World's Largest Nuclear Reactor is Finally Completed

Construction of the world's largest nuclear fusion reactor has been completed, but it won't be operational for another 15 years, according to scientists.

The International Thermonuclear Experimental Reactor (ITER), featuring 19 large coils that form multiple toroidal magnets, was initially scheduled for its first full test in 2020. However, scientists now anticipate a start date no earlier than 2039.

This delay suggests that fusion power, led by ITER's tokamak, is unlikely to provide a timely solution to the climate crisis.

At a news conference on Wednesday, July 3, ITER's director general, Pietro Barabaschi, acknowledged, "Certainly, the delay of ITER is not going in the right direction. In terms of the impact of nuclear fusion on the problems humanity faces now, we should not wait for nuclear fusion to resolve them. This is not prudent."

ITER, a collaboration among 35 nations including EU members, Russia, China, India, and the U.S., houses the world's most powerful magnet, capable of generating a magnetic field 280,000 times stronger than Earth's.

The reactor's ambitious design comes with a significant cost. Initially estimated at $5 billion with a 2020 start date, the project has faced numerous delays. The budget has increased to over $22 billion, with an additional $5 billion proposed for extra expenses. These unforeseen costs and setbacks have contributed to the recent 15-year delay.

For over 70 years, scientists have been working to harness nuclear fusion, the process that powers stars. Main-sequence stars generate immense energy without greenhouse gases or long-lasting radioactive waste by fusing hydrogen atoms into helium under extreme conditions.

Replicating stellar conditions on Earth is challenging. The tokamak, the most common fusion reactor design, involves superheating plasma and containing it within a donut-shaped chamber using powerful magnetic fields.

Maintaining control over the incredibly high-temperature plasma necessary for nuclear fusion remains a formidable challenge. The tokamak, a groundbreaking fusion reactor design introduced by Soviet physicist Natan Yavlinsky in 1958, marked a significant step forward. However, even after decades of research and development, scientists have yet to create a fusion reactor capable of producing more energy than it consumes.

A major challenge is managing plasma at fusion temperatures. Fusion reactors require temperatures far exceeding those of the sun due to their much lower operating pressures compared to stellar cores.

For comparison, the sun's core reaches about 27 million Fahrenheit (15 million Celsius) with pressures roughly 340 billion times Earth's sea-level air pressure.

Achieving the extreme temperatures needed to create plasma is comparatively straightforward. However, the real technical hurdle lies in confining this superheated material. Without proper containment, the plasma could damage the reactor or disrupt the fusion process. Scientists typically employ lasers or magnetic fields to effectively contain and control the plasma.