Medical isotope availability in doubt due to reactor closure

Nature : Technetium-99m is commonly used as a radioactive tracer for a number of medical diagnostic scans. Next month the Chalk River nuclear-research reactor in Canada, which produces 20% of the world’s technetium-99m, will shut down. Only six other reactors around the world, all of them quite old, produce the isotope. Medical facilities could face a severe technetium shortage if any of those reactors experience service disruptions before new reactors are brought on line in 2017 and 2018. A temporary shortage last occurred in 2009, when two reactors were turned off for repairs and maintenance. It is impossible to stockpile technetium-99m because it has a half-life of six hours. The isotope is a decay product of molybdenum-99, which has a half-life of 66 hours and is produced at the reactors via the bombardment of highly enriched uranium.