In this study, the neutronic performance of the ARIES-RS fusion reactor design using different types of thorium fuels, namely ThO2 or ThN dispersed in graphite or BeO, was investigated. Neutron transport calculations were conducted with the help of the SCALE4.3 system by solving the Boltzmann transport equation with the XSDRNPM code in 238 neutron groups and a S-8-P-3 approximation. Even though energy multiplication in the reactor was at low rates, a significant amount of fissile fuel U-233 was produced while providing sufficient tritium for the deuterium-tritium (DT) driver. Among the investigated fuel types, the blanket using ThN dispersed in a BeO matrix had the highest fissile fuel breeding values. (c) 2005 Elsevier Ltd. All rights reserved.