Benefits of Transitioning to a Thorium Cycle

Abstract

Projections of the total world nuclear electricity demand for the next century show that existing natural uranium (NU) resources will be severely challenged by 2070. One way to meet this challenge is to recycle spent plutonium from Light Water Reactors (LWRs) as starting fissile material in thorium-fuelled Heavy Water Reactors (HWRs). This arrangement obtains more total energy per unit of NU mined since no NU is required by the HWR fleet, which instead gets its fissile material from LWR spent fuel and from U-233 bred into the thorium. Modeling shows that world NU requirements up to the year 2130 can be reduced by 10% for a once-through Th-Pu fuel cycle and by almost 20% in a Th-Pu-U-233 fuel cycle where the U-233 in spent HWR fuel is recovered and used to top-up the initial fissile material. As an added benefit, the total decay heat of spent fuel in repositories, a limiting factor, is reduced by more than one third by the transmutation of LWR plutonium.