Physical-mathematical model of volume condensation and transport of aerosols inside the containment shell of a vver reactor

Abstract

radioactive aerosol by wetting it, diffusion on drops, and washing out of the drops which settle in the gravitational field. The spectrum of the aerosol remaining in the volume after the fog has cleared is different from the initial spectrum. Therefore the problem of radionuclide transport and condensation of the steam inside the volume enclosed by the containment shell are closely related with one another. They are also closely related with the problem of the transport and combustion of hydrogen because the presence of steam and drops strongly influences the formation of an explosive mixture. Ultimately, this complete problem is the aim of the investigation of the evolution of the steam, drop, and hydrogen-air mixture formed as a result of the rupture of a high-pressure loop. In the present paper we describe a physical-mathematical model of the microphysical processes which occur inside the containment shell as a result of a loss-of-coolant accident. The state of the medium inside the containment shell is determined by the air density ol(x, t), the steam density C(x, t), the water content P(x, t) density (the water content is the mass of the condensed moisture per unit volume), the temperature field T(x, t), the number density of drops n(x, t), and the density of the mixture (air + steam + drops) o(x, t). If necessary, it is possible to introduce the supersaturation field A(x, t), which is determined by the relation A(x, t) = C(x, t) -- M(x, t), where M(x, t) = m(T)(1 + fz) is the equilibrium density of steam in the system drops + steam + air;