Studies on sodium aerosol characteristics for safety studies of sodium cooled fast reactor

Abstract

The liquid sodium is used as coolant in Sodium cooled Fast Reactors (SFR's). When liquid sodium reacts with air it produced sodium combustion aerosols. These aerosol are very hazardous to the human and corrosive for instruments. In this context, the studies on the physical and chemical characteristics of sodium aerosol are very important for safety of SFR. In this article, the sodium aerosol characteristics and properties produced under normal operation as well as reactor accident are presented. The sodium aerosol in the cover gas region is produced by evaporation and condensation of sodium while in SGB and RCB sodium aerosol are produced by sodium combustion process. The size distribution (Mass Median Diameter-MMD) and concentration of sodium aerosol in cover gas varies from 1.0 to 12 µm and 0.02 to 31.5 g/m³ when temperature of the sodium pool increased from 250-550°C on other hand the MMD of sodium combustion aerosol is varies from 1.0 to 4.0 µm when relative humidity increased from 20 to 95%. The concentration of sodium combustion aerosol in RCB and SGB is 3-4 g/m³. The chemical nature of sodium aerosol in cover gas is pure sodioum (Na) while in SGB and RCB are compounds of sodium (NaOH, Na₂CO₃ and NaHCO₃).