A method of selecting one or more materials of specific
isotopic composition for use in a
neutron shield. A first
list of materials is provided, each material having a different
isotopic composition. Values of incident
neutron fluxes ϕg0 that the
neutron shield will encounter in use are provided. A set of criteria is provided, the set of criteria including one or more of:
neutron flux,
neutron dose, heating of a target protected by the neutron shielding, damage to the target, gas production within the target,
tritium production within the target, and transmutation of the target. For each criterion, an overall weight βcriteria is defined, and an intrinsic weighting factor αg is defined for each of a plurality of neutron energy groups based on the incident neutron fluxes. Using a computing
system, an overall
figure of merit Λ is calculated for each material in the first set of materials, wherein the overall
figure of merit Λ for each material is based on: determining a
figure of merit Λg for each neutron energy
group based on absorption and scattering coefficients of the material for each neutron energy group; for each criterion, determining a figure of merit Λcriteria for the criterion based on the figures of merit for each neutron energy group, weighted by the intrinsic weighting factors for the criterion; determining an overall figure of merit Λ based on the figures of merit for each criterion, weighted by the overall weight for the criterion. A second
list of materials is selected based on the overall figures of merit Λ of the materials, wherein the second
list is a subset of the first list.