A heterogeneous Thorium-based fuel design for a PWR aimed at increasing fuel cycle length

Abstract

A new heterogeneous Thorium based fuel design has been proposed for Pressurised Water Reactors in order to increase fuel cycle lengths. This design incorporates ThO2 pellets which have been included between UO2 fuel pellets to breed fissile U233 through transmutation of Th232. A heterogeneous design was chosen in order to increase the conversion ratio of the fuel beyond what has been achieved with homogeneous Thorium based fuels. The results of this dissertation have shown that it is possible to introduce this design into an infinite reactor simulation, where a high conversion ratio can be achieved in order to increase the fuel lifetime and thereby increase the fuel cycle lengths. The use of different fuel configurations have been explored to develop a concept design which can serve as a proof of concept for further development. This design has undergone preliminary optimisation steps and shows promise as an advanced fuel design. However, the occurrence of energy peaks within the fuel lattice causes some concerns for safety. The concept design studied for this dissertation has provided positive results and due consideration for further development is strongly advised. Some safety concerns have been addressed, but the use of Thorium based fuels is still met with major challenges and concerns which could not be addressed within the given time for this study.