from the conferences organized by TANGER Ltd. provisional website
Monitoring the mechanical properties changes is very important to assure structural integrity of NPP components, especially within the context of their operational life extension. Determination of current mechanical properties of several structural materials of NPP components, especially reactor internals, is not possible using the standard testing methods, in connection with the material volume necessary for the testing. In comparison with reactor pressure vessel, reactor internals are usually not covered by the system of surveillance samples as well as other hardly replaceable components of the primary circuit, e.g. primary piping, steam generator etc. Sampling of the optimal material volume usually brings adverse consequences of affecting the integrity of component or in several cases destruction of the whole evaluated component. For standard size specimens, it is also necessary to take into account the high activity of the material, with influence on the collective dose of hot cell facilities personnel. Aim of this work is to present the advantages of the semi-destructive testing method (instrumented hardness test method) in the process current mechanical properties evaluation of the hardly replaceable long-term operated NPP components. Instrumented hardness test method is a semi-destructive testing method for direct measurement of mechanical and fracture properties of materials including yield strength, ultimate tensile strength (UTS), strain hardening exponent, and fracture toughness. Semi-destructive testing techniques use technological processes and equipment enabling the direct determination of mechanical properties from the component surface without affecting its integrity. Advantage of semi-destructive degradation mechanisms quantification could be very promising for use in the field of nuclear energy for components of NPP as well as in other industrial sectors, e.g. chemical and petrochemical industry.Keywords: Mechanical properties, nuclear power plants, instrumented hardness test method
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