A physicochemical mechanism for the ignition of the Seveso accident

Abstract

The so-called Seveso ‘explosion’ of 10 July 1976 was completely unexpected, and various speculations about its initiation have been entertained, including the possibility of sabotage¹. Seveso has remained the focus of undiminished interest and publicity^1,2 and the puzzle concerning the occurrence of its accident persists. The explanation proposed here is based on our recent investigations of the relevent chemical kinetics and heat transfer phenomena. This physicochemical mechanism involves the combination of (1) exothermic reactions starting (personal communication from the Givaudan Company) below the previously known 230 °C threshold and (2) a thermal conduction–convection–radiation process responsible for channelling the normally negligible (in global sense) upper reactor wall heat into a small portion (10%) of the reactor contents, thus yielding the temperature range conducive to these exothermic reactions.