TRITON BURN-UP STUDY IN JT-60U

Time-resolved triton bum-up measurements have been performed using a n ew type of 14 MeV neutron detector based on scintillating fibres. The shot-integrated triton bum-up ratio was measured to be in the range 0. 3-2.0%. Time histories of 14 MeV emission after NE 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 increasin g with increasing toroidal ripple were determined between 0.05 and 0.1 5 m(2) s(-1), from the modelling of the time histories of the 14 MeV e mission after the NB turn-off.