Method for designing gas tag compositions

A method for designing a tag gas for use in a nuclear reactor gas tagging failure detection system, wherein a plurality of tag gases each having a unique, predetermined composition are disposed in respective fuel canisters to provide an indication of a leak in one or more of said canisters, said method comprising the steps of:

• (a) designating a target composition of a first tag gas for use in a first fuel canister and filling said first fuel canister with said first tag gas;
• (b) determining the actual composition of said first tag gas;
• (c) representing the actual composition of said first tag gas as a first node on a surface of a sphere and the composition of a plurality of other tag gases as a plurality of remaining nodes on the surface of said sphere, wherein the distances on said sphere between each of said nodes is represented as a plurality of internodal tie-lines;
• (d) randomly changing the location of each of said remaining nodes on said sphere;
• (e) determining the minimum distance on said sphere from each node to a tie-line connecting any two other nodes on said sphere;
• (f) selecting M remaining nodes which provide the longest distances from the nodes to tie-lines connecting any two other nodes and assigning said M nodes a fixed position on the surface of said sphere;
• (g) selecting N remaining nodes which provide the shortest distances from the nodes to tie-lines connecting any two other nodes;
• (h) randomly changing the location of each of said N nodes on said sphere followed by again determining the minimum distance on said surface from each of said N nodes to a tie-line connecting any two other nodes on said sphere;
• (i) repeating steps (d)-(h), where each time N is reduced by one in eliminating those nodes having the shortest distance to any tie-line connecting any two other nodes until the maximum distance on said sphere for all of the remaining nodes to tie-lines connecting any two other nodes on said sphere has been determined;
• and
• (j) determining the M' node having the longest distance to tie-lines connecting any two other nodes on said sphere and designing a second tag gas with a composition represented by the location of the M' node on said sphere.