INTERROGATION OF SPENT NUCLEAR FUEL CASKS USING COSMIC-RAY MUON COMPUTED TOMOGRAPHY

Properly accounting and safeguarding spent nuclear fuel are key components in the International Atomic Energy Agency’s mission of non-proliferation. Currently, no instruments are deployed that are able to verify the spent nuclear fuel contents of dry storage casks. Cosmic-ray muons provide an ideal probe for the heavily shielded casks due to their ability to penetrate thick, dense materials. Coulombic scattering of the muons, to first order, is proportional to the Z2/A of the material; this makes it especially sensitive to actinides, such as uranium and plutonium. The combination of these traits allows muons to be used to image and verify the contents of a sealed cask in situ. Here the analysis of the first muon scattering measurements of spent nuclear fuel dry casks is presented, which show a 2.3 σ confidence in the identification of a missing fuel bundle. Geant4 simulations are benchmarked against measurement data and show good agreement. Using the benchmarked simulations, the first study of computed tomography using cosmic-ray muon scattering is presented and further applied to the fingerprinting and monitoring of spent nuclear fuel casks. Finally, the feasibility of using cosmic-ray muons to perform a final verification of spent nuclear fuel-prior to permanent deposition in a geological repository-is investigated