling Wires
References
LER-80-054-01T, LER-80-54-1T, NUDOCS 8008120566
Download: ML19331B668 (3)

LER-1980-054, /01T-0:on 800724,loss of Decay Heat Flow Found Due to DH12 Closing.Decay Heat Pump 1-2 Halted.Bypass Valves DH21 & DH23 Opened & Pump Restarted.Caused by Shorted Fuse Clip Due to Personnel Pulling Wires

Event date:
Report date:
3461980054R01 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION f.RC FORM 3GG (7 77)

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6J 63 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h FIT] l_(NP-32-80-12) On July 24, 1980 at 0955 hours0.0111 days <br />0.265 hours <br />0.00158 weeks <br />3.633775e-4 months <br />, the control room operators observed a losp firT31 lof decay heat flow caused by DH12 going shut. Decay Heat Pump 1-2 was stopped. Bypass l l valves DH21 and DH23 were opened and the pump restarted.

At 2232 hours0.0258 days <br />0.62 hours <br />0.00369 weeks <br />8.49276e-4 months <br /> personnel,were l 0 4 yJT] l attempting to restore SFAS CH4 cabinet to normal when DH11 closed. Decay Heat Pump 1-2]

lwas stopped until DH11 was reopened. On August 3,1980, I&C personnel removed bistable l O s The bistable was reinstalled and ' qw l

y lBA413 and caused DH11 to close stopping fic',

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h g iThe first was caused by construction electricians who were pulling wires into a cabineti 11111 land shorted a fuse clip in the control circuit for DH12. The second was caused hv nro-l Icedural deficiency in that the MWO being used did not contain adequate restoration in-l i,

, 3 lstructions. The third event was caused by an error by the maintenance specialist. Thei l

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l TOLEDO EDISON COMPlud DAVIS-BESSE NUCLEAP.PCWER STATION UNIT ONE SUPPLEMENTAL INFORMA '^" FOR LER NP-32-80-12 DATE OF EVENT: July 24, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE _: Loss of Decay Heat Flow Conditions Prior to Occurrence: The unit was in Mode 5, with Power (MRT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence:

At 0955 hours0.0111 days <br />0.265 hours <br />0.00158 weeks <br />3.633775e-4 months <br /> on July 24, 1980, the control room operators observed a loss of decay heet flow. They noticed that there was no indication for the valve position of Decay Heat Isolation Valve DH12. The running Decay Heat Pump 1-2 was stopped to prevent damage due to a loss of suction. At 1011 hours0.0117 days <br />0.281 hours <br />0.00167 weeks <br />3.846855e-4 months <br /> the bypass valves (DH21 and DH23) were opened and system venting began. At 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> the DH Pump 1-2 was restarted and 1300 gpm flow verified.

Decay heat flow was lost for a 50 minute period.

At 2232 hours0.0258 days <br />0.62 hours <br />0.00369 weeks <br />8.49276e-4 months <br /> on July 24, 1980, personnel were attempting to clear lights on SFAS Channel 4 following Instrument and Controls personnel completion of Facility Change Request (FCR) 79-439A. Unaware that the trip circuit for Decay Heat Isolation Valve DH11 had been restored, he adjusted the constant current adjustment potentiometer (CCAP) switch level. This caused the output bistable (B/S) BA413 to eset, which resulted in the DH Isolation Valve DHil co close.

DH Pump 1-2 was tripped immediately by the operator. At 2234 DH11 was reopened and the pump restarted with flow of 1300 gpm verified. Decay heat flow was lost for a 2 minute period.

At 1554 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.91297e-4 months <br /> on August 8, 1980, Instruments and Controls personnel were performing work on bistable BA413 under MWO IC 547-80. When the bistable was removed, isolation valve DH11 vent closed.

Decay Heat Pump 1-1 was stopped to prevent damage.

This caused decay heat flow to be stopped for 3 minutes until the bistable could be replaced and the pump restarted.

These occurrences placed the unit'in violation of Tech'nical Specification 3.4.1 which requires at least one decay heat pump be in operation while the unit is in Mode 5.

Designation of Apparent Cause of Occurrence:

The cause of the 0955 hour0.0111 days <br />0.265 hours <br />0.00158 weeks <br />3.633775e-4 months <br /> occurrence was personnel error. While working in disconnect cabinet CDE-11B2, construction electricians were pulling wires and shorted out a fuse clip. This blew the 3 amp fuse in the valve control circuit causing DH12 to travel closed.

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• TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-32-80-12 The occurrence at 2232 hours0.0258 days <br />0.62 hours <br />0.00369 weeks <br />8.49276e-4 months <br /> was attributed to procedural inadequacy.

In-sufficient guidance on the Maintenance Work Order (MWO) covering the work, with regards to system restoration, led to steps being done out of sequence.

The personnel were under the impression that TP35 slide link was open and TB35 points 25 and 26 were jumpered per ST5031.01, SFAS Monthly Test, which was being performed to check out Maintenance Work Order IC FCR79-439A SFAS Reactor Coolant System Pressure to T-Sat.

In fact an I&C Technician had just removed the TP35 slide link and the jumper for TB35 points 25 and 26, to establish the normal system condition.

The occurrence at 1554 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.91297e-4 months <br /> on August 3, 1980, was attributed to personnel The maintenance specialist had previously reviewed the SEAS drawings error.

for the MWO and concluded the bistable could be removed with no special pre-cautions. He incorrectly detennined that the bistable de-energized the output relay to allow DH11 to open, when actually the re. lay is energized by bistable BA413 to allow DH11 to open.

Analysis of Occurrence:

There was no danger to the health and safety of the public or to station personnel.

In all three cases the loss of decay heat flow caused no significant increase in RCS temperature.

There was no damage to the DH pump since it was stopped immediately when the valve was confirmed shut.

Corrective Action

The first event was corrected by opening the DH11 and 12 bypass valves DH21 and DH23. DH pump 1-2 was revented and restarted on the bypass at 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br />.

The bicwn fuse was replaced, DH11 and DH12 were opened at 1051 hours0.0122 days <br />0.292 hours <br />0.00174 weeks <br />3.999055e-4 months <br />, and DH21 and DH23 were closed.

Flow was verified at 1300 gpm.

The details of the event and electrical work practices was discussed with the construction electrician and his supervisor.

f In the second case where DH flow was lost, DH11 was re-opened.

DH pump 1-2 was restarted and flow verified at 1300 gpm.

Additional, pertinent guidance will be provided on future Maintenance Work Order's with regards to system restoration.

In the third event the bistable was re-installed. DH11 was opened and pump 1-1 was started.

Flow was restored by 1457 hours0.0169 days <br />0.405 hours <br />0.00241 weeks <br />5.543885e-4 months <br /> on August 3, 1980.

A tag will be l

attached to this module indicating that its removal will allow DH11 to go closed.

l Two modules controlling Core Flood valves have been identified as operating in a similar manner, and will also be tagged to prevent inadvertent closing of the valves. The maintenance specialist who made the error was cautioned to use more diligence in doing his work.

Failure Data:

Previous loss of decay heat flow due to personnel errors were reported in NP-32-77-05, 32-77-09, and 33-80-54.

Previous losses of decay heat flow due to procedural error were reported in NP-32-77-3 and NP-33-80-53(80-043).