复杂地下硐室群核事故钚气溶胶扩散行为研究

Diffusion Behavior of Plutonium Aerosol in Nuclear Accidents in Complex Underground Chamber Group

涉核地下硐室群核事故产生的钚气溶胶威胁核设施的长期运营安全,现有关于封闭空间内的钚气溶胶扩散行为研究主要涉及简单硐室,而未涉及复杂地下硐室群,复杂地下硐室群核事故钚气溶胶扩散行为尚未得到充分揭示。首先对核事故钚气溶胶源项进行分析,讨论了钚气溶胶颗粒产生的方式和粒径分布特征,给出了硐室内钚气溶胶初始浓度的估算方法;然后通过分析钚气溶胶颗粒的空气动力学行为,给出了适合于描述钚气溶胶颗粒在硐室内传输的本构模型,建立了地下硐室群内钚气溶胶扩散行为模拟方法;最后以某复杂地下硐室群为例,采用Ventsim软件对两种释放场景(缓慢释放和剧烈释放)、不同释放位置条件下钚气溶胶的扩散行为进行了数值模拟,并对硐室群核事故应对措施展开了讨论。结果表明:钚气溶胶在硐室群内的扩散行为主要受核泄漏方式、核泄漏位置、钚气溶胶颗粒粒径以及通风系统的影响,通过合理规划硐室群布局、通风风路、防核泄漏措施等,可有效降低核污染扩散的风险。该研究结果对于地下硐室群核安全设计、核应急处理与核扩散风险管控等措施的制定具有一定的参考价值。

Plutonium aerosol generated by nuclear accidents involving nuclear underground chamber threa-tens the long-term operation safety of nuclear facilities.Existing studies on the diffusion behavior of plutonium aerosol in enclosed spaces mainly involve simple chamber,whereas the complex underground chamber groups have not yet been revealed.Therefore,the source term of plutonium aerosol in nuclear accidents is analyzed.Firstly,the generation mode and particle size distribution characteristics of plutonium aerosol particles are discussed,and the estimation method of initial concentration of plutonium aerosol in the chamber is given.Then,by analyzing the aerodynamic behavior of plutonium aerosol particles,a constitutive model suitable for describing the transport of plutonium aerosol particles in the chamber is proposed,and the si-mulation method for plutonium aerosol diffusion behavior in the underground chamber group is established.Finally,taking a complex underground chamber group as an example,Ventsim software is used to numerically simulate the diffusion behavior of plutonium aerosol under two release scenarios(slow release and severe release)and different release locations,and to discuss the countermeasures for muclear accidents in the chamber group.The results show that the diffusion behavior of plutonium aerosol in the chamber group is mainly affected by the nuclear leakage mode,leakage location,particle size and ventilation system.With reasonable planning of chamber group layout,ventilation design and anti-leakage measures can effectively reduce the risk of nuclear pollution proliferation.The findings of this study have certain reference value for making of measures of nuclear safety design,nuclear emergency treatment and nuclear proliferation risk control of underground chamber group.