Insights from the Risk Analysis of a Nearby Propane Tank Farm

Due to the flammability and explosion characteristics of the propane vapor cloud, a nearby propane tank farm could possibly present a significant risk to the operation of nuclear power plants. Accidental releases of propane may occur in the propane supply pipeline, at the propane storage tanks, or on the propane transportation routes due to propane transport trailer truck accidents. Loss of containment could result in toxic vapor cloud affecting the nearby nuclear plant control room habitability, Vapor Cloud Explosion (VCE) overpressure due to both deflagration and detonation, Boiling Liquid Expanding Vapor Explosion (BLEVE) missile impacts, and thermal radiation from BLEVE fireballs, flash fires, pool fires, and jet fires. The thermal radiation impact ranges of a pool fire, jet fire, flash fire, and BLEVE fireball is typically less than the shortest distance between the propane tank farm and the nearby nuclear plant. The explosion overpressure and missiles are the most critical hazards to the nearby nuclear plants. Only VCE overpressure greater than 1 psi and BLEVE missiles can potentially impact the PRA related structures and equipment at the nearby nuclear plant. The total frequency of unacceptable damage at the nearby nuclear plant resulting from accidents at the propane tank farm and from propane transport truck accidents is estimated to be less than 10 per year. This paper discusses the insights gained from the analysis of the risk impact on a nearby nuclear plant due to accidental release of propane from the propane terminal related operations, including the propane storage/distribution facility and the propane transport trucks. The important considerations used in the analysis of the risk scenarios resulting from a propane transport truck accident, large and small releases at the propane distribution facility, and exploding missile hazards are presented.