Truly unconfined deflagrations of ethylene-air mixtures

To estimate the possible over-pressure on the structures of a nuclear power plant under an external explosion, studies on unconfined explosions to provide the necessary elements to establish a safety rule, have been developed. The present research contract, carried out by a French group CEA-EDF-ENSMA, was divided in four stages: 1) Scale effect on the pressure field produced by spontaneous accelerations on blasts in an steady medium; 2) effect of a brutal discontinuity of the fuel gas concentration on the blast speed in a stratified medium; 3) effect of the blast-off energy on the explosion of a spherical ethylene-air mixture; 4) study of the influence of the shape and of the size of the cloud on the pressure field produced by the explosion