Deflagrations of Lean and Rich Hydrogen-Air-Steam Mixtures in Nuclear Reactor Containments

Abstract

During a severe accident in a nuclear plant, hydrogen-air-steam explosions may occur. Sixty six tests in a 0.5 m3 containment were carried out to study the flammability and the deflagration of hypo-and hyper-stoichiometric mixtures. The data of these and another 848 tests which can be found in literature were elaborated, compared and interpreted . The hydrogen rich mixtures are more unlikely to be flammable and thus, it is simpler to prevent them from exploding. On the other hand, their deflagration at the flammability limits would cause greater overpressures in a closed containment . Taking into account scaling problems, a method of utilizing the data and the knowledge acquired in the laboratory is then suggested in order to assess hydrogen risks in nuclear reactor containments, and furthermore to check deliberate ignition as a system to reduce such risks.