Advanced reactors are moving from fascinating designs to reality, as innovative companies invest in hardware for next-generation nuclear technology.
BWX Technologies Inc. will restart and expand production of TRISO fuel, which is necessary for several advanced nuclear reactor designs. The company’s announcement signals confidence by the manufacturer that the reactors that would use TRISO are likely to come to market. Over the last four years, X-Energy developed its own TRISO manufacturing process at Oak Ridge National Laboratory to support its reactor and other designs.
TRISO stands for “tristructural isotropic” and describes the particles that make up the fuel. It uses uranium similar to America’s 96 operating power reactors but in a different form.
Currently, commercial reactors in the United States use a uranium ceramic, surrounded by a metal wrapper. TRISO fuel starts with tiny particles of uranium that are combined with carbon and oxygen. Then the particles are wrapped with four different kinds of carbon layers, like coatings on risotto. The result is a particle that can withstand extremely high levels of heat.
Then thousands of the particles are embedded into either:
The prismatic blocks or the pebbles can be put in a reactor vessel filled with inert gas. When the reactor starts, it splits uranium atoms in the fuel and heats the surrounding gas to very high temperatures. The gas carries the heat energy away to be converted to electricity or to be used to do other work.
X-Energy is designing a pebble bed reactor that will allow plant operators to remove pebbles and add new ones as the reactor runs, so it does not have to shut down for refueling. Framatome, HolosGen LLC and Kairos Power LLC are also developing reactor technologies that would use TRISO fuel.
Reactors that use graphite or molten salt can run at far higher temperatures than current nuclear reactors. Higher-temperature heat has various industrial uses and makes electricity more efficiently. These advanced reactors will also make good partners for other carbon-free generators like intermittent solar and wind, because the reactors can change their power levels quickly to compensate for changes in wind or sun.
— Everett Redmond, NEI’s senior technical advisor
This is a very positive statement about the future of advanced nuclear power. The companies are laying the groundwork to support a new generation of reactors.
One of the customers for TRISO fuel could be the U.S. Department of Defense, which plans to use it in mobile reactors, that can be trucked in or airlifted to forward and remote locations. These reactors can run for years without refueling, eliminating the need for thousands of runs by diesel tanker trucks, which are vulnerable to enemy attack. The Defense Department specified TRISO fuel in its request for solutions because the fuel is so robust.
Combined with recent bipartisan legislation, this latest development in fuel demonstrates a growing momentum for new nuclear reactors. As designs advance toward market deployment, this new technology will ensure that nuclear energy continues to provide clean electricity and more.