Method and apparatus for repairing boiling water reactor shrouds utilizing tie-rods and braces

摘要

A method and apparatus for repairing nuclear reactor core shrouds having horizontal cracks in heat affected zones of welds joining a horizontal plate to upper and lower cylindrical sections of the shroud includes securing a plurality of braces between an upper shroud flange and a top surface of the horizontal plate near an inner edge of the plate. The braces are installed at a respective plurality of angularly spaced locations within the upper cylindrical section of the shroud and each have an upper notched end for bearing against a bottom edge of the flange and a lower notched end for bearing against the top surface of the horizontal plate and/or an outer peripheral edge of an upper core grid structure mounted on the top surface of the plate. The upper portion of each brace can be clamped to a tubular core sparger disposed within the upper cylindrical section and can be held in compression between the shroud flange and the upper core grid structure, or the horizontal plate directly, with a jacking bolt threadedly engaging the brace and having a lower end bearing against the upper core grid structure or the horizontal plate.