The safeguards MOX python (SMOPY) device combines gross neutron counting with low resolution γ spectroscopy to characterize any kind of spent fuel. The SMOPY uses online interpretation tools for the evaluation of measurement data. The system contains a well shielded and collimated CdZnTe γ detector and a fission chamber. The device is placed over the storage hole of the spent fuel assembly. The assembly is lifted through the open measurement cavity, and either it can be scanned or selected parts can be measured. The SMOPY device can verify and distinguish irradiated MOX fuel from low enriched uranium (LEU) fuel and can confirm the burnup of a spent fuel assembly.

The SMOPY device can also be operated in active mode using an AmLi source. This has been successfully demonstrated for underwater verification of canisters containing residues of irradiated HEU. This application is based on total neutron counting and detects the difference between induced fission and the active background.

(Source: IAEA Safeguards Techniques and Equipment)