Journal of Nuclear Fuel Cycle and Waste Technology

It is clarified in the radioactive waste transfer regulation that the concentration of radioactive waste for the major radio nuclide has to be examined when radioactive waste is guided to the radioactive waste stores. In case of the low level radioactive waste sample, the analytical results of radioactive waste concentration frequently show a value lower than minimum detectable activity (MDA). Since the MDA value basically depends on the amount of a sample, background value, measurement time, counting efficiency, and etc, it would be necessary to increase a sample amount with a intention of minimizing MDA. In order to measure a concentration of 129I in low and medium level radioactive waste, 129I was collected by using a distillation technique after leaching the simulated radioactive waste sample with a non-volatile acid. The recovery of 129I measured was compared with that measured with column elution technique which is a conventional method using an anion-exchange resin. The recovery of inactive iodide by using the distillation method and column elution were found as 86.5 0.9% and 87.3 2.7%, respectively. The recovery and MDA value calculated for distillation technique when 100 g of extracted solution of 129I was taken, were found to be 84.6 1.6% and 1.2 10-4 Bq/g, respectively. Consequently, the proposed technique with simplified process lowered the MDA value more than 10 times compared to the column elution technique that has a disadvantage of limited sampling amount.

Keywords

129I,Radioactive waste,MDA,Distillation technique,Recovery