AN EDDY CURRENT DEVICE FOR MEASURING ALUMINUM CLADDING ON URANIUM FUEL ELEMENTS
Uranium Fuel Elements for the N.R.U. reactor are clad in aluminum by an extrusion cladding process. It has been found convenient to clad the uranium with an aluminum sheath around 0.100 in. in thickness and afterwards to machine the aluminum to the required thickness. The total thickness of uranium and aluminum cladding is fixed by the size of the die through which it is extruded. Also since the uranium thickness is set by specification the total thickness of the two aluminum sides is fixed provided that uranium is undeformed. However, it is conceivable that the uranium could be fed through the die eccentrically resulting in a difference in thickness between the two aluminum sides. Since subsequent machining is performed relative to the aluminum outer surface this defect will appear in the final fuel element. If the defect is excessive it is desirable to detect it before machining. It was decided to attempt to make an eddy current device for this purpose smce it could be made simply reliably and cheaply. The difficulty lay in the thickness of aluminum which had to be measured. However, the fact that aluminum and uranium have widely differing electrical conductivities and that the total thickness of aluminum was constant, made the eddy current approach attractive. When a conductor is placed near a coil then the impedance of the coil is modified both in phase and magnitude. This modification is a function of the conductivity and spatial distribution of the conductor with respect to the coil. In the case of aluminum clad uranium, if a coil is placed near the cladding then the cladding thickness will affect the impedance of the coil which provides a means of sensing changes in thickness. (auth)
- Research Organization:
- Atomic Energy of Canada Ltd. Chalk River Project, Chalk River, Ont.
- NSA Number:
- NSA-12-007796
- OSTI ID:
- 4326539
- Report Number(s):
- CRRD-750; AECL-560
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- Canada
- Language:
- English
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