In 2020, Canadian Nuclear Laboratories provided five steel drums lined with cork to assimilate shocks to the Joint European Torus (JET), a vast fusion reactor in the United Kingdom. Inside each drum was a steel cylinder of a Coke can, clasping a wisp of hydrogen gas, just 10 grams of it.
This, however, wasn’t ordinary hydrogen but rather its rare radioactive isotope named tritium, in which two neutrons and a proton are attached in the nucleus. At $30,000 per gram, it’s almost as valuable as a diamond. When tritium is blended at high temperatures with its sibling deuterium, the two gases can burn like the Sun. The reaction could deliver abundant clean energy as soon as fusion scientists figure out how to spark it efficiently.
Last year, the Canadian tritium fueled an experiment at JET, indicating that fusion research is approaching a significant threshold, generating more energy than goes into the reactions. By getting to one-third of this breakeven point, JET offered reassurance that ITER, “a similar reactor twice the size of JET under construction in France, will bust past breakeven when it begins deuterium and tritium (D-T) burns sometime next decade. ““What we found matches predictions,” says Fernanda Rimini, JET’s plasma operations expert.
Most fusion scientists avoid the problem, arguing that future reactors can breed the tritium they need. The high-energy neutrons discharged in fusion reactions can split lithium into helium and tritium if the reactor wall is lined with the metal. Despite the demand for it in electric car batteries, lithium is relatively plentiful.