Material selection charts for optimised radiation shielding

Abstract

Material selection charts provide an objective metric to optimise the selection of engineering materials but have never been developed for radiation shielding. This can lead to sub-optimal choices in some cases, as we demonstrate in this paper. We have reformulated the radiation transport problem so that a material metric for any given shielding scenario can be computed, ranked, and mapped onto an Ashby map. By removing bias from the selection process, this has yielded non-obvious or even counter-intuitive candidates for further examination, which outperform the conventional choice of shielding materials, for example metal hydrides for fusion reactors and boranes for fast reactors in space. Key novelties are that this optimisation considers the type and energy spectrum of radiation, the composition of the target being shielded and what type of interactions should be minimised in the target. The high-throughput method, enables investigation of the shielding performance over time, finding that tantalum in a fast neutron flux, displays an improvement in shielding performance over time due to the formation ¹⁸²Ta that increases the scattering and absorption of neutrons in lower energy channels.