Patent Number: 048287822
Section: abstract

An arrangement for inspecting the fuel assemblies of boiled water reactors using an ultrasonic transducer probe. Each assembly contains a square array of fuel rods covered by a fuel channel slip. The probe accesses the fuel rods through a nosepiece in the shape of an inverted tripod located at the bottom of each assembly. The fuel rods are supported in each assembly by upper and lower tie plates, in the form of grids. The grids have first apertures for supporting the ends of the fuel rods, and second apertures which allow coolant water to flow between the fuel rods during operation. The probe is inserted through the second apertures of the lower tie plate grid, and rotated to inspect each of the four surrounding fuel rods for the presence of water inside the fuel rods. In order to access each of the second apertures in the fuel assembly, the probe is pivoted about a single pivot point in the nosepiece, the pivot point preferably being located in the trident which is non-symmetric with respect to the array of fuel rods. However, it can be located in any of the tridents or even slightly below the tripod. Moreover, multople single pivot points, one in each trident, can be provided to allow multiple inspections to occur in parallel.