S. Korea completes assembly of vacuum vessel sectors for ITER fusion reactor

South Korean companies have completed assembly of vacuum vessel modules for the International Thermonuclear Experimental Reactor, reaffirming the country's nuclear fusion capabilities.

The Ministry of Science and ICT said Wednesday it held a "Korea-ITER Fusion Day" ceremony at the ITER construction site in Cadarache, France, to mark the completion of assembly and installation into the tokamak pit of the final vacuum vessel sector module led by South Korea.

The ITER joint development project is the world's largest international science and technology cooperation initiative, pursued by seven countries — South Korea, the United States, the EU, Japan, China, India and Russia — to test and verify the feasibility of nuclear fusion energy.

The vacuum vessel, located at the innermost part of the fusion reactor, serves as a containment vessel that creates and maintains a high-vacuum environment capable of generating and sustaining ultra-high-temperature plasma exceeding 100 million degrees Celsius — the condition required for fusion reactions to occur. Nine sector modules, each measuring 11.3 meters tall, 6.6 meters wide and weighing approximately 400 tons, interlock to form the donut-shaped vacuum vessel. The modules are considered extremely difficult to manufacture, as they must meet stringent precision requirements along with strict quality and safety regulations and standards.

The vessel also acts as a primary radiation shield, blocking neutrons generated during the fusion process, and as a platform that precisely secures key internal components of the fusion reactor, including the blanket and divertor.

South Korea not only completed its originally allocated two sector modules but also took on an additional two modules assigned to the EU, bringing its total to four. The achievement demonstrates that South Korean companies have the technical capabilities needed to manufacture and assemble large-scale, high-precision fusion devices, and is significant as further proof of the country's international procurement capacity and competitiveness in the fusion industry.

Kim Sung-su, director general for research and development policy at the Ministry of Science and ICT, said the successful installation of the vacuum vessel sector modules "is like a showcase of South Korea's technological capabilities at a time when global competition in nuclear fusion energy development is intensifying." He added that the ministry "will continue to provide support to rapidly secure the core technologies needed for the early realization of fusion energy in the 2030s through the ITER project, and to strengthen the competitiveness of domestic industry."