Concentric-Sphere Design for Spacing of Tag-Gas Isotopic Ratios

An analytical tag-design scheme is presented that can be used to compute the isotopic compositions for a system of tag nodes, used to identify failed fuel assemblies in reactors with gas-bonded nuclear fuels. The tag nodes are located uniformly across the surfaces of two concentric spheres. This design minimizes the possibility of ambiguous leaker identification in the event of double-assembly failures, while reducing the enrichment requirements for the noble gases used to create the tags. Reducing the enrichment requirements lowers the overall tag costs and makes the design particularly well suited for reactors requiring large numbers of distinct tags.