The UK Atomic Energy Authority (UKAEA) and Czech Republic research organisation Centrum výzkumu Řež (CVŘ), have signed a multi-year use of facility agreement. This will enable unique testing of High Temperature Superconducting (HTS) tapes, critical for the development of the UK’s prototype fusion energy powerplant, the Spherical Tokamak for Energy Production (STEP). These tapes are intended to confine STEP’s fusion plasma, a superheated gas of hydrogen isotopes, in a tokamak. Under intense heat – 150m degrees celsius, ten times hotter than the core of the sun – and pressure, the isotopes fuse into helium, releasing energy as neutrons.

UKAEA will work alongside CVŘ to deliver a first-of-a kind test rig called Hi-CrIS (High neutron fluence Cryogenic Irradiation of Superconductors). The arrangement will collect data on how a neutron spectrum relevant to fusion energy impacts the superconducting properties of the HTS tapes. The Hi-CrIS rig, expected to be operational in 2026, will produce test results for shaping the design and lifespan of STEP’s superconducting magnetic components. These components will function under cryogenic temperatures (20 Kelvin/-253 °C) and be subjected to high flux energy neutrons.

The Hi-CrIS test rig will have globally unique capabilities, enabling samples to be tested under high energy neutron fluences at cryogenic temperatures and could further develop the knowledge of superconductor components at operating temperatures. Hi-CrIS could also enable alternative materials testing for the potential development of future fusion powerplants.

Under the agreement, samples of HTS tapes will be cooled to the same cryogenic temperatures. Maintaining this temperature during irradiation, transportation, and measurement is critical for understanding how the HTS tapes degrade in their operating environment. The samples will be irradiated with high energy neutrons using CVŘ’s LVR-15 light water tank-type research reactor and kept at 20 Kelvin during transportation and measurement within the rig.

“We look forward to working with CVŘ to build and operate the test rig using their LVR-15 research reactor.” said Fiona Harden, Hi-CrIS Technical Lead “The objectives of Hi-CrIS are critical to STEP’s design and this importance is recognised by CVŘ who has worked openly with us to put this agreement in place.”

Marek Miklos, Business Development Manager from CVŘ noted that working in partnership with the STEP team presents an opportunity to support the UK’s programme to develop a prototype fusion energy plant. The Hi-CrIS testing rig will open lots of opportunities for further material studies for fusion applications,” he said. UKAEA noted that in addition to testing superconductor components, Hi-CrIS may also allow testing of various other materials for the potential development of future thermonuclear power plants.

STEP, which aims to demonstrate net energy from fusion, will be built at West Burton in Nottinghamshire. The first stage of the STEP project is expected to create a "conceptual project" by the end of 2024. The UK government has allocated £220m ($276m) for this part of the work. The next stage will include detailed engineering design, as well as obtaining all the necessary permits and approvals for creating a prototype. The goal is to get a fully developed project and a building permit by 2032, which will allow the construction to begin. The operation of the tokamak is expected around 2040.

Image: LVR-15 research reactor at CVŘ (courtesy of Centrum výzkumu Řež)