Tritium distribution on the surface of plasma facing carbon tiles used in JET

Tritium surface profiles on divertor tiles used in JET were successfully determined applying imaging plate (IP) technique. The tritium intensities measured by IP were quite consistent with the previous tritium analysis made by full combustion measurements. Present results are summarized as follows. Most of the tritium in the divertor tiles was retained in co- or re-deposited layer and did not move because of their temperature was rather low. In addition tritium produced by D–D reaction are implanted in subsurface layers rather homogeneously, which seems the main tritium source for the inner divertor tiles with some thermal modification. Still there is another but very small tritium retention observed at the back side of the tiles, of which profile reflects the 2-D CFC structure, indicating preferential absorption and migration of tritium.