GoKawiilAn anonymous reader quotes a report from Ars Technica: Just over a year ago, the Trump Administration issued an executive order meant to accelerate the development of nuclear power in the US. While an entire startup ecosystem has developed around the use of different -- and typically smaller -- reactor designs, only one of them has been fully licensed so far, and there are no plans to actually build any instances of that design. The executive order directed the Department of Energy to have three different reactor designs reach criticality in a bit over a year. On Thursday, a startup called Antares announced that a test reactor it had placed at the Idaho National Laboratory had reached criticality, making it the first new design to cross this threshold. Criticality means that the nuclear reactions inside the hardware had become self sustaining; it does not mean the reactor had started to generate power. [...] 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.
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