To the issue of improving the operational reliability of the responsible parts of the NPP turbines

Abstract

This article deals with the possibility of increasing the operational reliability of some of the most responsible and stressed parts of the steam turbines at nuclear power plants - the rotor blades roots of the low pressure cylinder - and some of the results of research in this area are given. The appearance of damage in the rotor blades operating in the phase transition zone is due to corrosion cracking under stress in places of their concentration as well as corrosion fatigue and fatigue. The purpose of the presented article is to analyze the working conditions of blades roots working in the phase transition zone as well as the possibilities to increase their operational reliability and resource by replacing the material of the blades. The examination of the stressed - deformed state of the two - supports root of the mushroom type for 4 stage of the low pressure cylinder of the K-1000-60/1500 turbine is carried out within the limits of elastic deformations in the two-dimensional formulation of the problem using a software complex based on the finite element method and a comparison with the known experimental information. The construction zones that represent the greatest danger due to the load and geometric concentration of stresses are determined. The possibility of replacing the material of the rotor blades from the steel 12Х13Ш КП 45 which is currently used for the stronger steel 15Х11МФШ КП 60, is considered. The constructive decisions used by the manufacturer to increase the structural strength and durability of the considered rotor blades are analyzed. The results of this work can be used in the industry of power engineering, in the design and operation of steam turbines. It is proposed to use the obtained results to prevent possible damage in the concentration stress zones of the rotor blades roots of steam turbines.