Elemental analysis of low and medium level radioactive wastes using a closed-vessel microwave acid digestion

Destructive chemical decomposition methods to measure the concentration of radionuclides contained in the low and medium level radioactive wastes (activated carbon, dry active waste, evaporator bottom, sludge, spent resin, and zeolite) have been established since certain α - and β - emitting radionuclides cannot be measured directly by a proper radiation detector. In the sample preparation step, a complete decomposition of various radioactive wastes is a prerequisite for the chemical separation of certain radionuclides. For this purpose, a closed-vessel microwave acid digestion system in a radiation shield glove box was used. During this microwave acid digestion, the application of various mixed acid compositions, as well as the appropriate the temperature, time for a dissolution, and the power of a microwave are needed to completely decompose the radioactive wastes in order to verify the suitability of the proposed chemical decomposition methods, Re (similar to volatile 99Tc) is routinely used for a chemical yield tracer and the dissolved solutions are analyzed by ICP-AES. The closed-vessel microwave acid digestion technology used in this study provided a good recovery yield of over 95% for Re. Therefore, the established chemical decomposition conditions using the microwave technology will be applied to the above-mentioned radioactive wastes generated from Korea NPPs