Medium activity liquid radwaste treatment by using ion exchange

Abstract

BATAN is operating the G.A. Siwabessy Multipurpose Reactor (RSG-GAS) for various research purposes. The category of liquid radwaste generated in RSG-GAS is low-activity liquid radwaste (LALR) and medium-activity liquid radwaste (MALR). MALR contains several medium and long-lived radionuclides, such as Co-60 and Cs-137 with half-lives of 5.3 years and 30.17 years, respectively. These radionuclides are harmful to workers and the environment. Therefore, the removal of those radionuclides is vital before their release. This research analyzes the separation of Co-60 and Cs-137 from MALR using an ion-exchange apparatus (IEA) to determine the circulation time required to separate radionuclides from MALR. The MALR is continuously circulated in the IEA, and the radionuclide content in the effluent is measured with gamma spectroscopy. The measurement of radionuclides exposure to determine the decontamination factor was at the beginning and end of the process. Based on regulation, discharging wastewater is safe when waste activity is below 10-6Ci/m3. The R2201B and R2201C wastewater were examined in this study. The initial Co-60 and Cs-137 activity concentrations of R2201B were 1.1Ă—10-4Ci/m3 and 1.2Ă—10-4Ci/m3, while R2201C were 3.3Ă—10-4Ci/m3 and 6.9Ă—10-4Ci/m3, respectively. The results show that R2201B takes 160 hours circulation time, while R2201C takes 512 hours, with one resin replacement for each. The resin replacement on IEA is indicated based on radiation exposure measurements from outside of the resin column. A constant value of radiation exposure indicates that the resin has saturated and is no longer capable of ion exchange.