Kyoto Fusioneering, Ltd. (“KF”) has begun a joint development program with Daido Steel Co., Ltd. to establish commercial manufacturing technology for low-activation vanadium alloy, one of three candidate structural materials for fusion blankets. Under the program the two companies have melted and forged a cumulative 200 kg of high-purity vanadium into round bars and plates and are now jointly evaluating the manufacturing and processing technologies required to produce these materials. Going forward, the companies will proceed toward the fabrication of a blanket mock-up, with a view to the future practical application of this material as a blanket structural material for fusion machines.

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High-purity, low-activation vanadium alloy forged round bar and machined plate material (round bar: Φ45 × 750 mm; machined plate: 220 × 250 × 7.8 mm).

High-purity, low-activation vanadium alloy forged round bar and machined plate material (round bar: Φ45 × 750 mm; machined plate: 220 × 250 × 7.8 mm).

Background

Developing the blanket — the in-vessel component that absorbs the neutrons generated by the fusion reaction, recovers heat, and breeds the tritium fuel — is one of the key technical challenges on the path to realizing fusion energy. While several candidate materials, including reduced-activation ferritic-martensitic (RAFM) steel, are currently under research and development, low-activation vanadium alloy is receiving renewed attention from private fusion developers pursuing higher-temperature blanket designs. Vanadium retains strength to around 700°C, is the only one of the three candidates that is both non-ferromagnetic and ductile and has good chemical compatibility with liquid lithium and may also be attractive with FLiBe (a molten salt of lithium fluoride and beryllium fluoride).

The U.S. Department of Energy’s Fusion Science and Technology Roadmap lists vanadium alloys among the structural materials that must be developed and qualified for fusion service. The U.S. Fusion Materials Community Roadmap characterizes vanadium-based alloys as a higher-performance but higher-risk structural option than RAFM steel. Both identify the same constraint: supply chain infrastructure for producing large vanadium alloy heats is limited, because until now there has been almost no commercial demand for them.

At the same time, melting and forging high-purity vanadium alloy to the extremely low impurity levels required for fusion applications demands advanced manufacturing technology, and the production record is thin. Heats of roughly 200 to 1,200 kg were produced in the United States and Japan in the 1990s and early 2000s, almost entirely within national programs; commercial supply was never established, and published roadmaps now set targets in the range of 500 kg to one tonne per heat, across multiple heats, to demonstrate industrial qualification. In this field, Professor Takuya Nagasaka of the National Institute for Fusion Science (NIFS) is a globally recognized leader who has driven research and development for many years, and through joint research with his group, KF has built expertise in the specifications and evaluation methods required of materials for fusion energy plants. By partnering with Daido Steel, a company with advanced metal materials manufacturing technology, KF has begun moving production of high-purity vanadium alloy out of national-program research heats and into a commercial specialty steel supply chain.

Overview of Joint Development

Under this joint development program, Daido Steel will draw on the technological capabilities it has built up through the development and manufacturing of specialty steels and various alloys as a foundation for establishing the manufacturing technology needed to bring vanadium alloy to practical use. Combined with KF’s expertise in fusion energy plant design and materials specification, the two companies aim to establish a repeatable industrial process for producing low-activation vanadium alloy structural materials for fusion applications.

Specifically, the companies are jointly evaluating manufacturing and processing technologies for vanadium alloy materials, including plate and round bar. The first finished material — 7.3 kg of round bar and 2.6 kg of plate, shown above — was completed in August 2026, and approximately 70 kg in total will be delivered to KF. KF will machine and join this material, and estimate beginning fabrication of a blanket mock-up in 2027.

Outlook

Through the fabrication of a blanket mock-up using the structural materials obtained through this joint development, KF will advance blanket development and its commercialization.

KF develops blanket structural materials in parallel — vanadium alloy alongside the SiC/SiC composite it is developing independently — because a blanket structural material cannot be chosen in isolation from coolant, breeder, and operating temperature, and those choices differ across fusion developers. KF supplies the blanket, not the machine, and therefore has to be able to build it in more than one material system.

Going forward, KF will continue to collaborate with Japanese companies that possess advanced materials manufacturing and processing technologies, contributing to the formation of a fusion supply chain and industrial ecosystem built on cooperation among Japan’s private-sector companies.

Quotes

“In our 2026 Medium-Term Management Plan, Daido Steel has positioned the achievement of carbon neutrality by 2050 as one of its key priorities, with clean energy identified as one of our priority target fields. Vanadium alloy is widely recognized as a material with excellent properties, but its manufacturing difficulty has, until now, prevented it from achieving widespread global adoption. This development aims to establish the manufacturing technology needed to bring vanadium alloy to practical use, building on the technological capabilities we have cultivated through the development and manufacturing of specialty steels and various alloys, in support of the social implementation of fusion energy that Kyoto Fusioneering is advancing. Establishing mass-production technology for vanadium alloy represents a major technical challenge, but we will contribute to the realization of fusion energy through this development.”

— Shigeki Ueta, General Manager, Corporate Research & Development Center, Daido Steel Co., Ltd.

“The blanket is one of the most critical components on the path to the practical application of fusion energy, and the development of its structural materials is key. By combining Daido Steel’s advanced materials manufacturing technology with the expertise KF has built up in fusion materials, we have been able to move blanket development forward. Going forward, we will continue to work with companies across the industry to advance the technology development and supply chain construction needed for the social implementation of fusion energy.”

— Kiyoshi Seko, Representative Director, President & COO, Kyoto Fusioneering, Ltd.

About Daido Steel Co., Ltd.

Daido Steel Co., Ltd. (Headquarters: Higashi-ku, Nagoya; President: Tetsuya Shimizu) has, since its founding in 1916, supplied high-performance materials centered on specialty steel to a wide range of fields, including automobiles, industrial machinery, energy, aircraft, medical equipment, and digital devices. Guided by its corporate philosophy — “Pursuing the possibilities of materials to support the future of people and society” — the company creates value that goes beyond specialty steel through co-creation with its customers, working toward the realization of a sustainable society.

Corporate website: https://www.daido.co.jp/en/

About Kyoto Fusioneering

Kyoto Fusioneering is the world’s premier fusion technology and integrated systems developer. It delivers plasma heating, tritium fuel cycle, and tritium breeding blanket and thermal cycle systems that advanced fusion programs worldwide depend on, regardless of confinement approach. KF operates globally across Japan, the United States, the United Kingdom, Germany, and Canada. Visit us at kyotofusioneering.com.

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