Radiation Resistance Investigation of Hybrid Ultramicroporous Materials for Highly Efficient CO2/Xe and CO2/Kr Separation in Spent Nuclear Fuel Off-Gas

Radiation-resistant nanoporous adsorbent that can realize absolute CO₂/Xe (Kr) separation without Xe and Kr loss is crucial, but yet to be achieved for accurate and reliable nuclear fuel burnup analysis. Herein, two hybrid ultramicroporous materials (NbOFFIVE-1-Ni and TIFSIX-3-Co) are presented for highly efficient CO₂/Xe and CO₂/Kr separation in the nuclear reprocessing off-gas. Nearly complete CO₂/Xe (Kr) molecular sieving separations are achieved in NbOFFIVE-1-Ni with CO₂/Xe and CO₂/Kr selectivities both exceeding 11 000 before and after 50 kGy irradiation. Total photon cross sections of different elements, coordination number, and crystal orbital overlap population calculation that combines atoms, chemical bonds, and crystal structure are used to analyze the radiation stability of the hybrid ultramicroporous materials. Furthermore, the dynamic breakthrough and desorption measurement confirmed the ultra-low Xe (Kr) loss ratio (0.24% for Xe and 0.3% for Kr) of NbOFFIVE-1-Ni adsorbent under simulated reprocessing off-gas separation. This work not only provides a benchmark CO₂/Xe (Kr) adsorbent for reliable nuclear fuel burnup analysis but also proposes a new perspective to understand the radiation stability of hybrid ultramicroporous materials.