The US Department of Energy (DOE) is backing five projects to develop advanced nuclear reactor designs to be built in the United States by private industry. Under the Advanced Reactor Demonstration Program (ARDP), the DOE’s Office of Nuclear Energy's US$30 million initial funding is expected to grow to US$600 million over seven years with industry providing an additional 20 percent.

Though nuclear power has been very unpopular in the West over the past few decades, the need for a carbon-neutral future looks poised to spark a new generation of advanced reactors that will be very different from the light-water pressurized reactors that have dominated the nuclear power industry since the 1950s.

The goal of the latest DOE grants is to promote the development of reactors for deployment in 10 to 14 years that are not only more efficient and more economical to operate, but are also inherently safer to run, with designs that use more robust fuels and have cooling systems that can passively keep a reactor from melting down even if there's no power available.

The five reactor concepts under development include the Hermes Reduced-Scale Test Reactor by Kairos Power in Alameda, California. Intended to lead to the building of the commercial-scale Kairos Power Fluoride Salt-Cooled High Temperature Reactor (KP-FHR), this advanced test reactor is based on Tri-structural ISOtropic (TRISO) particle fuel and is cooled by a low-pressure fluoride salt coolant.

TRISO fuel comes in particle form and is composed of uranium, carbon, and oxygen, which are formed into kernels and then encapsulated in three layers of carbon and one of ceramic to prevent the release of radioactive waste. These poppy seed-sized kernels are then collected together into cylindrical pellets or billiard ball-sized spheres, which can withstand high temperatures in gas or salt-cooled reactors.