Sustainable ‘smouldering’ technology to tackle nuclear waste

A new research project will investigate an emerging, sustainable waste treatment technology based on smouldering combustion to efficiently treat nuclear graphite waste.

Researchers from the University of Nottingham‘s Faculty of Engineering have been awarded funding to explore the use of applied smouldering, or flameless combustion, as a novel thermal method to reduce nuclear graphite waste bricks to ash. This process will harness the energy contained within the graphite to destroy itself. 

The UK’s fleet of nuclear reactors use graphite moderator bricks, these are engineered blocks of high-purity, synthetic graphite, typically arranged into thousands of interlocking structures to form the core of gas-cooled nuclear reactors.

These graphite bricks become contaminated – primarily with Carbon-14 – over decades of operation. Nuclear Restoration Services is tasked with managing approximately 100, 000 tonnes of graphite upon decommissioning, representing ~33% of the total Intermediate Level Waste destined for the proposed Geological Disposal Facility.

Decommissioning reactors and managing the waste graphite presents significant technical and environmental challenges due to its physical condition as well as the long half-life of Carbon-14, which is around 5730 years, plus and other radionuclides, the volume of waste, and other persistent residual risks.

Smouldering is emerging as an energy-efficient alternative thermal technique that has been used to successfully manage similar non-volatile carbon-based wastes commercially, and presents strong potential as a new method to manage the UK’s nuclear graphite waste.

This research team – led by Tarek Rashwan, Oliver Fisher, and Rachel Gomes – will assess the feasibility of applied smouldering for nuclear graphite waste treatment through experiments, modelling, techno-economic analyses, and life cycle assessments alongside international partners between the UK and Canada.

Tarek Rashwan, Assistant Professor in Chemical and Environmental Engineering at the University of Nottingham said: “Novel environmental technologies are needed to manage challenging nuclear graphite waste sustainably. To tackle this problem, we aim to develop a new, energy‑efficient alternative to manage the UK’s substantial nuclear graphite waste, which has the potential to accelerate UK and international nuclear reactor decommissioning efforts.”