Transuranic Mixed Oxide Fuel Use in CANDU

Abstract

Advanced fuel cycles that move beyond once-through strategies are important methods of dealing with spent fuel inventories minimizing demand for long term depositories. Fast reactor technology provides a solution to close the fuel cycle but is costly and complicated. There is a potential for current thermal spectrum reactors, such as CANDU[1], to provide an initial step in the utilization of spent fuel and reduce the fast reactor infrastructure required. A popular method is the extraction of actinides (e.g. Np, Pu, Am, Cm, etc.) from spent fuel and combining them with natural uranium in a mixed oxide format to be utilized in current thermal reactors. The burning of actinide-based mixed oxide fuel in CANDU is explored herein. The TRUMOX fuel type has actinide contents of 4.75wt% and 3.10wt% and target burnup levels of 45 and 30 MWd/kgHE. The lattice is modeled in 2D with WIMS-AECL v3.121 and 3D super-cell calculations are performed in DRAGON v3.06. The 2-group homogenized cross section data is then utilized for full core simulations in RFSP. Time-average and instantaneous fuel ripple simulations were performed along with short-term refueling and an evaluation of reactor coefficients and control device worth. The TRUMOX fuel designs were found to operate within the standard CANDU safety limits and provided a suitable level of actinide destruction (between 35-42%). These simulations illustrate the potential for the CANDU reactor to be an initial step for the utilization of spent fuel and contributing to a more sustainable and efficient nuclear fuel cycle using proven reactor technologies.