Establishing Modular In-Chamber Electron Beam Welding Capability in the USA

Project Summary/Abstract:

Recent manufacturing and fabrication efforts for advanced light water reactors (ALWRs) in the United States have highlighted the need for new technologies and infrastructure to reduce production costs. To enable cost-effective development and deployment of small modular reactors (SMRs) and advanced generation nuclear units, the U.S. industry must consider advanced manufacturing/fabrication technologies and methods. This proposal presents a modular in-chamber electron beam welding (MIC-EBW) approach that can be used to join large-diameter, thick-section components such as reactor vessels, steam generators, and pressurizers. Using this approach, component welds up to 10 feet (3.05 meters) in diameter can potentially be completed in less than 90 minutes, compared to several weeks with conventional welding technologies. The MIC-EBW capability will be developed in collaboration with a major fabricator/manufacturer and demonstrated on 6-foot (1.82-meter) and 10-foot (3.05-meter) diameter, thick-section vessel components. Upon completion, this project will demonstrate the capability to produce large, thick-section components to support new nuclear production in the United States.

In 2017, DOE, in collaboration with EPRI, Nuclear AMRC, and NuScale Power, launched a project (DE-NE0008629) to manufacture and assemble several critical sections of a 2/3-scale reactor pressure vessel (RPV) using various advanced manufacturing and fabrication technologies, including EBW, diode laser cladding, powder metallurgy-hot isostatic pressing, and advanced machining. All EBW development/demonstration in the current project is being performed in a large EB vacuum welding chamber in the United Kingdom. No similar large-size EBW capabilities exist in the United States. For the United States to fully implement EBW of large-scale components, an even larger vacuum chamber (~35 feet long) would be required. This has led EPRI to propose the modular in-chamber EBW approach (MIC-EBW), which could be readily implemented by U.S. industry at considerably lower cost (~1/3rd).

Five objectives have been identified for this project:

• Develop and establish MIC-EBW capability at a major U.S. fabricator.
• Reduce overall welding arc time by up to 90% compared to conventional welding technologies used for vessel production.
• Successfully demonstrate a 10-foot (3.05-meter) diameter, 4.375-inch (110-mm) thick vessel EB weld in less than 90 minutes of welding time.
• Establish MIC-EBW capability to perform major RPV girth welds for the NuScale Power RPV.
• Develop manufacturing process plans based on the technology and required post-weld inspection/heat treatment.