| The macroscopic and single particle isotherms of cesium iodide, CsI, were studied using a Cahn 2000 electrobalance and an electrodynamic balance respectively. Type III Brunauer, Emmet, Teller (BET) isotherms were observed for both macroscopic and single particle CsI materials, indicating multi-layer adsorption. Single particle and droplet suspension techniques were perfected using a charged needle, a droplet gun, and an electrostatic powdered probe. Electron stepping was effectively used to determine particle charge ±10 charges, and mass ±0.01 picogram.; The macroscopic isotherm of cesium hydroxide, CsOH, was studied with the Cahn 2000 electrobalance, as a necessary prerequisite to study of CsI. Cesium hydroxide is a significant component of the containment aerosol inventory during a reactor accident. It is the planned primary aerosol specie to study in future work. CsOH presented several challenges in physically handling the as it is the strongest base known, solutions of it will etch glass. The corrosiveness of CsOH required a platinum-weighing dish in the Cahn 2000 to perform isotherm measurements.; Isotherm data obtained on CsI in the electrodynamic balance indicated a charge dependent adsorption effect for water vapor. The 6000 surface charges measured on the CsI particle by electron stepping in the electrobalance significantly increased the multi-layer adsorption of water compared to the uncharged CsI measured in the Cahn 2000. Chemisorption was also indicated for charged and uncharged CsI, as evidenced by the inability to completely regenerate in either case. The charge effect on water adsorption by CsI and other aerosol species may have a significant effect on the way that computer codes such as CONTAIN and AEROSIM calculate the release of radioiodine from a Pressurized Water Reactor (PWR) containment building following a transient. The study of other aerosol species, and the use of Mie scattering measurements to assess the size and rate of growth of these species in future work will more accurately define the release of radioiodine following a PWR transient. |
