Izvestiya vuzov. Yadernaya Energetika

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

Computer-simulated thermodynamic behavior of radionuclides U, Cl, Pu, Be, Ni, Am when radioactive graphite is heated in a carbon dioxide atmosphere

6/24/2019 2019 - #02 Modelling processes at nuclear facilities

Barbin N.M. Sidash I.A. Terentiev D.I. Alekseyev S.G.

DOI: https://doi.org/10.26583/npe.2019.2.16

UDC: 541.13+11

The article examines the computer-simulated thermodynamic behavior of radionuclides U, Cl, Pu, Be, Ni, and Am when radioactive graphite is heated in a carbon dioxide atmosphere over a wide temperature range.

The aim of the work is to estimate the equilibrium composition of the gas and condensed phases during a probable beyond design basis accident or reactor graphite reprocessing. Since graphite is a prevalent material of both decommissioned and advanced reactors, the formation of such a high-temperature system is not excluded. Obtaining such information about the composition of its phases by experimental methods can be difficult for many reasons, which makes it preferable to use complete thermal analysis methods to study the equilibrium behavior of this system.

The system thermodynamics in the equilibrium state was simulated by means of the TERRA computer software package involving the methodology of the model of ideal solutions for interaction products to estimate the equilibrium composition of the resulting phases. The calculations used sets of thermodynamic properties of individual substances from the IVTANTERMO and HSC databases.

It has been established that, in the studied high-temperature system, radionuclides U, Cl, Pu, Be, Ni, and Am as well as graphite are present in the condensed solution only in lower or average temperature ranges and, as equilibrium temperatures further increase, they are able to turn to gas forms. The study made it possible to define a set of basic reactions involving the above-mentioned radionuclides, determine the temperature ranges of their implementation and calculate their equilibrium constants.

Carbon dioxide in the upper region of equilibrium temperatures should not be regarded as inert with respect to graphite and especially radionuclides.

References

  1. Key Results of Rosatom Activity in 2015. Available at: http://www.rosatom.ru/about/ (accessed Jul 20, 2018) (in Russian).
  2. GEN-IV International Forum: Available at: https://www.gen-4.org/gif/jcms/c_59461/generation-iv-systems (accessed Jun 20, 2018) (in Russian).
  3. Levin V.Е. Nuclear Physics and Nuclear Reactors. Moscow. Atomizdat Publ., 1979, 288 p. (in Russian).
  4. OPB-8897. Federal Standards and Rules of Use of Atomic Energy. General Provisions of Safety of Nuclear Power Plants. Available at: https://files.stroyinf.ru/Data2/1/ 42948484294848446.htm/ (accessed Jul 20, 2018) (in Russian).
  5. Bukrinskij A.M. Management of Beyond Design Basis Accidents in the Existing Normative Documents of Russia. Yadernaya i radiatsionnaya bezopasnost’. 2010, no. 1, pp. 16-25 (in Russian).
  6. Skachek M. A. Treatment of the Fulfilled Nuclear Fuel and Radioactive Waste of the NPP. Moscow. MEI Publ., 2007, 448 p. (in Russian).
  7. Barbin N.M., Sidash I.A., Terent’ev D.I., Alekseev S.G. Computer modeling of thermal processes with participation of radionuclides of calcium, strontium and caesium when heating radioactive graphite in the atmosphere of carbon dioxide. Izvestiya vuzov. Yadernaya Energetika. 2017, no. 1, pp. 73-82 (in Russian).
  8. Vatolin N.A., Moiseev G.K., Trusov B.G. Thermodynamic Modeling in High-Temperature Inorganic Systems. Moscow. Metallurgiya Publ., 1994, 352 p. (in Russian).
  9. Moiseev G.K., Vyatkin G.P., Barbin N.M. Application of Thermodynamic Modeling for Studying of Interaction Taking Into Account Ionic Fusions. Chelyabinsk. YuUrGU Publ., 2002. 166 p. (in Russian).
  10. Belov G.V., Trusov B.G. Thermodynamic Modeling of Chemically Reacting Systems. Moscow. MGTU im. N.E. Baumana Publ., 2013, 96 p. (in Russian).
  11. Barbin N.M., Kobelev A.M., Terent’ev D.I., Alekseev S.G. Thermodynamic Modeling of Thermal Processes with Participation of Radionuclides of Chlorine, Calcium, Beryllium, Nickel, Caesium when Heating Radioactive Graphite in Water Vapors. Radiokhimiya. 2019, v. 61, no. 2, pp. 142-147 (in Russian).
  12. Barbin N.M., Kolbin T.S., Terent’ev D.I., Alekseev S.G., Spiridonov M.A. Thermodynamic Modeling of Radioactive Graphite Heating in the Atmosphere of Argon. Teplofizika vysokih temperatur. 2018, v. 56, no. 5, pp. 751-763 (in Russian).
  13. Barbin N.M., Kolbin T.S., Terent’ev D.I., Alekseev S.G., Kajbichev I.A. Thermal and Heatphysical Properties of a System Radioactive Graphite - Inert Gas When Heating. Computer Experiment. Inzhenerno1fizicheskij zhurnal. 2018, v. 91, no. 4, pp. 1139-1149 (in Russian).
  14. Barbin N.M., Kobelev A.M., Terent’ev D.I., Alekseev S.G. Thermodynamic modeling of thermal processes with participation of actinides (U, Am, Pu) when heating radioactive graphite in water vapors. Radiokhimiya. 2017, v. 59, no. 5, pp. 445-448 (in Russian).
  15. Myshkin V.F., Han V.A., Plekhanov V.G., Izhojkin D.A., Bespala Е.V. Spin Separation of Isotopes at Incomplete Oxidation of Carbon in Low-Temperature Plasma in External Magnetic Field. Izvestiya vysshih uchebnyh zavedenij. Fizika. 2014, v. 57, no. 10, pp. 127-132 (in Russian).
  16. Bobrakov A.N., Kudrinskij A.A., Pereslavcev A.V., Polkanov M.A., Shiryaevskij V.L., Artyomov A.V. The Thermodynamic Analysis of Processes of Plasma Processing of Low-Radioactive Waste in Mine Furnaces. Rossijskij khimicheskij zhurnal. 2013, v. LVII, no. 5, pp. 97-103 (in Russian).
  17. Sinyarev G.B., Vatolin N.A., Trusov B.G., Moiseev G.K. Use of Computers for Thermal Calculations of Metallurgical Processes. Moscow. Nauka Publ., 1982, 267 p. (in Russian).
  18. Bazhenov V.A., Buldakov L.A., Vasilenko I.Ya. Harmful Chemicals. Radioactive Materials. Leningrad. Khimiya Publ., 1990, 189 p. (in Russian).

thermodynamic simulation thermal processes equilibrium constant radionuclides radioactive graphite heating carbon dioxide