CCFE collaboration enhances capabilities of European fusion materials research

The neutrons that emerge from fusion reactions carry the energy to produce electricity, but their high-speed onslaught on the surrounding structures causes damage and activation – leaving materials researchers with a headache. Testing samples of suitable elements and materials is therefore a high priority, but the prodigious amount of energy – 14 mega electron-volts (MeV) – carried by fusion neutrons is difficult to reproduce. One of the few devices worldwide that can produce neutrons at this energy is the ASP accelerator operated by the Atomic Weapons Establishment (AWE) in Aldermaston, UK. CCFE scientists are collaborating with AWE, using this accelerator to collect experimental data about neutron-induced nuclear reactions taking place inside materials.

Though ASP – like all other available 14 MeV neutron sources – delivers neutron fluxes of the same energy, but of much lower intensity than a fusion plasma, experiments on such devices help with the validation of nuclear data which is needed to design suitable materials. The development of neutron-resistant materials for fusion power plants is based largely on computer simulations of the effect of the fast neutrons on the material’s atomic structure. CCFE is very strong in these theoretical fields and it also maintains one of the world’s most extensive libraries of nuclear reactions – the European Activation System, EASY. The data used in the simulations are not exhaustive – for instance cross-sections, which determine the likelihood of certain types of reactions to occur are not always available for the energy level of fusion neutrons. Lee Packer of CCFE’s Applied Radiation Physics Group explains the importance of having access to high-energy neutron sources: “We can now experimentally validate the data used to support our calculations in important areas, such as activation of materials. Previously, through collaborations with European experts in the field, we’ve assembled an extremely detailed set of cross-section predictions derived from theory to cover many types of nuclear reactions, but there’s no substitute for real experimental data to underpin such predictions.“

European Consortium on Nuclear Data

As part of this activity, CCFE has recently joined the European Consortium on Nuclear Data, a group of institutes that provides experimental data required for the validation of the nuclear data libraries that are being developed for fusion applications. CCFE’s joining means that, in ASP, the consortium now has access to a third 14 MeV neutron source – alongside FNG at ENEA, Frascati, and a device at the Technical University of Dresden. “We will also benefit from CCFE’s well recognised capability on simulating nuclear reactions in fusion materials” adds Maurizio Angelone from ENEA, who leads the Consortium.

Nick Holloway, CCFE, Christine Rüth, EFDA

The European Consortium on Nuclear Data is formed by ENEA, KIT, JSI, CCFE, the Polish University of Science and Technology and the Czech Nuclear Physics Institute.