Fires and explosions were an unwanted things and sometimes could not be controll. So the risk assessment needs to be done. Power companies managed a tank of diesel/HSD in large quantities, and inflict to a fire or explosion. Dows Fire and explosion index was a method of risk assessment that can be used because of the specific assessment. The objective of this research was to assess the risk of fire and explosion on the tank in power companies by the Dows Fire and Explosion Index method. This research used descriptive method with observational approach and interview. Interviews were conducted in K3 section and the fuels and chemicals section. The sources of primary data obtained from interviews and direct observation. Researchs object was a tank of diesel/HSD in unit 3 due to number more than 600 gallons, its capital density was greater than the residual/MFO, pressure and temperature were lower than the residual/MFO. The result showed that the value of F&EI on a tank of diesel/HSD at 75.24 as of into the classification of moderate. Radius of exposure in case of fire and explosion of diesel fuel tank is 19.26 m. The area of exposure in case of a fire and explosion of diesel fuel tank is 1164.7755 m² area. Value of area of exposed in case of fire and explosion of diesel fuel tank was US22.369.002,78.Thedamagefactorofdieselfueltank/HSDwas27 6.039.630,751. Loss control credit factor of diesel fuel tank/HSD by 0.71, so the value of the actual maximum probable property damage was US4.288.137,833.Themaximumprobabledaysoutagewere5daysandbusinessinteruptionduetofireandexplosionwasUS 81.187.939,39