Martínez-Ovalle S A, Garcia-Rodriguez A M, Vega-Carrillo H R, Sandoval-Garzón M A, Jaramillo Garzón W, Sajo Bohus L
Grupo de Física Nuclear Aplicada y Simulación, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia.
Grupo de Física Nuclear Aplicada y Simulación, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia.
Appl Radiat Isot. 2020 Jul;161:109175. doi: 10.1016/j.apradiso.2020.109175. Epub 2020 Apr 9.
Paraffin, water and water-extended polyester (WEP) were used as main moderator to design a mobile shielding for a 666 GBq 241Am-Be source used in oil industry. The shielding performance was estimated using Monte Carlo methods where the γ-rays induced by the neutron interaction with the shielding materials were also included. The spectra of neutrons and γ-rays around the shielding were estimated, as well as the total neutron and g-ray total fluences per history. The neutron source strength was used to calculate ambient dose equivalent rates, aiming to satisfy the international recommendation (2 mSv/h at the shielding surface). Moderators modify the neutron spectrum of the source reducing the amount of fast neutrons (0.5-11 MeV) and producing epithermal and thermal neutrons. During neutron transport in the moderator neutron capture and inelastic scattering produce gamma-rays. Paraffin has the best shielding performance however it is not suitable because can be affected by extreme temperatures. WEP and water have similar shielding performance, however water do not satisfy the international recommendations because at one site the neutron and γ-ray doses rates are larger than 2 mSv/h. WEP is the best option because fulfill the international recommendations, it is stable and temperatures where paraffin fails. The WEP-based shielding weights 66 kg.
石蜡、水和水基增强聚酯（WEP）被用作主要慢化剂，以设计一种用于石油工业中666 GBq 241Am-Be源的移动屏蔽装置。使用蒙特卡罗方法估算屏蔽性能，其中还包括中子与屏蔽材料相互作用产生的γ射线。估算了屏蔽周围中子和γ射线的能谱，以及每次历史记录中的总中子和γ射线总注量。利用中子源强度计算环境剂量当量率，旨在满足国际建议（屏蔽表面处为2 mSv/h）。慢化剂会改变源的中子能谱，减少快中子（0.5 - 11 MeV）的数量，并产生超热中子和热中子。在慢化剂中的中子输运过程中，中子俘获和非弹性散射会产生γ射线。石蜡具有最佳的屏蔽性能，然而它并不适用，因为它会受到极端温度的影响。WEP和水具有相似的屏蔽性能，然而水不满足国际建议，因为在一个地点中子和γ射线剂量率大于2 mSv/h。WEP是最佳选择，因为它满足国际建议，稳定且能在石蜡失效的温度环境下使用。基于WEP的屏蔽装置重66千克。
