Comparison study of AHWR-LEU equilibrium core using two different diffusion theory codes

Advanced Heavy Water Reactor (AHWR) with Low Enriched Uranium (LEU) as an external feed to Thorium is termed as AHWR - LEU. The LEU has been assumed to consist of 19.75% of ²³⁵U and 80.25% of ²³⁸U. It is being designed for discharge burn-up of about 60 GWd/Te. In our earlier studies, we have compared the various reactor physics parameters using different nuclear data libraries (ENDF/B VI.8 and ENDF/B VII). This paper presents the comparison of various reactor physics parameters estimated based on core simulations by using different diffusion theory codes based on different methods for solving diffusion equations namely FEMINA (Nodal expansion method) and 3D FAST (finite difference method). For this study, the lattice calculations were performed using ENDF/B VII.0 nuclear data library of 69 energy groups as well as 172 energy groups. The core calculations were performed using 2-groups and 4-groups condensed cross-sections. (author)