The max–min ant system and tabu search for pressurized water reactor loading pattern design

•An automatic loading pattern design tool for a pressurized water reactor is developed.•The design method consists of max–min ant system and tabu search.•The heuristic rules are developed to generate the candidates for tabu search.•The initial solution of tabu search is provided by max–min ant system.•The new algorithm shows very satisfactory results compared to the old one.

An automatic loading pattern (LP) design tool for a pressurized water reactor is developed. The design procedure consists of two steps: first, a LP is generated using max–min ant system (MMAS) and then tabu search (TS) is adopted to search the satisfactory LP. The MMAS is previously developed and the TS process is newly-developed. The heuristic rules are implemented to generate the candidate LP in TS process. The heuristic rules are comprised of two kinds of action, i.e., a single swap in the location of two fuel assemblies and rotation of fuel assembly. Since developed TS process is a local search algorithm, it is efficient for the minor change of LP. It means that a proper initial LP should be provided by the first step, i.e., by MMAS. The design requirements such as hot channel factor, the hot zero power moderator temperature coefficient, and cycle length are formulated in the objective function. The results show that the developed tool can obtain the satisfactory LP and dramatically reduce the computation time compared with previous tool using ant system alone.