During this experimental stage, the moisture concentrations and the operating temperatures at regeneration inlet and regeneration outlet of the auxiliary molecular sieve bed were monitored, with the experimental results shown in Fig. 4. Same as the experimental results of initial water removal of the auxiliary molecular sieve bed, the moisture concentrations at regeneration inlet and regeneration outlet of the auxiliary molecular sieve bed began greatly increasing when the regeneration temperatures of the auxiliary molecular sieve bed reached about 150 °C. With the regeneration temperature gradually increasing, the moisture concentration of regeneration outlet of the auxiliary molecular sieve bed firstly increased to 3204 ppm and gradually decreased to a low value equal to that of regeneration inlet, which almost kept stable to be 1384 ppm. At the same time, a large quantity of water was collected in the water separator of helium purification regeneration system and the total tritium-containing waste water was estimated to be 8.1 kg. The tritium-containing waste water was sampled again by isolating the water separator from regeneration system piping and alternately opening valve of V10 and V11. The specific activity of the tritium-containing waste water collected at this experimental stage was measured to be equal to that of the first sampling analysis being 6.1 × 109 Bq/L.