Researchers in the UK have devised a process that uses electricity to remove radioactive contaminants from irradiated nuclear graphite. The process could reduce the volume of waste from nuclear power plants that requires expensive and long-term storage. Graphite is used to maintain the fission chain reaction in certain types of nuclear reactors. Over 300,000 tonnes of nuclear graphite waste are estimated to be awaiting storage or disposal worldwide. Due to a high density of legacy reactors, approximately a third of the world’s irradiated graphite waste is within the UK. ‘Most of the advanced nuclear reactor technologies being proposed for future low carbon energy production will also use nuclear graphite, so this waste burden is likely to increase for future generations unless novel solutions are examined to treat, reduce and recycle this waste form,’ explains Abbie Jones from the University of Manchester. ‘Technologies that can minimise this burden will not only massively reduce costs of managing legacy wastes but also improve the sustainability of future nuclear reactors and help achieve net zero targets.’ The UK’s current strategy, as outlined by the Nuclear Decommissioning Authority, is to store the waste graphite temporarily to allow short-lived isotopes to decay prior to final disposal. However, storing nuclear graphite waste is expensive, space-inefficient and runs the risk of contamination. In response to these issues, Jones and colleagues set out to determine whether electrolysis in high-temperature molten salt media could be applied to decontaminate nuclear graphite. Team member Clint Sharrad says they chose to use molten salt due to its wide electrochemical window, allowing them to access electric potentials that could better force nuclear graphite contaminant removal.
Chemistry World 7th Oct 2021 read more »