Abstract: A lower internals nuclear reactor structure having a tubular core barrel with an upper and lower open end, coaxially supported therein. A reflector having an outside curvature that substantially matches the curvature of the inside surface of the core barrel and substantially contacts the inside surface substantially over an axial length of the core, is fixedly connected to the inside surface of the core barrel at a plurality of axial and circumferential locations to be substantially supported by the inside surface of the core barrel.

Abstract: A lower internals nuclear reactor structure having a tubular core barrel with an upper and lower open end, coaxially supported therein. A reflector having an outside curvature that substantially matches the curvature of the inside surface of the core barrel and substantially contacts the inside surface substantially over an axial length of the core, is fixedly connected to the inside surface of the core barrel at a plurality of axial and circumferential locations to be substantially supported by the inside surface of the core barrel.

Abstract: A method is provided for removing radioactive internals structural members in the core of a reactor pressure vessel in a containment vessel. The method includes placing a first cask in a first internals assembly, detaching radioactive first internals structural members from second internals structural members in the first internals assembly, placing the detached first internals structural members in the first cask, placing the first internals assembly in a second cask, and removing the second cask containing the first internals assembly and containing the casked detached radioactive first internals members from the containment vessel. The first internal members may be radioactive baffle plates, and the second internals members may be former plates bolted to the radioactive baffle plates. Novel tooling, framework and fixtures facilitate disassembling, moving and storing the radioactive baffle plates.

Abstract: A method is provided for removing radioactive internals structural members in the core of a reactor pressure vessel in a containment vessel. The method includes placing a first cask in a first internals assembly, detaching radioactive first internals structural members from second internals structural members of the first internals assembly, placing the detached first internals structural members in the first cask, placing the first internals assembly in a second cask, and removing the second cask containing the first internals assembly and containing the casked detached radioactive first internals members from the containment vessel. The first internal members may be radioactive baffle plates, and the second internals members may be former plates bolted to the radioactive baffle plates. Novel tooling, framework and fixtures facilitate disassembling, moving and storing the radioactive baffle plates.

Abstract: An apparatus and method are provided for replacing the existing lower internal components in a nuclear reactor vessel with new components. The alignment of the new lower internals to the pressure vessel and the existing upper internals is achieved by customizing the new lower internals on-site based on alignment measurements obtained by gages installed on the new core barrel and the existing upper core plate. The gages allow the custom machining of radial support keys on the lower portion of the new core barrel and the custom drilling of upper core plate alignment pin holes in the new core barrel.

Abstract: A mounting system for removably mounting the lower flange of the control rod guide tube over an opening in the upper core plate of a nuclear reactor is disclosed. The system includes a pair of resilient pin members and a pair of reinforcing pin members. The resilient pin members are mounted in a passage formed through first opposing sides of the guide tube lower flange. They are resiliently receivable in first bores formed on first opposing sides of the upper core plate to permit deflection thereof when the guide tube is subject to normal shear loads. The resilient pin members bear substantially all of the normal shear load to which the guide tube is subjected. The reinforcing pin members are mounted on the second opposing side of the guide tube lower flange. They are receivable in second bores formed on the second opposing sides of the upper core plate with a clearance. The reinforcing pin members bear substantially all of the abnormal shear load that exceeds the normal shear load.

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.

Abstract: A method of rapidly retubing a steam generator while it is vertically oriented in a containment vessel and keeping the level of radiation to which workmen are subjected at a minimal level.