Isotope Production: Dual Use Power Plants
Ease of Entry
The designers and owners of light water reactors did not simply ignore a potential commercial opportunity. Instead, they understood the limitations of their plants and decided that the material that could be produced was not worth the expense of providing a material production capability.
Since the reactor core of a light water reactor is limited in size by the size of the available pressure vessel, and since the core of a commercial light water reactor is invariably a high temperature, high pressure environment, it would be a significant engineering challenge to provide a capability to insert and remove materials on a schedule amenable to isotope production.
In contrast, a large portion of the core of a CANDU is a low pressure tank full of cool (70 C) water. It is fairly simple to design pipes and other access ports that allow carefully controlled material insertion into a portion of the core with an intense neutron flux.
In several cases, existing access tubes normally used for control systems have been modified to accept a suitable material for neutron irradiation. In one specific example, several CANDUs use Cobalt adjuster rods to allow the production of the very useful Co-60 isotope.
World Leadership
Canada now produces approximately 85 percent of the world’s supply of Co-60 and more than 50 percent of the Co-60 medical therapy devices and medical device sterilizers. It also produces most of the world’s supply of molybdenum-99, the precursor of Technetium-99m, the isotope that is the most widely used radioactive pharmaceutical. A person who has undergone tests involving imaging scans of the brain, bone, liver, spleen or kidney probably owes some thanks to the CANDU design.
The business of providing isotopes provides a nice income kicker when combined with the usual reactor business of providing electricity. It has provided Canadians with a substantial return on their nuclear technology investments while providing physicians with previously unavailable diagnostic and treatment tools.
