This refers to the TerraPower project envisaging the construction of fast neutron reactors that will use liquid metal sodium as a coolant and high-assay low-enriched uranium (HALEU) with a concentration of the fissile isotope U-235 ranging from 5% to 20% as fuel. The majority of modern light-water reactors use fuel with a U-235 concentration ranging from 3% to 5%, whereas nuclear submarines use fuel with a concentration exceeding 90%.
The use of HALEU will make it possible to reduce the size of fuel assemblies in the power units and the volume of concrete at the construction stage. Thanks to the use of liquid metal sodium as a coolant, each power unit will be able to raise its capacity from the design 345 MW to 500 MW during the hours of high demand.
The demand for electricity from data centers skyrocketed from 58 terawatt-hours (TWh) in 2014 to 176 TWh in 2023. The U.S. Department of Energy expects consumption in this segment to range from 325 TWh to 580 TWh by 2028 (depending on the scenario), which is comparable to the annual power demand in Turkey (342 TWh in 2024). Data center operators are usually comprised of high-tech companies, which attach great importance to their emission reduction policies. This is why data centers are becoming new drivers of demand for nuclear energy. It is no coincidence that Microsoft signed an agreement with Constellation Energy last year to restart the first power unit of the Three Mile Island NPP, which was suspended in 2019 after 45 years of operation.
Power demand growth is going to facilitate the commissioning of not only large but also small reactors. For instance, Deep Fission and Endeavour Energy reached an agreement in early 2025 to build pressurized water reactors (with a capacity of merely 15 MW each) for their subsequent placement in a 30-inch well at a depth of 1.6 km. Thermal energy that will be generated underground will be sent to the surface in order to produce electricity with a conventional turbine. The first facilities for supplying power to data centers are slated to come on stream in 2029.
