Breeder foam: an innovative low porosity solid breeder material

Ceramic foam or cellular ceramics are proposed as a new solid breeder material configuration. Such cellular breeder materials would have an open cell structure consisting of a network of three-dimensional interconnected ligaments. Ceramic breeder foams could address some of the challenges facing packed breeder beds and potentially enhance thermal performance, increase breeding ratio, and improve structural reliability. Foam densities are not limited to those of mono-sized pebble beds, thermal conductivities are higher compared with similarly dense pebble beds; and morphology changes are expected to be much smaller and slower than in pebble beds. Heat transfer between breeder and coolant walls can be enhanced in principal, by bonding the stand-alone breeder foam to the structure. Correlations of thermo-mechanical properties of ceramic foams are reviewed to highlight the potential advantages of a foam configuration for solid breeders.