What it is: The vacuum vessel is a 5,000-ton steel chamber that will house the world's first reactor-scale fusion plasma at ITER. The finished vessel will be hermetically sealed and will act as a first safety containment barrier. In its doughnut-shaped chamber, or torus, the plasma particles spiral around continuously without touching the walls. The nine 40-degree sections of the vessel are being constructed in various locations, with four coming from South Korea and the remaining five being built in Europe. Section no. 6 is the one that HHI just completed. The company reports that its next section, no. 7, is more than 90 percent finished.
The next steps: When the completed section no. 6 arrives at ITER, it will be transferred into the assembly building and put in place by an overhead crane to a laydown area. After a final helium leak test and site acceptance test, the component will be handed over to DYNAMIC SNC, the consortium chosen by the ITER Organization as its assembly contractor. DYNAMIC SNC is responsible for a series of installation activities, including diagnostics, instrumentation, and adding cable trays on the outer shell.
What they’re saying: “It is testimony to the ingenuity, skill, dedication, and perseverance of the industrial contractors in Korea, of the Korean Domestic Agency in its oversight, and of the wider ITER Vacuum Vessel Project Team that this first-of-a-kind component—one of the most challenging of the ITER machine—has been successfully manufactured,” ITER Director-General Bernard Bigot said. “The pride and sense of accomplishment of all those involved is commensurate with the size and complexity of the challenge.”
Deep dive: Construction on the vessel section no. 6 began in February 2012 by HHI. The section is formed primarily from four poloidal segments that fit together to make a D shape. Although each segment is different in design, each required the same step-by-step fabrication route. First, contractors formed and welded the inner shell, attached inner ribs and support housings, and installed in-wall shielding blocks. The final activity was fitting and welding the outer shell. By September 2019, the segments were ready to be assembled into the final D-shaped section, and the final components, upper and lower port stub extensions, could be attached through splice plates.
In March and early April this year, the section underwent a series of factory acceptance tests, including the critical pneumatic pressure and helium leak tests. HHI and Domestic Agency ITER Korea were able to demonstrate that the section fully met all ITER Organization technical specifications.
A ceremony on April 20 at HHI’s headquarters in Ulsan, Korea, was attended by Byungseon Jeong, first assistant minister, ministry of science and ICT; Young-seuk Han, president and chief executive officer of HHI; Sukjae Yoo, president of Korea's National Fusion Research Institute; Kijung Jung, director-general of ITER Korea; and more than 30 experts.
