Objective To investigate the separation efficiency of three physical separation methods for gaseous ¹⁴C, namely membrane separation, adsorption separation, and low-temperature separation, to screen for the optimal separation method, and to provide a reference for the separation and enrichment of ¹⁴CO₂ in online monitoring of ¹⁴C. Methods The experimental plan was designed, and three devices were constructed for separation and purification experiments. The purity, recovery rate, and separation time of CO₂ separated by the three methods were analyzed. Results All the three methods achieved the separation of CO₂. Under certain conditions, 20 mL of sample gas was obtained. The separation time of membrane separation method was 0.5 hour, CO₂ gas with a sample purity of 0.0486%-0.0488%VOL was obtained, and the recovery rate was only 2.5%−12.7%. The separation time of MOF material adsorption separation method was 24−30 hours, CO₂ gas with a sample purity of 20.2%−47.5%VOL was obtained, and the recovery rate was 57.3%−63.2%. The separation time of low-temperature separation method was 3 hours, CO₂ gas with a sample purity of 96.0%−99.8%VOL was obtained, and the recovery rate was 81.5%−92.5%. Conclusion The purity and recovery rate of CO₂ with low-temperature separation method were higher compared to membrane separation method and MOF material adsorption separation method. The separation time of low-temperature separation method was moderate. The low-temperature separation method can provide a reference for the enrichment technology of ¹⁴C in the rapid measurement of gaseous ¹⁴C effluent.

Objective Nowadays, radioactive xenon isotopes, including ^131mXe, ^133mXe, ¹³³Xe, and ¹³⁵Xe, are primarily released into the atmosphere through various reactor operation and major accidents of reactors. To improve the online monitoring capability of xenon in nuclear facilities and their gaseous effluents, a highly sensitive online xenon monitoring system was developed to monitor, warn, and alarm the activity concentration of radioactive xenon. Methods The online monitoring system for radioactive xenon gas in nuclear facilities was established using xenon membrane separation and concentration, xenon high-efficiency selective adsorption, and low-background gamma-ray spectrometry analysis methods. Results Under the operation mode of one-hour sampling and one-hour measuring, the minimum detectable activity concentration of the radioactive xenon online monitoring system for ¹³³Xe was approximately (1.43 ± 0.03) Bq/m³. Conclusion This system can be effectively used for online monitoring of xenon activity concentration in nuclear facilities such as nuclear power plants and isotope production reactors, as well as in gaseous effluents. It helps improve the safety level of personnel, the environment, and nuclear facilities.