Consideration on the Applicability of Electron Beam Welding for the Manufacture of Small Modular Reactor

Abstract

The overall technology required for the application of electron beam welding to ultra-thick plate pressure vessel in small modular reactors was considered. Electron beam welding has the advantage of reducing the manufacturing time compared with traditional arc welding, but it requires the construction of complex equipment and the establishment of related process technology. Based on the thickness of 150~250 mm, the electron beam welding equipment for application to SMR pressure vessel requires large-capacity equipment of 120~170 kV, 150 kW or more, which has never been commercially manufactured so far. A stable beam must be maintained for a constant time. Anti-arcing and seam tracking functions are also required. Electron beam welding of low-alloy steel has superior characteristics in terms of strength and toughness compared with arc welding. The welded area can be made into a base material by solution heat treatment. Cleaning and gap control are important for weld quality. Weld area should not be affected by magnetic fields. As circumferential welding overlaps in span at the welding start and end, it requires precise setting of welding parameters. For welding of large pressure vessel, customized cylindrical vacuum chamber or local vacuum chamber are suitable. It must be shielded from X-rays generated during welding.