DIAMOND – A Method of Characteristics neutron transport code using unstructured meshing

• Published in: Annals of nuclear energy 2020-03, Vol.137, p.107086, Article 107086
• Main Authors: Jain, Lakshay, Karthikeyan, Ramamoorthy, Kannan, Umasankari
• Format: Article
• Language: English
• Subjects: Constrained Delaunay Triangulation (CDT); Method of Characteristics (MOC); Neutron transport equation; Search based global ray tracing; Unstructured meshing
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2019.107086

•DIAMOND, a neutronics analysis code based on Method of Characteristics is developed.•Complex arbitrary 2D geometries are represented using Constructive Solid Geometry.•Problems decomposed into unstructured meshes using Constrained Delaunay Triangulation.•Search based ray tracing scheme used for laying global cyclic characteristic tracks.•Performance of triangular and traditional unstructured meshes has been compared.•DIAMOND benchmarked for problems with varying geometry and boundary conditions.•Results from DIAMOND show excellent agreement with the reference results. Advanced nuclear reactor designs using more complicated and heterogeneous geometries warrant precise modeling of the neutron transport phenomenon. The use of Method of Characteristics (MOC) with unstructured meshing renders an accurate representation for tracking the neutron transport in such heterogeneous media. The code DIAMOND is being developed for neutronic analysis of two-dimensional rectangular lattice/core problems using MOC. The problem of interest, represented by Constructive Solid Geometry (CSG) based processing module, is divided into unstructured meshes using Constrained Delaunay Triangulation (CDT). Search based ray tracing is used for laying down global cyclic tracks. The results from this code for a variety of benchmark problems have been validated against those obtained from other methods/codes. A performance comparison between triangular and traditional unstructured meshes is also presented. This paper provides a description of DIAMOND; equations governing the MOC formulation, the geometrical and meshing aspects along with its application to various benchmark problems.