Solubility of xenon in liquid sodium

Abstract

The solubility of xenon In liquid sodium was measured as a function of pressure (2-8 atm) and temperature (350-600°C). Henry's law was obeyed with the value of the Henry's law constant, KH = %,/P, ranging from 1.38 X atm-' at 600°C, where be and Pare the atom fraction and the partial pressure of xenon, respectively. The temperature dependence of solubility may be represented by loglo = (0.663 f 0.01) -(4500 f 73) T1, where X Is the Oslwald coefficient (the volume of xenon dissolved per unit volume of sodium at the temperature of the experiment). The heat of solution of xenon In sodium was 20.6 f 0.7 kcal/mol, where the standard state of xenon is defined as that of 1 mol of an ideal gas, confined to a volume equal to the molar volume of sodium.atm-I at 350°C to 1.59 X The solubility of noble gases in liquid sodium is of considerable interest because of the use of sodium as a coolant in nuclear fission reactors. Helium and argon are frequently used as sodium blanketing gases, and krypton and xenon are fission product gases which may be released to sodium from the fuel-pins. The solubilities of helium and argon in liquid sodium have been reported (9, 70), and that of krypton has been determined ( 7 ) . Measurement of the solubility of xenon was undertaken to provide data necessary for the evaluation of the consequences of fuel-pin cladding failure. ExperimentalReference 70 describes the details of the method used for the determination of the trace solubilities of gases in liquid metals and shows a schematic diagram of the solubility apparatus. In the present application, the procedure was as follows. Approximately 2500 cm3 of liquid sodium contained in a large vessel (saturator) was saturated with natural xenon at a preselected temperature and pressure by circulating the gas through the liquid via a coiled, perforated tube placed near the bottom of the saturator. A measured amount (-1500 cm3) of the saturated sodium was then transferred to another vessel (stripper) via a heated, valved Y4-in. sodium-transfer line which interconnected the bottom plates of the vessels. The volume of sodium transferred was calculated from the known geometry of the stripper and the liquid levels of sodium before and after transfer. The levels were measured with a Mine Safety Appliances Corp. liquid level probe operating on the capacitance principle.In the stripper the dissolved gas was separated from sodium by sparging with helium, which was introduced through an immersed 1 0-cm stainless-steel dispersion disc (Micrometallic Corp., 5-pm mean pore size). The resulting xenon-helium mixture was then slowly exhausted through a 6-mm X 8-cm column of activated silica gel cooled to -196OC, on which the xenon was adsorbed while most of the helium passed through unadsorbed. The gel was then heated at 3OO0C and the desorbed gas, now enriched in xenon, was analyzed for xenon with a Beckman GC-5 gas chromatograph used in conjunction with an electron capture detector.' To whom correspondence should be addressed.In this procedure the following precau...

Henry's Law: A Retrospective

“…It may be that we were unable to obtain a horizontal asymptote in plots of p͞X against X for the vapor pressures of chloroform-acetone solutions because there were not data at sufficiently low values of X to demonstrate the validity of Henry's law. Certainly, many examples exist in the literature in which the authors claim that they have demonstrated that Henry's law is followed in the system studied (2,15,16), usually by plotting pressure against mole fraction and seeing a straight line. We have seen that Giacobbe (2) correctly concluded that solutions of CO 2 in acetone follow Henry's law at pressures below 10 atmospheres.…”