Nuclear SMR welding breakthrough: A year's work now takes a day
David Szondy

Small Modular Reactor (SMR) construction shifts into high gear, as UK company Sheffield Forgemasters welds a full-size nuclear reactor vessel in under 24 hours instead of the usual 12 months. The rollout of this game-changing tech could be massive.

Modular reactors have the potential to revolutionize the nuclear power industry by turning nuclear generating plants from major civil engineering projects to factory-produced commodities. Instead of being essentially one-offs, modular reactors have a standardized design, can be mass produced, installed in any number required to serve local needs, and don't require the incredibly expensive buildings conventional reactors depend upon.

The problem is that there are bottlenecks in how to build reactors of any size. One is welding the vessels used to contain the reactor core, isolating it from the outer environment. Using conventional techniques, this can take over a year, but Sheffield Forgemasters have reduced this to under a day using what is called Local Electron-Beam Welding (LEBW) to complete four thick, nuclear-grade welds.

LEBW is a revolutionary method to weld two pieces of metal together using a high-energy density fusion process centered on a high-powered electron gun operating in a local vacuum. This melts and fuses components to one another and allows for an efficiency of 95%, deep penetration, and a high depth-to-width ratio.

The upshot is that Sheffield Forgemasters was able to complete a vessel three meters (10 ft) in diameter with 200-mm (8-in) thick walls with what is claimed to be zero defects and at lower costs. In addition, the welding machine can handle innovative sloping-in and sloping-out techniques to start and finish the weld.

This demonstration, a world first, is a significant milestone for the British nuclear sector, which has been moribund for decades with advances only in reactors for nuclear submarines, a couple of showcase power plants, and nuclear fuel processing. Now, the UK government is looking toward a nuclear renaissance, with new plants planned – including 15 modular reactors to be constructed by Rolls-Royce.

"The implication of this technology within the nuclear industry is monumental, potentially taking high-cost welding processes out of the equation," said Michael Blackmore, Senior Development Engineer and Project lead. "Not only does this reduce the need for weld-inspections, because the weld-join replicates the parent material, but it could also dramatically speed up the roll-out of SMR reactors across the UK and beyond, that’s how disruptive the LEBW breakthrough is."

David Szondy is a playwright, author and journalist based in Seattle, Washington. A retired field archaeologist and university lecturer, he has a background in the history of science, technology, and medicine with a particular emphasis on aerospace, military, and cybernetic subjects. In addition, he is the author of four award-winning plays, a novel, reviews, and a plethora of scholarly works ranging from industrial archaeology to law. David has worked as a feature writer for many international magazines and has been a feature writer for New Atlas since 2011.

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