Multi-component Liquid Metal Coolants with Regulated Properties for Space Nuclear Reactors in a Large Orbital Station D.N.KAGAN* SUMMARY The method of experimental investigation of thermodynamic functions of multi-component liquid-metal systems on the basis of alkali and alkali earth metals is proposed and realized. Being both high temperature and low temperature coolants simultaneously, these systems can be used for nuclear and solar power installations in space. Introduction These systems are the basis of the new kind of coolants and working fluids for energetics and technology. The method is based on calculation of characteristic functions (potentials) in the broad area of temperatures and concentration by integration of differential equations of chemical thermodynamics with experimental determination of: 1) under integral functions (partial and integral enthalpies of formation in all areas of named parameters of state) 2) boundary conditions (concentration dependencies of activities or Gibbs energies at one (not high) reference temperature T j = 400 K ). The advantages of this algorithm, which can be provided with reliable input experimental data and permits one to obtain an internally consistent thermodynamic description of the studied systems, are demonstrated. For solution of both experimental tasks, two groups of installations were constructed. The first group includes a complex of calorimetric apparatae with a level of sensitivity permitting the determination of the integral and partial enthalpies of formation of liquid-metal systems. The second group is based on determination of the activities of the components via partial pressure of the saturated vapor obtained by measurement of the intensity of their atomic flows. The data for the thermodynamic functions in the range 0 < Xj < 1 and 200 < T < 1500 K are obtained. All the data at high and extremely low temperatures were absent in literature. Physical interpretation of results are submitted. * Institute for High T emperatures of the Russian Academy of Sciences IVTAN, Izhorskaya, 13/19, Moscow, 127412, Russia
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