Helium-3, Savannah River

The isotope that cools almost all quantum computers exists only as a decay waste of the tritium in nuclear warheads. The US DOE harvests it during maintenance of the strategic stockpile at the Savannah River Site and then resells it in dribs and drabs: a near US/Russian monopoly, supply disconnected from civilian demand, price up from a few hundred to several thousand dollars a litre. No clear supply plan if quantum computing scales up.