A method for measuring radioxenon emanation with cryotrapping and γ spectroscopy

A method has been developed to eliminate environmental variables and macroscopic diffusive transport to obtain a direct measurement of radioxenon’s emanation coefficient, K, from a solid matrix. The emanation measurement apparatus (EMA) utilizes neutron activation and a cryotrapping technique with LN2, which increased gas trapping efficiency from 4 ± 3 to 78 ± 7%. Emanation values are measured by γ spectroscopy with a High Purity Germanium detector. Preliminary results from EMA demonstrated the capability of this new process to make reproducable emanation measurements with quantifiable uncertainty. Initial experiments produced U3O8 radioxenon emanation coefficients of 0.016 ± 0.002 for 133Xe and 0.025 ± 0.002 for 135Xe at temperatures ranging from 20 to 80 °C.