Cosmic-ray muon radiography of UO₂ fuel assembly

A technical demonstration of cosmic-ray muon radiography of a UO₂ fuel assembly was performed at Toshiba Nuclear Critical Assembly (NCA). The fuel assembly in the NCA was imaged through obstacles such as steel and concrete. The result suggested that the method can be applicable to assess the damage to the reactors at the Fukushima Daiichi nuclear power plant. Here, both scattering and displacement methods are presented, and the results are shown to agree with Monte Carlo simulations. In addition, detailed Monte Carlo simulations of the Fukushima Daiichi reactor were performed, which showed capability of muon radiography to locate the fuel in the damaged reactors. (author)