Determination of the Mechanical Characteristics of the Metal of the Equipment of Nuclear Power Stations from Hardness Measurement and Indentation Data

The main normative documents for the nuclear power industry of Ukraine, which regulate the determination of mechanical characteristics from hardness measurement data, are considered and analyzed. It has been shown that the use of these documents for monitoring the technical condition of the equipment of nuclear power stations, in particular of the metals of the bypass pipeline of the high-pressure pump SAOZ of the core emergency cooling system (08Kh18N10T steel), coil from the welded joint zone of the Du 600 inlet branch pipe of the IRA30S02 non-return valve (16GS steel), and the body shell of the dismounted PV2500-97-10A (09G2S steel) high-pressure heater calls for their more detailed justification. To determine the mechanical characteristics of metals and to increase the reliability of their evaluation in nondestructive monitoring, a standard developed by the Pisarenko Institute of Problems of Strength of the National Academy of Sciences of Ukraine is used. According to this standard, the evaluation is made not only on the basis of hardness measurement data, but also by the method of instrumented indentation. It has been shown that this method is more efficient for the determination of the strength characteristics of steels. The difference between the ultimate strength and yield strength values according to this standard and those obtained in tensile tests is not over 8.6% and not over 6.6%, respectively. When diagnosing the technical condition of the metal of pipelines, indentation tests allow one to determine strength characteristics not only in the axial and tangential directions, but also in the radial direction.