Advances in the Application and Understanding of the CHALMEX FS-13 Process
Doctoral thesis, 2022

During the last year, the European demand for electricity has increased and at the same time, the production of planned electricity generation has decreased due to unexpected weather conditions and war. Combined with a limited capability to store energy, low-carbon energy producers such as nuclear power is getting renewed attention in many countries. While having benefits such as reliable, clean, affordable and safe electricity production, the main concerns regarding nuclear power usually refer to the extremely long-lived and radiotoxic final waste. The main contributor to the long-lived radiotoxicity of the spent fuel is Pu and the minor actinides (Np, Am, Cm).

The Chalmers Grouped ActiNide EXtraction (CHALMEX) process is a solvent extraction process for the recycling of minor and major actinides as a group, from spent nuclear fuel. By recycling the actinides, and using them as fuel in fast reactors, one can significantly reduce both the overall environmental impact of the nuclear fuel cycle, the lifetime- and the radiotoxicity of the final waste.

By combining the extractants TBP with CyMe4-BTBP in the diluent FS-13, the CHALMEX solvent has been shown to have preferential physical properties for use in industrial processes. Separation of the actinides from a spent fuel solution is achieved in only 8 process stages. The co-separation of specific fission products is reduced by the use of masking agents and scrubbing stages. Overall, low degrees of fission product contamination is found in the actinide product stream (<1.5%).The kinetics of the system has also been shown to be compatible with contacting in centrifugal contactors. Despite observation of phase entrainment under certain conditions in a centrifugal contactor, the CHALMEX process is a promising process for the actinide separation from spent nuclear fuels.

Advanced recycling

Solvent Extraction



KB-Salen, Kemigården 4
Opponent: Terry Todd, Idaho National Lab, USA


Thea Lyseid Authen

Chalmers, Chemistry and Chemical Engineering, Energy and Material

Batch flowsheet test for a GANEX-type process: the CHALMEX FS-13 process

Solvent Extraction and Ion Exchange,; Vol. 40(2022)p. 189-202

Journal article

A comparison on the use of DEHBA or TBP as extracting agent for tetra- and hexavalent actinides in the CHALMEX Process

Journal of Radioanalytical and Nuclear Chemistry,; Vol. In Press(2022)

Journal article

Batch Tests for Optimisation of Solvent Composition and Process Flexibility of the CHALMEX FS-13 Process

Solvent Extraction and Ion Exchange,; Vol. 39(2021)p. 1-17

Journal article

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.

Subject Categories

Chemical Engineering

Other Chemistry Topics



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5134



KB-Salen, Kemigården 4


Opponent: Terry Todd, Idaho National Lab, USA

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