15 MeV~3 GeV电子加速器90°方向光子源项研究  

Research on Photon Source Term in 90°of 15 MeV-3 GeV Electron Accelerator

作　　者：赵锋[1] 杨立涛[1] 殷煜皓[1] 江君 任子珵 王萦 ZHAO Feng;YANG Litao;YIN Yuhao;JIANG Jun;REN Zicheng;WANG Ying(Suzhou Nuclear Power Research Institute Co.,Ltd.,Suzhou 215004,China)

机构地区：[1]苏州热工研究院有限公司,江苏苏州215004

出　　处：《原子能科学技术》2022年第10期2139-2145,共7页Atomic Energy Science and Technology

摘　　要：韧致辐射光子是电子加速器屏蔽设计中的重要源项。为研究90°方向光子源项特征以及靶体半径和厚度对90°方向光子源项的影响,采用蒙特卡罗程序MCNPX2.7对15 MeV~3 GeV电子束轰击铁靶后的辐射源项进行计算。分析了90°方向光子辐射剂量、光子能谱等源项随靶厚度和半径的变化。通过与0°方向光子源项以及靶体内级联电子沉积能量进行对比,进一步分析了90°方向的光子源项特点。结果表明,90°方向光子能量主要集中在10 MeV以内,光子能谱形状与入射电子能量关系较小。受级联电子在靶内能量沉积程度及靶体对光子自吸收的共同影响,靶体半径和厚度是影响90°方向光子源项的重要因素。在电子加速器的屏蔽设计中应考虑靶体尺寸差异所带来的影响,同时建议针对束流90°方向和0°方向光子源项的差异,对加速器辐射屏蔽和防护进行优化设计。The bremsstrahlung is an important source term in the shielding design of the electron accelerator.In order to study the characteristics of the photon source term in the 90°direction and the influence of target radius and thickness on the bremsstrahlung in the 90°direction,the Monte Carlo program of MCNPX2.7 was used to calculate the radiation source term from the 15 MeV-3 GeV electron beam incident on the iron target with different thicknesses and radii.The variation characteristics of radiation source items such as photon radiation dose rate and photon energy spectrum with target thickness and radius were obtained and comparatively analyzed.By comparing with the photon source term in the 0°direction and the energy deposition of cascade electron in the target,the main features of the photon source term in the 90°direction were obtained.Finally,the effects of beam power and beam intensity on radiation dose rates in the 90°and 0°directions were analyzed.The result shows that,due to the combined influence of electron energy deposition in the target and self-absorption of photons from the target,the radius and thickness of the target are expected as important factors which affect the photon source term in the 90°direction.The energy of the cascade electrons deposited in the target and the radiation dose rate in the 90°direction increases with the thickness.As the energy of the cascade electrons is completely deposited in the target,the radiation dose rate in the 90°direction will not change with the target thickness.The radiation dose rate in the 90°direction also increases with the target radius,but when the target radius is larger,the radiation dose rate in the 90°direction decreases due to the self-absorption.Apart from that,the effect of incident electron energy on the photon source terms in the 90°direction and 0°direction is different.More than 99%of the photons in the 90°direction are below 10 MeV,and most of them are within 3 MeV.In the 90°direction,the photon energy spectrum shape has little

关 键 词：电子加速器 屏蔽设计 韧致辐射 靶体尺寸 光子源项 

分 类 号：TL508[核科学技术—核技术及应用]