Thermal and epithermal neutron flux distributions measurement in thermal column of TRR using an experimental-simulation method.
For designing an appropriate neutron beam, the determination of neutron flux at any irradiation facility is an important key factor. Due to the importance of determining the thermal and epithermal neutron fluxes in a typical thermal column of a reactor, a simple and accurate technique is introduced in this study. Absolute thermal and epithermal fluxes were measured experimentally at a certain point using the foil activation method by neutron bombardment of bare and cadmium covered Au foils. The relative neutron fluxes were also derived simply by means of Monte Carlo simulation by accurate modelling of the reactor components. Finally, by normalization of the relative distribution flux with regard to information about the absolute neutron flux, the accurate thermal and epithermal neutron distributions were derived, separately.
A study of the use of palm fiber and palm shell as a thermal neutron radiation shielding material
Abstract Preliminary studies have been conducted to determine the benefits of using palm fiber and shells as thermal neutron radiation shielding materials. The method in this research using Neutron Activation Analysis (NAA). However, based on the results of SEM-EDX data analysis, it was found that palm fiber and shells containing carbon were 70.92% and 73.25%, respectively. Furthermore, the carbon element is expected to absorb thermal neutron radiation and its ability was analyzed by using the material activation method due to neutron exposure. For the purpose of this study, the BATAN PSTBM Neutron Radiography facility was used for the activation. Thermal neutron flux on gold pieces that passed the natural neutron radiation shield made from palm fiber and palm shells was analyzed before and after passing through the shield in the NAA PSTBM BATAN laboratory. This analysis showed that the attenuation coefficient of palm fiber is 0.9538 cm−1 and palm shells are 1.0837 cm−1. Therefore, it can be concluded that both materials can be used as thermal neutron radiation shielding materials.
An optimized neutron-beam shaping assembly for accelerator-based BNCT.
Different materials and proton beam energies have been studied in order to search for an optimized neutron production target and beam shaping assembly for accelerator-based BNCT. The solution proposed in this work consists of successive stacks of Al, polytetrafluoroethylene, commercially known as Teflon, and LiF as moderator and neutron absorber, and Pb as reflector. This assembly is easy to build and its cost is relatively low. An exhaustive Monte Carlo simulation study has been performed evaluating the doses delivered to a Snyder model head phantom by a neutron production Li-metal target based on the (7)Li(p,n)(7)Be reaction for proton bombarding energies of 1.92, 2.0, 2.3 and 2.5 MeV. Three moderator thicknesses have been studied and the figures of merit show the advantage of irradiating with near-resonance-energy protons (2.3 MeV) because of the relatively high neutron yield at this energy, which at the same time keeps the fast neutron healthy tissue dose limited and leads to the lowest treatment times. A moderator of 34 cm length has shown the best performance among the studied cases.