Searching for enrichment and gadolinia distributions in BWR fuel lattices through a Heuristic-Knowledge Method

A Heuristic-Knowledge Method was developed to determine the enrichment and gadolinia distribution in a fuel lattice of boiling water reactors. The method was called S15 and is based on the experience obtained for the fuel lattice design for this kind of nuclear reactors. It also takes advantage of the symmetry aspects found in a typical BWR fuel lattice. An objective function was used throughout the searching process, as well as the same degrees of freedom used by five different meta-heuristic techniques based on evolutionary algorithms. Using the S15 method forty iterations were needed to obtain the best solution i.e., the smallest value of the objective function through a minimization process. In order to assess the performance of the S15 method, it was compared to five other evolutionary techniques. The two-dimensional CASMO-4 code was used to obtain the neutronic parameters employed by the objective function. The objective function value was the main criterion used to qualify all the techniques. All the methods were applied to fuel lattices charged in three different real operation cycles of the nuclear reactors at the Laguna Verde Nuclear Power Plant (LVNPP). The results generated with S15 surpass those obtained by the five evolutionary techniques.