Year
2019
Abstract
The goal of this work is to characterize sources of spectral variation of the gamma-ray emissions of a filled uranium hexafluoride (UF6) cylinder. UF6 cylinders are a closely monitored part of the nuclear fuel cycle. To ensure the enrichment level is below licensed maximums, inspectors measure the gamma-ray spectrum emitted by the UF6 to verify the enrichment. However, the gamma-ray emissions at the surface of a UF6 cylinder can vary due to parameters other than enrichment. Parameters that vary from cylinder to cylinder include the spatial distribution of the UF6 material within a cylinder, the separation/fill date of UF6 cylinder material, the previous fill history of a cylinder, and the minor isotopic composition of UF6. In this work, the spectral variations are analyzed through simulations of a validated model of a UF6 cylinder and gamma-ray detection system. The spectral trends caused by these variations are quantified to determine the extent that each parameter contributes to the uncertainty of a UF6 spectral measurement.