Deep underground near Geneva, straddling subterranean Switzerland and France near Geneva, lies a massive perfectly circular tunnel with a circumference of 27km (17 miles). Construction of this doughnut was itself a feat of engineering in the 1980s, since tolerances had to be measured in millimetres to ensure the perfect circle was achieved.
The tunnel belongs to CERN, the European nuclear research centre, which is the world’s largest particle physics research laboratory.
Within this tunnel, electrons and protons are fired at ultra-high speeds and smashed into each other. Detectors record what happens and up to 5,000 physicists from around the world try to make sense of the findings, to produce a picture of what matter is made of, how it works, and how it behaves.
The big tunnel (elsewhere there are two smaller circular tunnels that house other research projects) originally housed the Large Electron Positron (LEP) collider but this was switched off in September 2000 after 11 years of operation.
The LEP was decommissioned and construction of a new experiment began – the Large Hadron Collider (LHC). LHC differs from LEP in that advances in technology enable the project to be cryogenically cooled to absolute zero using helium. This means that particles can be accelerated using super-conducting magnets at speeds close to the speed of light, faster than has ever been achieved before, and at energies of up to 14 TeV. LEP, by contrast, was a water-cooled project.
Within the LHC, in huge chambers roughly equidistant around the tunnel, massive detector machines are being built. Within these machines, the particles will be collided and the effect measure and analysed. Each detector is completely different, and each is effectively an individual research experiment.
The four experiments of the LHC are called ATLAS (a toroidal LHC apparatus), CMS (the compact muon solenoid), ALICE (a large ion collider experiment), and LHCb (a study of CP violation in B-meson decays at LHC).
All this high science means that the team in charge of materials handling at CERN are responsible for transporting and handling loads of mind-boggling expense and fragility. For example, in the ATLAS experiment, the detector has six million components. (‘Which means that even at 99% efficiency there are still 60,000 things that can go wrong,’ jokes David James, who is responsible for planning and coordination of the handling and lifting of the ATLAS experiment installation.)
Much of the assembly work is done at surface level – in fact the whole thing is built and tested at the surface, before being broken up again into parts that can be lowered 80m down an 18.4m diameter shaft into the cavern. Among the loads to be lowered are eight magnets that each weigh 100t and cost Euro 6m. Each of them is 26m long and 20m in diameter. ATLAS will be the largest integrated super-conducting magnet ever built, standing 22m high, 44m long and weighing 7,000t.
In an operation that began at the end of October 2004, local transport company Federici has been contracted to bring these pieces to the top of the shaft where DBS and Montalev sling them, turn the loads to vertical over the top of the shaft, lower them down, return them to horizontal once in the chamber, place them on supports and install them in their final position. A Brunnhuber EOT crane with two hoists will be used for lowering the magnets down the shaft. The provisional schedule is that one magnet will be installed every six months and by January, the first two magnets had been successfully lowered and put in place.
The ALICE and LHCb detectors will be installed in chambers used on the previous LEP project. For ATLAS and CMS, new chambers are being excavated. Construction of the CMS chamber has been delayed by rising groundwater seeping in, but construction of the detector at surface level for testing is well advanced. Sometime in early 2005 the contract for lowering the CMS detector will be awarded. The huge machine, reminiscent of but more complex and far larger than a large tunnel boring machines, will be taken apart again into sections weighing no more than 1600t. Each piece will be lowered by strand jacks and at the bottom they will be slid across on air cushions.
CERN’s transport and materials handling team is headed by Ingo Ruehl, a process engineer by background and a German national (the 20 European countries that fund CERN are well represented across the facility). His team is part of the installation coordination group.
Ruehl is responsible for an inventory of about 3,500 pieces of equipment, including two mobile cranes (a Liebherr LTM 1160 and an LTM 1030/2), 350 EOT cranes and 700 hoists, right down to numerous pallet trucks. There are also thousands of slings. APAVE, a technical conformity specialist, undertakes annual checks of all transport and lifting equipment.
Much of the equipment has been on site for years, for the LEP experiment and previous projects (CERN itself celebrated its 50th anniversary in 2004). Some of the EOT cranes used in the LEP project underground have been recycled for use above ground today. For the LHC project, 15 standard EOT cranes have been supplied by Italkran of Italy and Taim of Spain has supplied four special EOTs. Brunnhuber has supplied seven special cranes since 2002, up to 2 x 140t in size, and will supply an additional three cranes this year.
Aside from installing the four huge detector machines, the materials handling team is also responsible for moving and lowering 1,600 super-conducting magnets, cryogenically sealed and in the shape of 17m long pipes. Together, these cryodipole magnets will form a continuous pipe throughout the 27km tunnel through which the particles will travel. Before installation of these magnets can begin, a helium pipeline must be installed. However, quality control problems with the helium pipe by French contractor Air Liquide have totally thrown project planning and are jeopardising the 2007 completion date, admits Paul Proudlock, the technical coordinator and planning officer of the LHC project team.
The plan was that installation of the tubular magnet sections would arrive from suppliers on a just-in-time basis, be finished and installed in their cryogenic sleeves on site, lowered down a shaft (all will go down the same shaft) and transported through the tunnel to connect to the previous section. Because of problems with the helium pipe, this process cannot yet begin. There are now about 450 completed magnet sections ready for installation, plus hundreds more at various stages of readiness. It was never part of the plan to have so many on hand at any time. Visitors to the area will find, therefore, fields and bits of waste ground dotted around the area with big blue tubes all piled in a line. Each one of these is worth up to Euro 500,000.
The fact that they are encased in cryostatic sleeves protects them from the elements, but they still need handling with great care. Each weighs 35t and is sufficiently fragile that it must be kept close to horizontal at all times. Ruehl and his team have the task of transporting these into open storage, using special trailers with hydraulic levelling for handling shallow gradients. As this challenge becomes greater, the demands on his existing materials handling capability rise.
A pair of purpose-built prototype battery-powered straddle carriers, called Robotrucks, built by Rocla of Finland, have not always withstood the challenges placed upon them as they had problems in the design and have had to travel further and on slightly rougher ground than initially envisaged. The 160t Liebherr all terrain mobile crane is also used for loading and unloading these magnet sections, which will be supported by a 200 tonner that Liebherr is supplying in February.
Given that the high-value load is common-place at CERN, it is perhaps surprising that there are no special procedures, such as might be find on oil refineries or offshore installations. French regulations are observed on sites across the French border (on construction of the CMS experiment, for example) and Swiss regulations in Switzerland. Mostly this impacts upon contractors, who require paperwork for working in both countries. (Significantly, Switzerland is not part of the European Union.) There are differences in lifting regulations too. For example, on the Swiss side a permit can be obtained to use man-riding work platforms lowered from an EOT crane. This is not an option on the French side.
