260 33-7= 75 I I Literature Cited A DlBENZOTHIWWNE = 70 , I I I 0 FLUORENE 0 MENZOFURAN Q 60 (1) Amerlcan Petroleum Institute. "Selected Values of Properuee of Hydrocarbons and Related Compounds"; Chem. Thermodynamk Rop. Center, API Research Project 44, Texas A 6. M Unhrerdty: Colkge Station, TX, 1971. (2) Rleveechl, (3.; Ray, F. E. (10) k i m e r , S. F.; Murphy, R. V. The thermophydcal properties (viscosity, surface tension, a d dendty) of the equimolar mixture NaNo,-KNO, have been determined over the temperature range 300-600 OC in argon and in oxygen. The surface tendon is a linear function of the temperature and can be represented by the expression y(dyn/cm) = 133.12 -(6.25 X 10-2)T(oC). The viscosity may be calculated from the equatlon q(cP) = 22.714 -0.120T + (2.281 X 10-')T2 -(1.474 X 10-')Ta, for T in OC. The dendty of the equimolar mixture k given by p(g/cma) = 2.090 -(6.36 X 104)T('C). I n contrast to the surface tendon and the viscosity, the density k affected by the presence of nitrite, the thermal decomposition product of the nitrate anion.The equimolar moiten salt mixture NaN03-KN03 is being proposed as a heat-transfer fluld and a thermal-energy storage medium for various solar energy applications. I n these applications the maximum operating temperature will be in the range 500-600 OC. Industrial experience and previous experimental investlgations on this moiten salt mixture have generally been confined to temperatures below 450 OC. I n order to provkle data to solve various specific design problems associated with the use of these molten nitrate saits as heattransfer fluids, it is important that we know how the physical properties of these saits are affected by temperature and composition of the liquid and gas phases. I t is the purpose of this report to present and comment on the viscosity, surface tension, and density data which we have measured for equimolar NaN0,-KNO, over the temperature range 300-600 OC. Apparatus and Expertmental TechniqueThe thermophysical-property data for the equimolar NaN-O3-KNO3 mixture were taken by an instrument designed and bullt by the author at SNLL. This instrument is based on the principle of a damped, onedimenslonal, harmonic oscillator, i.e., the motion of a body suspended from a spring and Oscillating in a fluid. A description of the theoretical principles which govern the operating of this instrument, the details of construction, and its operation and response are discussed elsewhere ( 7 , 2). Only an abbreviated description of the various modes of operating of this instrument will be given here.The heart of the apparatus is a quartz spring oscillator, an electromagnet for remotely starting the spring oscillating, a position transducer for remote readout of the spring extension (ilnear variable differential transformer (LVDT)), and a gold plate suspended in a liquid whose vlscosity is being measured (see Figure 1). It is the viscous drag exerted on this plate by the liquid which causes damping of the oscillatory motion of the quartz spring.The rate of dampi...

By chemical analysis of samples taken under carefully controlled conditions, we have been able to show that the only reaction of any consequence that takes place in the equimolar binary NaN03-KN03 system over the temperature range °C is represented by N03~< =* N02~+ V202. Over this temperature range there is no evidence of the formation of any anionic oxygen species such as oxide, peroxide, or superoxide at concentrations greater than 10~5 mol/kg. Equilibrium constants for the above reaction have been determined over the temperature range 500-600 °C. The standard free energy for this reaction [ °(keal/mol) = 23 000 + 20.6 T) has been derived from the experimental data and is in good agreement with similar results for the single salts. A study of the kinetics of the oxidation of nitrite showed the rate of that reaction to be overall second order, first order with respect to both nitrite and oxygen. The rate constants have been measured from 400 to 500 °C, and from their temperature dependence the activation energy for the oxidation of nitrite was calculated: 26.4 kcal/mol.

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The thermal decomposition of Pu(C204).. 9 6H20 has been studied in both argon and oxygen using a combination of thermogravimetry and infrared spectroscopy. Decomposition in an inert atmosphere involves reduction of the cation to the trivalent state and its subsequent reoxidation to form PuO 2. In an oxidizing atmosphere, with unrestricted access of oxygen, reduction of the cation does not take place and decomposition to PuO 2 is through the oxycarbonate. The reduction of Pu(IV) appears to take place by a carbon monoxide catalyzed mechanism and the presence of carbort in the PuO,, decomposition product is attributed to the disproportionation of CO.Of the several processes used to prepare plutonium metal the most widely used involves the thermal decomposition of Pu(C204)2 " 6 H20 to the oxide (PuO2),. fluorination of the oxide to PuF 4 and the subsequent reduction of the fluoride to the metal with calcium. One particular disadvantage of this process is that the carbon which apparently arises as a consequence of the thermal decomposition of the oxalate, is carried through the process and appears as an impurity in the plutonium metal product. To aid in the removal of this carbon impurity the thermal decomposition of Pu(C20~)2 ' 6 H20 is done in air at 300 to 400 ~ Several earlier studies have been done on this process [1][2][3][4][5][6]. However, the interpretations were at variance with each other and as Glasner points out [7], the thermogravimetric results have had little support by other experimentation or observation.The present study makes use of both infrared spectroscopy and thermogravimetric techniques to follow the thermal decomposition of Pu(C20~)~" 6 H20 in both argon and oxygen to try to define explicitly the source of the carbon and to determine the effect, if any, of oxygen on the mechanism of the thermal decomposition of Pu(C~,O4h" 6 H20 itself. ExperimentalThe starting material, Pu(C2Oa)2 " 6 H20, was prepared by the method described by Harmon and Reas [8]. Briefly, this involved adding 1 M H~C204 and H202, for valence adjustment, to a Pu(NOa)4 solution (~ 4 M HNO~) held at 50 -55 ~

A self-consistent anode mechanism is proposed for the Ca/LiCI-KCI/ CaCrO4 thermal battery based on the results of single cell discharges and chemical analysis of the reaction products at the electrode-electrolyte interface. The proposed mechanism involves a combination of chemical reaction between the calcium anode and the lithium chloride in the electrolyte and electrochemical oxidation of the resulting calcium-lithium alloy.Because of its desirable characteristics of high reliability, long shelf life, a wide operating temperature range (--54 ~ to 71~ and ruggedness, the Ca/LiC1-KC1/CaCrO4 electrochemical system has been used for a number of years to provide power for various ordnance applications (1, 2). In these applications this system takes the form of a thermally activated pri-