Estimation of pressure during steam explosion in the sub-reactor room of NPP with RBMK-1000

Abstract

The article analyzes the scenario of a severe beyond the design basis accident with core melting at a nuclear power plant with RBMK-1000. Molten reactor core falls into the sub-reactor space filled with a steam-water mixture. The interaction of melt core and the coolant can lead to the creation of conditions for the occurrence of a steam explosion. Parameters of this steam explosion have been evaluated by Hugoniot adiabat method. Such approach considers the steam explosion as detonation phenomenon, where shock wave impacts initial multiphase mixture and initiates melt droplets fragmentation and high heat flux from melt to water. Mass, momentum and energy conservation equations for initial mixture and for equilibrium explosion products mixture lead to Hugoniot equation for the adiabat. The tangent from initial point (initial mixture) on the plane “mixture volume-mixture pressure” to the Hugoniot adiabat determines Chapman – Jouguet point, which characterizes steam explosion parameters. Our calculations have demonstrated that obtained values of steam explosions do not exceeds dangerous limits.