Managing the service life of heat-exchanging and mechanical equipment and pipelines operating at Russian nuclear power stations

We outline the main principles used to extend the terms specified in regulatory documents as the design service life of nuclear power stations.     

A new approach to the estimation of the erosion-corrosion wear of the equipment and pipelines at an NPP

A new calculation-experimental approach to improvement of the control of erosion-corrosion wear (ECW) at an NPP and the results of development of optimum technical solutions and methods of diagnostics, prediction, and managing of the erosion-corrosion processes are described. The possibility has been demonstrated of enhancing the reliability and the trouble-free operation of the power equipment of the II circuit of a power unit with a type-VVER reactor due to the implementation of the calculation-experimental monitoring of ECW of NPP pipelines.     

Determining the convective heat transfer coefficient by the “Half-space period” method

The method of determining the convective heat transfer coefficient by the half-space period, based on the laws of heat propagation through a semiinfinite body, is described and checked out experimentally.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 2, pp. 297–301, February, 1973.     

The structure and dielectric properties of thin PZT-type ferroelectric films with a diffuse phase transition

Abstract

By means of r.f. sputtering of the ceramic targets or pressed powder targets with the chemical constitution of Pb (Zr_0.52Ti_0.46W_0.01Cd_0.01) O₃ the polycrystalline thin ferroelectric films with the perovskite type structure and of thickness d_f = (1–2, 5) × 10^?6 m on metal (stainless steel, platinum) or ceramic (polycor) substrates have been obtained. In case of thin film deposition on steel substrate and on platinum at low temperatures (T_x < 723 K) the nonferroelectric intermediate layer with the same chemical constitution but with the pyrochlore type structure have been created. Results of the X-ray analysis and dielectric investigations (low frequency dispersion) have proved existence of such a structure. The structural phase transition (P4mm ? Pm3m) takes place in the thin ferroelectric films. This is a diffuse type transition and the degree of diffuseness depends on the structural perfection of the thin films. The measure of the structural perfection of the thin films was taken to be the mean value of the lattice strains (microdeformations) ? Δd/d ? where “d”-interplane distance and the mean dimension (D) of the areas of coherent X-rays scattering (crystallites). With increase in ? Δd/d ? and decrease in D the degree of diffuseness increases. For quantitative and qualitative describing of this dependence in thin PZT films the phenomenological model of diffused phase transition developed earlier by the authors for thin BaTiO₃ films has been applied. In this case a good agreement between theory and experiment have been achieved for low values of ? Δd/d ?.     

Investigation of the possibility of reconstructing strain diagrams using the neural network approach

The results of neural network computational-experimental estimations of the strength properties of steels based on the diagrams of surface local elastoplastic deformation are given. The presented neural network approach to conversion of the indentation diagram into the diagram of uniaxial tension makes it possible to unify the specimen-free technique of determining the main mechanical properties of the materials of equipment. Neural network models for constructing point and interval estimates for different levels of elastoplastic deformation are described.     

Determination of fracture toughness of 15Kh2NMFA vessel steel by kinetic indentation

A specimen free technique based on kinetic indentation for determination of the fracture toughness of materials is proposed. It is based on the iteration calculation of the specific indentation work which is taken to be equal to the fracture toughness of a material controlled at a defined indentation depth. This technique makes it possible to estimate the degree of embrittlement of materials of long-operating constructions by means of periodic natural nondestructive testing. Examples of the utilization of the technique for steels of nuclear reactor vessels are presented.