Stanovení pevnostních charakteristik komponent primárního okruhu jaderné elektrárny pomocí instrumentované indentace

Abstract

This master’s thesis deals with the possibility of determining the strength characteristics of a nozzle–safe-end–primary pipe weld joint in the primary circuit of a nuclear power plant using instrumented indentation testing. The aim of the work was to verify to what extent the results obtained at room temperature can be used to estimate the yield strength Rp0,2 and ultimate tensile strength Rm corresponding to the operating temperature of 300 °C. Reference values were obtained from tensile tests performed at elevated temperature. The results confirmed significant heterogeneity of mechanical properties across the investigated joint and showed that instrumented indentation is particularly suitable for local mapping of mechanical response. After temperature extrapolation, a relatively good agreement was achieved for Rp0,2 in some material regions, whereas a systematic overestimation was observed for Rm. More accurate temperature correlations are needed for a more precise determination of yield strength and ultimate tensile strength at reactor operating temperatures.