Japan Test Shows Clean Fusion Fuel Scheme Using Boron

Researchers in Japan have demonstrated, for the first time in a fusion reactor, a type of fuel that is plentiful and doesn’t produce damaging particles, Daniel Clery reported for Science.

Photo Insert: TAE is following a different recipe: fusing hydrogen nuclei—protons—with easily mined boron.

Although the reactions were nowhere close to achieving net energy and required even higher temperatures than standard fusion fuel, the result is a proof of principle for private fusion startup TAE Technologies, which argues that its path to a practical power plant faces fewer engineering roadblocks than conventional approaches.

The results show how the alternative fuel, a mix of protons and the element boron, “has a place in utility-scale fusion power,” TAE CEO Michl Binderbauer said in a statement.

Not everyone is convinced. “It’s an interesting experiment” but will do little to convince skeptics to switch fuels, says Dennis Whyte, director of the Plasma Science and Fusion Center at the Massachusetts Institute of Technology (MIT).

Fusion is often promoted as a carbon-free energy source that has a plentiful and cheap fuel—a mix of the hydrogen isotopes deuterium and tritium (D-T). In reality, tritium is rare and must be “bred” from lithium in the reactor itself; some scientists are concerned about future shortages.

When fused at high temperatures, D-T fuel produces copious high-energy neutrons that damage humans and reactor structures alike.

TAE is following a different recipe: fusing hydrogen nuclei—protons—with easily mined boron.

The reaction generates no neutrons and produces only harmless helium, but it requires temperatures of about 3 billion degrees Celsius—200 times the heat of the Sun’s core and 30 times hotter than what’s needed to fuse D-T.

Researchers have shown they can fuse protons and boron by using particle beams aimed at a solid target or by blasting plasma with lasers.

Now, a team has done it—on a small scale, at least—using a conventional fusion reactor called the Large Helical Device (LHD), at Japan’s National Institute for Fusion Science.

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