Raising the Roof3 October 2019
The nuclear power sector continues to drive demand for the world’s biggest cranes. Julian Champkin visited Hinkley Point, where Sarens and Favco have giant cranes at work, and reports on nuclear projects around the world.
Nuclear construction is not what it was. But, fossil fuel is out, and renewables are growing fast but are not yet able to meet all electricity demand. That leaves nuclear as an attractive option for many governments. Some 52 new reactors are currently under construction around the world, in 18 different countries, according to the International Atomic Energy Agency. Among those 18 countries, China leads with nine reactors under construction, India has seven, and Russia six. Argentina, Brazil, Finland, France, Turkey and the UK jointly trail with one apiece.
So nuclear construction is not on hold, but has certainly slowed. In the UK, the new station is at Hinkley Point in Somerset, at last proceeding after many years of governmental delay and indecision. The nuclear projects that are proceeding have several things in common in their requirements for cranes. One is duration of presence. Cranes at a new construction site can expect to be there for several years until the project is near completion. Another is capacity. Construction methods have changed, in part because of advances in crane design. It has meant that the ability to lift, and to carry, huge loads has become ever more important. Concrete is a major component of nuclear power construction, both for shielding and containment; and the quality of the concrete is critical. In today’s construction methods concrete components are cast not in situ but under cover, protected from the elements in enclosed temporary buildings near to their final positions, where temperatures and humidity can be strictly controlled. When the sometime-huge elements, such as reactor covers, are completed, the roof of the construction building is lifted off, the prefabricated element, which can weigh several hundred of tonnes, is lifted out and transported perhaps 100m to its final position. This requires not just large cranes, but very large cranes indeed. It is no accident that what is claimed as the largest land-based crane in the world, the Sarens SGC250, has just started work at Hinkley Point.
Sarens is a family-owned firm; it was started by the grandfather of the current executive director Hendrick Sarens. American crane-builder Lampsons, based in Washington state, is similarly a family concern. It is one that early on saw the need for specialised large cranes for the nuclear industry, and that has specialised in such cranes from its beginnings.
“In the 1970’s my grandfather, Neil Lampson, recognised the need for higher capacity heavy lift cranes in the nuclear industry” says director Kate Lampson. “We live in an area where a lot of this type of work was being done and in an answer to that need, the first Lampson Transi-Lift was built. Although it was only a small capacity machine by todays’s standards, the technology of being fully mobile while picking, moving a placing a load was new to the industry. Today we have models that range in capacities from 350 US ton to 3,000 US ton.
“My grandfather also pioneered the ‘over-the-top method’ of lifting, which allowed loads to be lifted directly in and out of the roof of a plant rather that cutting a hole in the side of a building to install and remove components.” The method, as we have mentioned above, is being used at Hinkley. “Both the Lampson Transi-Lift and the over-the-top method helped to revolutionise the nuclear construction industry.”
One aspect of that revolution involved the order in which different components of the plant were built. In the beginning, large components were built in first, then containment buildings were constructed around them. The over-the-top method reversed that. “In the beginning, access, clearances and overhead structures were a challenge” says Lampson. “The design of the Lampson Transi-Lift changed how power plants were designed and built in two ways. With the ‘over the top’ method, power plants were designed to allow for the placing and removal of components through the roof rather than through the side of a building. This allowed the majority of the plant’s buildings to be constructed first and the components to be placed inside them afterwards. [This ] post-containment construction— rather than having to construct the plant around the components or accommodate installation during construction—helped save the utilities time and money.
“In addition to the design of the buildings, the mobility of the Lampson Transi-Lift changed the industry as well. Ours was the first crane to be fully mobile under load, allowing it to travel around a job site to multiple lift locations. It had a smaller foot print to work in increasingly confined spaces, and the ability to move forward, backward and sideways in a crablike configuration all while picking, carrying and placing a load. This also helped save the utilities time and money.”
Many different components make up a nuclear power station, and many different objects and load ranges need to be lifted. “In the beginning the loads consisted of steam generators, turbines, reactors, condensers and cooling towers. These components weighed somewhere between 300–1,000USt, but as components grew in size, so did our Transi- Lifts. We now have models that can lift 3,000USt” says Lampson.
