MIT researchers develop mineral to prevent cracks in fusion reactors

FUSION reactors’ lifespans could be extended by more than ten years thanks to researchers from the Massachusetts Institute of Technology (MIT), who have developed a mineral-based solution to stop cracks forming in vacuum vessels.

The ITER fusion project has suffered several vacuum-related issues, causing lengthy delays to the construction of the world’s largest tokomak. Last year, cracks were found in the vacuum vessel thermal shield panels.

The cracks, caused by the accumulation of bubbles of helium atoms, render vessels unusable in around six to 12 months, according to MIT.

Mineral solution

Ju Li, a professor of material science and engineering at MIT, and his team of researchers at the MIT Energy Initiative found that adding iron silicate, an industrial mineral made during copper production, into a fusion vacuum vessel prevented cracks forming during a reaction.

The study findings suggest the use of the mineral could extended the lifespan of the vessel material to more than ten years.

The researchers concluded that adding around 1% (by volume) of iron silicate to the walls of a vacuum vessel could cut the volume of helium bubbles by half and reduce their diameter by 20%.

Counting all the individual bubbles of helium in the material, they found that the helium atoms spread around the iron-based structure rather than collecting in grain boundaries – the open spaces where the iron atoms are not structurally aligned. This reduces the chance of the bubbles pushing into those spaces and causing cracks.

Li said: “Having a lot of small bubbles is OK if they’re not in the grain boundaries.”

Li and his team are currently developing a startup company to commercialise the technology and aim to use 3D printing to produce the vacuum vessel material containing the iron silicate.