Design of a new unattended detection system to distinguish different types of assemblies at Fast Breeder Reactors

A key aspect of IAEA Safeguards is the verification of the correctness of declarations provided by a Member State. The Department of Safeguards provides detection systems installed at nuclear fuel cycle facilities to support these activities. Especially in Fast Breeder Reactors very different types of assemblies, like fresh and spent fuel, fresh and spent blanket fuel and non fuel items, are used in the core and their distinction with declaration independent methods is essential for the verification process. To achieve this, the IAEA installs and operates different types of detectors at key locations at the facility. This presentation describes one specifically designed detection system to measure relevant signals about assemblies, utilizing 3 He tubes and fission chambers for neutrons, ion chambers for gross-gamma and, for the first time, CdZnTe detectors for spectrometry under-water in unattended mode.