Culham Center for Fusion Energy, in a consortium with UK universities and Rutherford Appleton Laboratory, is developing a concept for a large neutron source to test materials for future fusion power plants including the proposed prototype, DEMO, that will follow the ITER project.
If approved, the FAFNIR project would give the designers of DEMO crucial data on materials with which to build the machine. It would also serve as a bridge to the planned International Fusion Materials Irradiation Facility (IFMIF), which is expected to play a similar role for the first generation of commercial fusion reactors.
Fusion scientists and engineers are increasingly focusing on materials research as attention turns to designs for reactors that will put power on the electricity grid. The extremely fast neutrons produced by fusion reactions in tokamaks carry an energy of 14 million electron volts (MeV) — about 70 times more than photons in hospital x-ray equipment — and pose a threat to the tokamak’s structures. The neutrons cause damage within the structure of the material which leads to swelling through the creation of voids. Effects such as embrittlement and hardening of the metal caused by accumulation of helium and hydrogen gases produced by transmutation (transformation of one element into another) mean that special materials must be developed that can stay the course throughout the reactor’s lifespan. As a result of transmutations caused by the neutrons, radioactive elements are produced within the tokamak components, so choosing materials that will shed their radioactivity quickly is another priority for safe decommissioning.
Read more on CCFE web site.