Materials irradiations in CANDU fuel bundles

Carrier bundles are special CANDU fuel bundles in which one or two fuel elements are replaced by unfuelled carrier elements containing specimens of various types for subsequent testing. Carrier bundles provide the capability of irradiating specimens of fuel channel materials in the real CANDU reactor environment. Corrosion, tensile, growth, stress-relaxation, and fracture specimens of pressure tube materials and flux and displacement damage monitors have been successfully irradiated in fifteen bundles in three CANDU reactors. The capability is available to recycle irradiated specimens in fresh bundles after a prolonged cooling-off period to reduce the irradiation fields. Plans are in place for an Advanced Carrier Bundle facility which allows fast recycling of highly radioactive specimens. This provides the capability of conducting long-term research programs in the power reactor environment, and of monitoring material properties in advance of the lead pressure tube