Advances in the Application and Understanding of the CHALMEX FS-13 Process

Doctoral thesis, 2022

In our modern, electrified society, electricity generation is a significant contributor to the emissions of greenhouse gases and global warming. To mitigate global warming effects, the energy system has to transition into low-carbon electricity production. Nuclear power safely produces electricity with overall carbon-emissions about half of those of hydroelectric power, and with comparable emissions to offshore wind turbines. The main contributor to the carbon emissions is the mining operations for fresh uranium in order to produce uranium fuels. Furthermore, the operation of a nuclear reactor produces very long-lived and very radiotoxic spent nuclear fuels. Due to the lifetime of the spent nuclear fuel of many hundreds of thousands of years, the spent fuel must be safely and securely isolated from man and its environment.

Spent nuclear fuel still contains more than 90% of its energy potential, just in the form of unused uranium. In addition, nuclear reactors produce plutonium and other actinides such as neptunium, americium and curium. These elements have a common characteristic: they are suitable for use in a reactor type referred to as fast reactors. By recycling spent nuclear fuel, studies have found that elimination of mining operations are possible, which will significantly decrease the carbon footprint of the nuclear fuel cycle. Moreover, the recycling of all the actinides will reduce the volume and radiotoxicity of the final waste requiring isolation.

In this work, the recycling of the actinides using the CHALMEX process has been studied. The focus has been gaining a fundamental understanding of process related parameters. In an optimised batch flowsheet, it was shown that separation of the actinides from the fission products can be achieved under process relevant conditions. It is believed that the CHALMEX process can offer a simple method of recycling of the actinides.