ML19340C828

Supplemental Info Re RO NP-32-80-12:on 800724,w/unit in Mode 5,loss of Decay Heat Flow Observed.No Indication for Valve Position of Decay Heat Isolation Valve DH12.Revision Replaces Supplemental Info for RO 80-058

ML19340C828
Person / Time
Site:	Davis Besse
Issue date:	12/01/1980
From:	Murray T TOLEDO EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
M80-2601, RO-NP-32-80-12, NUDOCS 8012170536
Download: ML19340C828 (4)

Text

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ASAE M3LEDO EDISON December 1, 1980 M80-2601 FILE: RR 2 (NP-32-80-12)

Docket No. 50-346 License No. NPF-3 Mr. James G. Keppler Regional Director, Region III Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 799 Roosevelt Road

• Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

Enclosed are three copies of the supplemental information sheet , for Licensee Event Report 80-058. These sheets have been revised, and the revisions are indicated by a "1" in the left margin of each sheet. There has been no change to the LER form.

Please destroy your previous copies of this supplemental information for LER 80-058 and replace with the attached revision.

Yours truly,

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/sa ~ -) L] C)Q4 w 7 .

Terry D. Murray Station Superintendent Davis-Besse Nuclear Power Station TDM/lj k Enclosure  ;-l ,

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cc: Mr. Victor Stello, Jr., Director Office of Inspection and Enforcement Encl: 40 copies Mr. Norman Haller, Director Office of Management Program Analysis Enc 1: 3 copies

()()

Mr. Luis Reyes g NRC Resident Inspector Eccl: 1 copy I/

THE TOLEDO ED: SON COMPANY EDISON PLAZA 300 MADISCN AVENUE TOLEDO, OHIO 43652 8012170538 DEC 101980

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-80-12

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DATE OF EVENT: July 24, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Loss of decay heat flow

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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 heat 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 Decay Heat Pump 1-2 was restarted and 1300 spm 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 Safety Features Actuation System (SFAS) Channel 4 following Instrument and Controls personnel completion of Facility Change Request 79-439A. Unaware that the trip circuit for decay heat isolation valve DHil had been restored, he adjusted the constant current adjustment potentiometer (CCAP) switch level. This caused the output bistable (B/S)

BA413 to reset, which resulted in the decay heat isolation valve DHil to close.

Decay Heat Pump 1-2 was tripped im=ediately by the operator. At 2234 hours0.0259 days <br />0.621 hours <br />0.00369 weeks <br />8.50037e-4 months <br />, DHil was reopened and the pump restarted with flow of 1300 gpm verified. Decay heat flow was lost for a two minute period.

1 At 1554 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.91297e-4 months <br /> on August 3,1980, Instrument and Control personnel were performing work on bistable BA413 under Maintenance Work Order IC-547-80. When the bistable was re-moved, isolation valve DH11 vent closed. Decay Heat Pump 1-1 was stopped to prevent damage. This caused decay heat flow to be stopped for three minutes until the bistable could be replaced and the pump restarted.

These occurrences placed the unit in violation of Technical 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 />s-occurrence

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was personnel error. While working in disconnect cabinet CDE-1132, construction elec-tricians were pulling wires.and shorted out a fuse clip. Th'is blew the 3 amp fuse in the valve control circuit causing DH12 to travel closed.

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. Insufficient l

j guidance on the Maintenance Work Order covering the work with regards to system restora-

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tion 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 ST 5031.01, SFAS Monthly Test, which was being performed to check out Maintenance Work Order LER #80-058 l

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e TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL TNFORMATION FOR LER NP-32-80-12 PAGE 2

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IC FCR 79-439A, SFAS Reactor Coolant System Pressure to T-sat. In fact, an I&C technician had just removed the TP 35 slide link and the jumper for TB 35 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 error.

The maintenanc'e specialist had previously reviewed the SFAS drawings for the main-tenance work order and concluded the bistable could be removed with no special pre-cautions. He incorrectly d2termined that the bistable de-energized the output relay to allow DHll to open, when actually the relay is energized by bistable BA413 to allow DHil to open.

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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 decay heat 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. Decay Heat Pu=p 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 blown fuse was replaced, DHil 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 gps. The details of the event and electrical work practices were discussed with the construction electrician and his supervisor.

In the second case where decay heat flow was lost, DH11 was reopened. Decay Heat Pump 1-2 was restarted and flow verified at 1300 gpm. Additional pertinent guidance will be provided on future maintenance work orders with regards to system restoration.

In the third event the bistable was reinstalled. DHil was opened and Decay Heat Pump 1l l-1 was started. Flow was restored by 1557 hours0.018 days <br />0.433 hours <br />0.00257 weeks <br />5.924385e-4 months <br /> on August 3, 1980. A tag will be attached to this module indicating that its removal will allow DH11 to go closed.

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.

Technical Specification Admendment 28 issued August 21, 1980 eliminates the requirement 1 of always maintaining power on DHil and DH12. This should eliminate inadvertent

. closings such as those experienced during this outage.

Failure Data: Previous loss of decay heat flow due to personnel errors were reported 1l in Licensee Event Reports NP-32-77-05, NP-32-77-09 and NP-33-80-54 (80-044) .

Previous losses of decay heat flew due to procedural error were reported in Licensee 1l Event Reports NP-32-77-03, NP-33-80-53 (80-043) and NP-33-80-71 (80-057) .

LER #80-058

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U. S. NUCLEAR REGULATORY COMMISSION NRC FORy 36s

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