The 2020s will be the decade of innovations in nuclear energy. The technologies and tools that will enable advanced nuclear reactors to become a reality are being developed now.
The U.S. Department of Energy’s Versatile Test Reactor (VTR) is one of those cutting-edge, specialized tools. Just getting under way, the VTR is intended to mimic the conditions that would exist in a category of advanced reactors now under development: fast reactors, which include sodium-cooled fast reactors, molten salt reactors and high-temperature gas reactors.
With a pressing need to reduce carbon emissions and a growing worldwide demand for electricity, it is urgent to commercialize advanced reactor technologies, many of which use molten salt, sodium or helium gas (instead of water, as current plants do).
Fast reactors are quite different than the reactors currently operating in the United States. When they run, the neutrons—subatomic particles that sustain the chain reaction—are moving with vastly more energy than in today’s reactors, in some cases with 100,000 times more energy.
Those more energetic neutrons have many advantages. They can split a much wider variety of atoms to make energy, including many atoms that were produced in today’s reactors and would otherwise be considered waste. They can run reactors that operate at much higher temperatures than are common today, which would produce steam that can be used for many more purposes. And many of those designs would run at far lower pressures, making them easier and less expensive to build.
There is a catch, though. No one is completely sure how all of the components of these new reactors would behave after a few decades in the stew of high-energy neutrons. And engineers don’t want to wait to find out.
With a simulated environment, engineers can bathe the components in neutrons at a pace three or four times faster than they would see in an actual power reactor, pull the parts out for evaluation, and if necessary, make changes and try again. This is exactly what the VTR would provide.
“We want to do a quick screening of these technologies,” said Kemal Pasamehmetoglu, executive director of the VTR project.
In fact, the reactor could also be used to test materials for other industries and for materials that could be useful in today’s reactors.
To prosper, experts say the U.S. needs its own high-tech test facility for fast neutrons.
“The nuclear leadership that we had in the world derived from our technical leadership,” said Irfan Ali, who is on the board of directors of Advanced Reactor Concepts, a sodium-cooled reactor developer. “For us to maintain that, we have to keep moving forward with the technology.”
Because of the lack of testing facilities in the United States, TerraPower LLC, the company backed by Bill Gates, has had to use a reactor in Russia, the BOR-60. But access to that reactor, and problems moving irradiated materials across international borders, make that a cumbersome route.
Congress gave initial approval to a versatile neutron source in the Nuclear Energy Innovation Capabilities Act, signed into law in September 2018. Two companies have already submitted a proposal to develop the reactor.
Once completed, the Versatile Test Reactor would enable the development of these fast reactors. Along with other types of advanced reactors, the next generation of nuclear will power our way of life into the future, without carbon emissions.