The Clinton nuclear power plant in Illinois could be set to make a vital isotope for nuclear medicine after GE-Hitachi Nuclear Energy and Exelon announced a feasibility study into the production of molybdenum-99 at the plant.
Molybdenum-99 (Mo-99) decays to produce technetium-99m (Tc-99m) that is used in around 50 million medical diagnostic imaging procedures every year. With a half-life of only six hours, Tc-99m is too short-lived to be transported to hospitals so is produced where it is needed in generators containing Mo-99. As Mo-99 itself has a half-life of only 66 hours, the world needs reliable, steady supplies of the isotope, most of which is made by irradiating uranium-235 targets inside a research reactor.
Most of the world's Mo-99 comes from only five research reactors: Canada's NRU, the Netherlands' HFR, Belgium's BR-2, France's Osiris and South Africa's Safari-1. Issues at some of the reactors in recent years have led to worldwide problems with the supply of this vital isotope. Earlier this year, a high-level committee of the OECD Nuclear Energy Agency called on governments to address underlying economic structures to help to ensure reliable supplies.
Clinton is a General Electric-designed 1067 MWe boiling water reactor (BWR) operated by Exelon in Illinois. It already produces cobalt-60 (Co-60) for medical use by inserting non-radioactive target rods of cobalt-59 into the reactor where they capture free neutrons and are transformed into Co-60. Now GE-Hitachi has said it is working alongside the US National Nuclear Security Administration's (NNSA) Global Threat Reduction Initiative to develop a design to allow the insertion and removal of activated molybdenum. This would be done on a weekly basis.
After leaving the reactor, the Mo-99 would be transported to processing facilities to be converted into a form suitable for shipping to US nuclear pharmacies. Kevin Walsh, senior vice president, nuclear fuel cycle for GEH, said the new technology could potentially meet approximately 50% of the country's projected supply needs of Mo-99.
The GEH method would avoid the use of highly enriched uranium (HEU), unlike most Mo-99 production which relies on HEU, especially in the target plates, but also in some cases in the fuel used to power the research reactors. Methods of production which remove the need for HEU, which could potentially be diverted for weapons use, are seen as an important anti-proliferation measure. South Africa's Safari-1 is capable of producing the isotope from a process which uses only low-enriched uranium in both the reactor fuel and targets, and last year its operator South African Nuclear Energy Corporation (Necsa) and its subsidiary NTP Radioisotopes (Pty) Ltd won a $25 million US federal award to supply HEU-free Mo-99.