Environmental airborne tritium monitoring system based on absorption of tritiated water on calcium chloride.

Abstract

Environmental monitoring of tritium around nuclear facilities is conducted in order to demonstrate compliance with regulatory requirements on the protection of members of the public. Multiple techniques are used to monitor its concentration in air, soil and flora. A new monitoring system was developed, which is based on the absorption of tritiated water on Calcium Chloride grains. Calcium Chloride has an improved capability to absorb water vapor, compared with other absorbents/adsorbents: it can absorb water vapor as much as three times its own weight. The Calcium Chloride is inserted inside a plastic bag where it interacts with environmental vapor through a membrane filter "window". The tritium absorption rate is then controlled by adjusting the free area of the membrane filter. After the determination of the tritium activity absorbed in the calcium chloride using a liquid scintillation system, a model is used to estimate its airborne concentration, considering the environmental conditions.