Analysis of Thorium/U-233 Lattices and Cores in a Breeder/Burner Heavy Water Reactor

Abstract

Commercial nuclear power plants rely on uranium as their primary fuel source. Though the amount of uranium available in the earth’s crust and in seawater is thought to be sufficient to provide power for centuries, if not millennia, economically it will not be able to do so for very long. As a result, the investigation of alternate fuel cycles is important. Thorium, with its fertility and high abundance, is a natural choice to replace uranium in future nuclear fuel cycles, and heavy water reactors are especially well suited to efficiently exploit thorium as a supplemental fuel. The objective of this project was to develop CANDU® 6™ reactor core configurations utilizing thorium “battery” bundles. Simulations of several reactor configurations incorporating thorium were performed using the DONJON and DRAGON reactor physics codes and are compared to a normal (i.e., fuelled with only natural uranium) CANDU® 6™ reactor core. The simulated designs were judged based on their ability to extend the length of time the fuel spends in the reactor (i.e., achieve higher burnup and reduce refuelling rate) while maintaining the net power output and criticality.