Today Lampsons is involved in the sole nuclear power station that is under construction in the US, at Plant Vogtle near Waynesboro, Georgia. A Lampsons Transi-Lift LTL-2600 2BC is currently on the site. “It has been there for about two years and will remain there for another two years” says Kate Lampson. “With regard to other nuclear power plants being constructed around the globe, there is talk that Japan is going to restart their nuclear program and when it does, one of our Lampson Transi-Lift LTL-3000 built specifically for Japanese nuclear plant construction will be used for those efforts.”
The roof-lifting method that Lampsons made possible is almost universally adopted now. In China, XCMG’s massive XGC2800 crawler crane raised the roof of the new Hualong power station currently under construction.
The XGC2800, known as ‘the mighty crane’, has a capacity of 2,000t. The dome of the Hualong reactor is a hyperboloid hemisphere made of 70 steel panels. It is 13.6m high, 45m in diameter, and weighs 226t. It is, says XCMG, four times the size of a basketball court.
“To lift a 226t load to a level 63m up in the air, and then fix it on top of the reactor facility with an accuracy of one millimetre, is absolutely a big challenge” said Zhu Zeming, general manager of the Hualong project. “With a 78m boom and 54m jib, the XGC2800 successfully landed the dome in its designated position for fixing in place; lifting, rotating, luffing aligning and unloading all went to plan. The job was completed in 30 minutes under the allotted time and the overall load factor was kept below below 85% throughout.”
It was not the first nuclear project for the XGC2800. In 2015 it had played a similar role at another major nuclear plant in Fuqing, Fujian province. There its assignment was to lift the first super-large component of the project, a huge steel lining module, with the positioning of which the civil construction phase of the project entered its peak period. The recent dome-lift at Hualong, in contrast, is part of the equipment installation phase in the main nuclear island, and is among the most critical control points in the construction schedule.
Other super-large cranes with nuclear capabilities include Demag’s Twin, which is effectively two CC8800 cranes joined together. “It can handle lifting capacity ranges that the vast majority of cranes are simply unable to reach” says Damien Bizjak, global marketing manager. “Its maximum lifting capacity is 3,200t, with a load moment of 43,900tm; that puts it in a league of its own. The crane was not designed specifically for nuclear projects. The main intent was for petrochemical, offshore or conventional coal or gas power plants, but it has been used on nuclear plants during the past year.”
There are of course many ancillary cranes beside the ultraheavies on a nuclear construction project. Offices, generator and transformer buildings, temporary accommodation for construction workers, permanent accommodation for staff will all be needed. A nuclear power plant is in effect a small town. “Crawlers are usually in demand on such jobsites” says Bizjak. “A main use is for pre-assembly; the size of the crawlers will depend on their duties. It usually goes from 100t to the 1,600t class as there are various stages in the construction process. All kinds of things need lifting, from the steel structure to the reactor parts to the condensers. For every load case you need very detailed load studies. The main lift equipment will stay on site from the beginning to the end of the project, which can be for several years. Less crucial equipment can be there for two weeks, two months, or half a year. It is usually a budget matter.”
Big Carl, the Sarens SGC-250 giant heavy-duty crane, stands out among the forest of tower cranes at the 250-acre site where the Hinkley C power station is being constructed. Bright yellow with a blue undercarriage, it is the largest land-based lifting machine in the world. It arrived at Hinkley Point having travelled by ship from Antwerp to Avonmouth, and then by road, carried on a fleet of 350 semi-trailers by UK special transport firm Collett. Two 600t crawlers assisted in erecting it.
“It took four years to design, and a year and a half to make it” said Dirke Vincke, senior project manager for Sarens. “A big issue in the design is that everything must be transportable by normal road transport. The jib cross-members are pin-jointed, not welded, so that the jib can be broken down for transport rather than having to be moved in one piece.” Another ingenious feature is that the counterweight boxes are filled with locally-sourced material to achieve a total weight of 100t per box. The same boxes, empty, are used for transport of crane components. The double use saves considerably on transport costs.
