Diamond Light Source unveils first ever images of fuel debris fallout particles from Fukushima
Unique synchrotron visualisation techniques offer new forensic insights into the provenance of radioactive material from the Fukushima nuclear accident to understand the sequence of events related to the accident.
The research, using Diamond’s unique combined capabilities of the I13 and I18 beamlines, sheds light on a unique combination of imaging and fluorescence measurements developed at Diamond. This enables the examination of individual particles to reveal details about the accident and looks at the material from an environmental stability point of view alongside the associated risks.
We decided to bring a radioactive particle from the Fukushima fallout to Diamond to undergo a comprehensive and independent analysis of its internal structure and 3D elemental distribution because relatively little is known about the physical and chemical nature of the radioactive particles and their long-term environmental effects.
He notes that the radioactive particle brought to Diamond was collected from within the restricted zone, in an area to the north of the nuclear plant. It was encased with protective Kapton tape and brought to the I13 beamline, which offers a unique combination of X-ray imaging and fluorescence capabilities.
Prof Tom Scott from University of Bristol commented; “We wanted to perform multiscale and multimodal measurements – by this I mean from micron to nanometre scale whilst looking at the chemistry, structure and functionality of the sample all in parallel. Diamond offers to the best of our knowledge the only beamline in the world where it is possible to perform such an analysis within a single experiment. The resulting visualisation has allowed for a comprehensive analysis of the particle.”
Principal Beamline Scientist, Dr Christoph Rau adds;
It is worth noting that the particle seems to have been stable for nearly 4 years – the time between being ejected from the plant and being collected for analysis. In addition, in the studied particle, the radioactive material is also encased within a glasslike silicon, analogous to the vitrification process used for the disposal of nuclear waste, which will further reduce the potential for radionuclides to leach out.
Previous investigations of material from Chernobyl found a similar affinity between iron and caesium, causing the formation of ferrites that greatly reduce the solubility of caesium within the environment. Similarly, the uranium in the sample was observed to exist in an insoluble form, and encased within the glassy material. Building on the success of these experiments and the unique capability offered by Diamond, a consortium of UK and Japanese Universities have been awarded a joint grant by UK Research and Innovation’s Engineering Physical Sciences Research Council and Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT) to carry on the research to examine larger particles closer to the site. This will underpin the distribution of material which contains fuel debris to better define the risk map.
Tom Scott concludes: “The work has significant relevance beyond nuclear accidents, and this approach and the techniques developed could in the future be used to image particles in air pollution in the UK and all over the world. For example, the ‘Asian Brown Cloud’, a layer of air pollution that covers parts of South Asia for several months each year, would be of great interest as it is found to be linked to health conditions killing two million people in Asia every year 2 .”
- World Nuclear Association. Fukushima Daiichi Accident. Online: http://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/fukushima-accident.aspx (Accessed 13 November 2018).
- Ahmad K. Pollution cloud over south Asia is increasing ill health. Lancet 360 (9332):549 (2002). DOI:10.1016/S0140-6736(02)09762-3.
The research has been supported by the Japanese Society for the Promotion of Science (JSPS), Daiwa Foundation and Saskawa Foundation, showing significant Japanese support and interest in the project.