A Temperature Compensation Method for Micron Level Measurement of Oxide Film Thickness

Accurate measurement of oxide film thickness on the surface of fuel cladding is of great significance for maintaining the safety of nuclear power plants. Eddy current testing (ECT) is the most commonly used technology for the pool-side measurement of the oxide film thickness, which has the merits of high sensitivity and resistance to irradiation. However, the measurement error of the ECT sensor will occur because the temperature of the fuel cladding is unknown. To improve the sensor performance, this paper presents a temperature compensation method. First, the influences of temperature fluctuation on the coil impedance are analyzed. Then, a temperature compensation method is proposed based on the approximately linear signal characteristics. The feasibility of the proposed method is demonstrated by measuring the oxide thickness at different temperatures. The experimental results show that the measurement error is reduced by over 80% and the compensation error is less than 7.25μm.