The crane’s design is unique. It is mounted on 128 bogies and runs on rails, but there are two different sets of bogies, and two sets of rails, that are used at different times. The main set of bogies are arranged in a large circle, 48.5m in diameter, and run on circular track; slewing is achieved by the entire crane rotating on the track, carried by these bogies. It can rotate a full 360 degrees, at a speed of six degrees a minute. Three circular tracks have been laid out at Hinkley, one adjacent to each of the buildings it will have to lift from or carry to.
These circular runways are joined by straight sections of track, along which the crane can travel using the second set of bogies, which are aligned fore-and-aft. To change position the crane travels along this straight section of track. The circular bogies are raised, and the straight ones are lowered, using hydraulic power from the crane's six power packs, each powered by two diesel engines. When the weight of the crane and load are on the straight-line bogies it can travel from one circular runway to the next. The circular tracks are laid a few centimetres higher than the straight-line ones, so that the flanges of the bogie wheels can pass over them without damage.
“What is special about this crane is that it can re-locate” says Vincke. “We can move it 200m from here, to the second of the three circular runways, in just 12 hours. That is a short time for such a huge crane. The third lifting location is another 200m away. The circle and straight-line system effectively triples our working area.
“The nuclear plant was designed so that the big prefabricated components could be built under cover, in those buildings by the circular tracks.” These temporary buildings bear the local name of ‘bunkers’. “I call the whole system ‘Lego construction’” he says. “It allows a huge saving.”
“One of its tasks at Hinkley will be to lift the roof of the construction bunker and set it to one side. Inside the bunker are concrete components that have been precast at ideal conditions of temperature and humidity, and we will lift those out of the building. The minimum radius of lift of this machine is 67m; the maximum is 165m. 1,650t is the expected heaviest lift here, which is remarkable at the radius involved, but the crane is actually overdesigned for the project".
Its digitalisation is state of the art. The drive cabin contains three screens. One is for LMI, giving radius information, boom angles and the like. One monitors the two hoists, and one gives the status of the power packs—six of them, each with two diesel engines providing hydraulic pressure; if one goes down the crane can continue operating on five. Martin Redmond is the man in the hot seat, operating the crane. “The cab is a standard design, used on all the Sarens SGC cranes,” he says.
“She handles very well, with no special quirks. You treat it with respect, and remind yourself that you are working on a very heavy lift, but it handles much the same as a smaller crane. It is still, after all, a crane. Everything is fully redundant, for safety; and the whole machine can be operated by a tablet, from outside the cab or on the ground, if you need to.”
Martin Westbury is construction director for Bylor, the consortium running the project. “The whole of our strategy is based on prefabrication of large elements, and Big Carl is integral for that” he said. “It will lift over 700 elements during its time here.”
There are of course many other cranes working on the project. “We have 29 on site at present, mostly tower cranes; we will have 51 at the peak, about a year and a half from now.” Possibly surprising is the small number of crawlers. “We have eight crawlers, used as general lifting devices, in the mid-capacity range. But look across the landscape and you will see that it is hard of access for crawlers.” There are many differences in level, where foundations and the like are being excavated; despite its size it is a congested site. “So instead of pick-and-carry we tend to use an umbrella system: one tower crane passes the load to its neighbour, and so on all the way across the site. We transport with trailers on the ground as well. We also have travelling tower cranes, on rails. We think that is safer in the long term.
“Many of the tower cranes are luffers, because of the interactions and close proximity to each other.” Among them is another record-breaker. The Favco 2480D Heavy Lift Luffing crane, owned and operated by Australian-based Marrs, is the largest capacity tower crane in the world. It has a capacity of 330t at 15m radius and will lift 100t to a 45m radius with around 130m of hook height and no support ties. It is fully rated to operate in wind speeds up to 20m per second, which is more than double that of crawler cranes; it also has a higher operating speed.Once, nuclear power was thought of as part of the space age future. It is appropriate then that the Favco bears the slogan, ‘Owned and operated by the Men from Marrs'.”