What Is Nuclear Fusion? Researchers Closer To Materials For Future Reactors

All commercial nuclear power generation on Earth utilizes a nuclear reaction called fission, which is essentially splitting the nucleus of a heavy atom into two smaller nuclei, a process that generates a large amount of energy. However, another type of nuclear reaction, the opposite of fission, is a source of perhaps a lot more energy.

Called nuclear fusion, it is the process which powers the sun and all other stars in the universe. For fusion to occur, two atomic nuclei need to come together and combine to form a new type of atomic nucleus. In the case of the sun (as in the case of most stars), it is two hydrogen nuclei fusing to form a helium nucleus. Hydrogen, with only one neutron and one proton in its nucleus, was the first element to be formed from the primordial soup of particles at the beginning of the universe.

If nuclear fusion could be reproduced on Earth, it would mean clean energy for everyone on the planet. Unlike nuclear fission, whose byproducts are radioactive material, nuclear fusion using hydrogen would produce helium, an inert gas that isn’t harmful to humans or to the environment under normal circumstances.

“Helium is an element that we don't usually think of as being harmful. It is not toxic and not a greenhouse gas, which is one reason why fusion power is so attractive,” Michael Demkowicz, associate professor in the Department of Materials Science and Engineering at the Texas A&M University, explained in a statement Monday.

The problem in doing that, though, is that the helium produced in any fusion reactor on Earth would destroy the material that makes up the reactor. And that could lead to a catastrophic accident as a large amount of energy produced by the reaction flows out.

“Literally, you get these helium bubbles inside of the metal that stays there forever because the metal is solid. As you accumulate more and more helium, the bubbles start to link up and destroy the entire material,” Demkowicz explained.

He worked with researchers from Los Alamos National Laboratory (LANL), New Mexico, as well as a former student from Massachusetts Institute of Technology, and together, they “discovered a way to make materials that may be suitable for use in future fusion reactors.”

These materials are nanocomposite solids which are made of stacks of thick metal layers. Inside them, helium doesn’t make destructive bubbles but instead, spreads out in long channels, much like veins in living tissue. The researchers think the helium could move through this network of veins and exit the material without damaging it.

“We were blown away by what we saw. As you put more and more helium inside these nanocomposites, rather than destroying the material, the veins actually start to interconnect, resulting in kind of a vascular system,” Demkowicz said.

The research team was led by LANL’s Di Chen, and it published a paper, titled “Self-organization of helium precipitates into elongated channels within metal nanolayers,” in the journal Science Advances on Nov. 10.