Abstract
An experiment involving a simulated blanket with an opening has been performed using the line source and annular blanket system developed under the JAERI/USDOE collaborative programme in order to examine the effects of the opening on neutronics parameters such as the tritium-breeding ratio. The annular test assembly was rectangular in shape and consisted of a lithium oxide blanket covered with graphite and SS304 which simulated the graphite armour plate and first wall in a fusion device. A large opening (376 mm × 425.5 mm) was made in the middle of the test blanket. This opening simulated a neutral beam injector.
Tritium production rates and reaction rates were measured inside the blanket. Neutron spectra and reaction rates were also measured on the surfaces of both sides with and without the opening of the inner cavity. The opening decreased the number of low energy neutrons contained in the cavity and especially decreased
6Li 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.