Cesium vapor source based on gas-regulated heat pipe for an autonomous thermionic egc

Abstract

The results of work on the development of a source of cesium vapor for a thermionic EGC based on a gasregulated heat pipe and investigations of its basic technical characteristics in the cesium vapor range 30-700 Pa are presented. It is shown that the evacuation capacity and zero response time of a gas-regulated heat pipe based vapor source and the possibility of continuously monitoring the cesium vapor pressure via the temperature in the adiabatic zone and the pressure in the gas reservoir are all effective.One-and multiple-element electricity generating channels (EGCs) are used in different space nuclear power facilities and have been tested in our country for more than 40 years. Over this period of time, a great deal of operating experience has been gained and the general features of complicated experiments and individual features inherent to different designs of EGCs have been determined [1][2][3].An EGC consists of a cylindrical emitter with nuclear fuel and a collector which are separated by an interelectrode gap into which cesium vapor flows for efficient conversion of the heat produced from the decay of nuclear fuel into electricity. In most cases, thermostats with liquid-metal cesium are used as the cesium vapor generator. However, the most promising arrangement is a source of cesium vapor based on a gas-regulated heat pipe [4]. A cesium vapor generator for EGC satisfying the following requirements has not yet been developed: 1) stable feeding of cesium vapor and maintenance of the required (optimal) constant pressure of the cesium vapor fed into the interelectrode gap during the entire service life of the thermionic electricity generating channel;2) possibility of continually removing the residual gases and gaseous fission products of the fuel from the interelectrode gap.The first experiment in using a gas-regulated heat pipe as a cesium vapor generator for thermionic EGC was positive [5].In the present paper, the results of an investigation of the serviceability of a cesium vapor generator based on a gasregulated heat pipe are presented. Such systems for feeding cesium vapor can be used to develop autonomous thermionic EGC, which will make it possible to increase substantially the reliability of the entire thermionic nuclear energy facility.The gas composition in the interelectrode space of the converter has a large effect on the serviceability of an EGC. An analysis from this point of view of a gas-regulated heat pipe as a source of cesium vapor shows that, simultaneously with stable feeding, uncondensible gases are continually removed by diffusion from the interelectrode space by analogy with the action of a steam jet pump occurs. The evacuation action of the cesium vapor source based on the gas-regulated heat pipe was analyzed according to the scheme displayed in Fig. 1.