British company pioneers new nuclear welding technique

19 February 2024

Sheffield Forgemasters has completed weld-assembly of a full-sized small modular reactor (SMR) nuclear vessel demonstrator assembly using Local Electron-Beam Welding (LEBW). It said the technique took less than 24 hours to complete four, thick, nuclear-grade welds, typically requiring a year of work to complete.

The ground-breaking welded SMR vessel (Image: Sheffield Forgemasters)

"With a diameter of three metres and a wall thickness of 200mm, construction of the vessel showcases the reliability and capabilities of LEBW, setting a dramatic new standard for weld-joining thick-walled components, previously untrialled in a demonstrator model," the company said.

Sheffield Forgemasters deployed specially developed parameters, meticulously fine-tuned during the welding development stage, including innovative sloping-in and sloping-out techniques to start and finish the weld, ensuring a clean and complete weld-join.

"We are delighted to have reached a significant milestone in assembling a nuclear vessel demonstrator, using electron beam welding for the first time at this scale, with 100% success and no defects," said Jesus Talamantes-Silva, research, design and technology director at Sheffield Forgemasters.

Michael Blackmore, senior development engineer and project lead, added: "The implication of this technology within the nuclear industry is monumental, potentially taking high-cost welding processes out of the equation.

"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."

Sheffield Forgemasters - the only company in the UK with the capability to manufacture the large forgings required for SMRs - said the demonstration of LEBW technology's potential opens new horizons for "more efficient, low-cost and less time-heavy nuclear assemblies" and also has far-reaching implications for other projects which require thick-walled welded assemblies.

"We thank the government's Department for Energy Security and Net Zero for enabling the project through its Nuclear Innovation Programme," said Jacob Pope, development engineer and LEBW machine tool installation lead. "We also thank our esteemed partner, Cambridge Vacuum Engineering, for their invaluable support throughout this endeavour. Their remote and on-site assistance played an instrumental role in the success of this milestone, highlighting the collaborative spirit that drives us forward."

"Future company activities include an upcoming joint industrial project supported by key participants from the USA and UK," Sheffield Forgemasters said. "The objective is to initiate a code case or multiple cases to facilitate the deployment of this technology in accordance with the standards set by the American Society of Mechanical Engineers (ASME)."

In December, Sheffield Forgemasters said it was on track to regain ASME status as a supplier of heavy forgings and castings to the civil nuclear market, to position it for the proposed large-scale expansion of nuclear capacity in the country.

The company, which was acquired by the UK's Ministry of Defence in 2021, says an ASME Section III Division I NCA 3300, NCA 4000 and NQA-1 Code survey and audit, recommended it for Material Organisation (MO), and welding (NPT) accreditations. ASME MO and NPT status means it can supply castings and forgings (material) for civil nuclear applications and also be qualified to carry out weld construction activities on these materials.

Researched and written by World Nuclear News