Benchmark Study of Simulations of Silicon-Equivalent Aluminum Phantom Using Thermal Neutron Flux Measurements at Some Irradiation Positions in Tehran Research Reactor

In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor to modulating its electrical, optical, and structural properties. Among various areas of research reactor utilization, neutron transmutation doping of silicon is a well-established technology desired by industry. The design and construction of an irradiation channel require calculations and benchmark studies to validate the calculations performed. This work is based on the measurement of thermal neutron flux inside an 8-inch aluminum phantom using gold foils positioned radially inside it. The irradiation positions were simulated using the MCNPX computational code to investigate the conformity of the code data with the experimental data. The results showed noticeable discrepancies between the measured data inside the TRR thermal column and the obtained simulation data obtained. These differences may be due to some physical properties of the thermal column nose that need to be properly considered for precise simulation of the irradiation conditions. While benchmark study for the other selected irradiation position near the TRR core showed an average 25% relative discrepancy between the simulation and experimental data. The simulations carried out inside an optimized irradiation channel designed for 6-inch silicon ingots showed that have a thermal neutron flux of at least in order of 1012 would be achievable. This makes it possible to complete the doping process in 2 to 3 days of operation of the TRR reactor at its full 5 MW power.