Hydrogen release in the interaction structural materials based on aluminum with water in terms of light-water reactor active core
The formation of hydrogen and the risk of hydrogen explosion, the hydrogen ab-sorption of structural metallic materials is a complex problem of providing hydrogen and radiation safety of nuclear power plants (NPP) with water coolant. This problem is not thoroughly studied the process of interaction of structural materials during operation in the reactor coolant (water or steam), leading to the formation of hydrogen.
High corrosion resistance of several metallic materials provide pestiviruses oxide layers (film formed on their surface), which can be destroyed by mechanical, chemical and other influences.
So, for example, aluminum is established that in alkaline solutions with the metal surface is removed a layer of aluminum oxide Al2O3, and then the aluminum efficiently reacts with water with great release of heat, hydrogen and solid product.
Studies of the kinetics of hydrogen accumulation in hydrogenogenic compositions has allowed to figure out the patterns of the transformation process, the oxide layer of aluminium in collaboration with a number of chemical activators, water and oxygen.
Are unexplored kinetics and mechanism of transformations of the oxide layer on the surface of aluminum in the composition of the heterogeneous system aluminium – aluminium oxide – the external environment under the influence of factors of nuclear power systems in normal and incident (emergency) modes of operation.
In this work, we have investigated the kinetics of hydrogen generation gidrometeo-rologii compositions containing aluminum, pre-irradiated by γ-radiation of 60оC at room temperature in air and in aqueous media simulating the coolant of VVER reactors.
The studies were conducted using aluminum as a model in relation to the zirconium in the range of stress of metals aluminium and zirconium are close (standard electrode potential in water of aluminium – 1.66 In, zirconium – 1,59).
Found that used in the kinetic method allows to obtain valuable information about the chemical transformations of oxide layers on the surface of aluminum and zirconium and other structural materials, when exposed to factors that mimic the conditions of the active core of VVER and RBMK reactors.
The oxide layers of aluminum when exposed to factors nuclear facilities (radiation, high temperature, products of radiolysis of the water environment, oxygen) undergo transformations that lead to the violation of their continuity. Plots of the resulting "pure" metal at the defects of the structure of the damaged oxide layer diffuse water molecules, exothermic reactions which lead to corrosion of the aluminium with the formation of molecular hydrogen and solid products.
The mechanism of participation of hydrogen and solid products in the destruction of the oxide layer of aluminium is studied.
Discovered the process of transformation of the oxide layers of metals should be taken into account when developing models of corrosion of structural materials in con-ditions of complex influence of factors of the active core of the nuclear power unit.Full version (russian)