The distribution in the plasma of coolant-Helium impurity leaked from the first wall has been calculated and numericall results have given. The peak of the distribution is within the scrape-off layer (SOL). When Helium comcentration at the plasma center is required to be less than 5 percents, permitted Maximum-Leak-Rate (MLR) N_max is about 0.35×10^-3 mol/s and the biggest flaw allowed is with the length of about 3.1mm and the width of 0.63 mm. The main factors effecting the impurity distribution and concentration are such as the temperature and density at the edge of plasma, the temperature and density scrape-off lengths in SOL and the wall temperature.

A neutron transport code and a charged-ion radiation damage code have been linked to simulate neutron induced defects in the static, multi-component amorphous target. In simulating collision cascades, replacement collisions have been taken into account, especially. It corrected the value of DPA about 10%~20%. Improper replacements were recorded also. The radiation damage in two kinds of materials candidated for the first wall in fusion reactor is calculated. Calculation gives the production rates of PKA and DPA, gas production rates and their depth distributions. The results show that damage distributions are almost uniform body distributions, the DPA value of PE-16 is a little larger than that of SS316, the hydrogen production rates is nearly two times as much as that of SS316, the helium production rates is 1.45 times as much as that of SS316. It means that the radiation damage of PE-16 is more serious than that of SS316. The cross section data from MC(87) n library is used in the calculation.

A Monte-Carlo Neutron Transport Program and Neutron Radiation Damage Program are presented for studying radiation damage in the First Wall. The programs are used to static multi-component amorphous target. With the average wall load 1MW/m², the following calculating results for EHR first wall (type 316 stainlees steel)have been performed using designed neutron spectrums at EHR first wall: the PKA energy spectrums (30eV to 1MeV), average displacement per atom rate (20.6dpa/a), average helium and hydrogen production rates (247.18appm/a and 721.15appm/a). It is shows that Hybrid Reactor's radiation damage more serious than pure Fusion Reactor's by comparison of above results and EHP's calculated results in the same wall load. The cross-section data from MC (87) n library is used in this calculation.