基于钕铁硼磁粉的α表面污染模拟方法研究

Study onαradioactive surface contamination simulation method based on NdFeB magnetic powder

目的针对核应急医学救援实战化训练需求,研制安全可靠的α表面污染模拟源应用于实际训练。方法使用便携式α表面污染检测仪测量α面源,总结变化规律;运用磁场模拟α辐射场,使用钕铁硼磁粉作为磁源,通过磁粉与胶体混合在磁场中充磁制备成磁粉胶体,再将磁粉胶体涂抹于物体表面作为模拟源,使用特定的检测电路检测,按照一定转换公式,将电压值转换为计数率或活度值,实现α表面污染的模拟。结果使用便携式α表面污染检测仪测量α面源的计数率在α射线射程范围与测量距离呈线性关系;使用钕铁硼磁粉和胶体制备的模拟源磁感应强度在0.5~3 cm范围能够模拟α表面污染计数率的变化规律;同时能够模拟洗消的变化过程。结论基于钕铁硼磁粉的α表面污染模拟方法安全可靠、无辐射危害,能够应用于α表面污染检测、洗消的模拟训练,对提高训练水平,提升核应急救援队伍的实际救援能力具有一定应用价值。

Objective To develop a safe and reliable simulative source for nuclear emergency medical assistance training.Methods α surface sources are measured by a portable α surface radioactivity detector to summarize the correlations. A magnetic field is used to simulate the α-radiation field, and NdFeB magnetic powder is used as the magnetic source. Magnetic powder mixed with colloid is magnetized in a magnetic field to prepare magnetic powder colloid. The magnetic powder colloid is applied to the surface of an object as a simulated source. A specific detection circuit is designed to detect the simulated source. By using a certain conversion formula, voltage value is converted into count rate or an activity value to simulate the α surface contamination. Results The count rate of the α surface source measured by the portable α detector shows a linear relation with the measuring distance within the range of the α beam. The simulated source prepared by using NdFeB magnetic powder and colloid has the properties of α surface contamination, and can simulate a real measurement of α surface radioactivity within the range of 0.5~3 cm. Besides, signal decrease in process of decontamination can also be simulated.Conclusion The α radioactive surface contamination simulation method based on NdFeB magnetic powder is safe and reliable, and has no radiation hazard. It can be applied to the training of α surface radioactivity detection and decontamination,which has certain practical value for improving the training level and consequently improving the actual assistance ability of the nuclear emergency assistance team.