电子辐照加速器屏蔽墙中预埋管道倾角对辐射防护性能影响的蒙特卡罗计算  

Influence of inclined angle embedded pipe in shielding wall on radiation protection performance for electron irradiation accelerator

作　　者：郑芳[1] 陈志[1] 徐榭[1] 

机构地区：[1]中国科学技术大学核科学技术学院,合肥230027

出　　处：《辐射防护》2017年第1期27-33,共7页Radiation Protection

基　　金：国家自然科学基金资助项目(NSFC11375182);安徽省科技攻关计划项目(1401042001)

摘　　要：电子辐照装置屏蔽墙中总存在一些较大口径的管道如辐照电缆传输孔道,这些管道的存在势必会降低屏蔽体的局部屏蔽能力。为定量评估管道对屏蔽效果的影响,本文以3 Me V电子辐照加速器为例,采用蒙特卡罗MCNP程序分别模拟计算了电子打靶以后产生的能谱中1 Me V以下和1 Me V以上不同单能光子入射同一屏蔽体时,管道以不同角度穿透屏蔽墙时管道出口处及屏蔽墙外辐射场分布;并比较了在不同墙厚下这两个能段对管道出口处辐射场的影响程度。计算结果表明:不同单能光子入射屏蔽体,在管道穿墙角度≥45°时,管道出口处辐射场变化不再明显,对于1 Me V以下的低能光子在墙外的透射辐射场基本可忽略,对于1 Me V以上的能量光子,其墙外光子透射辐射场随角度增大影响显著;随着墙厚增加,低能光子衰减越显著,高能光子在管道穿墙夹角设计中越占据了主导地位。Some large diameter ducts through the shielding wall of the electronic irradiation equipment such as the radiation cable channel, will inevitably reduce the shielding capacity of the shielding wall. In this research, target photon spectrum of 3 MeV electron irradiation accelerator was divided into two segments ： below and above 1 MeV. Distribution of radiation fields near the ducts＇ outlet were simulated at different inclination angles of pipes using the Monte Carlo code MCNP. As angle design is closely linked to shielding wall thickness, influence on the radiation field from two ranges of energy levels with different wall thickness were also compared. The results showed that scattered radiation field at the duct outlet was almost unchanged when photons of different energies passed through the shielding wall with the angles of the pipe no less than 45°. The fields of penetrating radiation outside the wall could be ignored for photons below 1 MeV. With the increase of inclination angles, the influence was significant for photons above 1 MeV. In addition, with the increase of wall thickness, lower energy photons were attenuated rapidly and the contribution from higher energy photons took the dominant role.

关 键 词：电子辐照装置 倾角 管道 MCNP 

分 类 号：R142[医药卫生—公共卫生与预防医学]