Displacement damage parameters for fusion breeder blanket materials based on BCA computer simulations

Based on the MARLOWE code, a refined binary collision approximation (BCA) simulation model has been developed which is particularly suited for light mass and polyatomic ionic solids in a fusion environment. Main features of the model are described, including appropriate extensions of the kinematical procedure and the ion-solid interactions. Defect yields from the simulated collision cascades are used for deriving displacement cross sections in Be, Li 2 O, Li 2 SiO 3 , Li 2 SiO 4 and Li 2 TiO 3 . Comparisons with standard results show that there is an energy dependence which is strongly correlated with the spectrum of primary knock-on atoms. In particular, for lithium ceramics the contribution of damage induced by secondary helium and tritium is remarkable even in a fast neutron flux. The total displacements per atom in a fusion demonstration reactor blanket obtained by means of BCA-simulation results is in general lower than NRT-values by about 30% for the lithium breeder materials, but higher by around 90% for beryllium. These differences can be attributed to differences of binding properties and crystalline structure of the respective material, which also influence the defect composition.