Under the nanoscope

Any material that is put to work in a challenging environment will sooner or later show signs of wear and tear. If that material is part of a nuclear reactor, then the problem of maintaining its integrity is particularly acute. While big accidents such as those that occurred at Three Mile Island and Chernobyl tend to be the result of human error, materials failures in components such as secondary cooling systems do happen and remain a major source of concern.

Understanding how the steels used in nuclear reactors develop cracks or brittleness, as a result of being subjected to heat and radiation, is exactly the kind of problem that Oxford’s Department of Materials is helping to solve with its powerful analytical instruments. These can explore materials with a resolving power sufficient not only to see but to identify individual atoms, a vital capability when trying to understand how they work. A key part of this activity is OPAL, the UK Centre for 3-dimensional Atom Probe Analysis funded by EPSRC and led by Professor George Smith, FRS.

Working with a number of companies from the international nuclear industry, head of department Professor Chris Grovenor and his colleagues have revealed how impurities and external oxidation and corrosion of steels and other metallic components used in existing reactors contribute to embrittlement or fracture. This information is vital in predicting the safe operating lifetime of nuclear plant. ‘We’re also helping to design completely new materials for the next generation of power plants, including fusion reactors’, says Professor Grovenor.

The same analytical tools are being brought to bear on a surprisingly wide range of problems. For example, Professor Grovenor is collaborating with Rothamsted Research on the detection of critical trace elements like arsenic in rice and selenium in wheat. ‘No one is sure how these plants traffic and store these elements that can have a significant influence on human health’, says Professor Grovenor. ‘If we understood the critical mechanisms, we might be able to work out how to reduce arsenic pick up from contaminated groundwater and increase the amount of beneficial selenium in European diets.’

Several of the most advanced instruments are installed on the University’s Begbroke campus a few miles outside Oxford. ‘Begbroke has energised our entire research portfolio’, says Professor Grovenor. ‘It has allowed us to install very large-scale, state-of-the-art facilities of a kind that industry recognises as being necessary to study industrial-scale problems.’ The Begbroke Nano project, funded by a government initiative to encourage UK nanotechnology and manufacturing, allows smaller companies to carry out advanced nanoscale characterisation backed by the expertise of University researchers.

Oxford’s materials scientists are at the forefront of the effort to find technological solutions for the 21st century. ‘We’re trying to solve the key scientific and technological problems that limit the introduction of new materials to the marketplace’, says Professor Grovenor.