Hydroxides solubility, early work

Early work (53) in in-reactor fuel test loops showed that radiolytic oxygen can be suppressed by maintaining 5 to 10 cm Dg/kg DgO dissolved in the coolant and that operation at pH 10 with lithium hydroxide minimizes deposition of magnetite (Fe304) particles on the fuel sheath surfaces. These conditions minimize corrosion and correspond to a minimum solubility of magnetite. With these coolant conditions the fuel surface remains clean and heat transfer is unimpeded—they are the key to the successful use of carbon steel piping, components, and fittings for the CANDU coolant circuit. A simple and effective chemistry control and coolant purification circuit was developed (54). 

The final product mixture contains unreacted alkanes and mono- and disulfochlorides in the approximate ratio of 15 1. This mixture is saponified with 10% aqueous sodium hydroxide at 80°C. Higher temperatures should be avoided so that sulfochlorides do not undergo desulfonation [1]. Phase separation occurs in a settler—the upper and lower phases contain almost all the alkanes and chloroalkanes and the water-soluble salts (sulfonates and sodium chloride), respectively. After cooling, a second-phase separation allows to eliminate NaCl almost totally. The 20% aqueous solution of sulfonates is then fed to an evaporator working at 300-350°C (melting range of the SAS) from which a nearly dry product is recovered. Several patents, issued in the early 1990s, are related to the saponification of sulfochlorides [59-63]. 

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