Two critical facets of the development of fusion power, materials and tritium breeding, require dedicated test facilities. For material research low flux neutrons sources exist but are not powerful enough to fully qualify materials for fusion reactors. For tritium breeding the situation is even more serious, with idea being developed theoretically without any experimental verifications.

There are two different types of device possible to satisfy these needs:

  • Fusion reactor dedicated to nuclear environment research
  • Particle accelerator beam to simulate nuclear environment

Particle accelerator neutron sources

Neutron sources, based on particle accelerator technology, would seems to be, by far, the cheapest and fastest way to useful test facilities.

The International Fusion Materials Irradiation Facility (IFMIF) is part of the Broader Approach agreement between Japan and Europe and planned to be built in Japan. It is discussed in a 2012 entry in the ITER Newline: Common controls in ITER and IFMIF.

The paper, Overview of the IFMIF/EVEDA project motivates and explains the project in detail. It is a neutron source intended as a test facility to develop new advanced materials for the plasma-facing components of fusion reactors. The device is based on a linear accelerator to generate neutron fluxes in the order of 1018m-2s-1 with an energy of 14.1 MeV as in a fusion reactor. The machine will accelerate deuterium ions and send them onto a lithium target to produce the neutron flux.

Principles of IFMIF: deuteron accelerator and lithium target to produce neutrons

Layout of IFMIF device

The facility will be constructed in Japan. At the present time, only prototype devices for IFMIF are actually in construction and the timescale for the full IFMIF device is unclear.

Fusion engineering test reactor facilities

Numerous fusion devices have been proposed with the principle objective to be engineering test facilities over the past few decades. For ITER, the engineering test aspect, has been much reduced and many people now see it as mainly a fusion plasma research platform, its contribution beyond this will be limited.

In the USA the need for fusion device to act as an engineering test facility was propose many decades ago in 1980s, it has carried the name, Fusion Nuclear Science Facility (FNSF) and has been through many studies confirming the requirements. In the US there has been recent interest in Spherical Tokamaks to fulfil this role, e. g. Fusion nuclear science facilities and pilot plants based on the spherical tokamak, Menard et al. , it is not obvious funding will be available for such a facility in the USA.

In China such a test facility does have funding,  China Fusion Engineering Test Reactor (CFETR) and so seems likely to happen.

With a tokamak radius of 7.2 m it will be bigger than ITER.


Fusion power plant success will depend on test facilities

The timescales and features of these facilities play a vital role in the planning for the next steps of fusion power plant development as shown in the page, Timescales advertised for Commercial Fusion Power Plant. Given the complexities and lack of understanding of Breeder Blanket technologies, a passage through an intensive program of development seems indispensable before committing to a fusion power plant design. Unfortunately, in some countries, the political pressure to arrive at "Unlimited Energy" as soon as possible seems too strong to take a prudent path.