基于气溶胶再悬浮模型的钚污染区环境评价

Environmental Evaluation of Plutonium Contaminated Sites Based on Aerosol Resuspension Model

核装置中的钚材料在试验及事故条件下会以气溶胶形态释放到环境中,可造成环境污染和人员可吸入危害。针对陈旧辐射污染区的钚气溶胶再悬浮评估可以弥补钚气溶胶扩散数值模型无法开展钚泄漏事件中长期环境危害评估的不足,对于确认污染区因自然及人为扰动引起的钚气溶胶环境浓度波动及对应的净化处理工作具有指导意义。以大气物理学、地质学和辐射剂量学为基础建立钚气溶胶再悬浮经验模型,通过对典型陈旧辐射污染区进行试验测量和数值分析,并利用该模型对典型陈旧辐射污染区钚气溶胶再悬浮的环境危害进行了评估。结果表明:土壤侵蚀度是决定钚气溶胶再悬浮程度的内因;核爆试验场的钚气溶胶再悬浮程度远低于含钚材料的非核爆试验场;自然及人为扰动均会造成短期内陈旧污染区钚气溶胶环境浓度的剧烈波动;通过土壤净化可使污染区域的钚气溶胶再悬浮浓度降低至环境允许标准。

The plutonium material within the weapons grade nuclear devices will exist in the form of plutonium aerosol,which is released from the source-term and deposits in the soil after nuclear tests or accidents. Due to the natural and artificial perturbation,the plutonium aerosols deposited in the soil will resus pend into the air again. The assessment of plutonium aerosol resuspension of the dated radioactively con taminated regions will provide instructional data for studying the concentration fluctuation of plutonium aerosol in the environment and the related edaphic cleanup,which can make up the deficiency of aerosol dif fusion model in evaluating the environmental hazards of dated plutonium contaminated regions. By compa ring the resuspension parameters of plutonium aerosolization in typical dated nuclear contaminated areas, including nuclear test sites and a nuclear accident area,this paper finds out that the soil eroding is tho in trinsic factor of plutonium aerosol resuspension;the airborne contaminated concentration of plutonium aerosol resuspension in the nonnuclear test site is much higher than that in the nuclear test sites; natural and human disturbance will cause in the short term drastic fluctuation of the airborne contaminated concen tration in dated radioactively contaminated regions; through soil purification, plutonium aerosol resuspen sion concentration in the pollution areas can drop to meet the related environment standard.