The problem of studying the microstructure of liquid-metal coolants by the methods of molecular dynamics and statistical geometry is formulated for engineering the structure of reactor materials. Attention is focused on the topological features of the atomic configurations of melts for lithium, sodium, and lead.Even though liquid metals have been used in nuclear technology for 50 years, little attention has been devoted to studying their microstructure and atomic dynamics. At the same time, such studies are needed to understand how doping adjusts the microstructural and thermodynamic properties of liquid metals. This is also important to be able to predict how liquid metal coolants are modified (by additives chosen beforehand) and that such coolants will behave safely in the liquid-metal loops of nuclear reactors under different operating conditions, for example, with loss-of-seal in air [1].In this connection, computer simulation of metallic melts by methods of molecular dynamics and statistical geometry deserves close attention. Molecular-dynamics models of liquid metals and computed correlation functions, verified by experimental data on the scattering of short-wavelength radiation, make it possible to predict the change in the properties of an alloy and engineer a coolant on the basis of prescribed indicators.In the present work, attention is focused on the topological features of the atomic configurations of lithium, sodium, and lead melts.Microstructure of the Liquid. It is generally accepted that the fluctuation-dense part of the liquid matrix of metals at all times consists of almost regular tetrahedra joined in pairs along the faces [2, 3]. At the same time, there is still no unique criterion for selecting these tetrahedra from a simplicial decomposition of a random packing of atoms of the liquid. The geometrical tetrahedrality factor [2] used for this purpose is not unique because it is a monotonnic function of the degree of deviation of the Dalone simplex from a regular tetrahedron (Fig. 1). A different criterion is needed to choose the dense part of a liquid matrix that is characterized by an explicit functional feature.Molecular-Dynamics Simulation of Liquid Metals. The Larsson pair potential was used for the molecular-dynamics simulation of a lead melt. The Fourier transform of the local Ashcroft potential [3] was used for alkali metals (Li, Na). The metals were modeled using the program system in [4] within the framework of the NVT ensemble in a cubic cell with edge length L and periodic boundary conditions with time step ∆t (see Table 1).The radial distribution functions g(r) of the atoms and the structure factors S(q) were calculated. The negligible differences between the structure factors obtained and the experimental curves for the metals studied attest to the fact that the correct pair potentials were chosen and that the molecular-dynamics model of the melts is adequate.Analysis of the Microstructure of the Molecular-Dynamics Model of Liquid Metals. The method of statistical geometry was used...

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Studying liquid water in a frame of band theory shows that varying a reduction-oxidation (RedOx) potential of aqueous solution can be identified as shifting Fermi level in its band gap. This medium becomes the reductive one when Fermi level is shifting to the conduction band due to populating hydroxonium level () + 3 3 3 H O , OH of these local electronic levels in the band gap of non-stoichiometric water in the corresponding solutions.

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