Last updated 16:05, Wednesday, 13 August 2008

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Engineering triumph: One of the six-metre diameter steel lifting girdles

CORUS Northern Engineering Services (CNES) has successfully completed the manufacture of two, six-metre diameter steel lifting girdles that will be used to remove the 400-tonne heat exchangers from the reactors at Calder Hall.

Each reactor has four vertically-mounted heat exchangers. These are outside the reactor building and were clad for insulation and weather protection.

The heat exchangers weigh around 400 tonnes and measure 27m in length with a diameter of 5.5m. This will represent the largest ever lift in the UK nuclear industry.

CNES delivered the lifting girdles to its customer Nuvia Limited (formerly NUKEM Limited) at the end of February 2008.

Nuvia is one of several contractors chosen by Sellafield Limited to decommission the Calder Hall site. Part of Nuvia’s responsibility was to design lifting girdles and cradles to enable the heat exchangers to be lifted, tailed and transported a lay-down area.

To do this, two lifting girdles were required to lift and tail the vessels, which is where CNES’s fabrication and machining expertise came in.

The lifting girdles were manufactured at CNES’ Structural Workshops in Scunthorpe. Materials for the project were bought from Corus Construction & Industrial. The manufacturing process for the carbon steel girdles involved profile cutting and rolling the circular shapes, machining and welding the interfaces between the two girdle halves, assembly, stress relieving, finish machining, painting and delivery.

Machining was carried out at CNES’ Scunthorpe machine shop using a large horizontal boring machine. CNES also had to construct spider structures to brace the two halves of the girdle during fabrication.

Each half has a trunnion fitted at 90° to the joint face, this necessitated boring a hole in the fabrication, manufacturing and fitting the trunnion to the required tolerance. The girdles were then stress relieved and finish machined on the joint faces.

The fitted bolts used to fasten the two halves together measured almost one metre in length with a diameter of 115mm. The units were inspected and painted prior to delivery to Nuvia.

Steve Snowden, Production Control Engineer at CNES Structural Workshops, said: “Nuvia selected CNES because it trusted us and felt confident that we possessed the necessary technical expertise to carry out the job.

“We could also handle the front-end engineering that was required, plus provide all the traceability, method statements and other quality assurance-related factors that were key to the project.

“We also understand all the health and safety related regulations that are always our highest priority and we have the necessary fabrication, machining and surface treatment expertise to carry out the work to the required standards.”

AMEC, the international project management and services company, has formed an alliance with Corus Process Engineering (CPE) to provide, at the Corus site in Workington, a comprehensive test rig design, build simulation and experimental test service to Sellafield and other nuclear licensed sites.

The alliance brings together Corus’s extensive test rig design and manufacturing capability and AMEC’s nuclear technical expertise in decommissioning, waste and reactor technology to deliver the full range of large-scale experimental test rig projects.

AMEC’s multi-disciplinary teams of experts in chemistry, corrosion, wasteform and process engineering based at the Westlakes Science Park and at AMEC’s laboratory complex in Warrington will work with Corus’s experienced test rig design and manufacture team to deliver a comprehensive technical solution form the extensive Corus facilities.

Bob Stevenson, CPE’s Commercial Manager, Nuclear, said: “This alliance builds on the synergies between both organisations and enables a complete service to be offered to UK Nuclear clients, bringing benefits to Cumbria and the Sellafield site in particular.”

Greg Willetts, Director of Laboratory Services for AMEC’s nuclear business said: “Both organisations have a long term commitment to the Cumbrian community. Working together with Corus we can bring additional benefits to our clients and generate high quality job opportunities for the local area.”

AMEC is a focused supplier of high-value consultancy, engineering and project management services to the world’s energy, power and process industries. With annual revenues of over £2.3 billion, it delivers and maintains strategic and complex assets for its customers.

AMEC’s nuclear business has more than 50 years’ experience in the civil and defence nuclear industry.

Corus is Europe’s second largest steel producer, with revenues of £9.7 billion and crude steel production of 18.3 million tonnes in 2006, primarily in the UK and the Netherlands.

Corus is a subsidiary of Tata Steel, the world’s sixth largest steel producer.

Corus Process Engineering (CPE) operates from Workington, and with 19,500m2 of fabrication and mechanical workshops, is a world-leading supplier of nuclear waste transport and spent fuel flasks.

As a key supplier to the nuclear industry for over 40 years, CPE’s projects have typically involved design, manufacture, installation and commissioning of waste storage, handling and decommissioning equipment, test rigs, shield doors and gamma gates to industry quality standards.