Development of Novel Treatments for Carbon-based radioactive wastes

The nuclear energy and weapons programmes of the past 70 years have created a legacy of waste and contamination around the world. Amongst the very diverse and complicated wastes arising from these programmes are a range of "orphan" wastes. These are wastes which are not suitable for treatment in existing processing plants and for which there is no currently accepted treatment option.

This project will determine the feasibility of a wholly new approach to treatment of orphan radioactive wastes. The overarching longer-term research vision is for a three-stage waste treatment process. First, smouldering the waste (in the same way that coal smoulders in a fire) to burn the carbon and produce a small volume of stable radioactive ash that can be encapsulated (generally in cement) and placed into a container (comprised of steel or concrete) for future geological disposal. Second, capturing safely the radioactive emissions that are released by the smouldering process. These are in the form of microscopic particles of radionuclides and carbon dioxide gas that contains the radioactive element, Carbon 14. This capture will make use of similar technologies to those being explored to remove carbon dioxide from the atmosphere to tackle climate change. Bacteria will be used to stimulate the production of carbonate and/or phosphate minerals, removing the radioactivity from the gases and capturing them into a stable mineral (i.e. into a rock) . Finally, this process of capturing the radioactivity into a mineral will be performed as part of the encapsulation process either for the radioactive ash (prior to placing it in a container) or for other radioactive wastes, so as to reduce the final volume of radioactive material that requires disposal.

In order for any treatment process of orphan wastes to be accepted by the UK regulatory authorities, it is critical that no radioactive gases are emitted. Hence, this research project will focus on demonstrating the feasibility of capturing (1) 14C as a stable carbonate and (2) other particulate radioactive emissions into stable phosphate minerals. The project will focus on demonstrating feasibility for a single wasteform, graphite, which is the largest volume orphan waste. If feasibility can be demonstrated, other research projects will follow to explore the smouldering process and the use of the carbonate and phosphate minerals for encapsulation of the radioactive ashes, created by the smouldering process.

Impact of this research will be ensured through the University of Strathclyde's, Advanced Nuclear Research Centre (ANRC). The ANRC is funded with support from industry and provides a pipe-line to take technologies developed through fundamental laboratory research, through pilot-scale testing and into the workplace. Current industry members of ANRC each commit funding to supporting this pipe-line, and include EDF, Babcock International, Bruce Power and the National Nuclear Laboratories.

Results will be reported regularly via ANRC technological board meetings, as well as within nuclear industry magazines and at industrially-led technical meetings within and outside the UK. If successful, the research will open the door to thermal treatment of orphan wastes. Not only will this benefit the UK public, in terms of reduced hazard on nuclear sites, it also has the potential to be an exportable treatment technology that can benefit the UK economy.