Developments in reprocessing of spent nuclear fuels for the thorium fuel cycle

Kapitel i bok, 2015

Thorium, which is a fissile nuclide, was considered as a fuel for nuclear power plants in the beginning of the nuclear era. Then it was more or less forgotten for 30-40 years but is now gaining renewed, increased interest. There are several reasons for the fact that thorium was abandoned, and some of them are actually reasons for taking it up again today. One reason is the production of plutonium in the traditional uranium cycle. In the beginning this was desired (e.g., for weapons production) while today many nations want to limit the amounts of plutonium for nonproliferation reasons. Other reasons for abandoning thorium as a nuclear fuel are the difficulties in reprocessing, as the oxide is highly insoluble. This, however, can be an advantage for a once-through nuclear fuel cycle where the used nuclear fuel is placed untreated in a final repository. In addition, thorium is more abundant in the Earth's crust than uranium, making it possible to run nuclear power using the once-through cycle considerably longer. Whether this is good or bad is in the eye of the beholder.All in all, there are several pros and cons of using thorium as a fuel. They have all been known for more than 50 years, but due to changes in politics and general opinion some of them have become more or less important. In this chapter, both the recovery of virgin material as well as use and reprocessing of thorium-based nuclear fuel will be discussed in detail. The main focus is, contrary to many previous reviews, not the reactor physics but rather the chemical processing technologies.