Abstract: Apparatus for engaging and aligning lower ends of rodlets, or pins, of a nuclear fuel assembly insert. The apparatus facilitates positioning the insert within guide tubes of a nuclear fuel assembly. The nuclear fuel assembly insert rodlet alignment apparatus includes a mounting rack for attachment to a reactor or spent fuel pool edge, a first fixed plate attached to the mounting rack's lower end, and a second sliding plate attached to the first fixed plate. The first and second plates are respectively provided with first and second comb structures each comprised of elongated, linear, pointed teeth arranged in a spaced manner along an edge of a generally flat plate. The lower end of a crank, or rotating shaft, is coupled to the sliding plate by means of suitable linkage permitting the sliding plate to be moved on the fixed plate between a first position wherein the two comb structures are non-overlapping and a second position wherein the two comb structures overlap.