Neutron and thermal calculation of blanket for high power operating condition of fusion reactor

As the international thermonuclear experimental reactor (ITER) project has proceeded to the engineering design activity (EDA) phase, the design parameters of the reactor have been reconsidered from those in the conceptual design activity (CDA) phase. The fusion power is one of the parameters being reconsidered. In the primitive assessment, the possibility of a fusion power of 1.5-3.0 GW was indicated. With simultaneous enlargement of the reactor dimensions, the neutron wall loading would be 1.2-2.3 times as high as that in the CDA phase. A tritium breeding blanket with ceramic breeder pebbles, proposed by Japan in the CDA phase, has been investigated for the accommodation of these high fusion powers. For a layered pebble bed-type blanket, the breeder and neutron multiplier layer thicknesses have been adjusted to allow a power variation from 1.5 to 3.0 GW. The neutron and thermal performance of the blanket design have been evaluated, and the tritium inventory in the blanket has been estimated. It has been shown that the layered pebble bed blanket is basically applicable to the high power operating conditions. (orig.)