The International Atomic Energy Agency’s Experience Verifying Spent Fuel Using the Digital Cerenkov Viewing Device

The Digital Cerenkov Viewing Device (DCVD) has been used for many years by International AtomicEnergy Agency (IAEA) safeguards inspectors to verify the presence of nuclear material in spent nuclearfuel stored in water. The DCVD was primarily used for measuring long-cooled fuel and/or when it has alow burnup. While important to overall safeguards goals, the DCVD was limited to infrequent use due toits bulk and limited applicability. With the aid of Member State Support Programmes (MSSP), theDCVD’s capacity was expanded to include verification of the integrity of spent nuclear fuel (i.e. detectpartial defects). The DCVD can make these measurements in a few seconds without any movement of thefuel assembly and evaluate the data in-situ, whereas traditional radiation detectors would take longer andrequire the fuel assemblies to be moved. Because of the additional capacity, speed of measurement, andthe recent need of several Member States to send large quantities of spent nuclear fuel to difficult-toaccessstorage (e.g. dry casks), the DCVD has been used extensively to verify entire cooling pondsinvolving thousands of fuel assemblies. Such verification campaigns resulted in effective verification oflarge number of fuel assemblies with unprecedented productivity prior to the transfer campaign. Followupscan be organized as necessary without perturbations to the transfer operation. While the instrumenthas been successful, there is room for improvement. The IAEA has been working with several MSSPs torefine the DCVD to enable its use in more measurement scenarios, to make it more user friendly, and toimprove the sustainability of the instrument over the long-term. This paper will give an overview of theapproved use cases for the DCVD and provide a summary of its recent use and resulting improvement ofproductivity for IAEA inspections. Finally, the paper outlines some of the remaining challenges and thetheoretical basis of the planned improvements, including the results of an open challenge aimed atevaluating image processing technologies.