Kyoto Fusioneering (KF), a startup spun out of Kyoto University, has begun operating its Unified Integrated Test Facility 2 (UNITY-2). The plant is engineered to demonstrate a self-sufficient deuterium-tritium (D-T) fuel cycle, a critical enabling technology for future commercial fusion power plants. UNITY-2 integrates a molten salt loop with a fuel extraction system to validate the core processes of tritium breeding and recovery. This development addresses one of the primary engineering challenges for D-T based concepts like tokamaks and stellarators, which require a continuous, on-site supply of tritium fuel. The facility's commissioning marks a significant step in developing the balance-of-plant technologies necessary for fusion energy. Source: Kyoto Fusioneering

The UNITY-2 system circulates a molten salt of lithium and fluorine, known as Flibe, which serves as the tritium breeder material. Inside a fusion reactor's blanket, neutrons would react with lithium to produce tritium. To simulate this process without using radioactive materials, UNITY-2 injects deuterium, a stable hydrogen isotope, into the Flibe loop as a surrogate for tritium. The primary objective is to demonstrate efficient extraction of this surrogate fuel from the molten salt. This integrated approach allows for testing the dynamics of the entire fuel loop, from breeding medium circulation to purification, providing essential data for designing the tritium breeding ratio systems of future power plants. Source: Kyoto Fusioneering

The UNITY-2 system circulates a molten salt of lithium and fluorine, known as Flibe, which serves as the tritium breeder material.

A key component of the UNITY-2 facility is the vacuum sieve tray (VST) distillation column, which separates the deuterium from the Flibe. As the molten salt flows through the VST, the low-pressure environment facilitates the release of the dissolved hydrogen isotopes. This technology is crucial for achieving a closed fuel loop, minimizing tritium inventory, and ensuring the economic viability of a D-T fusion plant. The successful operation of the VST within an integrated system is a primary goal of the UNITY-2 experimental campaign. Beyond fuel cycle development, Kyoto Fusioneering is also advancing other essential fusion components, including high-efficiency gyrotrons and advanced divertor systems for plasma-facing heat management. Source: Kyoto Fusioneering

The development of a robust fuel cycle is a global priority, as the world's tritium supply is limited to a few dozen kilograms, far short of the needs for a fleet of commercial fusion reactors. Programs like ITER will consume a significant fraction of the existing inventory for their D-T campaigns, highlighting the urgency for effective breeding technologies. By demonstrating a viable path for tritium self-sufficiency, KF's work directly supports the broader transition from physics experiments to engineering prototypes capable of sustained operation. The data from UNITY-2 will inform the design of breeding blankets for various public and private fusion reactor concepts currently under development worldwide. Source: Kyoto Fusioneering