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Tritium surface distributions on the plasma-facing surface and four sides of JET Mk IIA divertor tiles employed in the D-T operation phase of JET were measured by Tritium Imaging Plate Technique (TIPT). Tritium distribution on the plasma-facing surface was consistent with carbon deposition profiles and asymmetric in both poloidal and toroidal directions. The toroidal asymmetry was attributed to the alignment of the tiles preventing direct impact of flux lines to tile edges. Accordingly, no significant carbon deposition or tritium accumulation was observed on two sides facing the toroidal direction. As already reported, heavy codeposition retaining high levels of tritium was observed on the plasma-shadow area of the horizontal target tile surface and the bottom side of the vertical target tile of the inner divertor region where it was kept relatively cool by water coolant. In addition, TIPT has clearly distinguished at least two different carbon deposition layers with different tritium retention in poloidal direction, showing that the poloidal asymmetry on the horizontal target tiles is due to the different carbon deposition properties in the poloidal direction. All the results suggest that tritium retention in the divertor area, which was determined by the carbon/hydrocarbon distribution, correlates closely with divertor geometry andmore » surface temperature.« less

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.