Application of silver-exchanged zeolite for the mitigation of civilian radioxenon releases

Abstract

The radioxenon releases from civilian nuclear installations are significantly affecting the International Monitoring System (IMS), which is being deployed for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). These civilian radioxenon releases are disturbing and limiting the detection capability of the noble gas component of the IMS for CTBT-related events. Substantial reductions of civilian radioxenon releases would significantly improve the detection capability of the noble gas component of the IMS. For a long time, activated carbon has been the standard for trapping radioxenon from gaseous effluents in the nuclear industry. In this work, we demonstrate the potential of silver-exchanged zeolites for replacing activated carbon and providing a higher radioxenon trapping efficiency. For this purpose, three activated carbons and five silver-exchanged zeolites are compared through their Xe adsorption properties in helium - and nitrogen bulk gas. The effect of moisture in the inlet gas stream on the Xe adsorption properties is considered as well. The most promising silver-exchanged zeolite is then further investigated for its practical application by studying the effect of column geometry, flow rate and temperature. Finally, the durability of this adsorbent against irradiation and desorption/adsorption cycles is examined for its application in the nuclear industry. Recently in the literature, some metal-organic frameworks have been demonstrated to be quite selective for the adsorption of xenon over other gas components. The Xe adsorption properties measured on two metal-organic framework materials will be presented to put their potential application for radioxenon mitigation into perspective.