Nuclear fusion has seen some exciting advances, and the promise of clean, efficient energy does seem to be creeping closer to reality. But skeptics point to practical issues we may not be trying hard enough to solve—issues that will inevitably weigh down our reactors when they finally arrive.
A new study led by Terence Tarnowsky, a nuclear physicist at Los Alamos National Laboratory, focuses on one key part of the problem: finding a supply of tritium, a fundamental ingredient for fusion. Tarnowsky, who will present his findings next week at the ACS Fall 2025 conference, suggests tapping into the thousands of tons of radioactive waste material to support tritium production.
In a successful fusion reactor, tritium and deuterium—two lightweight hydrogen isotopes—fuse and release a gigantic load of energy in the process. By contrast, current nuclear plants run on fission, or the splitting of heavy atoms such as uranium, which also generates a hefty amount of power but produces long-lived radioactive byproducts. This waste material just “[sits] around the country,” presumably for a million years, and costs hundreds of millions of dollars each year to manage, Tarnowsky explained to Gizmodo during a video call.
Meanwhile, the promise of fusion is shadowed by an inevitable shortage of tritium, an extremely rare and unstable hydrogen isotope. “There are only tens of kilograms [of tritium]—both natural and artificial—on the entire planet,” Tarnowsky said. And it doesn’t help that nuclear experiments worldwide are burning through those tiny supplies at an alarming rate. “So, where is this tritium supposed to come from?”
Breeding tritium in labs is a viable option, but again, there’s a very good reason we haven’t found the perfect recipe; it’s a “tricky fuel to deal with,” Tarnowsky said.
“If you breed tritium now, it’s not like you can stash it in a container for 30 years from now, because it decays to helium-3 very quickly,” he explained. “And it also has the chemistry of hydrogen. Hydrogen likes to get out of things; it likes to get stuck in walls. So it’s a hard thing to deal with.” For context, the half-life of tritium is 12.3 years, meaning it decays to half of its original amount in that time.
Tarnowsky’s proposal combines previous theories with recent technological advancements. Simply, the idea is to employ a superconducting linear accelerator to beam radioactive waste material surrounded by molten lithium salt. Doing so would trigger the decay of