Structure of top nozzle for nuclear fuel assembly

摘要

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.

主权项

1. A joining structure for joining a top nozzle and a guide thimble, the joining structure comprising:
an outer guide post having a hollow cylindrical shape and an external thread formed on an outer circumferential surface of a lower end portion of the outer guide post; an inner-extension tube head comprising
an annular retaining part formed on an upper end portion of the inner-extension tube head and having an outer diameter greater than that of other portion of the inner extension tube head, andan internal thread formed on an inner circumferential surface of a medial portion of the inner-extension tube head; an inner-extension tube body having a hollow cylindrical shape and including
a first external thread formed on an outer circumferential surface of an upper portion of the inner-extension tube body, anda second external thread formed on the outer circumferential surface of a lower end portion of the inner-extension tube body; and a wedge having a hollow cylindrical shape and including at least one stop protrusion formed on a bottom surface of the wedge, the stop protrusion extending a predetermined length in an axial direction of the wedge, the wedge being separated from the inner-extension tube body and the outer guide post, wherein the inner-extension tube body is coaxially inserted into the outer guide post, the inner-extension tube head is mounted on a top of the outer guide post, the first external thread of the inner-extension tube body is engaged with the internal thread of the inner-extension tube head, the second external thread of the inner-extension tube body is engaged with an internal thread of the guide thimble, and the wedge is mounted on the outer circumferential surface of the inner-extension tube body and disposed between a bottom end of the outer guide post and the guide thimble.