ETD

• gamma spectroscopy
• HPGe detector
• Monte Carlo simulation
• neutron activation
• OpenMC
• reactor physics

This thesis presents the development, application, and experimental validation of a Monte Carlo model of the Budapest University of Technology and Economics (BME) Training Reactor. The work combines numerical simulations performed with the open-source Monte Carlo code OpenMC with experimental measurements based on neutron activation techniques and high-resolution gamma spectrometry.
After introducing the theoretical foundations of neutron transport and Monte Carlo methods, the OpenMC code is described with particular emphasis on its treatment of geometry, materials, nuclear data, and tallies. A detailed model of the BME Training Reactor is then implemented, including the core configuration and irradiation positions relevant to the experimental campaigns. Reaction rates are calculated using evaluated nuclear data libraries, and their role in reactor analysis is discussed.
The experimental part of the thesis focuses on neutron activation measurements performed using metallic foils irradiated during two distinct irradiation campaigns. The induced activities are measured using HPGe detectors, whose characteristics, calibration procedures, and efficiency determination are described in detail. Special attention is devoted to the use of the activation foils for the characterization of the neutron field, following well-established methodologies reported in the literature.
Finally, the experimental results are compared with the corresponding Monte Carlo calculations. The agreement between measured and calculated reaction rates is analyzed, and observed discrepancies are discussed in terms of modeling assumptions, nuclear data uncertainties, and experimental limitations. The results demonstrate the capability of Monte Carlo simulations to accurately reproduce neutron activation measurements in a research reactor environment, while also highlighting the importance of experimental validation for the assessment of computational models.