Abstract: Disclosed herein is a joint structure between a top nozzle and a guide thimble. The joint structure includes an outer guide post, an inner-extension tube head, an inner-extension tube body, a wedge and the guide thimble. The outer guide post is provided with an external thread formed on a lower end thereof. The inner-extension tube head includes an annular retaining part formed on an upper end thereof. An internal thread is formed on a medial portion of the inner-extension tube head. An external thread is formed on each of upper and lower ends of the inner-extension tube body. A stop protrusion is provided under a lower end of the wedge. The wedge is welded to the inner-extension tube body after the top nozzle has been joined with the guide thimble. A stop protrusion receiving depression is formed in the guide thimble.

Abstract: The present invention relates to an anti-fretting wear spacer grid having a plurality of canoe-shaped springs formed thereon, wherein each of the canoe-shaped springs includes: a fuel rod-contacting part having a flat surface having a predetermined longitudinal length so as to have linear contact with the fuel rod; a curved face-connecting part formed on the upper and lower portions of the fuel rod-contacting part; a leg-connecting part formed on the end portion of the curved face-connecting part; and legs each being formed of a plate shape having a predetermined length and connecting the both sides of the leg-connecting part with one unit grid cell surface.