Assessment of Parallel Simulated Annealing Performance With the NEXUS/ANC9 Core Design Code System

The method of parallel simulated annealing is being considered as a loading pattern optimization method to be used within the framework of the latest Westinghouse core design code system NEXUS/ANC9. A prototype version of NEXUS/ANC9 that incorporates the parallel simulated annealing method was developed. The prototype version was evaluated in terms of robustness, performance and results. The prototype code was used to optimize LPs for several plants and cycles, including 2-loop, 3-loop and 4-loop Westinghouse plants. Different fuel assembly lattices with IFBA, WABA and Gadolinium burnable absorbers were also exercised in these cores. Different strategies were evaluated using different options in the code. Special attention was paid to the robustness and performance when different number of parallel processes were used with different size of Markov chain.