Material behavior of JT-60U plasma facing components and installation of B/sub 4/C-converted CFC/graphite tiles

Wall damages of the JT-60U plasma facing components in the recent operation are more serious than in the previous one. Erosion of carbon fiber composite (CFC) divertor tiles due to field ripple of the toroidal coil is observed. Several bolt-loosening divertor tiles are eroded or disconnected. Mechanical fracture of CFC first wall tiles is found. The first application of B/sub 4/C-converted CFC tiles (surface-boronized ones using conversion method) is also shown. The B/sub 4/C-converted tiles have been installed to the outboard striking zone of the divertor plate and in use satisfactorily in the high power heating divertor operation.