Imaging plate technique for determination of tritium distribution on graphite tiles of JT-60U

The tritium imaging plate technique was applied to determine surface tritium distributions on graphite tiles used as the first wall and W-shaped divertor in JT-60U, in which tritium produced by the D–D nuclear reaction in the plasma was implanted and/or deposited depending on the incident energy. Measured samples were isotropic graphite (IG-430U) and CFC graphite (CX-2002U), used as divertor tiles and/or baffle plates just outside the divertor. Tritium areal distributions on graphite divertor tiles, dome units and baffle plates of JT-60U were successfully measured for the first time. Tritium distributions observed in JT-60U tiles can be explained by homogeneous implantation of high energy tritium which is influenced by redeposited layers and redistributed by the temperature increase due to the plasma heat load. The tritium retention in graphite heated above 800 K was significantly small.