Model of emission of contaminating substances into the atmosphere on contact of solid uranium hexafluoride with moist air

A mathematical model which takes account of the basic chemical and physical processes which play a fundamental role in the contact between solid uranium hexafluoride and moist air is developed. The model parameters are estimated using numerical modeling and experimental data obtained by other authors: the rates of homogeneous and heterogeneous chemical reactions. The emission is modeled mathematically in different approximations. Estimates are obtained for the density of emission fluxes for uranium hexafluoride, uranyl fluoride, and hydrogen fluoride. The dependences of these fluxes on the temperature and moisture content of air are determined. It is shown that the calculations of the emission flux of uranyl fluoride according to the homogeneous mechanism give results which are too high by a factor of almost 3. For air temperatures above 293 K only a homogeneous chemical reaction can occur between water vapor and uranium hexafluoride. At lower temperatures homogeneous and heterogeneous chemical reactions can occur. __________ Translated from Atomnaya énergiya, Vol. 103, No. 4, pp. 241–247, October, 2007.