Innovation can mean challenging old assumptions. When it comes to nuclear energy, one assumption ripe for rethinking is about size.
Today’s nuclear reactors are very large; one can generate enough carbon-free electricity to meet the energy needs of 735,000 households. They are pillars of our grid.
But not everybody lives on the grid, and in remote places, most electricity comes from burning diesel fuel, which is dirty and expensive. If the place is remote enough, diesel fuel can be hard to deliver. Other electricity customers who are on the grid need an alternate supply in case the grid goes down.
Enter the micro-reactor, compact enough to be shipped by truck or helicopter. Some can be set up in days; all can run for years without refueling.
And they aren’t just smaller versions of today’s models. They use different fuels and different cooling systems. They have few moving parts, can vary their output automatically to meet changes in demand and run without a crew of human operators.
In March, one developer, Oklo Power, released substantial details on its design, when it applied to the U.S. Nuclear Regulatory Commission for permission to build a demonstration model, planned for the Idaho National Laboratory.
Oklo said that its Aurora powerhouse would provide 1.5 megawatts of electricity. That’s a little more than 1 percent of the capacity of a reactor on the power grid today. But the Aurora could also provide heat for other purposes, which U.S. grid-scale reactors typically do not do, but would be very useful in the off-grid arctic.
Because of its inherently safe design, the Aurora does not require operator actions, or on-site operators. Its safety relies on natural forces. The reactor module would be installed underground, with an A-frame building on top that would have space for community use.
The A-frame is not entirely for show; it will support a crane that can be used to move fuel and equipment. But the building is intended to make an attractive addition to a rural settlement, serving as the main point for community interaction.
The fuel is richer in atoms that can be split to make energy, so it can last 20 years. The fuel runs cooler and can’t get hot enough to damage itself, partly because the core is so small. The material that transfers heat from the reactor to the part of the plant that makes electricity is different, too: it’s carbon dioxide, so the system is smaller and lighter.
Oklo, a Silicon Valley start-up, isn’t alone in developing a new reactor; Companies like Bill Gates’ TerraPower, GE Hitachi Nuclear Energy, Kairos Power, X-energy and others are also preparing designs. Some are start-ups and some have substantial experience in big reactors.
But Oklo is the first to submit an application. And there is another distinction.
Today, to build a reactor, both the design and the site have to be included in the application to the NRC. But Oklo, although it has sites lined up, says that with a design that is so small and able to operate without water, that there is a very small environmental impact for both the construction and operation. And since the Aurora will often be displacing fossil fuels, the powerhouse will provide an environmental benefit to the local community and to the planet. Therefore, advance specification of the location should no longer be necessary. It can be built in a much wider variety of places, and the site can be selected later, the company says.
With new plant designs large, small and in between, reactor developers are challenging our assumptions about nuclear energy, and their innovation will bring reliable, carbon-free electricity to more people.
