Key Technology of the Online Discriminating Measurements for HTO

During the online monitoring for tritium, the effectiveness of measurements is decided by the performance of the discrimination devices(Nafion). Experiments have been made to examine the performance of Nafion in terms of gas instantaneous flux and temperature. The research shows that a permeability as high as 90% can be reached for HTO in the Nafion while less than 0.19% for HT. More than 99% of HTO can be separated which gives a discriminating ratio between HTO and HT above 10⁶ with a single-stage Nafion provided that a good control of temperature and humidity as well as gas instantaneous flux have been achieved.