Abstract:
Methods and apparatus for mapping pipe and valve bores in a reactor pressure vessel (RPV) of a nuclear reactor are described. In one embodiment of the apparatus, a main bar and an adjustable chuck facilitate positioning of a digital indicator inside a valve bore. In the one embodiment, the main bar is rotatably coupled to the chuck, and the chuck includes four movable jaws. A data acquisition element, which includes a digital indicator, is movably coupled to the main bar and configured to move substantially coaxially to the main bar. To map the circumference of the bore, the main bar and the chuck are inserted into the valve bore, and the chuck is used to center the main bar coaxially within the valve bore. The data acquisition element is positioned at a first location along the main bar, and the main bar is rotated so that the digital indicator maps the circumference of the bore. The data acquisition element is then moved to different locations along the main bar to map the circumference of the bore at different locations.
Abstract:
A method for upgrading/repairing existing piping systems of a nuclear reactor without removal/replacement of the old piping. The process involves the steps of machining a counterbore of exposed corrosion-susceptible material and then depositing a corrosion-resistant weld material, thereby isolating the weld joint from corrosion susceptibility. A tool is inserted into the inside diameter of the piping system through an inspection port, valve body or segment removal. Then a tool mounting fixture equipped with axial and rotational capabilities is positioned in relation to the weld joint and locked in place. The tool mounting fixture remains locked in place throughout the entire repair process. A work surface mapping module is programmed to first gather relative reference points throughout the entire repair region. Upon data acquisition completion, the system creates a map of the existing inside diameter configuration. Then in successive stages, a machining head module and a welding head module are respectively manually installed and remotely operated by computer control. The machining and welding processes follow the existing configuration such that upon completion, the final repair blends with the piping inside diameter contour.