Detecting 137Cs Breakthrough in an Ion Exchange Process

High-level radioactive wastes can be transformed to low-level wastes by removing137Cs through selective ion exchange processes. Since the short-lived daughter,137inBa produces the 662-keV gamma-ray normally attributed to137Cs, equilibrium may be broken, and observation of the 662-keV gamma-ray cannot be used to detect cesium breakthrough. Two detectors viewing the output line, but separated sufficiently to measure the137mBa decay between them, are used to detect137Cs breakthrough based on deviation from the normal137mBa decay. Detection evaluated for the process separation time, counting time, fractional breakthrough detectable, and accuracy and confidence of the measurements are discussed.