Design and Neutronic Evaluation of Thorium Fuel in Pressurized Water Reactors

The purpose of this thesis is to study the feasibility of a high content thorium fuelled pressurized water reactor. The focus is on the neutronic behaviors. Thorium based fuel design options with four different fissile components are investigated. Standard uranium oxide is used as the reference fuel. The analysis is performed using the statistical codes MCNP and MCB. First, the fuel compositions are adjusted to obtain the required discharge burnup 55 MWd/kgH.M. under a fixed power density. Next, neutron spectrum, power profile, reactivity coefficients as well as kinetic coefficients are studied. The calculation shows a significant reduction of the quantity and quality of plutonium can be achieved if 233U or MEU is used as the fissile component. Plutonium is the main source of proliferation potential and radiotoxicity generated during the irradiation of the standard UOX fuel. At the same time, although the coolant temperature coefficient for thorium with 233U as fissile component is slightly positive, negative feedbacks from fuel and coolant are large enough for the safety issues during normal operation. If 233U and LWR spent fuel grade plutonium is mixed properly and used as the fissile component, the breeding ratio can be about 1. The neutron spectrum created in this case is more thermal than that in case of thorium fuel with plutonium as fissile material. All the coefficients are in reasonable range. Especially, the coolant temperature coefficient is negative. Last, a simple shutdown study was carried out. The shutdown margin is enough in both hot shutdown events and cold shutdown events