Determination of¹⁴C in spent moderator ion-exchange resin from Bruce Nuclear Generating Station A

Abstract

Spent ion-exchange resins are produced in the purification of coolant and moderator systems during the normal operation of CANDU (Canada deuterium uranium) nuclear reactors. Carbon-14 is a radionuclide of concern in disposal of ion-exchange resins because of its relatively long half-life, its potential high mobility and its ability to be easily incorporated into organisms. Only limited data are presently available on the¹⁴C concentrations of spent from CANDU reactors. To establish a more comprehensive datahase for this radionuclide, concentrations of¹⁴C were determined for two moderator resins from Bruce Nuclear Generating Station A. Mixed bed resins were separated into anion and cation fractions using a sugar solution, and the¹⁴C concentrations were determined for each fraction. Carbon-14-was located predominantly on the anion beads. Samples of anion resin were found to undergo an 81% loss in the¹⁴C concentration over a period of 160 d following the sugar separation procedure. Some evidence is given to suggest this loss in¹⁴C may result from microbial activity. Concentrations and distributions of other predominant radionuclides, such as⁶⁰Co and¹⁵³Gd, are discussed as well.