Abstract: An apparatus and method are provided for servicing an irradiated nuclear control rod underwater in a reactor building servicing pool. A turntable containing a plurality of spaced apart tools is positioned adjacent to the control rod. A first tool aligns the turntable relative to the radioactive roller mounted to the control rod by a radioactive pin therethrough. The turntable is indexable to position a second tool adjacent to the radioactive roller and pin, with the second tool being effective for freeing the radioactive pin from the control rod. The turntable is indexable for positioning a third tool adjacent to the radioactive roller and pin for removing the radioactive pin and the roller from the control rod. In further embodiments of the invention the turntable is further indexable for positioning a fourth tool adjacent to the control rod for reaming the pin aperture through which the radioactive pin was mounted.

Abstract: To facilitate safe loading of a thermal sizing mandrel in an elongated channel of open rectangular cross section, a corner rod die is first lowered into a fixture, and then a channel is lowered into the fixture to a vertical position surrounding the die. A mandrel is inserted downwardly through the channel open interior to press corner rods of the die outwardly against the channel corners to elastically reform the channel substantially to a specified geometry. Mandrel insertion is facilitated by inducing vibratory energy therein and by forming shoes in the fixture acting against the channel outer sides to square off the mandrel cross section in advance of mandrel insertion.

Abstract: A fuel bundle for a boiling water nuclear reactor having an improved water rod is disclosed, this water rod having two discrete compartments upper and lower for containing water. The bottom compartment flows moderator from the bottom of the fuel bundle through the water rod compartment to discharge points located through the water rod side walls between the upper most spacers; the top compartment opens upwardly and is naturally filled with liquid moderator settling out of the upwardly flowing moderator during reactor operation. There results the requisite presence of liquid moderator within the water rod for supplying the upper two phase region of the fuel rod with nearly full moderator density. At the same time, water flow through of the water rod from the bottom of the fuel bundle to the upper two phase region of the fuel bundle improves the thermal hydraulic performance.