Year
2008
Abstract
The Digital Cherenkov Viewing Device (DCVD) is an instrument for safeguards inspections of spent nuclear fuel assemblies, which was developed as a joint project by the Canadian and Swedish Support Programs for the IAEA. It was approved by the IAEA in 2004 as a gross defect tester. The inspectors use the DCVD to inspect the inventory of spent nuclear fuel assemblies in storage ponds, and the device records the characteristic Cherenkov light that is emitted from highly radioactive nuclear material. Current studies have focused on whether the DCVD can be used also as a partial-defect tester. A computer model of the Cherenkov light emission from spent nuclear fuel with partial defects is under development. The model creates images as they would appear in the DCVD inspection device. The modeling is made in two steps. First, source terms of the Cherenkov glow are created by simulating the interaction of gamma rays emitted from the fuel rods, using the Monte Carlo code GEANT4. Then, the detector image is created from the source terms using the ray-tracing code ZEMAX. Two authentic fuel assemblies of the 9x9 Atrium fuel type have been simulated, for which real DCVD images exist. In each assembly, one fuel rod had been substituted with a homogeneous zircaloy rod. The qualitative agreement between real images and model images is shown.