NDTnet 1998 Aug, Vol.3 No.8

Abstract

To improve the quality of the fuel rod cladding tubes for all types of nuclear pressurized and boiling water reactors a new eddy current inspection method was developed in mid 1980. The first experiments have shown that aside from the operational advantage of the eddy current method (such as high efficiency, the absence of aqueous medium that is necessary for the ultrasonic testing method, the simplicity of the probe adjustment), this method is capable of detecting very dangerous defects in the claddings, that are poorly or even not detectable by the ultrasonic method (such as small cavities with sloping edges at the inner tube surface, defects located at an angle to the tube axis, tightly closed cracks, overlaps etc.) In a short period of time the eddy current equipment and the inspection instruction were developed and in 1989 this method was included in the specification for the zirconium alloy tubes - fuel rod claddings for pressurized and boiling water reactors VVER and RBMK. During the recent 10 years after the eddy current method was commercially introduced the equipment and the inspection technique were permanently updated. The new eddy current defectoscope having two microprocessors allows defects 30 and more microns deep at the inner and outer tube surfaces to be detected in real time domain with minimum tube overrejection. Its sensitivity is comparable to that of ultrasonic defectoscopes. The block diagram of the eddy current defectoscope, its technical parameters and detected defects in the zirconium alloy tubes during testing under the production conditions are described.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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