Patent Number: 047160187
Section: abstract

An improved end plug for attachment on an end of a cladding tube of a nuclear fuel rod facilitates using a gripper tool for loading the fuel rod into a nuclear fuel assembly. The end plug includes an inner portion adapted to be inserted into the end of the tube and an outer portion adapted to extend from the end of the tube when the inner portion is inserted therein. The outer plug portion has a body part disposed adjacent the tube end and a leading part disposed remote from the tube end. The leading part of the outer plug portion has a hollow interior cavity defined therein, an exterior annular truncated surface defined on a terminal end thereof and an exterior annular tapered surface defined on a lateral side thereof. The exterior tapered surface extends between and merges with the body part and the exterior truncated surface and provides sufficient angular inclination so as to facilitate insertion of the end plug when mounted on the fuel rod tube end into the fuel assembly. The interior cavity in the leading part has an inner end, an outer opening defined at and surrounded by the exterior annular truncated surface and an interior annular wall surface interconnecting the inner end and the outer opening. An undercut annular groove is defined in the interior wall surface of the cavity, has a larger diametrical size than the interior wall surface and is spaced from the cavity opening. The groove is engageable by the gripper tool when fitted through the cavity opening for loading the fuel rod into the nuclear fuel assembly. The leading part has a thickness between the exterior tapered surface thereon and the interior cavity undercut groove therein which is less than the radius of the groove and greater than the width of the exterior truncated surface, and the interior wall surface of the cavity has an axial length between the exterior truncated surface and the undercut groove which is greater than the axial width of the groove, such that the leading part is provided with sufficient wall structure laterally surrounding the interior cavity to react the forces created by engagement of the gripper tool within the cavity groove.