INTEGRAL EXPERIMENT ON EFFECTS OF LARGE OPENING IN FUSION-REACTOR BLANKET ON TRITIUM BREEDING USING ANNULAR GEOMETRY

An experiment involving a simulated blanket with an opening has been p erformed using the line source and annular blanket system developed un der the JAERI/USDOE collaborative programme in order to examine the ef fects of the opening on neutronics parameters such as the tritium-bree ding ratio. The annular test assembly was rectangular in shape and con sisted of a lithium oxide blanket covered with graphite and SS304 whic h simulated the graphite armour plate and first wall in a fusion devic e. A large opening (376 mm x 425.5 mm) was made in the middle of the t est blanket. This opening simulated a neutral beam injector. Tritium p roduction rates and reaction rates were measured inside the blanket. N eutron spectra and reaction rates were also measured on the surfaces o f both sides with and without the opening of the inner cavity. The ope ning decreased the number of low energy neutrons contained in the cavi ty and especially decreased Li-6 tritium production by 10% inside the blanket at the opposite side of the opening. The Monte Carlo code GMVP using the JENDL-3 nuclear data library predicted the measured nuclear parameters in the test blankets, such as the tritium production rate, to within 10% accuracy.