Experimental study on pressurized water reactor imaging using cosmic ray muons

This study presents cosmic-ray muon transmission imaging of a nuclear reactor. A high-spatial-resolution drift-tube muon tracker with an active area of 1.1 × 1.1 m 2 was deployed at Unit 1 of a commercial nuclear power plant in China, which is a "Hualong One" pressurized water reactor, and operated for six months to record muon flux from various directions. Prior to fuel loading, a two-dimensional absorption map of the reactor was reconstructed from coincident muon events, which clearly resolved the reactor core and surrounding structures. After fuel loading, measurable changes in the absorption signal were observed in the fuel region. Monte Carlo simulations yielded reactor and core-specific imaging results that were in good agreement with the experimental measurements. In addition, the impact of tracker spatial resolution on image quality was analyzed. These findings indicate that muon transmission imaging is a promising method for reactor imaging.