01 September 2021

A.L.M.T. Corp. (hereinafter called "A.L.M.T."), a group company of Sumitomo Electric Industries, Ltd., was awarded a 3.5-billion-yen contract by the National Institutes for Quantum and Radiological Science and Technology (QST) to supply a tungsten monoblock,*¹ an important component of the ITER,*² which is under construction in France.

In recent years, movement to achieve carbon neutrality (decarbonization) for the purpose of breaking away from fossil fuels, such as petroleum and coal, is growing. In the meanwhile, “fusion energy” using nuclear fusion reaction is attracting attention as a permanent energy source that can provide a fundamental solution to energy problems and environmental problems because it does not emit carbon dioxide, a cause of global warming. Currently, fusion energy is at the stage of demonstration of technical and scientific viability using the ITER, for which preparation is being made under international cooperation among six countries and one region (Japan, the EU, the US, Russia, China, South Korea and India).

The tungsten monoblock developed and manufactured by A.L.M.T. is an important component of a device called a “divertor.*³“ The world’s first “unbreakable tungsten” has been highly evaluated for its thermal shock resistance, withstanding a thermal load of more than 2,000 degrees Celsius and remaining unbreakable for a period of more than three times the number of operation cycles required by the ITER, which led to the award of the contract.

In response to the award of the contract, A.L.M.T. will set up a new mass production line at the Sakata Works (Sakata City, Yamagata Prefecture) and start its operation in September 2021. With thoroughly improved production efficiency using IoT, this new line will realize eight times or more production capacity compared to that of the conventional line.

With the growing need for stable supply of environmentally friendly clean energy, expectations for fusion power generation are rising. As a company that contributes to the achievement of the SDGs, A.L.M.T. aims for adoption of tungsten monoblocks not only for the outer part of the ITER divertor, which is Japan’s assignment, but also for the inner part of it, which is the EU’s assignment. A.L.M.T. also aims to supply materials to the research institutes of fusion prototype reactors for power generation in the project member countries and region, such as Japan, Europe and the US, and contribute to the practical application of fusion reactors.

A.L.M.T. Tungsten monoblock
1. Main feature: Excellent thermal shock resistance
A fusion reaction occurs in a plasma exceeding 100 million degrees Celsius, and the surface temperature of the divertor, which discharges and removes impurities unnecessary for maintaining this plasma, reaches a maximum of 2,300 degrees Celsius. Therefore, the components of ITER are required to have extremely high-level characteristics, and tungsten, which has the highest melting point among metals, is used. A.L.M.T. has developed a tungsten material suitable for nuclear fusion reactors and created a monoblock in which tungsten and oxygen-free copper are bonded by a special bonding method.

When the tungsten monoblock was evaluated using the equipment owned by QST, it exhibited excellent thermal shock resistance since no cracks were observed even during an evaluation for a period of more than three times the number of operation cycles required by the ITER. In addition, unlike the conventional material, the developed material had no surface ridges due to deformation, so its excellent thermal stability was confirmed. Based on these successful results, A.L.M.T. conducted an evaluation using a mock divertor made of the tungsten on a scale similar to that of the actual machine. In this evaluation as well, all tungsten monoblocks had no cracks under conditions far exceeding the requirements of the ITER Organization, and the material was recognized as “unbreakable tungsten” for the first time in the world.

2. Process until the award of the contract and future mass production plan
A.L.M.T.’s involvement in fusion energy dates back to 1985, when QST’s fusion reactor went into operation. A.L.M.T. has built a relationship of trust by supplying QST with products of stable quality for a long time by making full use of its powder metallurgy technology cultivated through integrated production, from raw material processing to special treatment. In addition, the outstanding performance of the tungsten monoblock was highly evaluated, which led to the award of the contract. A.L.M.T. will set up a mass production line of the product in the Sakata Works (Sakata City, Yamagata Prefecture), which will come into operation in September 2021. With thoroughly improved production efficiency by using IoT, the new production line will realize eight times or more production capacity compared to that of the conventional line.

*1: Tungsten monoblock
A component made of tungsten material with a size of approximately 30 mm x 30 mm x 10 mm. It is skewered by a copper alloy cooling pipe to form a unit.

*2: ITER: ("The Way" in Latin) is one of the most ambitious energy projects in the world today.
The world's largest tokamak, a magnetic fusion device designed to prove the feasibility of fusion reactions as a large carbon-free source of energy based on the same principle that powers the Sun and stars. The amount of fusion energy a tokamak can produce is directly related to the number of fusion reactions taking place in its core, reaching 500 MW of fusion power.
The core of the device is a donut-shaped part where ultra-high temperature plasma is generated, and fusion reactions occur in the plasma. The plasma is approximately 7 m high, 16 m in outer diameter and 800 m³in volume.

*3: Divertor
A device for receiving high heat flow and particle flow generated by plasma and discharging and removing impurities unnecessary for maintaining plasma.
The procurement of the outer target, the inner target and the dome was assigned to Japan, the EU and Russia, respectively.