Muon Imaging of Hydrotreatment Reactors

This study presents the design and simulation-based validation of a muon imaging system tailored for potential applications in industrial hydrotreatment units. The system is built around a two-panel plastic scintillator hodoscope, equipped with silicon photomultipliers and read-out via a CAEN FERS-A5202 acquisition system. The detector was calibrated using a stepwise ``staircase'' method and characterized under open-sky and controlled conditions. We conducted muon flux attenuation measurements to validate its response using variable lead shielding. We found agreement with simulations generated using the MEIGA framework and realistic cosmic ray spectra from the ARTI simulation chain. With the detector response validated, we modelled muon transmission through a realistic 3D representation of a hydrotreatment tower, incorporating internal variations in catalyst bed density. By reconstructing angular muon fluxes and computing relative attenuation maps, we demonstrated the system's capability to detect internal density contrasts. Simulation results indicate that 20~hours of exposure to vertical muon flux is sufficient to retrieve structural information. In comparison, inclined configurations (30$^\circ$ and 60$^\circ$ from vertical) require extended exposure times--up to 8~days--yet remain feasible within industrial monitoring schedules. These findings highlight the feasibility of muography as a non-invasive diagnostic tool for complex industrial infrastructure. The proposed system shows strong potential for real-time monitoring of catalyst bed integrity and long-term structural analysis in high-pressure chemical reactors.