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Interserve is constructing 11 models, up to 27m high and 500t in weight, for Sellafield’s Evaporator D facility. However, instead of building them on site, Interserve is fabricating them offsite, at Ellesmere Port 90 miles away, and then transporting them to site by road and sea.
The modules are being constructed for primary contractor Costain. They vary in size. The first two, which have now been transported to Sellafield, are 10m high, 7.5m wide and almost 10m long, and weigh more than 100t. The largest will be 27m x12.5m x 7.5m and will weigh more than 500 tonnes.
The modules comprise structural steel frameworks of stainless steel and carbon steel, containing vessels, pipework and other process equipment. They are fabricated at Interserve's five-acre, indoor facility near Ellesmere Port. This is near Interserve's pipework facility where the pipe sections are specially welded, X-rayed and pressure-tested to meet the exacting standards required.
Transporting finished modules to the dock at Ellesmere Port, 1.5km away, involved some road alterations, the movement of street furniture and approval to use the bridge crossing over the M53 to accommodate the loads. At the dock the modules were loaded onto a barge before sailing 90 miles north to a beach by the Sellafield site on the Cumbrian Coast.
Interserve project manager David Bolton said: "This is the first time in the UK that the nuclear sector has chosen to prefabricate modules of this size and scale off-site. The benefits of Sellafield Ltd's modular strategy and of using a dedicated facility are significant: the ability to operate in a controlled workshop environment alleviates many of the traditional constraints of on-site construction within an operational facility; and since the Evaporator D facility is adjacent to other existing facilities and has a limited footprint, off-site construction ensures maximum safety and minimises intrusion in the operational complex.”
He added: "It's very important that the high-integrity, stainless steel elements of the modules aren't cross-contaminated, and it's possible to pre-commission each module within our facility, saving valuable time at Sellafield. Once the modules are constructed we use laser-scanning techniques to demonstrate and assure that the frameworks, vessels and pipe-work are installed within the tight dimensional package tolerances.
"The final task is to wrap the modules in a specialist shrink-wrap protective coating before the heavy-load specialist is brought into the equation. Interserve has been involved in making numerous modular structures for the chemical, oil and gas sectors and we know the importance of maintaining the package integrity during the road and sea transportation phase. This is why we designed the facility with self-propelled modular transporters (SPMT) in mind so they could simply drive in underneath the module, pick it up off its supports and drive away."
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