Apparatus for measuring the pitch between adjacent rods in a nuclear fuel assembly

This patent describes an apparatus for measuring the pitch between adjacent rods in a row of spaced-apart rods in a nuclear fuel assembly, comprising: a support plate; a carriage; a wand, dimensioned to traverse the row of rods, extensibly appended from the carriage, the carriage being slidably mounted on the support plate for transversely moving the wand along the row of rods; a pair of spaced-apart, non-contacting proximity sensors, spaced apart less than the outside diameter of the rod of smallest diameter in the row of rods, attached to the wand to consecutively pass by each of the rods in the row of rods for generating a first and a second output signal, respectively, corresponding to each sensor's proximity to a rod as it passes by the rod; and means for measuring the linear movement of the carriage in transversely moving the wand along the row of rods to relate the position of the pair of spaced-apart, non-contacting proximity sensors to the output signals generated thereby