Calculation of the C5G7 3-D extension benchmark by ARES transport code

High-fidelity neutron transport calculation is essential to enhance and improve the design of nuclear systems. This paper describes the transport solvers in ARES and presents ARES solutions of the 3-D extension C5G7 benchmark problem, a small LWR core model without spatial homogenization. The transport calculation is paralleled based on spatial-angle domain decomposition and optimal sweeping scheduling algorithm, which makes it possible to conduct neutron transport calculations with fine enough discretization to get high-resolution solutions. The multiplication factor and the normalized pin power are computed and compared with the reference MCNP calculations. Refinement in spatial and angular discretization was investigated and the calculation accuracy is studied via the difference of the multiplication factor from reference value and via the root-mean-square and maximum norm of the error in the pin power. The results were found to be in good agreement with reference, demonstrating that ARES can reach a good accuracy in complex criticality calculations.