دراسة حاسوبية لتصميم حزمة نترونية حرارية في مفاعل البحث المنخفض الاستطاعة من النوع منسر للتصوير بالنترونات الحرارية

Abstract

Thermal neutron beam was designed at the low-power research reactor of type Miniature Neutron Source Reactor (MNSR) with 30 kW thermal power for thermal neutrons radiography. The neutron beam was located in the reactor pool with vertical direction and parallel the outer irradiation sites. The design of the neutrons collimator was performed using MCNP4C code. Continuous energy cross-section data of the all fissile and non-fissile materials from the ENDF/B-VI library and  thermal neutron scattering functions distributed with the MCNP4C code. Thermal, epithermal and fast neutron energy ranges were selected as: <0.4eV, 0.4eV-10keV and greater than 10keV, respectively.

To obtain a high quality image at the beam exit and prevent the effect of the gamma rays on the image quality, the bismuth was used to absorption a gamma rays. In this design, the L/D ratio of this facility had the value of 111. The thermal neutron flux at the beam exit was about 1.853 ×10⁵ n/cm².s. If such neutron beam was built into the MNSR many scientific applications would be available using the thermal neutrons radiography.