Development of the SH3-ACNEM Simulator Program in order to Solving the Forward and Adjoint neutron Diffusion Equation for Hexagonal Geometry Reactor Cores

Abstract

To perform a neutronic analysis of the reactor core, it is necessary to develop nuclear computing software to produce multi-group constants and numerical solutions to the multi-group neutron diffusion equation. For this purpose, some methods are used in nuclear calculation codes that, in addition to the necessary accuracy of cost and computing time, are optimal. This paper discusses the average current nodal expansion method as well as higher orders of flux expansion. Then, the discretization of the neutron diffusion equation with ACNEM is shown, which has the ability to calculate in optimum time and with good accuracy. The discretization of the Forward and Adjoint neutron diffusion equation is performed for two-dimensional hexagonal geometry in two energy groups and then the SH3-ACNEM reactor core simulator is developed. To verify; the calculations for the IAEA-2D reactor core are performed and compared with valid references. It results that the computational error improves from 11.36% to 3.52% by increasing the flux expansion order from quadratic polynomials to five.

Keywords

• simulator
• nuclear calculation
• diffusion equation
• hexagonal geometry
• acnem