Patent Number: 046831088
Section: abstract

An apparatus and method for under water remote replacement of the screws which secure together first and second structures in the internal region of a nuclear reactor core, wherein the screws are received and counterbored screw bores in the first structure. First, one or more lateral recesses are machined in the side wall of the counterbore portion. Then an external hex head screw with a shoulder flange is inserted in the screw bore and is threadedly engaged with the second structure with the flange seated in the counterbore portion. A locking cup with a central hex opening is fitted over the hex head of the bolt in the counterbore portion. Then a bifurcated die is seated against the first structure with die fingers extending into the cup, and a drive member is driven through the die coaxially with the screw to move the die fingers against the side wall to deform it into the recesses, thereby locking the assembly in place.