Triton burn-up study in JT-60U

Time-resolved triton burn-up measurements have been performed using a new type of 14 MeV neutron detector based on scintillating fibres. The shot-integrated triton burn-up ratio was measured to be in the range 0.3 - 2.0%. Time histories of 14 MeV emission after NB turn-off have been analysed based on the classical slowing-down theory. Assuming the loss of fast tritons can be represented as a diffusivity, values increasing with increasing toroidal ripple were determined between 0.05 and 0.15 , from the modelling of the time histories of the 14 MeV emission after the NB turn-off.