STUDY OF THE THERMOMECHANICAL AND TRITIUM RELEASE BEHAVIOR OF LI2ZRO3AS TRITIUM BREEDING CERAMIC FOR THE EUROPEAN BIT BLANKET CONCEPT

Among key issues identified for the BIT blanket concept developed in E urope is the physical integrity of the ceramic breeder pellets under o perating conditions. The latter depends among other factors on the the rmal, mechanical and elastic characteristics of the ceramic material. Relevant parameters such as thermal conductivity lambda, mechanical st rength (diametral compressive strength sigma(d)), Young's modulus E an d Poisson's ratio nu have been determined. Their variation in the 75-8 5% TD range and the resulting variation of the expression (1 - nu) lam bda sigma(d)/E which is to be taken into account to predict whether or not pellets will fracture under given thermal stress conditions, were investigated. The above expression increases with increasing material density reflecting an improvement of the fracture resistance. In para llel, the tritium release behaviour of materials just described was in vestigated using out of pile tritium release annealing tests. Results show that in the density range explored and for grain size of 1 to 2 m u m, no significant change in tritium release is observed. This study indicates that within certain limits an increase in Li2ZrO3 density ca n help fulfill the BIT concept requirements.