Unifying via conformal mapping coarse-mesh neutron diffusion calculations in Cartesian and hexagonal geometries (Q1917888)

The paper discusses the extension of the highly accurate nodal method for solving the neutron diffusion equation to hexagonal geometry problems, for which the method is not directly applicable due to the difficulty associated with singularities caused by the geometry. It is shown that by using the invariance property of the diffusion operator under conformal transformation, the singularities can be removed via conformally mapping of a hexagonal node to a rectangular node, making it very easy to extend a nodal code from Cartesian geometry applications to hexagonal geometry applications. Thus applications to the two different geometries can be unified in a single nodal code. The method is implemented in a Westinghouse diffusion code ANC-H. It is demonstrated that the method works very well.