TRITIUM SORPTION BY CEMENT AND SUBSEQUENT RELEASE

In a fusion reactor or tritium-handling facilities, contamination of c oncrete by tritium and subsequent release from it to the reator or exp erimental room is a matter of problem for safe control of tritium and management of operational environment. In order to evaluate this triti um behavior, interaction of tritiated water with concrete or cement sh ould be clarified. In the present study, HTO sorption and subsequent r elease from cement were experimentally studied. (1) Sorption experimen ts were conducted using columns packed with cement particles of differ ent sizes. From the analysis of the breakthrough curve, tritium diffus ivity in macropores and microparticles were evaluated. (2) From the sh ort-term tritium release experiments, effective desorption rate consta nts were evaluated and the effects of temperature and moisture were st udied. (3) In the long-term tritium release experiments to 6000 h, the tritium release mechanism was found to be composed of three kinds of water: initially from capillary water, and in the second stage from ge l water and from the water in the cement crystal. (4) Tritium release behavior by heat treatment to 800 degrees C was studied. A high temper ature above 600 degrees C was required for the tritium trapped in the crystal water to be released.