The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 30, 1994
Filed:
May. 12, 1993
John A Kervinen, Palo Alto, CA (US);
General Electric Company, San Jose, CA (US);
Abstract
A method for determining the thickness of ferromagnetic material deposited on a nuclear fuel rod. Calibration samples of known thickness and known permeability are placed between the probe of an eddy current sensor and a conductive surface. A plurality of calibration points are plotted to provide a characteristic complex impedance diagram for a probe excited at a predetermined frequency. Then the complex impedance of the probe excited at the selected frequency is measured when in proximity to a fuel rod having a corrosion layer of unknown thickness and unknown magnetic permeability. For each probe position, the two components of the complex impedance, i.e., the inductive reactance and the resistance, are determined and plotted on the characteristic complex impedance diagram. The position of the measured data point relative to the calibration points enables one to determine the lift-off error due to the presence of ferromagnetic material.