Read our COVID-19 research and news.

ITER Chooses a Cautious, Slower, Approach To Fusion

Governments responsible for the ITER fusion project approved a conservative approach to its construction today in which just a bare-bones reactor will first fire up in 2018. Meeting on 17–18 June in Mito, Japan, the ITER council—with representatives from the project’s seven members: China, the European Union, India, Japan, Korea, Russia, and the United States—agreed on a phased construction approach to reduce the overall risk that the project would fail, with the result that the first power-producing plasma generated by the reactor will be delayed by between 18 months and 2 years.

ITER aims to demonstrate that nuclear fusion, the process that powers the sun and other stars, is a practical energy source on Earth. After more than 2 decades of research and design work, the ITER organization was officially created in October 2007 and land in Cadarache, France, has been prepared for the reactor’s construction to begin this year. Since 2007, researchers have been busy updating the ITER design that was drawn up in 2001 to incorporate the results of recent research in plasma science. First results of this redesign effort were presented to the ITER council in June 2008 and the body called for an independent assessment of the cost implications. Although ITER staff have made no official statement on how expensive the proposed changes will be, sources say they could increase ITER’s cost 30% above the current €10 billion pricetag, half of which is for construction.

According to David Campbell, deputy head of ITER’s fusion science and technology department, staff are working on a complete package to present to the council in November that will include the redesign, a revised schedule, and a new cost estimate. To make sure they were on the right track, ITER officials asked the council to approve a phased approach to constructing the reactor. By 2018, ITER staff want to build a basic device, essentially just the vacuum vessel, the superconducting magnetic coils to hold the plasma in place, and the cryogenic system to cool the coils. “The idea is to shake down the core system, demonstrate a first plasma, then integrate other systems,” Campbell says. “It reduces risk: If something goes wrong it’s easier to get at it and fix it.”

Once staff members demonstrate that they can control a plasma of normal hydrogen, they will add in components such as diagnostic instruments, heating systems, the diverter (which removes burnt fuel), and the blanket (which lines the inside of the vacuum vessel and absorbs neutrons produced by a burning plasma). With those components in place, researchers should be able to make their first attempts at a burning plasma, using a mixture of the hydrogen isotopes deuterium and tritium as fuel. Once this has started, the interior of the reactor will be radioactive and so harder to modify. The phased approach will delay this first D-T fusion from early 2025 to late 2026.