Effect of core calculation models on optimum cycle length analyses of pressurized water reactors

The e€ect of core calculation models on an optimum cycle length which corresponds to minimum power generation cost was investigated in this paper. Systematic analyses of equilibrium cores were carried out using a simple one point reactor model and a detailed two-dimensional core model that took into account an actual loading pattern of a core. The analyses were performed assuming several di€erent numbers of fresh fuel assemblies. In the two-dimensional core model loading pat- terns of equilibrium cycle which were well optimized by the OPAL code through the simulated annealing method were utilized to perform accurate estimation. When feed enrichment was ®xed and independent of cycle length the optimum cycle length predicted by the one point reactor model occurred at integer batch as expected. On the other hand the optimum cycle length predicted by the two-dimensional core model occurred at fractional batch in some cases under the above condition. Therefore a multi-dimensional core calculation model that can take into account an actual loading pattern is required to evaluate the accurate optimum cycle length