Izvestia Vysshikh Uchebnykh Zawedeniy. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Conceptual capabilities of a pyroelectrochemical technology for the thorium engagament in the fast neutron reactor fuel cycle

11/15/2018 2018 - #04 Fuel cycle and nuclear waste management

Naumov V.S.

DOI: https://doi.org/10.26583/npe.2018.4.04

UDC: 621.039.534

The use of thorium in a combination with plutonium in nuclear power offers a solution to the problem of reducing the accumulation of long-lived transplutonium nuclides. Along with this, the existing uranium fuel cycle (UFC) has such disadvantage as vulnerability to unauthorized use of nuclear materials. The thorium fuel cycle (TFC) does not have these drawbacks.

The engagement of thorium in nuclear power is possible provided there is a respective technology to reprocess irradiated thorium. A fuel cycle based on thorium oxide may not differ in principle from the developed pyrochemical fuel cycle containing uranium and plutonium oxides. In a compact state, it is by electrolysis of molten salts from thorium-containing electrolytes that thorium oxide is most commonly obtained. Most of the studies into the physicochemical and electrochemical behavior of thorium in molten haloids of alkali and alkaline-earth metals were conducted in the 1960s and the 1970s.

Since an extensive experimental material has been accumulated by now to justify the use of pyroelectrochemical and chemical processes for regeneration of fuel in molten salts, then it has also been proposed that technologies to reprocess fuel in molten chlorides of alkali metals should be used resulting in a crystalline product that can be used for the fuel element fabrication.

Unlike uranium and plutonium, thorium has a simpler behavior in molten salt environments. In molten salts, thorium exists predominantly in the form of Th4+, and the mixture of uranium and thorium dioxides with a content of ThO2 of up to 50% can be obtained by electrolysis of molten salts.

Therefore, the existing amount of knowledge about the chemistry of thorium allows one to regard the use of pyrochemical processes in production of thorium oxide as highly promising, and the available data on the physicochemical properties of thorium and its compounds in high-temperature molten salts makes it possible to state that the pyroelectrochemical technology can be potentially used in production and reprocessing of thorium fuel.


