Tritium profiles in tiles from the first wall of fusion machines and techniques for their detritiation

Tritium profiles on a TFTR graphite tile exposed to D-D plasmas and a JET g raphite tile from the first tritium campaigns were examined by full combust ion, thermogravimetry and thermal desorption. Combustion measurements revea led that >98.9% of the tritium is trapped in a layer <50 mu m thick, the re mainder being spread throughout the tile. The tritium distribution on the t ile surface is not homogeneous. A significant fraction resides in the gaps between tiles. Graphite disks from the plasma-exposed side of JET tiles hea ted up to 1100 degrees C under a helium stream containing 0.1% hydrogen sho wed the highest tritium release rate at similar to 850 degrees C. The agree ment between tritium measurements by full combustion and thermal release wa s reasonably good. Tritium on graphite tiles was released to >95% under a s tream of moist air at about 400 degrees C. A large fraction of tritium can be removed from the tile surface with adhesive tape. (C) 2000 Elsevier Scie nce B.V. All rights reserved.