Assessment of the activation, decay heat, and waste disposal of the US helium-cooled ceramic breeder test blanket module in ITER

The radioactivity inventory and decay heat in the US helium-cooled ceramic breeder (HCCB) test blanket module (TBM) have been assessed at shutdown and for several times thereafter. The sub-module will have its own FW and structural container box that houses the breeder and beryllium pebble bed units, arranged in an edge-on-configuration. Low activation ferritic steel (F82H) is used as the structure and helium is used as a coolant. The breeder beds are made of Li2TiO3 pebbles in which lithium has been enriched up to 75% in Li-6. Pulsed operation mode is assumed. During operation in the D-T phase, the total heating rate in the TBM is ∼263 kW. The total amount of tritium generated in the breeder and the beryllium multiplier is ∼9 g and 0.07 g, respectively, after reaching the 0.3 MWa/m2 fluence limit. At shutdown, the total radioactivity and decay heat levels are ∼0.89 MCi and ∼0.002 MW, respectively. These values drop sharply after 1 min to ∼0.098 MCi and ∼0.0006 MW. The contribution from the F82H structure is the dominant one up to ∼10 years following shutdown. After ∼10 years, the contribution to the total activation and decay heat from the breeder material is the dominant one due to the generated tritium. The WDR of various components are far below unity and thus are well within ITER regulatory guidelines.