The nuclear industry continues to evolve; as does the future for nuclear power generation. According to a 2021 article by World Nuclear Association, "around 10% of the world's electricity is generated by about 440 nuclear power reactors. About 50 more reactors are under construction, equivalent to approximately 15% of existing capacity. In 2019 nuclear plants supplied 2,657 TWh of electricity, up from 2,563 TWh in 2018. This is the seventh consecutive year that global nuclear generation has risen, with output 311 TWh higher than in 2012."
Projections for growth are mixed. The demand for carbon reductions is a motivator for growth while the high cost of construction of large plants is a deterrent.
There is a new generation of reactor designs that promises advantages that could make them more attractive in the decades to come. The new nuclear plants come in a variety of sizes and shapes, different makes and models. They all offer enhanced safety design features.
So, what are some of the key differences between the new nuclear designs?
First, some background. The reactors in operation today are mostly second-generation light water reactors (i.e., Gen II) – they use water to moderate the reactivity of uranium, allowing fission to occur. The fission process produces heat, turning water into steam, which is then used to spin a turbine generator to make electricity. Third-generation reactors add in new safety features which make the plants even safer. The two new AP1000s that are nearing completion at Southern Company’s Vogtle site are examples of Gen III+ reactors.
New reactors being designed today are considered fourth-generation design. Small modular reactors are essentially a miniature version of the light water reactors we use today, with the advanced safety features added in. The benefit of these is that they are small, which means they can be built with less capital and in less time, and they can be scaled to a variety of needs.
Fourth-generation reactors offer some new possibilities that are exciting. Again, there are many makes and models of fourth-generation or advanced reactors and some have been in development at our national laboratories for decades. One of the most interesting designs uses liquid sodium instead of light water.
Using sodium instead of water allows for faster reactions and that means higher temperatures – and much higher efficiencies. Combining a sodium fast reactor with a molten sodium storage system is interesting, because it retains heat for long periods. Another benefit of a sodium fast reactor is that it can be used to produce hydrogen efficiently. Hydrogen can then either be burned to generate electricity or stored in fuel cells to power vehicles or in other applications.
An advanced reactor like the sodium fast reactor design has all the added safety features from years of operating experience, and also offers some interesting additional features that could make them attractive as we build our carbon-free future.