Application of minimum plutonium criteria at EOC to optimize the fuel loading pattern in VVER-1000 reactors

Most of the strategies yet implemented to optimal fuel loading pattern design in nuclear power reactors, are based on maximizing the core effective multiplication factor (K_eff) to extract maximum energy and lowering the local power peaking factor (P_q) from a predetermined value. However, a new optimization criterion could be of interest, aiming at maximum burn-up of the plutonium content in fuel assemblies, i.e., minimization of remaining plutonium in spent fuel at the end of cycle (EOC). In this research, we developed a new strategy for optimal fuel core loading pattern of a VVER-1000 reactor, based on multi-objective optimization: lowering the P_q, maximization of the K_eff and minimization of remaining plutonium (Pu) in fuels at EOC. This strategy has been implemented considering exact calculations of fuel burn-up during the equilibrium cycle using WIMSD and CITATION calculation codes. We used the genetic algorithm to find the optimum fuel loading pattern. Simulation results show that this strategy can reduce the remaining Pu of the fuels at EOC while considering limitations on core power peaking and multiplication factor.