This paper documents fuel cycle analysis of an intermediate spectrum critical reactor with natural uranium and thorium as feed materials and continuous recycling of uranium with transuranics and thorium with uranium (mainly 233U). The objective of the effort was to determine the impacts of both intermediate spectrum and U/Th feed versus the reference fast spectrum and U-only feed case. In this context the intermediate energy regime is considered to be between 1 eV and 0.1 MeV. The potential benefits of introducing thorium into the natural resource feed include extending the availability of uranium resources as well as potential operational/safety benefits, particularly related to the void coefficient in some reactor designs. Two systems were analyzed at a near-equilibrium condition, a high void boiling water reactor with 54% of fissions occurring in the intermediate energy regime and a D20 cooled pressurized water reactor with 65% of fissions occurring in the intermediate energy regime. The systems analyzed in this study were determined to be self-sustaining at equilibrium when accounting for loss rates in fabrication and separations, and exhibit similar resource utilization when compared to a fast system. Differences in performance versus a fast system are driven to some extent by the fact that eta for 233U and 239Pu at intermediate energies is never as high as for 239Pu at fast energies.