Alkali metal detectors for coolant leakage monitoring in thermionic nuclear power systems

The paper presents results of development of alkali metal detectors based on laminated compositions with a sensing element of a thin-film graphite coating. Results of bench tests of the detectors with leakage of various alkali metals, including lithium, are described. Experimental results are presented for the use of the detectors in bench investigations of thermionic fuel elements (TFE) with liquid metal cooling circuit. Basic technical characteristics of this class of detectors are determined from the investigations performed. A design is presented of a working medium (cesium) absorber unit intended for sorption and assessment of mass of cesium consumed during operation of a thermionic nuclear power system (NPS) for spacecraft. The paper also discusses promising materials for the sensing element of the detector.