DETECTING CS-137 BREAKTHROUGH IN AN ION-EXCHANGE PROCESS

High-level radioactive wastes can be transformed to low-level wastes b y removing Cs-137 through selective ion exchange processes. Since the short-lived daughter, Ba-137m produces the 662-keV gamma-ray normally attributed to Cs-137, equilibrium may be broken, and observation of th e 662-keV gamma-ray cannot be used to detect cesium breakthrough. Two detectors viewing the output line, but separated sufficiently to measu re the Ba-137m decay between them, are used to detect Cs-137 breakthro ugh based on deviation from the normal Ba-137m decay. Detectors evalua ted for the process, separation time, counting time, fractional breakt hrough detectable, and accuracy and confidence of the measurements are discussed.