Reactor physics study of square and hexagonal lattice cell using MANTRA (Method of ChAracteristics based Neutron TRAnsport Code) coupled with resonance treated multi energy group cross section library

Abstract

Since last few years we have been developing a computer code MANTRA (Method of ChAracteristics based Neutron TRAnsport Code) in phased manner to solve neutron transport equation using Method of Characteristics (MOC) for lattice (i.e. assembly) as well as full core with a flexibility of choosing boundary condition out of vacuum/periodic/reflective options appropriate for the simulation. In literature, we have already reported about the development and performance of the code in triangular mesh network for mainly lattice level calculation with reflective and periodic boundary conditions and to some extent core level calculation with vacuum boundary condition using the processed cross section of benchmark problem. Later, we have explored the advantage of linear source assumption over the commonly used flat source assumption within a mesh in some selected transport calculations (where the variation in neutron flux is substantial) using MANTRA. We have also demonstrated the application of Krylov subspace iteration in a matrix-free framework to accelerate the solution of MANTRA for solving complex problems in effective manner. In continuation of the work, MANTRA is now coupled with WIMSD multi energy group cross section library. For the purpose of coupling, a module is developed in the code to process the cross section data and apply resonance treatment to account for the self-shielding effect of the resonant nuclides. The resonance treatment requires estimation of Dancoff factor, which is carried out using MANTRA for various arrangement of fuel elements. Finally, a number of benchmark problems based on PHWR, BWR, VVER lattices are studied with resonance treated library to compare the performance of MANTRA with other internationally recognized codes like HELIOS, DRAGON, WIMSD, MCNP etc.