Comparison of the once-through and closed nuclear fuel cycles with regard to waste disposal area required in a geological repository

This study aims to compare the once-through and the standard closed nuclear fuel cycles with respect to waste disposal area required (for spent fuel and high-level waste) in a permanent geological waste repository. Utilizing the code MONTEBURNS, relevant compositions and decay heats are obtained for several selected burnup values. Then, using the code ANSYS, disposal areas needed for waste types under consideration are determined. Results are expressed in terms of “total electrical energy (MWe-yr) produced per unit waste disposal area (m2)”, which is taken as the decisive parameter to compare the two cycles. It can be concluded that: the once-through cycle displays an advantage up to nearly a burnup of 40,000 MWd/t with regard to waste (spent fuel and high-level waste) disposal density; however, at higher burnups, the standard closed cycle is better than the once-through.