Ural Federal University: UrFU Chemists Create the Basis for a New Type of Nuclear Reactor

Employees of the Institute of High-Temperature Electrochemistry UB RAS (IHTE UB RAS) have selected the optimal composition of molten salts for nuclear reactors of a new type (liquid salt reactors). Reactors using molten salts are safer, more economical, and more environmentally friendly: in the event of an emergency shutdown, the molten salt will spontaneously solidify, and the absence of water will not lead to steam explosions a priori. Scientists all over the world are working on such reactors. There are no analogues yet.

“At the IHTE of the Ural Branch of the Russian Academy of Sciences and at UrFU, there are works that are quite significant for the Russian Federation. In particular, our researchers are studying the physical and chemical properties of molten salts, which are potential media of liquid-salt nuclear reactors,” explains Yuriy Zaykov, research supervisor of the Institute for Electrochemical Technologies at the Ural Branch of the Russian Academy of Sciences and head of the Department of Electrochemical Production Technologies at UrFU.

The molten salts, the composition of which the Urals chemists are working on, can be used both as a reactor medium and as a coolant. The development of salt mixtures with optimal properties for liquid salt reactors at the Institute of Water Physics, Ural Branch of the Russian Academy of Sciences is conducted within the framework of the Urals Interregional Research and Education Center of World Class (UIREC) Advanced Industrial Technologies and Materials.

“In liquid salt reactors, nuclear processes will take place in an environment of molten salts, which must meet a number of requirements, such as low melting point, low corrosivity, low viscosity, low vapor pressure, high heat capacity and electrical conductivity, high solubility of actinide and lanthanide fluorides, low cost, low toxicity. Potential composition of molten medium is rather limited – some fluoride, chloride, possibly nitrate salts. But by changing the content of the components in the mixture, we can obtain melts with desired properties. We selected optimal compositions of molten salts that provide the operating temperature of the reactor (500-750 °C) and have the thermophysical and hydrodynamic properties required for the heat exchange fluid,” explains Olga Tkacheva, Head of the Laboratory of Electronic Processes at the Institute of Electronic Technology of the Urals Branch of the Russian Academy of Sciences.

To study the physicochemical properties of molten salts, the laboratories of the Institute of High-Temperature Electrochemistry UB RAS have unique high-class equipment, such as a high-temperature rheometer to determine viscosity, a device to measure thermal conductivity, thermal conductivity, heat capacity at temperatures from room temperature to 1600 °C by laser flash, high-precision equipment to determine the elemental composition of substances.

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The concepts of a molten salt power reactor and a solid fuel thermal reactor emerged almost simultaneously. The world predominantly took the second path, since there were ready developments in the military nuclear program. The United States was the furthest along in the development of liquid salt reactors: in the 1960s, the Oak Ridge National Laboratory built the MSRE reactor (Molten-Salt Reactor Experiment). The reactor operated for five years, then it was stopped (due to financial unprofitability), and the program was closed. In Russia this topic has been dealt with since the 1970s. At the beginning of the 1990s, the development work also stopped. Today there is renewed interest in liquid salt reactors. In 2019, Rosatom announced plans to build a research liquid-salt reactor.

UIREC was created to unite the potential of educational and scientific organizations of the real sector of the Sverdlovsk, Chelyabinsk and Kurgan regions. Ural Federal University was the initiator of the creation and performs the functions of the UIREC project office. The idea of creating the scientific and educational center was supported by Russian President Vladimir Putin during his visit to UrFU in July 2019.

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