B_4C俘获热中子时产生的次级γ光子所致有效剂量的研究

Research on Effective Dose Caused by Secondary Gamma Photons Produced when B_4C Capturing Thermal Neutron

防护装具用含硼材料中10B俘获热中子时,产生的0.48 MeV次级γ光子经过材料自身衰减后对人体造成的有效剂量,与材料吸收热中子(被俘获)所减少剂量作比较,可评价所用屏蔽材料的合理性。通过建立保守的数学模型,在1.5 cm和2.0 cm两种厚度屏蔽材料情况下,分别计算了未经碰撞的γ光子和经康普顿散射的γ光子所致的总有效剂量。得到的屏蔽材料感生γ射线对人体造成的有效剂量,在材料厚度1.5 cm时为0.89 pSv,2.0 cm时为0.85 pSv,它们都不到防护材料所减少的热中子剂量(10.4 pSv)的8.7%,初步证明材料中使用B4C的合理性。

This paper mainly describes the effective dose caused by the material-reduced 0.48 MeV secondary γ photon when ^10B in boron-containing material used in the protective equipment captures the thermal neutron and then compares it with the reduced dose of the thermal neutron absorbed （captured） by the material, and thus evaluates the rationality of the material used for shielding. Through the establishment of a conservative mathematical model, we separately calculate the dose produced by gamma photons without the collisions and dose generated by gamma photons by the Compton scattering on the conditions of 1.5-centimetre-thick and 2.0-centimetre-thick materials. The final conclusion then can be drawn that the effective dose to human body caused by secondary photon of shielding material is 0.89 pSv, providing that the thickness of the material is 1.5 centimeters while 0.85 pSv if it is 2 centimeters, which are both less than 8.7%, of the reduced thermal neutron dose and thus the rationality of applying B4C in the material is proved.