Electrical methods

• The Direct Current-Reversal Potential Drop (DCRPD) method is based on the measurement of electrical resistivity of metallic materials. Material property changes in irradiated RPV can be used as indicators for the degree of the degradation. One physical effect that can be used for the detection of irradiated material degradation is the electrical resistivity. If the change of electrical resistivity is a well-defined function of the neutron fluence, and if the effect is large enough compared with that of other influencing parameters, it can be used to monitor the material embrittlement.
• Thermoelectric power measuring method (TEPMM) is based on the fact that a thermal flux driven by a constant temperature gradient in electrically conductive materials is accompanied by an electric current and analyses the electric voltage over this gradient. The voltage or thermoelectric power (TEP) created hereby is proportional to the temperature gradient. The material-dependent proportionality factor is called Seebeck coefficient (SC). The change of the SC due to neutron irradiation, thermal and mechanical ageing was observed experimentally. These effects are well known as a cause of drift in thermocouples, which are widely used as temperature sensors. A clear correlation between the SC, the neutron fluence and the embrittlement can be observed.