Use of CdZnTe detectors to analyze gamma emission of safeguards samples in the field

This paper describes the use of commercial CdZnTe detectors in safeguards applications which require the qualitative assessment of the gamma radiation of irradiated nuclear material to distinguish it from activated non-nuclear material. Such measurements are required to verify the operator declarations on irradiated items in a reactor, cooling pond or in a hot cell. Gamma spectra of irradiated nuclear material and non-irradiated nuclear material are measured with miniature CdZnTe detectors and evaluated using specialized software. It is concluded that small-sized CdZnTe detectors are the best choice for characterizing high-level waste, items in hotcells, irradiated fuel assemblies and irradiated non-fuel items. These small detectors can easily be shielded, collimated and brought close to the item to be verified, often allowing in situ measurements. Their resolution is sufficient to resolve the fission product gamma lines of spectra taken from irradiated fuel assemblies with a cooling time of just a few days. Various safeguards applications are described, gamma spectra are shown and the information derived from these measurements is discussed.