In-situ repairing a boiler equipment of a primary circuit of a nuclear reactor, by making a cut around an original nozzle along a line, removing the original nozzle, setting up a new nozzle, and welding new nozzle to bottom along line

摘要

The method comprises: making a cut around an original nozzle (17) along a line (L) with a closed contour, where a boilers equipment comprises a fabricated well casing defining an internal volume and having a curved bottom (11), and the original nozzle connected to the bottom by a weld; removing the original nozzle; setting up a new nozzle having a passage (35) opening at an inner end in the internal volume; welding the new nozzle to the bottom along the line with the closed contour; and performing a local stress relieving heat treatment along a seam of the new nozzle to the bottom. The method comprises: making a cut around an original nozzle (17) along a line (L) with a closed contour, where a boilers equipment comprises a fabricated well casing defining an internal volume and having a curved bottom (11), and the original nozzle connected to the bottom by a weld; removing the original nozzle; setting up a new nozzle having a passage (35) opening at an inner end in the internal volume, where the inner end is defined by an inner edge; welding the new nozzle to the bottom along the line with the closed contour; and performing a local stress relieving heat treatment along a seam of the new nozzle to the bottom, where the weld is spaced from the inner edge by a predetermined distance of 300-900 mm that is equal to a distance of the original weld. The bottom has a thickness of lower than 150 mm along the line with closed contour. The heat treatment is carried out while placing an insulating bell around the weld and by heating the seam according to a predetermined program. The heating is carried out using electrical resistors placed on both sides of the seam. The bottom presents an opening after removing the original nozzle. The method further comprises machining a chamfer on a peripheral side of the opening before setting up the new nozzle, completing the internal coating along the seam of the new nozzle at the bottom, and separating the original nozzle of the spray pipe before the step of cutting along the closed contour line. The well casing presents an external wall (27) and an internal coating covering an inner face with the external wall. The passage is connected towards an outside of the well casing to a spray pipe. The nozzle comprises a spray tube placed inside the well casing in an extension of the passage. The original nozzle comprises a thermal protection cuff placed in the passage and presenting a first length. The new nozzle including another thermal protection cuff placed in the passage and presenting a second length that is greater than the first length.