Introducing advanced thorium–based fuel cycles in SA : an evolutionary approach

Abstract

Past experience in several thorium fuelled research- and power reactors provides the basis and history of thorium. The material properties, fertile- and fissile isotope properties as well as the decay chain of thorium are discussed for purposes of evaluating thorium as a source of fuel. The different thorium-based fuel designs for PWR cores are discussed and resulting difficulties and solutions are outlined. The different options for each strategy are compared in terms of advantages and disadvantages. A process of elimination selects the best option for each strategy, which results in a combination of mitigation and optimisation strategies to be implemented at the starting point of the roadmap. Certain countries have made significant progress with regards to the thorium-based fuel cycle (e.g. India and Norway) and nuclear technology in general (South Korea). Each country is introduced with a summary of their approach and policy. The current context of nuclear technology and the nuclear fuel cycle in SA is given. The identified lessons and policies are applied to the South African context, which results in different goals aimed at achieving a thorium-based fuel cycle in the future. These goals form an integral part of the roadmap to implement thorium-based fuels in SA. The prices of uranium and thorium are discussed. This chapter focuses on the economic advantages of thorium-based fuel cycles, especially the fuel cycle cost and the refuelling outage costs. Thorium-based fuels can extend the refuelling cycles, which in turn reduce the fuel requirements and the spent fuel for disposal, as well as the reactor downtime for refuelling. The results show that both (Th/U)O2 and (Th/Pu)O2 present economic benefits over traditional uranium fuel cycles. The total savings were calculated by adding the fuel cycle savings and the refuelling outage saving. (Th/U)O2-fuel proved to be the most economical and Eskom could save up to 49 billion rand in 60 years. Based on the research and results obtained, a systematic strategic thorium-based fuel implementation roadmap is developed. Economic-, strategic- and historical aspects direct the roadmap. The advantages of thorium-based fuels are summarised and form the initiative to implement thorium-based fuels in SA. A timeline (which forms the basis of the roadmap) is developed. The roadmap consists of three different phases. Phase 1 starts in 2013 and extends to 2030. Phase 2 starts in 2031 up to 2044 and Phase 3 from 2045 to 2060. Each phase is discussed with regard to construction, implementation and research activities. This roadmap will progress and advance to future technologies, corresponding to the evolutionary approach.