Application of the FRAM Isotopic and Enrichment Gamma-ray Spectral Analysis Code to Enriched Uranium blended with Uranium-233

A criticality safety review of an enriched uranium facility at a U.K. nuclear site highlighted a number of items in long term storage that were defined as enriched uranium blended with uranium-233 (233U). Given the reactivity of 233U relative to 235U it was considered necessary to determine the proportion of 233U by mass present in these items. Non destructive assay (NDA) practitioners deployed high resolution gamma-ray spectrometers to the facility and undertook long duration data acquisitions on individual items. The Los Alamos National Laboratory’s (LANL’s) FRAM Isotopic Gamma-ray Analysis Code(1) was used to determine the isotopic composition of each item necessitating modification of the FRAM standard uranium parameter set to encompass 233U and its associated radioisotopes. This paper describes the analysis of these spectra and gives gamma-ray regions of significance for spectrometry practitioners undertaking analysis to quantify 233U content.