Performance of a Li2TiO3 pebble-bed in the CRITIC-III irradiation

Lithium metatitanate (Li2TiO3) is a candidate material for tritium breeding in fusion reactor pebble-bed blankets. 173 g of Li2TiO3 pebbles were irradiated for 334 full power days (FPD) to a burnup of 0.9% 6Li in the CRITIC-III experiment in AECLʹs NRU reactor. A key objective was to determine tritium release over a wide temperature band from 200°C to 900°C. On-line release and temperature measurements are reported in this paper. New analytical methods led to calculated inventories ranging from 15 wppm average at the lowest temperature of operation (200°C outer surface to 700°C inner surface) to less than 1.2 wppm average at 375°C outer-surface temperature and 875°C inner-surface temperature. The thermocouples indicated that the bed remained stable during the irradiation, which included thermal shocks from 90 reactor shutdowns. From this swept-capsule irradiation, Li2TiO3 appears to be a good candidate for fusion blanket pebble-beds.