AXIAL: a system for boiling water reactor fuel assembly axial optimizationusing genetic algorithms

A system named AXIAL is developed based on-the genetic algorithms (GA) opti mization method, using the 3D steady state simulator code Core-Master-PREST O (CM-PRESTO) to evaluate the objective function. The feasibility of this m ethodology is investigated for a typical boiling water reactor (BWR) fuel a ssembly (FA). The axial location of different fuel compositions is found in order to minimize the FA mean enrichment needed to obtain the cycle length under the safety constraints. Thermal limits are evaluated at the end of c ycle using the Haling calculation; the hot excess reactivity and the shutdo wn margin at the beginning of cycle are also evaluated. The implemented obj ective function is very flexible and complete, incorporating all the therma l and reactivity limits imposed during fuel design analysis; furthermore, a dditional constraints can be easily introduced in order to obtain an improv ed solution. The results show a small improvement in the FA average enrichm ent obtained with the system related to the reference case that has been st udied. The results show that the system converge to an optimal solution, it is observed that the mean fuel enrichment decreases while all the constrai nts are satisfied. A comparison was also performed using one-point and two- points crossover operator and the results of a sensitivity study for differ ent mutation percentage are also showed. (C) 2001 Elsevier Science Ltd. All rights reserved.