一体化快堆钠火事故后气溶胶的控制

Control of Aerosols after Sodium Fire Accident in Integrated Fast Reactor

  • 摘要: 为避免一体化快堆钠工艺间发生钠火事故产生的大量钠气溶胶及其他放射性气溶胶对人体造成伤害,方便对钠火产物进行处理,对工艺间内的钠气溶胶进行抑制以减少气溶胶再悬浮和扩散,以苯乙烯St和丙烯酸丁酯BA为主要单体,丙烯酸和甲基丙烯酸为功能单体,通过乳液聚合法制备了成膜型气溶胶固定剂。通过实验确定了合成过程中引发剂和乳化剂的最佳用量分别为单体总质量的1.25wt%和乳液总质量的1.5wt%;3种不同单体比例的固定剂样品中,St∶BA=1.75∶1的样品具有最高的气溶胶捕集率,6 h可达99.43%;经过雾化固定后,气溶胶颗粒的再悬浮得到了有效控制,相比自然沉降的16.15%再悬浮率,雾化固定后气溶胶颗粒再悬浮率仅为0.19%。因此,苯丙乳液雾化固定剂可应用于一体化快堆钠火事故后的放射性气溶胶控制,有效捕集气溶胶并阻止其再悬浮。

     

    Abstract: Styrene-acrylate emulsion fixation agent is used in control of radioactive aerosols of integrated fast reactors. In integrated fast reactor design, radioactive aerosol control represents a critical safety requirement. To mitigate hazards from sodium aerosols and other radioactive particles generated during potential sodium fire accidents in sodium processing compartments, while facilitating post-accident residue management, effective suppression of aerosol resuspension and dispersion becomes imperative. This study developed a film-forming aerosol fixing agent through emulsion polymerization using styrene (St) and butyl acrylate (BA) as primary monomers, with acrylic acid and methacrylic acid as functional monomers, specifically for sodium aerosol capture. Conditional experiments first established optimal dosages of initiator and emulsifier at 1.25wt% and 1.5wt% of total monomer mass and emulsion mass, respectively. Three fixing agent samples with varying monomer ratios (St∶BA = 1∶1, 1.75∶1, and 2∶1) were subsequently synthesized and aerosol natural settling experiments and aerosol capture experiments were designed to characterize the aerosol capture performance of the three fixative samples. An experimental setup was constructed, consisting of an aerosol capture test bench, an aerosol generator, an aerosol particle size spectrometer, and a fixed agent atomization device. The above experiment was conducted based on experimental design and experimental setup. Comparative aerosol capture experiments revealed the St∶BA=1.75∶1 formulation demonstrated superior performance, achieving 99.43% capture efficiency within 6 hours, significantly exceeding the 78.32% natural sedimentation rate observed in control trials. Resuspension tests further confirmed the agent’s effectiveness, showing aerosol resuspension rates reduced from 16.15% in natural sedimentation scenarios to merely 0.19% following aerosol fixation treatment. Microstructural analysis through SEM revealed the optimized formulation formed continuous polymer films that effectively encapsulated aerosol particles, while FTIR characterization verified successful copolymerization of functional groups enhancing interfacial interactions. The results show that the styrene-acrylate emulsion fixing agent enables superior radioactive aerosol control in sodium fire scenarios compared to passive sedimentation, with capture efficiency improvements exceeding 20 percentage points. The film-forming mechanism provides durable suppression of aerosol resuspension, reducing post-deposition particle remobilization by two orders of magnitude. The 1.75∶1 St/BA ratio optimizes the balance between polymer film flexibility and adhesion strength required for effective particle encapsulation. This research demonstrates the technical feasibility of applying polymeric fixation agents for enhanced radioactive aerosol management in advanced reactor systems, offering significant safety improvements over conventional passive containment strategies.

     

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