Monitoring spent nuclear fuels (SNF) is an important task to ensure reliable stewardship of waste management and prevent potential proliferation of nuclear materials. In this regard, cosmic ray muons have emerged as one of the promising non-conventional radiographic probes because they have high energy and large penetration capability in dense and large materials such as uranium fuel and lead or concrete shielding. Despite the various benefits of using cosmic ray muons, they are not widely used for monitoring SNF casks because of the naturally low muon flux at sea level, 10,000 m-2min-1. To overcome this limitation, two quantities—scattering angle and momentum—for each muon event must be measured during the measurement. Although many studies demonstrate that there is significant potential for measuring momentum in muon tomography, none of them has successfully measured both the muon scattering angle and the muon momentum in the field. In this paper, we show the results of reconstructed images of SNF casks using a new muon spectrometer-tomography system which combines (i) a fieldable Cherenkov muon spectrometer with momentum resolution, ?p/p~10% and (ii) a momentum integrated muon tomography algorithm. Our results demonstrate that imaging resolution is significantly improved and measurement time reduced by a factor of 3 or 4. We anticipate our proposed muon spectrometer-tomography system will expand the applicability of cosmic ray muons by maximizing their utilizability in SNF cask monitoring as well as various other disciplines and ensure security of nuclear materials by preventing proliferation and national security threats.
Year
2022
Abstract