Design studies on nuclear properties on the Flibe blanket for helical-type fusion reactor FFHR

The Force-Free Helical Reactor, FFHR, is a demo-relevant heliotron-type D-T fusion reactor. The blanket design for FFHR is improved in nuclear properties by using a one-dimensional neutron transport calculation. Nuclear properties, including tritium breeding ratio (TBR), nuclear heating and induced radioactivity, are evaluated. From the viewpoints of TBR and nuclear heating, the breeding zone is divided into three layers. The first layer consists of a 100% Flibe layer for cooling the first wall and efficient transfer of thermal energy. The second layer is filled up with Be pebbles in order to increase the TBR and the interactive surface area for reducing the amount of corrosive TF (tritiated fluorine) molecules. The third layer is a 100% Flibe layer. In the improved blanket, the local TBR is 1.2 and the energy deposited in the Flibe is calculated as 55% of the total nuclear heating. The effect of nuclear transmutation on Li, Be, F is also discussed.