SEDL / STP / STP223-EB / STP41994S

Eddy Current Measurement of Clad Thickness

Allen, J. W.
Metallurgy Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.

Nance, R. A.
Metallurgy Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.

Oliver, R. B.
Metallurgy Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.

Pages: 13    Published: Jan 1958

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Abstract

The basic principles of eddy current testing as applied to metal thickness and cladding thickness measurements are discussed. Results of a series of studies are illustrated with the impedance changes of a probe coil plotted as functions of test frequency, thickness of the part inspected, or its electrical conductivity.

Data are also presented which indicate that the impedance curve determined as a function of lift-off is complex in nature, having at least two inflection points. Special emphasis is given to an inspection method developed at the Oak Ridge National Laboratory for determining the thickness of cladding on the Mark X fuel plates used in the Materials Test Reactor. Results of this inspection method are presented illustrating its capability to measure small cladding thicknesses accurately and reliably.