193. Understanding TerraPower’s Natrium Reactor Design and Demonstration Project Progress

In the proverbial shadow of the Naughton Power Plant, a station in Kemmerer, Wyoming, that will stop burning coal at the end of this year, TerraPower is constructing what it calls “the only advanced, non-light-water reactor in the Western Hemisphere being built today.” The project represents more than just a new power source—it’s a symbolic passing of the torch from fossil fuels to next-generation nuclear technology. “We call it the Natrium reactor because it is in a class of reactors we call sodium fast reactors,” Eric Williams, Chief Operating Officer for TerraPower, said as a guest on The POWER Podcast. The Natrium design is a Generation IV reactor type, which is the most advanced class of reactors being developed today. “These designs have a greatly increased level of safety, performance, and economics,” Williams explained. Williams said the use of liquid metal coolant enhances safety. “Liquid metals are so excellent at transferring heat away from the reactor, both to exchange that heat into other systems to go generate the electricity or to remove the heat in an emergency situation,” he said. “For the Natrium reactor, we can do that heat removal directly to air if we want to, so that provides a very robust safety case for the reactor.” The design is also safer because it can run at low pressure. “The primary system is at atmospheric pressure; whereas, current pressurized water reactors have to pressurize the system to keep the liquid from boiling—to keep it in a liquid state,” Williams explained. “Liquid metal sodium doesn’t boil until about 800 to 900 degrees Celsius, and the reactor operates down at 500 degrees Celsius, so that can remain a liquid and still be at a very high temperature without having to pressurize it.” The liquid metal coolant also provides performance benefits. “One of those is the ability to store the energy in the form of molten salt heat coming out of the nuclear island,” said Williams. “That is really giving us the ability to provide basically a grid-scale energy storage solution, and it really matches up well with the current needs of the modern electricity grid.” Meanwhile, the energy storage aspect also allows decoupling the electricity generation side of the plant—the energy island—from the reactor side of the plant, that is, the nuclear island. That allows the energy island to be classified as “non-safety-related” in the eyes of the U.S. Nuclear Regulatory Commission (NRC). “That side of the plant has nothing to do with keeping the reactor safe, and that means the NRC oversight doesn’t have to apply to the energy island side of the plant, so all of that equipment can be built to lower cost and different codes and standards,” Williams explained. Notably, this also permits the grid operator to dispatch electricity without changing anything on the nuclear island. “That allows a different kind of integrating with the grid for a nuclear plant that hasn’t been achieved yet in the U.S.,” Williams said. “We’re very excited about that—the safety, the performance, and economics—and it really gives us the ability to have a predictable schedule, and construction will be complete in 2030.” While there is clearly a lot that needs to be done, and first-of-a-kind projects rarely go off without a hitch, Williams seemed pleased with how the project was progressing. “We’re really excited to be working in the state of Wyoming. It is just an outstanding state for developing any kind of energy project, including nuclear energy. The people in the community are really welcoming to us. The state legislators are always looking for ways to remove any obstacles and just explain to us how to get the permits we need and everything. So, the project has been going really well from that standpoint,” he said. In the end, Williams appeared confident that TerraPower would hit its current target for completion in 2030.