Control rod transfer device

A transfer device for moving a control rod assembly between fuel assemblies employing an overhead crane, the control rod assembly having a plurality of spaced control rods which are supported from an overhead web frame, wherein the control rods are designed to be inserted within a plurality of spaced guide thimble tubes in the fuel assemblies, the transfer device comprising:

• an upper latch tube assembly having a longitudinal axis;
• an elongated inner member, slidably supported within the upper latch tube assembly and operable to telescope substantially coaxially with the longitudinal axis;
• a gripper assembly supported from a one axial end of the elongated inner member, having an actuation shaft reciprocally, slidably supported within the elongated inner member to move substantially along the longitudinal axis a selected distance to actuate a gripper at an axial first end of the gripper assembly opposite a second end of the gripper assembly adjacent the one end of the elongated inner member, another end of the elongated inner member including a bail adapted to attach to the overhead crane;
• an interlock assembly attached to the upper latch tube assembly selectively coupling said elongated inner member to the upper latch tube assembly at one or another of two elevations along the longitudinal axis, the one elevation being in a substantially extended position the another elevation being in a substantially retracted position;
• an elongated enclosure assembly extending along the longitudinal axis having a length at least substantially equal to the height of the control rod assembly, the enclosure assembly substantially rigidly connected to one end of the upper latch tube assembly and having another end configured to key on the top of the fuel assembly;
• and
• a plurality of alignment cards laterally disposed in a spaced tandem array along the length of the enclosure assembly, each of the alignment cards having openings that are aligned and sized to pass a control rod of the control rod assembly so that the control rods are withdrawn into the enclosure assembly in alignment with the guide thimble tubes of the fuel assembly, the alignment cards further including a central opening through which the gripper assembly can pass through and at least some of the alignment cards' central opening sized to pass at least a portion of the elongated inner member.