Abstract
The problem of closing the nuclear fuel cycle is not only related to the development of new types of nuclear fuel and the operation of fast neutron reactors, but also to the complex schemes for the pyrochemical reprocessing of spent nuclear fuel (SNF), which, in turn, require adherence to strict process parameters. In particular, this concerns the operation of the reduction of oxidized SNF mainly by metallic lithium. The paper presents the basic scientific principles and the results of experimental verification of the operation of an electrochemical sensor for measuring oxygen in molten salts in pyrochemical reactors for the reprocessing of spent nuclear fuel. The sensor design consists of two combined electrochemical cells based on the solid electrolyte ZrO2-Y2O3 with a common reference electrode. The sensor allows continuous measurement of the oxygen activity in the oxide-chloride melt and the partial pressure of oxygen in the gas atmosphere above the melt directly during the process of pyrochemical processing. Experimental verification of the sensor performance was performed in a reactor with LiCl-Li2O melts at a temperature of 650 ° C. The resource of continuous sensor operation exceeded 500 hours, and the number of thermal cycles without destruction was at least 20. The sensor readings were found to depend on the specified Li2O content in the LiCl melt.
Highlights
Currently, in a number of countries, complex schemes are being developed for the pyrochemical processing of spent nuclear fuel (SNF), including a number of technological operations in reactors with molten salts and strictly controlled inert atmosphere [1,2,3]; the efficiency and technological parameters of this operation are largely determined by the oxygen content of the salt melt and the partial pressure of oxygen above the melt
This paper demonstrates the basic principles of operation and presents an experimental verification of the performance of an electrochemical sensor with two electrochemical cells for measuring the oxygen content of a LiClLi2O melt and the atmosphere above it in a laboratory reactor at 650 ° C
The tests have shown that the oxygen sensor in the LiCl-Li2O melt reacts to changes in the concentration of Li2O oxide, while in the measured range the dependence of the EMF 2 sensor on the content of Li2O is linear and reproducible
Summary
In a number of countries, complex schemes are being developed for the pyrochemical processing of SNF, including a number of technological operations in reactors with molten salts and strictly controlled inert atmosphere [1,2,3]; the efficiency and technological parameters of this operation are largely determined by the oxygen content of the salt melt and the partial pressure of oxygen above the melt. It is worth noting that in the case of the reduction of oxidized SNF, the control and maintenance of a given concentration of oxygen ions in the melt in a certain range are necessary. When performing other operations (electrorefining, chlorination), the presence of oxygen in chloride melts is extremely undesirable and control of oxygen content is necessary.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
