The Localization of Finely Dispersed Caesium Radioaerosols from Off-Gases

Abstract

Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aerosols with a particle size of less than 0.1 μm and volatile radioactive iodine compounds. The decontamination process is based on the method of the agglomeration cocrystallization of finely dispersed and other aerosols in the gas phase by including the aerosols in the inner structure of large-particle non-radioactive aerosols of ammonium salts, for example, NH4Cl or (NH4)2SO3. For 137Cs, the most ecologically dangerous long-lived radionuclide, the setup ensures a decontamination factor of 102 to 103 in one decontamination stage. Because the setup consists of three consecutive stages of the same type, the cumulative decontamination factor can reach to 106 - 107. To localize radioactive iodine as I2, HI, HOI, HIO3, and CH3I from vapor-air flows, the setup uses a unit containing special granulated sorbents based on inorganic compounds. Developed at the Institute of Physical Chemistry, Russian Academy of Sciences, these sorbents effectively remove various radioactive iodine species (inorganic species and methyl iodide) from steam-air flows, ensuring decontamination factors of at least 104. The proposed technological scheme will allow vapor-gas flows to be cleaned of radioaerosols and all volatile radioactive iodine species at decontamination factors of not less than 104.