The same process that powers the Sun could provide unlimited clean energy. However, before that happens, scientists need to solve one big problem. They need to keep reactor walls from trapping fuel.
A new study from Princeton Plasma Physics Laboratory (PPPL) reveals an issue that could affect the safety and efficiency of nuclear fusion power plants. The research was published in Nuclear Materials and Energy. It focuses on how fuel gets stuck in reactor walls, which could make future nuclear power plants more difficult to maintain.
In order for nuclear fusion to work inside a device called a tokamak, scientists heat plasma and use powerful magnets hold it in place. The plasma fuels the fusion reaction, but some of it can hit the reactor walls and get absorbed. This process could lead to fuel buildup over time, resulting in a system that is less efficient and harder to regulate.
Shota Abe is a physicist at PPPL and lead researcher on the study. He said, “The less fuel is trapped in the wall, the less radioactive material builds. This issue is especially important for future nuclear fusion power plants like ITER which is a massive project being built in France.
Scientists have been researching boron-coated walls in fusion reactors because boron helps keep plasma clean. However, the new research shows that boron isn’t actual the problem. The real problem is carbon. Even small amounts of carbon can trap fuel which makes it harder to remove. Florian Effenberg is a physicist on the research team. He said, “Carbon is really the troublemaker.”
The research tested boron-coated graphite samples inside DIII-D, a tokamak operated by General Atomics in the U.S. The results of their experiments showed that for every five units of boron, two units of fuel got trapped. That means even very small traces of carbon could cause major issues for future fusion plants.
Currently, many fusion reactors use graphite (a form of carbon) for their walls. However, based on these findings, scientists now plan to replace graphite with tungsten, which doesn’t trap as much fuel. Effenberg said, “We want to get rid of all the carbon and have clean tungsten walls,”.
The biggest challenge for future nuclear power plants using fusion energy is dealing with tritium, a radioactive isotope of hydrogen fuel, that must be carefully managed. If too much fuel gets trapped in the walls, it could violate safety regulations, forcing reactors to shut down.
Alessandro Bortolon is another scientist involve in the study. He said, “There are strict limits on how much tritium can be in a reactor. If you go over the limit, that’s a showstopper.”
By developing ways to reduce fuel buildup, this research is helping nuclear fusion take a big step forward. If the new wall material is successful, fusion could one day provide clean, limitless energy, reducing our dependence on fossil fuels.
With each discovery, scientists are moving closer to making commercial nuclear fusion a reality. This new research brings us one step closer to the future of energy.