Commonwealth Fusion Systems has achieved a significant milestone with the installation of a crucial component of its Sparc demonstration reactor on Tuesday morning.

The newly installed part is a massive 24-foot wide, 75-ton stainless steel circle, forming the foundation of the tokamak, which is the doughnut-shaped core of a fusion reactor. This component, known as the cryostat base, was manufactured in Italy and shipped to CFS’s site in Devens, Massachusetts, after traveling halfway around the world. It is anticipated that this reactor will be the first of its kind to generate more power than it consumes.

According to Alex Creely, Director of Tokamak Operations at CFS, “This is the first piece of the actual fusion machine.” Construction work at the site has been ongoing for over three years, with the company building the necessary infrastructure and machinery to support the reactor’s core.

Creely emphasized the significance of this milestone, stating, “It’s a big deal for us, as it marks a transition to a new stage of the project. We’re no longer just building an industrial facility, but also constructing the actual tokamak itself.”

CFS is among several startups that have emerged in recent years to pursue fusion power, which promises to deliver gigawatts of pollution-free electricity from hydrogen fuel derived from seawater. Investors have high hopes for this technology to meet future power needs, which are rising rapidly due to the increasing demand from heavy users such as electric vehicles and data centers.

Backed by investors including Bill Gates’s Breakthrough Energy Ventures, CFS is considered one of the most promising companies to demonstrate the commercial feasibility of fusion power. In December, the company announced that its first commercial-scale reactor will be located outside Richmond, Virginia.

The Sparc reactor is expected to become operational in 2027, and if successful, it could be the first tokamak to produce more power than it consumes. So far, only the Department of Energy’s National Ignition Facility has achieved scientific break-even in a series of successful experiments, with the first experiment taking place in December 2022.

However, the NIF’s reactor differs significantly from CFS’s, as it uses lasers to compress a fuel pellet to fusion conditions. In contrast, CFS’s tokamak uses magnets to confine and compress 100 million degree C plasma into a tight doughnut shape, allowing fusion to occur.

Tokamaks rely on superconducting magnets to generate the powerful magnetic fields required to contain the plasma. These magnets need to be cooled to -253 degrees C using liquid helium. The cryostat plays a crucial role in maintaining these frigid conditions, acting as a thermos to insulate the magnets from ambient temperatures. According to Creely, “The cryostat base is essentially the bottom of the thermos.”

Upon receiving the cryostat base, the CFS team had to carefully unbox and inspect it, similar to someone opening an Amazon package. However, unlike a typical package, it took the team several days to remove the shipping material and an additional week to ensure that the component was not damaged during shipping.

The CFS team then proceeded to move the cryostat base to the tokamak hall, where it was carefully positioned onto precisely placed bolts protruding from the concrete foundation. “Then you grout it in,” Creely explained.

In addition to the cryostat base, work is ongoing on the other three major components of the tokamak, which will be assembled simultaneously into their final configuration later this year or early next year. Following this, CFS will undertake a commissioning process to ensure that all the components are functioning together as planned, a process that is expected to take several months.

Creely emphasized the complexity of this process, stating, “This is a first-of-its-kind project. There’s no simple ‘on’ button to press, and it will take time to get everything working together seamlessly.”