PARALLEL COMPUTING ADAPTIVE SIMULATED ANNEALING SCHEME FOR FUEL ASSEMBLY LOADING PATTERN OPTIMIZATION IN PWR’s

摘要

An adaptive control scheme of simulated annealing(SA) parameters derived from polynomial-time coolingrnschedule is presented in terms of the efficiency enhancement of the SA algorithm. The paralle l computingrnadaptive SA optimization scheme which incorporates the optimization-layer-by-layer(OLL) neutronicsrnevaluation model is then applied to determining the optimum fuel assembly(FA) loading pattern(LP) inrnKorea Nuclear Unit 11(KNU 11) PWR using seven Pentium personal computers(three Pentium II 266rnMHz and four Pentium Pro 200 MHz). It is shown that the parallel scheme enhances the efficiency ofrnthe SA optimization computation significantly but that it can get trapped in local optimum LP morernfrequently than the single processor SA scheme unless one takes preventive steps. As a way to preventrntrapping of the parallel scheme in local optimum, we proposed using multiple seed LP's instead of a singlernLP with which the individual processors start each sta ge and discussed how to determine the multiple seedrnLP's. Because of high efficiency of the parallel scheme, acceptability of hybrid neutronics evaluationrnmodel which is slower but more accurate than OLL model into parallel optimization calculation isrnexamined from the standpoint of the computing time. By demonstrating that the FA LP optimizationrncalculation for the equilibrium cycle core of the KNU 11 PWR can be completed in less than an hour onrnseven Pentiums, we justified the routine utilization of the hybrid model in the parallel SA optimizationrnscheme.