To address this concern, the International Atomic Energy Agency (IAEA) has published a collection of recommended practices that should help research reactor operators optimize the availability, safety and reliability of their plants. The report Optimization of Research Reactor Availability and Reliability: Recommended Practices is now available for download on the IAEA website.

The publication draws on the experience of 12 reactor operators and institutions, of differing size and from various geographical locations. It focuses on an array of operational management areas including: risk-informed maintenance and planning; configuration management; communication and operating experience; and corrective action management.

"The reliance on a limited number of research reactors and, specifically, the age of these reactors is closely linked to the issue of the global shortage of medical isotopes and could lead to serious consequences," explained nuclear engineer Ed Bradley from the IAEA's Research Reactors Group in the Division of Nuclear Fuel Cycle and Waste Technology.

There are just five research reactors worldwide that produce the majority of the global supply of molybdenum-99 (Mo-99), the isotope used to makeTc-99m. With these facilities ranging in age from 42 to 51 years, IAEA experts are continuing to work on issues specific to ageing research reactors and examining ways to extend their operational life.

A sixth reactor, Australia's recently constructed OPAL at Lucas Heights, is expected to commence Mo-99 production soon. However, development work on two reactors in Canada - each expected to produce enough molybdenum to meet the bulk of global supply - was cancelled earlier this year.

This supply issue could remain a problem for several years to come. "No new isotope production facilities have been commissioned for several decades, and it will take time before new reactors start producing isotopes," Bradley explained. "Modifications to currently operating facilities are also being developed, but these will also take some time to fully implement."

Bradley continued: "Anyone interested in isotope supply over the short- to interim-term must address the reliable operation of these ageing facilities as a priority. At the IAEA, we gathered recommended practices directly from research reactor operators with demonstrated performance excellence. Our aim was to make sure that practical advice is made available to operators to help ensure facilities operate to produce medical isotopes as required."

• Belgium's nuclear regulator has this week given permission for the Institute of Radioelements in Fleurus to resume production of medical isotopes. The facility had been out of action since an unexpected release of iodine-131 in August. Meanwhile, the High Flux reactor in Petten, the Netherlands, will restart on 16th of February 2009, following an unplanned shutdown, also in August.