  1. Murogov V.M., Troyanov M.F., Shmelev A.N. The use of thorium in nuclear reactors. Moscow. Energoatomizdat Publ., 1983, 96 p. (in Russian).
  2. Kang J. and von Hippel F.N. U-232 and the Proliferation Resistance of U-233 in Spent Fuel. Science and Global Security. 2001, v. 9, pp. 1-32.
  3. Alekseev P.N., Glushkov E.S., Morozov A.G., Ponomarev-Stepnoj N.N., Subbotin S.A., Zhurikov D.F. Тhe Concept of possible involvement of thorium in the nuclear power sector. Izvestia Visshikh Uchebnhikh Zavedeniy. Yadernaya Energetika. 1999, no. 1, pp. 10-18 (in Russian).
  4. Chang Y.I. The Integral Fast Reactor. Nucl. Technol. 1989, v. 88, no. 129, pp. 161-170.
  5. Skiba O.V., Savochkin Yu.P., Bychkov A.V., Porodonov P.T., Babikov L.G. and Vavilov S.K.Technology of Pyroelectrochemical Reprocessing and Production of Nuclear Fuel. Proc. Int. Conf. on Future Nuclear Systems: Emerging Fuel Cycles & Waste Disposal Options (GLOBAL’93), Sept.12-17, 1993 Seattle, Washington, 1993, v. 2, pp. 1344-1349.
  6. Inoue T. and Tanaka H. Recycling of Actinides Produced in LWR and FBR Fuel Cycles by Applying Pyrometallurgical Process. Int. Conf. on Future Nuclear Systems (GLOBAL’97), Oct. 5-10, 1997, Yokohama, Japan, 1997, v.1, pp. 646-650.
  7. Smirnov M.V., Yudina L.D. Equilibrium potentials of metals in molten electrolytes. 1. Equilibrium potentials of thorium in chloride melts. Izvestiya AN SSSR, Otdelenie khimicheskikh nauk. 1959, no. 2, pp. 251-258 (in Russian).
  8. Smirnov M.V., Kudyakov V.Ya., Posokhin Yu.V., Chukreev N.I., Krasnov Yu.N. Electrochemical behavior of thorium in sodium chloride and equimolar mixture of the chlorides of sodium and potassium. Atomnaya energiya. 1970, v. 27, no. 4, pp. 419-423 (in Russian).
  9. Smirnov M.V., Kudyakov V.Ya., Posokhin Yu.V., Shishkin V.Yu. Study of physical, chemical and electrochemical behavior of thorium in melts of alkali metal halides. Radiokhimiya. 1976, v. 18, no. 4, pp. 639-647 (in Russian).
  10. Kudyakov V.Ya., Smirnov M.V., Chukreev N.I., Posokhin Yu.V. Formation of bivalent thorium in the medium of molten potassium chloride. Atomnaya energiya. 1968, v. 24, no. 4, pp. 448-452 (in Russian).
  11. Kudyakov V.Ya., Smirnov M.V., Posokhin Yu.V., Krasnov Yu.N. The equilibrium of a metal thorium with melts of alkali metal chlorides containing its ions. Trudy Instituta Electrokhimii UNC AN SSSR, Sverdlovsk, 1972, no. 18, pp. 27-32 (in Russian).
  12. Emelyanov V.S., Evstyukhin A.I. Investigation of molten salt systems based on fluoride thorium. Message 1. Atomnaya energiya. 1956, v. 1, no. 4, pp. 107-112 (in Russian).
  13. Emelyanov V.S., Evstyukhin A.I. Investigation of molten salt systems based on fluoride thorium. Message 2. Atomnaya energiya. 1956, v. 1, no. 5, pp. 80-85 (in Russian).
  14. Vokhmyakov A.N., Desyatnik V.N., Kurbatov N.N. Interaction of thorium tetrachloride with alkali metal chlorides. Atomnaya energiya. 1973, v. 35, no. 6, pp. 424-423 (in Russian).
  15. Smirnov M.V., Kudyakov V.Ya., Solyulev A.B. The Volatility of the Tetrachloride of Uranium and Thorium from their Molten Mixtures with Alkali Metal Chlorides. / Second all-Union conference of uranium chemistry (16-18 October 1978, Moscow). Abstracts of reports. Moscow. Nauka Publ., 1978, pp. 93-94 (in Russian).
  16. Chiotti P., Jha M.C., Tschetter M.J. Reation of Thorium and ThCl4 with UO2 and (Th, U)O2 in Fused Chloride Salts. J. Less-Common Metals, 1975, v. 42, no. 1, pp. 141-161.
  17. Voronov N. M., Sofronova R.M., Voitekhova E.A. High-temperature chemistry of uranium oxides and their compounds. Moscow. Atomizdat publ., 1971, 360 p. (in Russian).
  18. Baraboshkin A.N. Electrocrystallization of metals from molten salts. Moscow. Nauka Publ., 1976, 279 p. (in Russian).
  19. Baraboshkin A.N., Puzakov V.V. Martem’yanova, Z.S. The Structure of uranium dioxide precipitation obtained by the electrolysis of molten mixture potassium, lithium and uranium chlorides. Trudy Instituta Electrokhimii UNC AN SSSR, Sverdlovsk. 1971, no. 17, pp. 108-117 (in Russian).
  20. Kotel’nikov R.B., Bashlykov S.N., Kashtanov A.I., Men’shikova T.S. High-temperature nuclear fuel. Moscow. Atomizdat Publ., 1978, 432 p. (in Russian).

thorium oxide fuel thorium fuel cycle options pyroelectrochemical processes electrochemical behavior of thorium fuel reprocessing