Viability Assessment of Noble Gas Bundle Tagging for Failed-Fuel Identification in CANDU Reactors

Current limitations of Canadian Deuterium Uranium (CANDU) reactors to reliably locate defective fuel bundles have created interest in new identification techniques. Noble gas tagging, which would involve the addition of specific combinations of Kr and Xe isotopes to the fuel-to-sheath gap during manufacturing, has the potential to offer a means of locating failed-fuel bundles on power, where the released tag could be measured in the primary heat transport system by mass spectrometry. Moreover, the technique could be of particular interest for demonstration irradiations with new fuel bundle designs. This work outlines preliminary considerations on the applicability of noble gas tagging for CANDU reactors. This assessment involved the determination of suitable tag isotopes, the simulation of the impact of the tag on the thermal performance of a fuel element, and the determination of the detection limit of a quadrupole inductively coupled plasma-mass spectrometer instrument for krypton samples with typical aqueous concentrations in the range of 10^-12 to 10^-9 (mol_Kr/mol_H2O).