THE EFFECT OF NEUTRON-IRRADIATION ON THE TRAPPING OF TRITIUM IN CARBON-BASED MATERIALS

Carbon-based materials are considered for protection of plasma-facing components in the next step fusion device. To investigate the effects of neutron damage on the tritium behaviour an experimental study on the tritium retention of various neutron-irradiated graphites and carbon/carbon fibre composites was started. The irradiation dose of the specimens ranges from 10(-3) to 3.5 dpa g and the irradiation temperature from 390 to 1500 degrees C. A comparison of tritium retention in pre- and postirradiated carbon-based materials as a function of the sample temperature is reported in this paper and the results are discussed. The first results indicate that the retention of tritium is higher in irradiated graphite than in unirradiated graphite and depends largely on the density and microstructure. The retention is also influenced by the tritium loading temperature. Graphite of type S 1611, irradiated at 400 and 600 degrees C up to a damage of 0.1 dpa g, retained about two times more tritium than the unirradiated material.