On an improved box-scheme finite difference method based on the relative event probabilities

The accuracy of the neutron diffusion calculations can be significantly affected by changing mesh point positions in the Box-Scheme Finite Difference Method (BSFDM). Accordingly, optimizing mesh point positions with respect to the relative region's importance for the 2-D rectangular geometry, light water reactors are addressed in this paper. In this study, we present a new algorithm approximation form based on the relative event probabilities (REPs), which can be directly used to evaluate the relative region's importance for optimizing mesh points positions in BSFDM. In accordance with this method, in regions with greater importance, the number of meshes is more than that in regions with less importance. So, the implementation of this method makes an adaptive nonuniform mesh point distribution through the entire reactor core unlike the usual methods. The results are benchmarked against two well-known solutions, namely the TWIGL seed-blanket and the Rod Bundle BWR. The results all suggest that the proposed method has a better accuracy in all benchmarking cases compared to the usual method for any arbitrary mesh point numbers. •Developing a novel algorithm for improving the Box-Scheme Finite Difference Method (BSFDM).•Considering the relative event probabilities (REPs) for developing the proposed algorithm.•Distributing mesh point positions throughout the reactor core with respect to the relative regions's importance.•Evaluating the accuracy of the proposed algorithm for different benchmark problems and various mesh point numbers.•Achieving a better accuracy of the results based on this method compared to the usual method.