Scientists using the UK’s synchrotron science facility – Diamond Light Source in Oxfordshire, England – have presented their research into radioactive waste containment at the world’s largest science conference – the American Association for the Advancement of Science (AAAS) annual meeting, held on 11-15 February in Washington DC. In a statement yesterday, Diamond Light Source Ltd said this work may help to inform the UK’s policy on radioactive waste disposal.
Diamond Light Source works like a giant microscope, harnessing the power of electrons to produce bright light that scientists can use to study anything from fossils to jet engines to viruses and vaccines.
Claire Corkhill from the University of Sheffield is using Diamond’s Long-Duration Experiment (LDE) facility to study the way that cement – an important material used in the storage and disposal of radioactive waste – reacts with water as it becomes hydrated over a period of hundreds of years. Corkhill said the research that the University of Sheffield is doing at Diamond is “ground-breaking”, and its findings could help to “shape future approaches” to radioactive waste disposal.
Key to the UK’s strategy for disposal is the plan for a Geological Disposal Facility (GDF). Under this plan, highly radioactive waste, immobilized in cement would be interred deep underground.
“But it’s important that we anticipate exactly what impact this approach could have on the surrounding environment,” said Diamond’s director of physical sciences, Trevor Rayment. “Some of this waste can take hundreds of thousands of years to decay to safe levels, and so scientists are trying to uncover the long-term result of interaction between radionuclides and their surroundings over these long timescales – that’s where the Diamond synchrotron becomes particularly important.”
Rayment added: “Timescales are crucial when it comes to nuclear research. Any facility expected to contain highly radioactive waste will need to remain functional for an extremely long period of time. Until recently, it’s been impossible to use synchrotron light to study interactions that take place over extended timescales. But, in a world first, Diamond has engineered a long-duration experimental facility that allows users to study sample behaviour in the intense detail afforded by synchrotron light but over a two year period: much longer than has ever before been possible.”
According to the statement, Corkhill has discovered that a new cement material for the GDF, developed by her research team, forms a number of mineral phases known to absorb highly radioactive elements, such as technetium-99.
Corkhill said: “Armed with the knowledge that these phases form, and knowing how quickly, supports the use of our new cement material in the GDF. We hope that these results will influence the design of the GDF and help improve its long-term safety.”
She added: “The pattern of peaks identified in cement essentially act as a ‘fingerprint’ telling us which cement minerals are present. The really exciting thing about using the LDE facility is that we are able to obtain very high resolution, time resolved patterns, something that is not possible using a normal laboratory instrument.”
Among the institutions using analytical tools at Diamond for research into nuclear energy, the University of Manchester is exploring radioactive contamination of the environment both inside and beyond the UK’s planned GDF. The University of Bristol is studying the fallout from the Fukushima disaster and opportunities to improve the radioactive waste clean-up process.
The Manchester group is using one of Diamond’s spectroscopy beamlines, B18, to study how radionuclides, including transuranic materials, which arise from nuclear processes, combine and interact at the atomic level with natural minerals and microbes in the earth. Bristol recently used one of Diamond’s spectroscopy beamlines, I18, to study the residual contamination left over from the Fukushima nuclear accident that took place in Japan in 2011. An understanding of contamination of this sort on a molecular level can help to better understand how to manage and contain radioactive waste, according to the statement.
Diamond is a not-for-profit limited company funded as a joint venture by the UK government through the Science & Technology Facilities Council in partnership with the Wellcome Trust.
The synchrotron, which is located on the Harwell Science and Innovation Campus near Didcot, is free at the point of access through a competitive application process, provided that the results are in the public domain. Over 7000 researchers from both academia and industry use Diamond to conduct experiments, assisted by about 500 staff.
Source: World Nuclear News