Commonwealth Fusion Systems (CFS) achieved a significant milestone on Tuesday morning with the installation of a crucial component for its Sparc demonstration reactor. This component, known as the cryostat base, is a 24-foot wide, 75-ton stainless steel circle that serves as the foundation for the tokamak, the doughnut-shaped core of the fusion reactor. CFS aims for this reactor to be the first of its kind to generate more energy than it consumes. The cryostat base was manufactured in Italy and transported halfway across the globe to CFS’s facility in Devens, Massachusetts.
“This is the first piece of the actual fusion machine,” said Alex Creely, CFS’s director of tokamak operations, in an interview with TechCrunch. The site has been under development for over three years, focusing on constructing the buildings and machinery necessary to support the reactor’s core. Creely emphasized the importance of this milestone, stating, “It’s a big deal for us, because it means we’re transitioning into a new stage of the project where we’re not just building an industrial facility — we’re also now building the actual tokamak itself.” CFS is among several startups that have emerged in recent years to explore fusion power, which has the potential to provide gigawatts of pollution-free electricity using hydrogen fuel derived from seawater. As global energy demands soar, particularly with the rise of electric vehicles and data centers, investors are banking on fusion technology to meet future energy needs. CFS, backed by Bill Gates’s Breakthrough Energy Ventures and other investors, is seen as a leading contender to demonstrate the commercial viability of fusion power. The company announced in December 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 energy than it consumes. To date, only the Department of Energy’s National Ignition Facility (NIF) has achieved what is known as scientific break-even in a series of successful experiments, the first of which occurred in December 2022. However, the NIF operates differently from CFS’s tokamak, using lasers to compress a fuel pellet to reach fusion conditions, while CFS’s approach relies on magnets to confine and compress a plasma heated to 100 million degrees Celsius into a doughnut shape for fusion to occur.
Tokamaks use superconducting magnets to generate the strong magnetic fields necessary to contain the plasma, which must be kept at -253 degrees Celsius using liquid helium. The cryostat plays a crucial role in maintaining these low temperatures by insulating the system from ambient heat, functioning similarly to a thermos. “The cryostat base is basically like the bottom of the thermos,” Creely explained. Similar to receiving an Amazon package, CFS needed to unbox and inspect the cryostat base before installation. However, this process took several days to remove the shipping materials and an additional week to ensure that no damage occurred during transport, according to Creely.
Once inspected, the cryostat base was moved to the tokamak hall, where it was aligned with precisely positioned bolts on the concrete foundation. “Then you grout it in,” he added. In addition to the cryostat base, work is ongoing on the other three major components of the tokamak, which are expected to be assembled into their final configuration either late this year or early next year. Following that, CFS will embark on a lengthy commissioning process to ensure all components work together as intended. “This is the first of its kind,” Creely noted. “There’s not just an on button; it doesn’t just turn on.”
