A Mechanism for collecting uranium from used nuclear fuels

Associate Professor Byungchan Han
Department of Chemical and Biomolecular Engineering, Yonsei University

■ Engineering & Technology /

A Mechanism for collecting uranium from used nuclear fuels

A group of researchers at Yonsei discovered key mechanisms for the development of nuclear fuel recycling processes

A group of researchers at Yonsei University has discovered key mechanisms for efficient recycling of used nuclear fuels using pyro-electrochemical the reactions.

Using first principles-based computational modelings, Professor Byungchan Han at the Department of Chemical and Biomolecular Engineering at Yonsei University proposed an atomic-level description of the electrorefining process in which uranium deposits on a solid electrode from an ionic state solvated in a molten salt. The study was published in the March 2016 Electrochimica Acta and the International Journal of Energy Research, the leading journal in nuclear science and technology.

Currently, nuclear power plants in South Korea use and discard 700 tons of used fuels annually, which is temporarily stored inside power plants. The capacity of the nation’s high-level nuclear waste disposal facilities, operated by each nuclear plant, will begin to reach full saturation around 2024. In 2016, the South Korean government responded by announcing a roadmap to permanently disposing of the high-level radioactive nuclear waste by 2053. The securement of the sites, however, has been met with strong public resistance and faces great concern regarding proper management to prevent potential accidents over the next hundreds of thousands of years.

To overcome these challenges, ten countries, including South Korea and the United States, are working on developing a new concept, referred to as pyroprocessing technology, to electrochemically recycle the used nuclear fuels at a high temperature. The method provides incredible benefits in the management of high-level nuclear waste, such as dramatic volume reduction of discarding waste, recycling of used nuclear fuels, and nonproliferation stances.

The design of an effective pyroprocessing system, however, has been limited due to lack of accurate understanding of the mechanisms and the nonexistence of any database of material properties, including uncertainties in experimental measurements.

Using advanced computational methods, the researchers were able to predict key thermodynamic and kinetic properties of uranium solvated in molten salt, leading to successful capture of the atomistic-level mechanism for its collection onto a tungsten electrode. Furthermore, they simulated nucleation and growth processes of the deposited uranium, which was validated by experimental observations.

Professor Han believes that the significance of the research is that this database of key properties can be used as the groundwork towards developing an efficient and safe pyroprocessing system.

Updated in Feb 2017

Kwon, C., Kang, J., Kang, W., Kwak, D., Han, B., “First principles study of the thermodynamic and kinetic properties of U in an electrorefining system using molybdenum cathode and LiCI-KCI eutectic molten salt” Electrochimica Acta, doi: 10.1016/j.electacta.2016.02.123

Kwon, C., Kang, J., Han, B., “First-principles based computational study on nucleation and growth mechanisms of U on Mo(110) surface solvated in an eutectic LiCI-KCI molten salt” International Journal of Energy Research, doi: 10.1002/er.3527