Patent Number: 040070859
Section: description

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1 of the drawings is shown an insert 10 in which the markings are holes extending through the insert. The holes 11 provide the clock pulses and the larger holes 12 at right angles to them provide the further markings which supply the numerical identification as indicated in the drawing, the letter L indicating the lead-in position for each decade. Typically for an insert 1/4 inch in diameter the holes 11 have a diameter of 3/64 inch and the holes 12 a diameter of 1/16 inch. Similarly FIG. 2 of the drawings shows an insert 13 in which the markings are grooves 14, 15. The grooves 15 are deeper than the grooves 14 to provide the further markings which supply the numerical identification and lead-in positions as in FIG. 1. Typically for an insert 1/4 inch in diameter the grooves 14 have a nominal depth of 0.007 inch and the grooves 15 a nominal depth of 0.014 inch. FIG. 3 of the drawings shows the insert 10 of FIG. 1 held by crimping of sheath 16 within a nuclear fuel element 17 which also includes nuclear fuel pellets 18 within the sheath 16. In FIG. 4 of the drawings the fuel element 17 is shown being drawn through an encircling eddy current reading head 19 in the direction of arrow 20. In the eddy current head electrical pulses from an oscillator 21 are modulated in response to the presence of the markings on the insert within the fuel element and these modulated pulses are compared with the pulses from the oscillator 21 in a mixer and amplifier 22 from which high and low level pulses are obtained. These high and low level pulses are fed into a pulse height discriminator 23 in which the high level pulses are distinguished and with the combined high and low level pulses (clock pulses) applied to a logic circuit including decoder equipment which converts the data provided by the high level pulses into decimal form for printing or visual display in conventional manner.