On Wednesday, the US Nuclear Regulatory Commission announced that it had issued its first construction approval in nearly a decade. The approval will allow a company called TerraPower to begin work at a site in Kemmerer, Wyoming. That company is widely recognized as being financially backed by Bill Gates, but it is attempting to build a fundamentally new reactor, which is sodium-cooled and incorporates energy storage as part of its design.
This does not mean that it will get approval to operate the reactor, but it is an important step for the company.
The TerraPower design, which it calls Natrium and developed jointly with GE Hitachi, has several innovative features. Perhaps the most notable of these is the use of liquid sodium for cooling and heat transfer. This allows the primary coolant to remain liquid, thereby avoiding any of the challenges posed by the high-pressure steam used in water-cooled reactors. But there is a risk that sodium becomes highly reactive when exposed to air or water. Natrium is also a fast-neutron reactor, which may allow it to consume some isotopes that would otherwise end up as radioactive waste in more conventional reactor designs.
The reactor is relatively small compared to most current nuclear plants (345 MW versus about one gigawatt), and includes energy storage. Instead of using the heat extracted by the sodium to boil water, the plant will put the heat into a salt-based storage material that can either be used to generate electricity or stored for later use. This would allow the plant to operate around renewable energy that would otherwise be priced lower. The storage system will also allow it to temporarily produce up to 500 megawatts of electricity.
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