Izvestia Vysshikh Uchebnykh Zawedeniy. Yadernaya Energetika

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

Computer modeling of thermal processes with calcium, strontium and cesium radionuclides when radioactive graphite is heated in the carbon dioxide atmosphere

3/22/2017 2017 - #01 Modelling processes at nuclear facilities

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

DOI: https://doi.org/10.26583/npe.2017.1.07

UDC: 541.13+11

Nuclear power plants are one of the main sources of power generation. In designing nuclear reactors, no technical solutions for decommissioning were provided, nor were there safe technologies of handling irradiated reactor graphite. Decommissioning of uraniumgraphite reactors represents a complex of difficult tasks connected with the choice of optimum ways and methods for handling radioactive graphite. Computer modeling of reactor graphite processing by heating in carbon dioxide makes it possible to determine the behavior of radioactive elements. Using computer modeling, the behavior of Ca, Sr and Cs was studied when the radioactive graphite was heated in the carbon dioxide atmosphere. It is found that calcium is present as vapors (Ca, CaO, CaCl, CaCl2), ions (Ca+, CaO+) and condensed forms (CaCO3, CaCl2, CaO). Strontium is present as vapors (Sr, SrO, SrCl, SrCl2), ions (Sr+, SrO+) and condensed forms (SrCl2, SrCO3, SrO). Cesium is present as vapors (Cs, CsCl), ions (Cs) and a condensed form (CsCl2). The main reactions are identified and their equilibrium constants are determined. The obtained data show that, at temperatures of 573 to 973 K, vapors of calcium, strontium and cesium chlorides are generated. A temperature increase to 1373 K leads to the thermal ionization of cesium chloride and formation of ionized cesium. A temperature increase to 2273 K results in the thermal ionization of strontium and cesium and formation of ionized calcium and strontium.

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thermodynamic modeling thermal processes equilibrium constant radionuclides radioactive graphite heat carbon dioxide