Just over a year ago, the Trump Administration issued an executive order to accelerate nuclear power development in the US. The order directed the Department of Energy to have three different reactor designs reach criticality within a bit over a year. On Thursday, startup Antares announced that its test reactor at the Idaho National Laboratory had reached this milestone, making it the first new design to cross this threshold since the executive order was issued.
Criticality means that the nuclear reactions inside the hardware have become self-sustaining; it does not mean the reactor has started to generate power. Antares is one of several companies developing reactors based on a new fuel system called TRISO, which takes some of the complexity and safety concerns out of the reactor design and places them in the fuel design.
The TRISO fuel design consists of tiny pellets with a uranium oxide core surrounded by multiple layers of carbon that can moderate the energy of both neutrons and lighter nuclei released by fission reactions. The entire assembly is encased in a hard ceramic shell designed to withstand the highest temperatures produced by the encased uranium. As long as the reactor can keep the TRISO pellets contained, there should be no risk of meltdown or release of the most dangerous isotopes.
However, safety concerns remain, as neutrons will still escape and potentially convert surrounding material into unstable isotopes. To mitigate this, Antares’ design surrounds the TRISO with a graphite sheath to slow down most of these neutrons. Additionally, the company uses sodium to transfer heat from the reactor to a heat exchanger, where it is transferred to pressurized nitrogen that drives a turbine in a closed Brayton cycle setup.
The current test reactor, called Mark 0, is not connected to the power-generation portion and is being used solely for validation of the company’s modeling and generation of safety data. The next step will be to run the entire system, including electrical generation, which is expected to happen next year.
While the work was done at a Department of Energy lab, Antares is collaborating with the Department of Defense’s Project Pele program for developing a mobile nuclear reactor and has also received support from NASA. The success of this test marks an important milestone in the development of small modular reactors, which could potentially provide a safer and more efficient alternative to traditional nuclear power plants.
**Tags:** [antares], [modular-reactor], [nuclear-power], [criticality]
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**Notes:** The article has been rewritten for clarity, with the title changed to better reflect the story. The content has been expanded to provide more context and details about the TRISO fuel design and Antares’ collaboration with other organizations.
Source: Original article