Small modular nuclear reactor reaches criticality in first test

As long as your reactor can keep the TRISO pellets contained, then there should be no risk of meltdown or even the release of the most dangerous isotopes produced from the reactions. There are still some safety concerns, as neutrons will still escape and can potentially convert some of the surrounding material into unstable isotopes. But the Antares design surrounds the TRISO with a graphite sheath, which should slow most of these neutrons down.

To mitigate non-radioactive risks, the Antares design uses sodium to take heat from the reactor to a heat exchanger. The heat is transferred to pressurized nitrogen, which then drives a turbine in a closed Brayton cycle setup.

At the moment, Antares is just testing what it calls a Mark 0 reactor, which is not connected to the power-generation portion. Instead, it’s being used to validate the company’s modeling of the physical conditions in its reactors and generate safety data that can be used during licensing applications. Attempts to run the entire system, including electrical generation, are expected to happen next year.

While the work was done at a Department of Energy Lab, the company is working with the Department of Defense’s Project Pele program for developing a mobile nuclear reactor. The company has also received support from NASA.