Patent Number: 051241161
Section: claims

1. A method for keying exterior grid cells in a nuclear fuel assembly having grid assemblies formed form interleaved grid strips with the grid assemblies forming interior and exterior grid cells, comprising: a. inserting a grid key having a T-shaped first end and a main body portion bent at approximately a 45 degree angle into the window of the exterior grid strip of the exterior grid cell such that the top of the T-shaped first end is inside the window and parallel to the longitudinal axis of the grid assembly;  b. rotating the main body portion of the grid key approximately 90 degrees such that the top of the T-shaped first end is perpendicular to the longitudinal axis of the grid assembly and behind the exterior grid strip;  c. pulling the main body portion away from the exterior grid strip in a vertical rotating motion to move it approximately 90 degrees to a vertical position whereby the top of the T-shaped first end pulls the exterior grid strip away from the center of its cell defined by the grid assembly.