Nanocomposite materials can pave the way for fusion power plants

nanocomposite-material-fusion-power-plant_1Inside MIT's Alcator C-Mod Tokamak nuclear fusion reactor.

On the theoretical level, fusion, the process that fuels the sun, can provide unlimited clean energy for humanity. However, fusion-based power plants have seemingly been out of range from the realm of practicality, simply because scientists are not aware of many materials that could survive the punishing conditions concocted inside a fusion nuclear reactor. But a collaborative effort from Texas A&M University and the Los Alamos National Laboratory could potentially change this to make way for nanocomposite materials that would buttress the fusion nuclear reactors of the future.

Now in the simplest equation, the sun is fueled by fusing of two hydrogen atoms, each with one proton, into helium atoms, which contain two protons. Simply put, helium is the byproduct of the reaction. And while helium is not known as a toxic or a greenhouse gas, it does play its unfortunate part in harmfully spoiling and destabilizing the materials used for a nuclear reactor. To that end, helium does have the habit of bubbling through the solid materials, much akin to the phenomenon of bubbles formed inside a carbonated drink. As Dr. Michael Demkowicz, associate professor in the Department of Materials Science and Engineering explained –

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. [However] literally, you get these helium bubbles inside of the metal that stay 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.

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In a bid to solve this issue, the researchers experimented with materials made of nanocomposite solids – composed of stacks of thick metal layers. And to their astonishment, the scientists found out that heliums behave quite differently in the presence of such structures. Instead of making disruptive bubbles, the helium made long channels inside the material, thus resembling the veins in our living tissues. As Demkowicz said –

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.

In other words, the researchers are looking at the good possibility of helium actually being able to exit the material (via these network of long channels), instead of causing structural weakness with their bubbles. And this solution, in turn, can pave the way for essentially helium-resistant nuclear reactor materials. And even beyond fusion power plants, scientists are also weighing other potential advantages of such vascular networks inside nanocomposite metals. Demkowicz concluded –

Applications to fusion reactors are just the tip of the iceberg. I think the bigger picture here is in vascularized solids, ones that are kind of like tissues with vascular networks. What else could be transported through such networks? Perhaps heat or electricity or even chemicals that could help the material self-heal.

Source: Texas A&M University

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