Radioactive gas diffusion behavior in the medium of mathematics analytic calculation process is complicated. Firstly, the diffusion model of the radioactive gas within the medium is expounded. Secondly, with the extrapolated boundary in the low-concentration side, the solution of explicit finite difference and implicit finite difference are discussed in the paper. Finally, their error, feasibility and precision in the practical application are investigated by numerical numeration and simulation experiment. After further study, the numerical met...
