FPCB Eddy Current Pancake Sensor Development to Measure Cr Coating Thickness

Since the accident at the Fukushima nuclear power plant, research is being conducted worldwide on strengthening the nuclear power plant safety. In particular, a nuclear fuel rod, a core part of a nuclear reactor, is an essential part to secure safety. The method of chromium(Cr) coating on existing nuclear fuel (Zr-Nb alloy) rods can be applied to existing commercial nuclear reactors. In addition, because of its clear advantages in terms of oxidation resistance and strength increase at high temperatures, research is being actively conducted to utilize it as an alternative fuel rod. However, to apply to existing commercial reactors while maintaining the advantages of coating, a nuclear fuel rod with a uniform thickness must be used, making the development of a highly reliable measurement technology for the entire Cr coating thickness of the fuel rod critically important. In this study, a basic study was conducted to evaluate the thickness of Cr coating the nuclear fuel rod. Sensor design parameters were determined through simulation, and based on this, two types of FPCB pancake sensors were developed. In addition, experiments were conducted to measure the Zr-Nb alloy and Cr coating rods and plates with different Cr coating thicknesses. Based on the experimental results, the development of eddy current inspection technology using the FPCB pancake sensor and the possibility of Cr thickness evaluation were confirmed.