An analysis of pressurized heavy water reactor fuel for nuclear safeguards applications using muon scattering tomography

Abstract

Muon Scattering Tomography (MST) relies on multiple Coulomb scattering (MCS) of high energy cosmic ray muons in matter to reconstruct 2D and 3D images of targets of interest. Targets such as nuclear fuel and containers for spent nuclear fuel are difficult or impossible to image using conventional X-ray techniques due to the presence of shielding and the high density/high-Z nature of the materials involved. MST is a modern non-destructive technique using naturally occurring radiation to assay such materials and geometries. This technique is particularly well suited for applications in spent nuclear fuel management and nuclear non-proliferation since scanning time constraints are more relaxed compared to applications of border security. The Cosmic Ray Inspection and Passive Tomography (CRIPT) detector and associated Geant4 simulation were used for this investigation. A unique capability of CRIPT is the reconstruction of the muon momentum with a spectrometer. Presented here are measurements of un-irradiated Pressurised Heavy Water Reactor (PHWR) fuel bundles in contrast with a lead stack, steel-loaded, and voided fuel bundle analogues (“fakes”). The results presented here show that MST can effectively be used to verify the contents of spent fuel storage containers and is the first experimental analysis of PHWR fuel in contrast with “fake” bundles in a safeguards context. In cases where statistics (exposure times) are not limited, ceramic UO2, Pb, and weighted/un-weighted “fake” fuel bundles can be both statistically and qualitatively distinguished which serves to demonstrate the efficacy of MST for nuclear safeguards/non-proliferation applications.