"Catastrophic release" defined. "Catastrophic release" means an uncontrolled emission, fire or explosion involving one or more highly hazardous substances or explosives that presents imminent and substantial endangerment to the health of the employees, the public health or the environment. The term includes events that occur within a building or other structure that contains the substance or explosive.
Nev. Admin. Code § 459.95235
NRS 459.3818