Abstract: At approximately 6:30 a.m. on April 24th, 2000, Employee #1 was working in the TEM 5 machine primefill enclosure in the commercial manufacturing center, building #106. Zirconium potassium perchlorate (ZPP), was stored in the vibratory feeder mechanism inside the enclosure. Employee #1 entered the area through the primefill maintenance door and, as he was working inside the enclosure, a charge of static electricity ignited either the ZPP in the vibratory feeder mechanism or the residual ZPP on the walls inside the enclosure. This resulted in an explosion that killed Employee #1. Employee #2, who was not working in the enclosure, sustained minor head injuries. Employee #1 was not wearing conductive footwear at the time of the explosion.