UPDATING FISSION PRODUCT CHEMISTRY DATABASE BASED ON RECENT INVESTIGATION IN FUKUSHIMA-DAIICHI NUCLEAR POWER STATION (2) TEMPERATURE EFFECTS ON THE DEPOSITION BEHAVIOR OF CsOH AEROSOLS ON CONCRETE MAIN PHASE-CaCO₃

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The trapping behavior of cesium (Cs) on concrete, such as pedestal and shield plugs, was assessed through multiple deposition tests of CsOH aerosols on concrete main phaseCaCO₃ within a temperature range of 170oC to 570oC under humid conditions. The deposition rate of CsOH aerosols on CaCO₃ as a function of temperature was examined. X-ray diffraction analysis revealed the presence of water-soluble Cs₂CO₃ on CaCO₃ samples up to 420oC, but negligible detection above this temperature. This finding is supported by quantitative analyses of Cs weight gain and chemical analysis, demonstrating an increase in deposition rate up to 420oC, followed by a decline thereafter. The increased deposition rate is attributed to the chemical interaction between CsOH and CaCO₃, while the diminished rate beyond 420oC may result from the decomposition of CaCO₃ under steam, thereby reducing the available reactant for the chemical reaction with CsOH.