Several hours of fire and numerous explosions destroyed the Pacific Engineering Company plant in Henderson, Nevada, that manufactured ammonium perchlorate (AP) for rocket fuel. This incident began about 1130 PDT on May 4, 1988, with a fire in their Batch House that grew out of control and caused a first large explosion at about 1153 PDT. The final and largest explosion occurred about 1157 PDT. Damages to the surrounding community were surveyed and interpreted as airblast overpressures versus distances, which allowed an estimate of 1-kiloton nuclear free-air-burst for the equivalent explosion yield. This could be reproduced by 250-tons TNT burst on the ground surface. Weather reports were obtained from the National Weather Services which indicated somewhat enhanced airblast propagation downwind toward northerly directions and attenuated airblast propagations upwind in southerly directions. It was impossible, for lack of winds aloft information below about 500 m above ground, to determine whether there was any atmospheric acoustic airblast focusing. Several seismic recordings in Las Vegas showed the greatest ground motion resulted from the airblast wave passage, traveling at near acoustic speed. Ground wave arrival times were not sufficiently precise to allow seismic speed interpretations. Of the 4000 tons of AP apparently stored in and around the plant, it appears that about 1500 tons detonated in the largest explosion. This leads to a conclusion that the TNT airblast equivalence factor for AP is near 1/6. An independent estimate, based on analysis of more ideal close-in structural deformations, suggested an equivalence factor of 1/3.

An explosion at the PEPCON ammonium-perchlorate plant on May 4, 1988, in Henderson, Nevada, broke more than 10,000 windows and caused over $70 million damages to the Henderson-Las Vegas communities. A lawsuit by a conglomerate of insurors led to "discovery" of 77 claims for various injuries. Most of the 306 people treated at hospitals did not participate in this suit; their injury costs were apparently paid by medical insurance and not incorporated into the combined damage claim. Their records could not be obtained for analysis because of patient privacy considerations. Nevertheless, their number from the newspapers could be compared to window damage claims to show roughly one laceration victim per 100 broken window panes. Damage analyses led to a determination that the equivalent TNT yield of the largest and most damaging explosion was about 250 tons, surface burst. Weather conditions and glass damage claims were combined to provide a plan map of overpressure isobars for comparison with injury claims from the lawsuit. A number of examples are compared to results from other incidents.

On May 4, 1988, the PEPCON plant experienced three major and several smaller explosions that caused over $70 million in property damage and caused two deaths. The PEPCON plant produced Ammonium Perchlorate (AP), a major ingredient for rocket fuel. The PEPCON plant and the nearby Kidd Marshmallow plant were totally destroyed by the detonations. The initiating event for the explosions was a fire that originated in the Batch Dryer Building and spread to adjacent storage. Several factors combined to cause the AP in the major storage fields to detonate, the most important being lack of adequate separation between storage units. Welding and flame cutting procedure with poor fire watch protocol was the prime candidate for fire ignition. There were no automatic fire suppression systems at the plant. Buildings including the Batch Dryer Building were made of combustible building material (fiberglass). There was poor housekeeping and no control of AP dust generation. AP was stored in combustible polyethylene drums, aluminum tote bins, 30-gallon steel storage drums and fiber reinforced tote bags. There were high-density storage practices. In addition, a contributing factor to the rapid fire-spread was that the wind that day was blowing directly from the batch dryer building to the storage areas. This paper claims that if codes, standards, and well-known hazard identification safety techniques were implemented at PEPCON, then the disaster would have been averted. A limited scope probabilistic risk assessment was conducted to establish the effectiveness of various preventive and mitigative features that could have been deployed to avert the disaster. The major hazard at the PEPCON site was fire and explosion involving the processing, production and storage of AP, which was then and is currently stored as a class 4 oxidizer.