Thermodynamic Analysis of the Oxidation of Radioactive Graphite in a Multicomponent Melt in an Inert Atmosphere

• Published in: Russian metallurgy Metally 2018-08, Vol.2018 (8), p.700-706
• Main Authors: Barbin, N. M., Kobelev, A. M., Terent’ev, D. I., Alekseev, S. G.
• Format: Article
• Language: English
• Subjects: Americium; Beryllium oxide; Calcium compounds; Carbon dioxide; Carbon monoxide; Cesium compounds; Chemistry and Materials Science; Chlorine compounds; Europium compounds; Evaporation; Graphite; Inert atmospheres; Materials Science; Mathematical analysis; Metallic Materials; Oxidation; Plutonium; Potassium carbonate; Radioactive wastes; Reclamation; Sodium carbonate; Sodium chloride; Strontium oxides; Uranium; Vapor phases; Vapor pressure
• ISSN: 0036-0295; 1555-6255; 1531-8648
• DOI: 10.1134/S0036029518080025

Graphite occupies a specific place among the entire mass of accumulated radioactive wastes. The problem of reclamation of spent graphite has not yet been solved in the world. The behavior of radioactive graphite in the multicomponent CuO–NaCl–KCl–Na 2 CO 3 –K 2 CO 3 melt in an argon atmosphere in the temperature range 373–3273 K is studied by thermodynamic simulation with the Terra software package, which is intended for calculating the phase compositions and the thermodynamic and transport properties of arbitrary systems. The calculation was performed using a database on the properties of individual substances. At 1273 K, graphite burns to form carbon monoxide and carbon dioxide. The condensed compounds of cesium, chlorine, and uranium evaporate at 1573 K. An increase in the system temperature to 1873 K leads to the vapor pressure of condensed nickel. Condensed strontium oxide transforms into a vaporized state at 2273 K. The condensed compounds of plutonium, calcium, and europium transforms into a vaporized state at 2373 K. Condensed beryllium oxide evaporates at 2473 K. A further increase in the temperature to 2673 K leads to the evaporation of condensed americium(III) oxide. Only a vapor–gas phase is present in the isolated system in the temperature range 2673–3273 K.