New glass sensors could make commercial nuclear fusion viable

A new generation of durable sensors capable of monitoring commercial nuclear fusion reactors in real time is being developed by UK researchers.

The team, led by Bangor University in partnership with Sheffield Hallam University, plan to identify whether glass sensors developed in 1960s could function in the extreme conditions of a nuclear fusion reaction. If not, the researchers will design and develop new glass sensors.

In December 2022, researchers in the United States for the first time generated more energy from a nuclear fusion reaction than was put in, opening up the possibility that the technology could be both commercially viable, and able to supply abundant, clean energy. But one of the requirements to move from experimental reactions to commercial power generation is reliable monitoring. This means overcoming the extreme conditions created in a fusion reaction: temperatures of 150-200 million degrees Centigrade and highly energetic fast-moving neutrons.

One way of monitoring a fusion reaction is to count the number of neutrons it gives off using scintillators – blocks of material in which a sparkle of light is created each time it is hit by a neutron. By counting the flashes of light, it’s possible to calculate the number of neutrons and the amount of energy being produced – helping to ensure everything is working as intended.

However, existing scintillators are mostly made from either crystal or polymer, which are either difficult to make and limited in size and shape, or lack the durability to withstand the more extreme conditions created by fusion reactions. The sensors currently used to calculate the energy output from fusion reactions tend to be cumbersome and awkward, and do not allow real-time and long term monitoring of the fusion process. For commercial nuclear fusion reactors to be run safely and efficiently, sensors will need to work reliably for years.

Dr Michael Rushton from Bangor University’s Nuclear Futures Institute is leading the new project. He said: “Glass has intrinsic radiation tolerance, so can survive well in very harsh conditions. It also has the advantage that it can be made in very different shapes, from fibres to plates which means sensors can be made for a range of situations within a reactor. And it’s fairly low cost to manufacture. We also hope to be able to ‘tune’ the sensors to work with different types of radioactive particle, so they may also be used for other applications, such as airport or medical scanners.”

Glass sensors able to register radioactive particles were first developed in the 1960s, but they only work if particles are travelling relatively slowly. The Bangor University team is initially seeing if particles emanating from a fusion reaction could be slowed down sufficiently to allow these sensors to work based on their existing composition. If this isn’t possible, then they will use machine learning approaches to identify new configurations of glass that could be effective in the conditions found within nuclear fusion. The new sensor designs will then by manufactured by their colleagues at Sheffield Hallam University.

Professor Paul Bingham from Sheffield Hallam University said: “This research will develop an entirely new range of glass-based sensors for some of the most extreme environments on Earth. This means it could not only help accelerate safe development and deployment of fusion energy technologies, but also have wide-ranging applications in other fields in the future.”

The two-year research project is funded through UK Research and Innovation’s Engineering and Physical Sciences Research Council. It involves Bangor and Sheffield Hallam Universities, the University of Birmingham, the ISIS Neutron and Muon Source at the Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory as well as a number of commercial partners.