Experimental methods for investigation of radioactive gas diffusion in solids

Features of application of the desorption method for studying diffusion in gas and vapour solids labelled by radiactive indicators are considered. Two variants of diffusion installations designed for determination of the diffusion coefficient on radioactivity measurements of both gas and solid phase (in vacuum and in the inert atmosphere) are developed and tested. Influence of initial concentrated profile degassing, the diffusion mechanism (volumetric diffusion, degassing kinetic mode a.o.), the presence of radioactive decay on the form of kinetic curves is discussed. The general solution of the equation set for dissociative diffusion under boundary conditions of the desorbed method is obtained. Kinetic curves of gas release in the framework of the diffusion model with time confinement are computed. The methods suggested are tested using diffusion of radioactive inert gas-radon-222 in polyethylene of low density