A joint UK-Korea research project to develop high-temperature superconducting (HTS) cables, a key component for the UK's next-generation fusion power plant, STEP (Spherical Tokamak for Energy Production), has entered its second phase. The cable prototype developed in Phase 1 demonstrated outstanding current-carrying performance and durability, reaching the limits of the test facility. In Phase 2, the plan is to extend the cable's length to enhance the reliability and technological maturity of the HTS magnet.
Seoul National University's (SNU) Center for Superconducting Applications announced on the 1st that it has completed Phase 1 of joint research with UK Industrial Fusion Solutions (UKIFS), which leads the STEP fusion power project under the UK Atomic Energy Authority (UKAEA), and has signed a contract for Phase 2. The total contract value for both phases amounts to 8.4 billion KRW.
STEP is a large-scale national strategic infrastructure project aiming to build a fusion power plant by 2040. The first phase of the project, with a budget of approximately 390 billion KRW from 2019 to this year, is underway to develop the conceptual design for a fusion power plant based on HTS magnets, to be built in Nottinghamshire, UK.
Fusion power generates energy by replicating on Earth the fusion reactions that occur inside stars like the sun. This is typically achieved in a donut-shaped device called a tokamak, where plasma heated to over 100 million degrees Celsius is confined by powerful magnets to trigger fusion reactions. As a future clean energy source that produces no carbon or radioactive waste, fusion power is gaining attention as a solution to potential electricity shortages driven by advancements in artificial intelligence (AI) and other technologies.
SNU's Center for Superconducting Applications and the UKAEA jointly conducted Phase 1 of the HTS cable development under a joint research agreement worth approximately 1.8 billion KRW, which ran from June 2023 to March of this year. This collaboration was driven by the expectation that the 'no-insulation HTS' technology, proposed by Professor Han Seung-yong of SNU's Department of Electrical and Computer Engineering, could reduce the size of conventional superconducting magnets to less than one-fifth, leading to significant reductions in construction and operational costs.
In Phase 1, the joint UK-Korea research team designed a 3.6-meter HTS cable prototype. During performance tests conducted in July of this year at the SULTAN test facility, part of the Swiss Federal Institute of Technology Lausanne (EPFL), the cable achieved the maximum conditions the facility could provide: a magnetic field of 10.9 Tesla (T, a unit of magnetic field) and an operating current of 91 kiloamperes (kA, a unit of current).
The cable prototype showed no performance degradation even after undergoing more than 1,400 charge-discharge cycles, including 1,389 repeated load tests at 85 kA and 10.9 T. This is considered an unprecedented achievement in the field of HTS cables since the SULTAN facility began operations in 1992.
SNU and the UKAEA have signed a Phase 2 technology development agreement worth approximately 6.3 billion KRW. From July of this year until March 2027, they will advance the performance and length of the HTS cable prototype. The goal is to design a tens-of-meters-long HTS cable applicable to the actual STEP system, and to develop manufacturing technology and a cryogenic performance evaluation system in preparation for commercialization.
SNU stated, "The two institutions are also expanding their scope of cooperation to include the design, manufacturing, and evaluation of a prototype for the 'TF (Toroidal Field) HTS magnet,' a core component of the STEP fusion system. This is expected to deepen the collaboration on compact fusion technology and contribute to enhancing technological excellence."
