电子束辐照装置屏蔽体预埋管道处的辐射场计算

Radiation field calculation outside the duct-embedded shielding wall of an E-beam irradiator

电子束辐照装置的屏蔽墙内总有预埋管道,这些管道将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,本文用蒙特卡洛程序MCNP模拟计算管道中心线上与屏蔽体外受管道影响区域的辐射剂量。结果表明,随着管道与墙体夹角的增加,屏蔽体外光子能谱逐渐变软且辐射剂量不断降低。夹角大于50°,角度对剂量的影响不再明显;而墙外辐射剂量受管道直径影响显著。根据计算结果,针对管道贯穿墙体的情况提出了一些屏蔽设计中值得参考的建议。

Duct-embedded shielding walls of an electron beam irradiator may weaken the shielding effect locally. In order to evaluate how this happens to the E-beam irradiator, the radiation dose distribution outside the duct-embedded walls and on the pipes axis were simulated by the Monte Carlo code of MCNP. The simulation results show that with increasing duct angles to the wall, the photon energy spectrum softens and the radiation dose reduces generally, but at the angles exceeding 50°, the radiation doses are not in apparent decreases. In addition, the duct diameter is an important factor for the radiation shielding. Based on the simulation, suggestions are given for reference of shielding designs of cable irradiation facilities.