METHOD FOR MEASURING THICKNESS OF CLADDING LAYER FORMED ON NUCLEAR FUEL ROD SURFACE AND INCLUDING FERROMAGNETIC MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a method for accurately measuring the thickness of a cladding layer, that is formed on the covering surface of a nuclear fuel rod and includes a ferromagnetic material. SOLUTION: The probe for an eddy current sensor is arranged on the surface of a cladding layer, including a ferromagnetic material. The probe has a coil, and the coil passes through only the cladding layer including the ferromagnetic material and is excited by AC with a frequency selected to form the complex impedance of the probe. In this case, the complex impedance expresses the change in permeability of the cladding layer including the ferromagnetic material, change in thickness and a change in conductivity excites the probe by the AC with the frequency, and measures the complex impedance for expressing the thickness of the cladding layer including the ferromagnetic material.