4.15.6.1 Irradiation Damage

Greenwood calculated damage parameters for solid lithium tritium breeder materials irradiated in the fusion breeder reactor (FUBR) and breeder exchange matrix (BEATRIX) series of irradiations in EBR-II and FFTF reactors.186 He showed that most of the displacement damage arises from fast neutron reac­tions such as elastic and inelastic scattering rather than from the 6Li (n, a) T reaction. The displacements per atom is only an estimate of the total energy available for creating displacements in a compound and does not directly relate to observable damage effects due to the high probability of recombination effects.

Leichtle and coworkers149,150 evaluated damage correlation parameters in fusion and fission reactor systems for the ceramic breeder materials Li2TiO3, Li4SiO4, and Li2O. A sophisticated damage calculation taking into account all relevant primary knock-on atoms (PKAs) was performed to obtain displacement damage parameters for these low-mass polyatomic materials. They arrived at a concise fusion-fission correlation of irradiation effects. Such compar­isons have been performed for typical fission neutron flux spectra of a thermal and a fast reactor system. In

preparation for an IEA-framed international program on high fluence breeder irradiation, Fischer et a/.150 performed analyses of lithium burnup and displace­ment damage in Li2O, Li4SiO4, and Li2TO3 for a HCPB-type DEMO blanket design (Figure 63).