It should be noted that the type of molecular sieve for molecular sieve bed of helium purification system can be 5A or 13X for the simultaneous adsorption of water (including trace of tritium) and carbon dioxide, while that for auxiliary molecular sieve bed of helium purification regeneration system can be various zeolite which has a high affinity for water such as 3A, 4A, 5A, 10X and 13X etc. The 5A molecular sieve and 13X molecular sieve are commercial adsorbents commonly used to remove both water and carbon dioxide for industrial gas purification (Yang, 1987). The auxiliary molecular sieve bed is only used to recover the tritium-containing waste water, so most of the commercial zeolites that can strongly adsorb water are suitable for the auxiliary molecular sieve bed.