Optimization of boiling water reactor loading pattern using an improved genetic algorithm

When a nuclear power reactor is shut down between successive operation cycles, refueling or reloading is needed. Developing a good refueling or reloading pattern is called "loading pattern optimization". It is a large, combinatorial optimization problem with a nonlinear objective function and nonlinear constraints. An algorithm based on the genetic algorithm was developed to generate optimized boiling water reactor (BWR) reloading patterns. The proposed algorithms are demonstrated in an actual BWR plant. In test calculations, candidates that shuffled fresh and burned fuel assemblies within a reasonable computation time were obtained.