血液中Na活化放射性测量的蒙特卡罗模拟

针对超临界事故中人体受到中子辐照后感生的24Na活度测量，采用MCNP软件建立蒙特卡罗模拟模型，分别模拟不同类型NaI探测器对24Na衰变的两条射线全能峰的探测效率和塑料闪烁体探测器对24Na衰变的射线总计数的探测器效率。模拟结果表明:井型NaI探测器与圆柱型相比，24Na衰变的1.38 MeV和2.76 MeV 射线全能峰探测效率分别提高了4.30倍和4.11倍；塑料闪烁体探测器对24Na衰变的射线的探测效率是NaI探测器对24Na 射线的探测效率的1.72倍；同时粗略计算了探测器计数与人体所受中子辐照剂量之间的关系。

Monte Carlo simulation of radiation measurement of Na activation in blood

For 24Na activity measurement of human body activated by neutron irradiation in the supercritical accident, the MCNP code is used to create a Monte Carlo simulation model. Two-γ-ray total-energy peak detection efficiency of 24Na decay using different types of NaI detectors, and total β-ray number detection efficiency of 24Na decay using plastic scintillator detector are simulated. The simulation results show that, for the 1.38 MeV and 2.76 MeV γ rays of 24Na decay, the efficiency of the well-type NaI detector is 4.30 times and 4.11 times that of the cylindrical one; the β-ray detection efficiency of 24Na decay using the plastic scintillator detector is 1.72 times the 24Na γ ray detection efficiency using the NaI detector. Meanwhile, a rough calculation of the relationship between the detector counts and the neutron irradiation dose of human body is carried out.