In 2018, NASA successfully tested a prototype fission reactor in this program.
From the link:
NASA and the Department of Energy’s National Nuclear Security Administration (NNSA) have successfully demonstrated a new nuclear reactor power system that could enable long-duration crewed missions to the Moon, Mars and destinations beyond.
And:
The prototype power system uses a solid, cast uranium-235 reactor core, about the size of a paper towel roll. Passive sodium heat pipes transfer reactor heat to high-efficiency Stirling engines, which convert the heat to electricity.
And:
The Kilopower team conducted the experiment in four phases. The first two phases, conducted without power, confirmed that each component of the system behaved as expected. During the third phase, the team increased power to heat the core incrementally before moving on to the final phase. The experiment culminated with a 28-hour, full-power test that simulated a mission, including reactor startup, ramp to full power, steady operation and shutdown.
Throughout the experiment, the team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.
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The BBC article in the original post refers to TRISO fuel. This is the type of fuel used in pebble bed reactors, and is very resistant to meltdown and other accidents.
- Pete
In other small nuclear reactor news, the US Air Force intends to award a contract for an Oklo microreactor to be installed at Eielson Air Force base in Alaska.
Oklo’s Aurora Powerhouse is a vertically oriented compact passive fast-spectrum reactor derived from the Experimental Breed(ing) Reactor-II (EBR-II) that uses liquid metal as a coolant. The company recently uprated its design’s capacity offerings to between 15 MWe and 100 MWe. The compact fast reactor uses a high-assay, low-enriched uranium (HALEU) metallic uranium-zirconium fuel enriched to about 19%.
Oklo, notably, already has an agreement with with Idaho National Laboratory (INL) to demonstrate down-blended HALEU in a commercial-scale Aurora reactor within a 2026 or 2027 timeframe, and it is seeking licensing for the Idaho Falls project.
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As noted, Oklo is currently in the licensing process with the NRC. They have had a few problems getting the design approved, but this type of reactor is unusual for the NRC. Everyone is trying to figure out the requirements for licensing such a new and different design.
BTW, the name Oklo comes from a place in Gabon, Africa, where French scientists first documented the existence of an ancient nuclear fission reactor, which operated there for thousands of years. Mother Nature invented nuclear fission reactors long before any human.
- Pete