THREE-DIMENSIONAL CELL CALCULATIONS FOR A FUSION REACTOR GAS-COOLED SOLID BLANKET.

Neutronic cell calculations for a minimum lithium and tritium inventory solid gas-cooled fusion power plant blanket are investigated by three-dimensional Monte Carlo methods, and predict a substantial difficulty in attaining sufficient breeding, in contrast to previously published results. Actual three-dimensional configurations, heterogeneities, and material compositions as imposed by mechanical, hydrodynamic, and heat transfer considerations, are accounted for. A gross blanket breeding ratio of 1. 067 plus or minus 0. 026 is obtainable for the considered reference design. That value is thought inadequate if calculation and data uncertainties and reprocessing and system losses are accounted for. The authors' results update previous one-dimensional Discrete Ordinates results which predicted an overly optimistic gross blanket breeding ratio of 1. 184 for the same design. These were based upon assumed preliminary material compositions and did not realistically model the configurations. For satisfactory breeding in such designs, stainless steel needs to be replaced by an alternative structural material for a better neutron economy in a predominantly soft spectrum. Three-dimensional cell studies seem necessary for reliable estimates of parameters in such a basically heterogeneous system.