Compositional design of an amphoteric chemical trap for the capturing of gaseous cesium and iodine in UO2 nuclear fuel

Abstract

A chemical trap in the form of Ba-Al-Si-O that captures gaseous cesium and iodine has been developed for application to UO2 nuclear fuel. A key issue for better trapping efficiency is to secure the ability to capture individual fission gases, in this case for cesium and iodine. This can be done through chemical trapping with the presence of chemical compounds that spontaneous react with them. In this study, based on thermodynamic estimations, a promising composition of 1BaO-1Al2O3-1SiO2 (mole ratio) is suggested for amphoteric trapping. The chemical design was confirmed experimentally under simulated conditions approximating an actual fuel environment. In each experiment for cesium and iodine, the trapping reaction was confirmed to occur at 650 °C in a reducing atmosphere. This study provides a methodology for compositional design and empirical confirmation to shed light on an accident-tolerant fuel development strategy that reduces the release of fission gases.