No abstract available

No abstract available

[en] This communication is dedicated to an examination of copper corrosion products (CP) in the conditions of real aqueous-chemical regime (ACR) parameters. The deposition of these CP in steam-generating zones (up to 85% of their total amount) stimulate local types of corrosion. The solubility in Cu CP (Cu₂O, CuO, Cu(OH)₂)-water (H₂O)-gas (H₂, O₂)-conditioning additives (HCl, KOH) systems was determined by computer modeling according to the minimum Gibbs energy criterion on the basis of selected and matched thermodynamic constants for various chemical forms of copper under standard conditions. As a result of the authors' calculations they obtained the solubilities in water of CuO, Cu₂O and Cu(OH)₂ when changing the dosage of active gases from 0 to 10^-2 mole/kg of water, of acid or equal to that of saturated vapor of pure water. Thus, they were able to monitor the behavior of copper CP in conditions modeling those of real ACR in operating heat exchange units, including in conditions deviating from the standard

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[en] Copper corrosion products (CP) solubility under state parameters of actual aqueous chemical regimes (ACR) whose sedimentations in the steam-generating sections (up to 85 % of the total amount) stimulate local corrosion types, is considered. The consideration from the viewpoint of equilibrium thermodynamics of chemical equilibria in multicomponent water-salt systems in their refraction for intracontour corrosion processes and mass transfer permits to obtain the missing information in the quiding materials on ACR and explains technical consequences of variations in the normalized parameters

[en] To improve water-chemical NPP regimes calculations of iron solubility up to 600 K temperature in Fe₃O₄-H₂O-O₂ and Fe(OH)₃-H₂O systems are performed using a system of selected and consistent values of thermal constants of various chemical iron forms in standard aqueous solution state. Calculations have shown that up to 423 K in aqueous medium containing oxygen, magnetite is unstable and is oxidized first up to Fe(OH)₃ and then - up to Fe OOH and Fe₂O₃. Calculations complying with experimental data have demonstrated the presence of maximum on the curve solubility-temperature in desalinized water containing 10 μkg/kg of oxygen. A sequence of processes of oxygen effect on water regime and corrosion prduct deposition in a condensate-feed circuit of NPP boiling reactor is proposed. It is proved that under oxygen water chemistry of condensate-feed circuit after magnetite transfomation into gematite, reduction of soluble iron form inlet to reactor loop occurs, which allows one to expect reduction of γ-radiation dose rate buildup around the primary loop pipelines

[en] To simulate construction material corrosion product mass transfer model in power plant circuits calculation of iron oxide and hydroxide solubility, depending on water chemistry parameters: temperature, pH-value, content of dissolved in water hydrogen and oxygen, is carried out

[en] Two steps may be singled out in this proposed approach to formulation of an informationally controlling model of the water-chemical regime of the circuit. The first is calculation of the solubility of the corrosion products (singly or jointly) under circulation conditions, and the second is establishment, on the basis of a physicochemical model, of quantitative relationships between the solubility, corrosion, and mass transfer of the CP of the structural material. This approach proved successful, i.e., a quantitatively calculable relationship exists between intracircuit corrosion-erosion processes and the equilibrium solubility of the stable corrosion product or a corrosion product controlling the solubility or iron. The present communication is concerned only with examination of the solubility of the products of iron corrosion. The degree of development of the model and the ultimate aim of the predication are determined by the problem at hand. The calculations presented may serve as the fundamental basis for construction of a complete model of mass transfer of CP in the circuits, supplementation of which by thermal hydraulic, including purely mathematical, modeling would lead to creation of information-control systems for maintaining the quality of the WCR of operating power plants

[en] The existence of the quantitative correlation between mass transfer and equilibrium solubility of corrosion products of construction materials in water circuits of power plants is shown. Thermodynamic and mathematical methods of modeling and calculating for these processes are developed. The results for iron based materials - aqueous solution systems in a wide range of temperature, pH, oxygen-hydrogen concentrations are presented. The optimization conditions for mass transfer, sedimentation of corrosion products for BWR, PWR reactors, etc. have been obtained

[en] The thermodynamic analysis of the behaviour of boiling water reactor coolant on the basis of solubility in Fe₃O₄-H₂O-O₂ system is performed for the purpose of establishing the iron existence forms in non-sedimentated suspended corrosion product particles as well as iron concentration of corrosion origin in power plants. It is shown that the iron solubility in the considered system with temperature variation occurs through the maximum at 423 K. Below this temperature the crystal Fe(OH)₃ is responsible for its value, at higher temperatures - magnetite. The growth of equilibrium oxygen concentration from 0.1 to 1000 μg/kg H₂O only slightly increases the magnetite solubility