Tritium Retention in the Gap Between the Plasma-Facing Carbon Tiles Used in D-T Discharge Phase in JET and TFTR

Tritium accumulating in codeposits in the gaps between plasma facing components is a safety concern in next step fusion machines as suitable removal techniques have yet not been developed. We report on Imaging Plate measurements of the tritium areal distribution on the side surface of graphite/CFC tiles installed in the TFTR bumper limiter and JET Mk IIA divertor, both of which were exposed to D-T discharges. The tritium profiles on the four sides of TFTR tiles showed a short- and long-range decay pattern. In case of JET divertor tiles, only a small amount of tritium retention was detected on the tiles side facing the toroidal direction, while tritium retention was very large on the side facing the poloidal direction. These retention properties showed that the orientation or alignment of plasma facing component plays important role on the tritium retention in the gaps of those machines.