火災[kasai] conflagration
火災保険[kasaihoken] fire insurance
核災害[kakusaigai] nuclear disaster
公務災害[koumusaigai] accidents in line of duty
災い[wazawai] calamity

災禍[saika] accident
災害[saigai] calamity
災難[sainan] calamity
災難に遭う[sainanniau] to meet with misfortune
災厄[saiyaku] calamity