核泄漏事故核素近海迁移中各因素影响分析

Influence analysis of various factors of radionuclide migration in coastal waters under nuclear leakage accidents

为了研究核素在近海域迁移中各因素的影响,本文采用理论分析方法,建立了大气核素干、湿沉降分析模型,并建立了悬浮物对放射性核素吸附沉降模型和海洋生物富集模型,给出了各因素的影响程度。结果表明:干沉降通量比地面核素浓度低3~4个数量级,湿沉降通量比干沉降通量大2个数量级。悬浮物对放射性核素的吸附沉降率随沉积通量、分配系数和作用时间的增大而增大;分配系数为10^4 L/kg和生物量为10^-5 kg/L时,生物富集使放射性活度减小了10%左右。短期核素扩散中,源项、对流扩散、干湿沉降和半衰期较短核素衰变影响较大;长期核素扩散中,源项、半衰期较长核素衰变和悬浮物影响较大;生物富集影响一直很小,可以忽略。

To study the influence of various factors of radionuclide migration in coastal waters,the dry and wet sedimentation analysis model,sorption and sedimentation model,and bioaccumulation model were established based on a theoretical analysis.The influencing degree of each factor was given.Results show that the dry sedimentation flux is three to four orders lower than the ground radionuclide concentration,and the wet sedimentation flux is two orders larger than the dry sedimentation flux.The sorption and sedimentation rate by suspended solids increases with the increase of the sedimentation flux,partition coefficient,and interaction time.When the partition coefficient is 10^4 L/kg and the biological concentration is 10^-5 kg/L,the bioaccumulation makes the intensity of radioactivity decrease by approximately 10%.The source item,convection diffusion,dry and wet sedimentation,and radionuclide decay with a short half-life are of great influence in the short-term analysis of radionuclide diffusion.The source item,radionuclide decay with a long half-life,and suspended solids are of great influence in the long-term analysis of radionuclide diffusion.Furthermore,the bioaccumulation influence is always small and can be neglected.