Recent advances on the use of reprocessed fuels and combined thorium fuel cycles in HTR systems

Highlights: • Simulations include HTTR, VHTR, DB-MHR and LS-VHTR systems. • The systems were simulated with the codes SCALE 6.0, ORIGEN 2.1, WIMSD-5, MCNP5 and MCNPX 2.6.0. • Analyses were focused on the neutronic evolution and fuel composition during burnup. • The adopted methodologies confirmed the codes capabilities to simulate specific situations. - Abstract: This paper presents the results of studies developed at the Department of Nuclear Engineering of the Universidade Federal de Minas Gerais – Brazil (DEN-UFMG) on the use of reprocessed fuels and combined thorium fuel cycles. These studies involved simulations of Very High Temperature Reactor (VHTR), Liquid-Salt-Cooled Very High-Temperature Reactor (LS-VHTR), High Temperature Engineering Test Reactor (HTTR) and Deep Burn Modular Helium Reactor (DB-MHR) systems and the analyzes focused mainly on the neutronic evolution of the systems and fuel composition during burnup using models developed with established nuclear code systems such as SCALE 6.0 (KENO-VI/ORIGENS), MCNPX 2.6.0, MCNP5, ORIGEN 2.1, and WIMSD-5. The results show that the adopted methodologies of studies confirmed the capabilities of the codes to simulate specific situations in steady state or transient operating conditions.