An automatic system to search for the optimal loading pattern of boiling water reactors - 15384

An automatic loading pattern design system for Boiling Water Reactors (BWRs) has been developed by INER. The system consists of two programs, AUTOLPD, an automatic loading pattern (LP) design code, and AUTOROD, an automatic control rod pattern (CRP) design code. Both codes use Genetic Algorithm (GA) as the optimization method and SIMULATE-31 as the three-dimensional core simulator. There are two important innovative techniques featured in AUTOLPD. One is that the fuels in the 1/8-symmetric line and on the non-1/8-symmetric region are allowed to exchange. The other one is that the Control Cell Sub-Pattern Swap (CCSPS) concept serves as a crossover mechanism. On the other hand, AUTOROD has been set up with Maximize Cycle Length (MCL) and Control Axial Offset (CAO) modes simultaneously to account for different operational strategies. AUTOROD is also equipped with a fast rod-worth evaluator to filter disqualified CRPs before being sent to SIMULATE-3 calculation. AUTOLPD and AUTOROD have been successfully integrated into one system with two feedback mechanisms in order to raise cycle length and shutdown margin to meet the targets. The system has been tested independently and integrally via several realistic cycles of Kuosheng Nuclear Power Plant. The results show that AUTOLPD and AUTOROD can find the optimized loading pattern and control rod pattern satisfying the requirements individually as well as globally. It also proves that the developed automatic system is able to apply to actual reload core design for the intra-national BWRs. (authors)