Abstract <p>Based on the theory of combustion and explosion, the scientific principles of steam explosion are described. The possibility of its implementation in reactors in which pressure relief is carried out by means of a valve is considered. The essential conditions for the occurrence of this explosion have been determined, such as transfer of the vapor–liquid mixture in the reactor to a critical state; impact initiation of a steam explosion and formation of a weak shock wave; development of a steam explosion by propagation of a shock wave through the reactor; and release of explosion products into the surrounding space. The example shows and defines the conditions for a steam explosion to occur in the internal volume of a reactor.</p>