A Cable Tray Fire At A Commercial Nuclear Power Plant

DOE-HDBK-1116-98

APPENDIX B

A CABLE TRAY FIRE AT A COMMERCIAL NUCLEAR POWER PLANT

A commercial nuclear power plant experienced a serious inplant cable tray fire. The fire

was started by an engineer who was using a candle to check for air leaks through a fire wall

penetration seal. The fire spread and was fought on both sides of the reactor building and

cable spreading room wall by plant and local community fire fighting personnel. Efforts to

put out the fire were made difficult by several factors: delay in notifying personnel of the

exact location of the fire, physical location of the fire in the cable trays, and the high

differential pressure between the cable spreading room and the reactor building that

resulted in high air flow rates through the wall.

The effects of the fire on the plant were almost immediate. All Unit 1 emergency core

cooling systems were lost, as well as the capability to monitor core power. To remove

decay heat, low pressure water from the condensate pumps and manual operation of

primary relief valves were used until normal decay heat removal systems could be made

operational. Control power to motor operators and pump controls was established using

temporary jumpers allowing the plant to be brought to a stable shutdown condition. There

was no release of radioactivity.

Lessons Learned

The inability to put out the fire was caused, in part, by the large air flow through the

penetration that prevented the carbon dioxide and dry chemicals from smothering

the fire. Compounding this were the fire fighters' difficulty in seeing exactly what

was burning and working in the confined spaces, which made access to the

affected areas difficult.

The use of water at an early stage would have extinguished this fire and prevented

the loss of circuits not already affected. Although the suggestion to use water was

made repeatedly by the local community fire chief, plant personnel were concerned

about the effects of grounds and shorts on plant operation and potential personnel

hazards.

Community fire fighting personnel did not arrive at the scene until approximately

45 minutes after they were called. Part of the delay was the need to process

temporary radiation monitoring badges.

The community fire department special water hose nozzle for electrical fires was not

compatible with the plant's hose.

A fire watch, who normally has no other duties but to watch for potential fires, had

not been assigned.

B-15