Summary report of incineration plenum fire: Building 771, July 2, 1980

At about 1100 on July 2, 1980, a temperature rise above normal was recorded on charts monitoring operation of the incinerator in Room 149, Building 771. The plenum overheat alarm sounded at 1215, emergency actions initiated, and the fire was extinguished and mop-up began at about 1300. Investigation determined that the fire in the plenum was caused by a heat rise in the system, a deteriorated bypass valve on the No. 3 heat exchanger (KOH scrubber), nitration of the urethane seal on the HEPA filter media to the filter frame, and accumulation of metallic fines on the filter media. It was concluded that the management system responded properly, except for the ring- down system to activate the Emergency Operations Center