Year
2012
Abstract
Room temperature (RT) gamma detectors are simple and easy to use in the verification of nuclear material. They are normally lighter and smaller than high resolution detectors, which require liquid nitrogen or mechanical cooling. Until recently, routine non-destructive assay verification activities conducted by the IAEA employed two types of RT detectors: sodium iodide (NaI) and cadmium-zinc-telluride which both have limitations - quite poor resolution in the first case and low efficiency in the second. The newly-introduced lanthanum bromide (LaBr) detector provides advantages of high detection efficiency together with higher resolution in comparison with a NaI detector. Additionally, the fast light output provides low dead-time and good performance when operating in a high gamma background. This article describes the numerous applications where the IAEA employs the LaBr-based systems for safeguards verification purposes, in particular for: fuel rods and fuel pellets verification; verification of bulk uranium items, including recycled uranium; uranium hold-up measurements; and possible applications for plutonium verification. The article also includes a description of the software developed and used for the applications together with a theoretical study and the numerical modeling carried out for the analysis of LaBr spectra and interpretation of gamma line intensities into measured material characteristics.