The presented device is a compact gamma and fast neutron data acquisition system (DAQ) for passive and active NDA of SNM. The DAQ weights just 8 kg, including batteries for more than 3 hours of continuous operation. It connects up to 4 organic detectors with Pulse Shape Discrimination (PSD) capability and runs PSD in real time on the radiation signals. It measures the energy of the interaction of gamma and neutron radiation separately and combines these values with an accurate determination of the Time-of-Flight at level of 1 nanosecond, to uniquely characterize the material under essay. It provides identification of neutron sources such as Cf-252, Am-Be, Pu, U, Am-Li, Pu-Be, also in presence of high gamma field, and covers scenarios where heavy shielding, moderating material, and masking sources are present. The paper reports laboratory measurements performed with the use of samples of reactor grade Pu and Cf252. The laboratory measurement demonstrates the capability of easily determinate spontaneous fission and (,n) reactions. The device is already in use by the IAEA Safeguards for the assay of critical assemblies and its technology is already implemented in the fast neutron collar (FNCL) deployed by the IAEA Safeguards for fresh fuel verification. Moreover, it has been demonstrated the capability of the system to identify SNM isotopic composition using the spectrum of the energy deposited by gamma and neutron radiation in the organic scintillator. Starting from these results, we extrapolated and described the potential use in major identified unattended scenarios. The system could be deployed for attended inspection and is already designed for scalability to variate detection efficiency as well as different levels of gamma resolution.
Year
2024
Abstract