| 摘要 |
<p>Replacing a defective tube, which extends vertically through a hole (10) in the convex floor of a pressurised water nuclear reactor pressure vessel, comprises removing the tube and machining away some of the old weld metal (14) around the hole inside the vessel to leave a flat area (15). A part-spherical hollow bowl (20) is then welded to the vessel interior to cover the hole (10) and a second hole (24) is drilled in the bowl in line with the hole (10) in the vessel. A recess (23) is formed around hole (24), and a new tube (18) is inserted through the aligned holes and welded to bowl (20), the weld metal filling the recess. <IMAGE></p> |
