Striving to eliminate the use of highly enriched uranium (HEU) in production of the world’s most widely used medical radioisotope, the Department of Energy in November awarded $10.9 million to NorthStar Medical Radioisotopes to produce molybdenum-99. The Wisconsin company will, ironically, use one of the last remaining HEU-fueled nuclear reactors in the US to make the product. HEU, which is at least 20% 235U, is considered to be a proliferation risk because it is an important step toward producing nuclear weapons–grade uranium, usually defined as 85% or greater 235U.
The US has no domestic source of 99Mo, whose decay product, metastable technetium-99, is used in 16 million US medical procedures annually. Most of the world’s output of the short-lived isotope is produced in a few research reactors in Canada and Europe that use fission targets enriched to 93% 235U. A South African reactor has been partially...
