Impact of armor materials on tritium breeding ratio in the fusion reactor blanket

We have studied the impact of armor materials on the tritium breeding ratio (TBR) in the fusion reactor blanket by Monte Carlo neutron transport calculations. In case a neutron multiplier is applied in the blanket, the TBR is decreased by installing the tungsten armor. On the other hand, the TBR is increased by installing the beryllium armor. The reduction of the TBR due to the installation of the tungsten armor is increased with increasing the volume ratio of the beryllium to the tritium breeder in the blanket. The blanket design without the tungsten armor is recommended from the view point of the TBR, since the design margin is very little for the TBR. On the other hand, the reduction of the TBR due to installation of the tungsten armor can be mitigated by installing the breeder region in the first layer in the multi-layered concept. By modification of the Li enrichment and the arrangement of the breeder/neutron multiplier, decreased TBR due to installation of the tungsten armor can be improved.