Scientists in the United States are developing a method to recycle nuclear waste to make tritium – a rare version of hydrogen which serves as one of the main fuels in nuclear fusion.
Nuclear fusion is a process that fuses two atoms together to release heat which can turn generators. The generators will ensure a supply of large amounts of electricity that is almost emission-free. Therefore, in theory, it is thought to be one of the cleanest forms of energy.
Nuclear power plants operating today rely on nuclear fission, which results in energy generation, but there is also a lot of nuclear waste generated that remains radioactive for years.
The nuclear fusion process, which provides power to the stars in the universe, on the other hand, would result in very little radioactive waste being produced at the end.
The process would require the fusion of deuterium and tritium. While the former is readily available, the US currently has a shortage of tritium.
“Right now, the value of commercial tritium is about $15 million per pound [$33 million per kilogram], and the U.S. doesn’t have any domestic capability to create it,” says Terence Tarnowsky, a physicist at Los Alamos National Laboratory (LANL).
Making tritium for nuclear fusion reactors
Tritium is found naturally in the upper atmosphere, and its major commercial producers are the reactors in Canada. In a press release, Tarnowsky says that the current total tritium inventory on the planet is about 55 plus or minus 31 pounds [25 plus or minus 14 kilograms].
55 pounds [25 kilograms] is enough to power more than 500,000 homes for six months, as per his estimates. “This is more than the residential units in Washington, D.C.”
Meanwhile, the US has thousands of tons of nuclear waste produced by commercial nuclear power plants. These contain highly radioactive materials, which require expensive storage to keep them safely contained.
Therefore, the scientists saw an opportunity to assess the feasibility of using still-radioactive nuclear waste to generate valuable tritium.
Simulations show nuclear waste could be a good source
Tarnowsky conducted multiple computer simulations of potential tritium reactors to evaluate the designs’ production and energy efficiency.
The simulated reactor designs use a particle accelerator to jump-start atom-splitting reactions in the nuclear waste.
As atoms divide in the simulation, they release neutrons and ultimately produce tritium after a series of other nuclear transitions, the press release says.
The accelerator feature would allow operators to turn these reactions on or off and is considered safer than the chain reactions that take place in a typical nuclear power plant.
As per the estimates, this theoretical system running on 1 GW of energy could produce about 4.4 pounds (2 kilograms) of tritium annually. He projects that the design would produce more than 10 times as much tritium as a fusion reactor at the same thermal power.
The next plan is to generate a dollar cost for tritium production once he has more sophisticated calculations of the reactor’s efficiency. The simulations will also be refined to precisely evaluate the efficiency and safety of the reactor’s design.
Tarnowsky also plans to develop new code for a model that surrounds nuclear waste with molten lithium salt, an established design for reactors with uranium fuel that has only been used for scientific experiments.
“Energy transitions are a costly business, and anytime you can make it easier, we should try,” Tarnowsky says.
There are currently many companies in the pursuit of building the first commercial nuclear fusion power plant in the US and globally. If the design sees the light of day, it could provide power to the future fusion reactors and ensure a less-emission energy transition.
Los Alamos National Laboratory and the National Nuclear Security Administration have funded the research.
The scientist will present his results at the American Chemical Society (ACS) fall meeting. ACS Fall is being held from August 17 to 21.
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