Monte Carlo simulation of portal detectors of a steel factory. Comparison of measured and simulated response

Metal scrap is widely used in steel production. Millions of tons of scrap metal are traded each year worldwide; hence, both national and international authorities have shown an increasing interest in the probing and detection of radioactivity contamination in scrap metal. In order to minimize and/or avoid economical losses and material contamination, portal monitors have been installed at the entrance point of installations of many steel industries. Portal monitors typically consist of large organic scintillation detectors. The purpose of this study is to simulate such detectors and compare simulation results with experimental measurements in order to understand, calibrate and effectively use the detectors’ response. Monte Carlo simulations of these systems demonstrate the assumptions that have to be made for optimal matching of measured and simulated results. As it was reported in previous studies, we observed a difference between measured and experimental values next to the light guide. In this work, we propose a transition area near the boundary surface of the scintillator and the light guide; this results in a good qualitative and quantitative agreement of measured and simulated results. This study will also define a guideline for later portal monitor simulations and a reliable estimation of the portals’ efficiency.