THE BEHAVIOR OF CERAMIC BREEDER MATERIALS WITH RESPECT TO TRITIUM RELEASE AND PELLET/PEBBLE MECHANICAL INTEGRITY

In situ tritium release experiments from several candidate fusion blanket ceramic breeder materials have been performed in the High Flux Reactor (HFR) at Petten over the last few years. The sixth experiment, EXOTIC-6, contained pellets of LiAlO2, Li2ZrO3, Li6Zr2O7 and Li8ZrO6 and pebbles of Li4SiO4 and Li2ZrO3 which were irradiated up to a lithium burnup of 3%. A large number of temperature transients and purge gas composition changes were performed. From the temperature transients tritium residence times have been determined. Some preliminary results were presented at the 17th Symposium on Fusion Technology (SOFT) held in Rome in 1992. In the present paper results of a further analysis of the residence times are presented together with some postirradiation examination results. The LiAlO2 pellets showed a better mechanical stability than the Li-zirconates pellets. The pebbles remained intact. The tritium residence times determined from the tritium inventories were in good agreement with those previously determined from temperature transients. The tritium release characteristics of the materials investigated remain substantially unchanged up to the maximum lithium burnup achieved in this experiment.