Study of cesium volatility from sodium carbonate based melts
Purpose of this study was to obtain thermodynamic data on cesium volatility from sodium carbonate-based molten salts for application to the Rockwell-ETEC molten salt oxidation process. At 1073 to 1373 K, volatility tests were conducted on a horizontal and a vertical transpiration apparatus using a carrier gas composed of CO{sub 2}(g) and H{sub 2}O(g) which was passed over or bubbled through a sodium carbonate bath containing cesium carbonate and various additives. The major vapor species was identified to be CsOH(g) except when greater than 3% chloride is present in the melt, then the major vapor species is CsCl(g). The decrease in volatility of cesium as a function of cesium concentration in Cs{sub 2}CO{sub 3{minus}}Na{sub 2}CO{sub 3} mixtures follows Raoult`s law very closely. Thus, this system exhibits close to ideal solution behavior. Addition of 22.5 wt % sodium sulfate decreases the cesium volatility by just under a factor of 2, and the addition of 10.0 wt % sodium chloride increases the cesium volatility about an order of magnitude. The addition of 2.0 wt % ash, molecular sieve, or silica show little or no effect. However, the data indicate that higher concentrations of ash will decrease the cesium volatility. For the addition of 22.5 wt % sodium sulfate the activity coefficient, {gamma}(Cs{sub 2}CO{sub 3}){sup {1/2}}, is calculated to be 0.720 {plus_minus} 0.068, and for the addition of 10.0 wt % sodium chloride, the activity coefficient, {gamma}(CsCl), is calculated to be 8.118 {plus_minus} 2.317. Assuming that Henry`s law applies, these activity coefficients are used to extrapolate the effect on cesium retention in the molten salt oxidizer of sulfate and chloride at lower cesium concentrations.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10154136
- Report Number(s):
- UCRL-ID--115768; ON: DE94012588
- Country of Publication:
- United States
- Language:
- English
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