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Diamond is jewel in Costa ain's crown

SITE REPORT

The UK's biggest laboratory will be home to some of the country's brainiest boffins.

But it isn't just the scientists that have to put their thinking caps on.Alasdair Reisner visited Oxfordshire to see how Costain is handling the £66 million Diamond Synchrotron project

TO THE passing motorist it looks as though the Martians have landed.As you speed down the A34 in Oxfordshire you will catch a short glimpse of a silver saucer, seemingly coming into land in fields near Didcot.

And this first impression is not entirely unfounded. For this 'spaceship' is indeed floating just above the ground just outside the Rutherford Appleton Laboratories. Furthermore it is expected to contain an array of space age equipment and technology.

But don't call out the Men in Black quite yet.

While this doughnut shaped phenomenon may have the appearance of science fiction it is firmly grounded in science fact.

The Diamond Synchrotron, as the structure is known, is the largest ever single science investment project by the Department of Trade and Industry.

When complete, the ring-shaped building, which covers a site the size of four football pitches, will house equipment generating highly focused ultraviolet light and X-rays.These will be used to probe the molecular structure of materials more effectively than was previously possible.

The development of the synchrotron will involve installation of around £100 million-worth of equipment, including a linear accelerator.This will speed up electrons before they enter a storage ring, where their energy can be bent off, using magnets, as beams of light or as X-rays for use in experiments.

But before any of this happens there has to be a building to house all the equipment.

Enter Costain.The firm was taken on in spring 2003 under a £66 million contract to build the distinctive 'mothership' structure that bears an uncanny resemblance to the GCHQ listening centre.Given the precise nature of the experiments that the synchrotron would be used for, it was not difficult to determine what was going to be the major issue for the contractor.

Costain project director Tony Scott says: 'The beamlines are microfocused, so they are getting down into measurements that we never come across in the construction industry. So, our work is being carried out to very high tolerances.We are constructing walls and portals to millimetres.'

This accuracy is all the more difficult to achieve given the nature of the concrete used for parts of the scheme.

Iain Gilmour from project manager Capita Symonds explains: 'Highdensity concrete has to be used for the radiation shielding.The higher the mass of the concrete the thinner it needs to be.'

For every 50 mm the team can shave off the thickness of the walls by using denser concrete, the diameter of the whole structure falls by 2 m.

With this in mind the team went looking for a suitable concrete supplier.They found Viaton, which produces barytes concrete that weighs in at 3,500 kg/cu m, more than 50 per cent denser than normal concrete mixtures.

'The good thing is that it is 1.5 times as dense and only five times more expensive, ' jokes Mr Gilmour.

But getting the density right is only a small part of ensuring the concrete comes up to standard.

'Pouring concrete is not an exact science, ' admits Mr Scott.'We have had to do a lot of trials to build up a correlation between the plastic density and finished cured density.We cannot measure the concrete in the finished works as that would require destructive testing, which we can't do because the whole idea is to make it homogeneous and solid.'

So what would happen if something did go wrong and the concrete was poured outside of parameters?

'We have to make sure that does not happen. If it did we would have to remove it and that would be a disaster.We check every load of concrete before the shutters go up, when the shutters are up, during the pouring and after the pouring, ' says Mr Scott.

To ensure the concrete's quality, Costain, its concrete subcontractor Byrne Bros and the client surveyors all carry out these checks.

Mr Scott says: 'These are the highest tolerances we have ever worked to with concrete. I don't think I will ever come up against anything like this again.'

The concrete may be dense but that does not prevent the storage rings and experimental floor from 'floating' above the ground.

That may sound like something from Star Trek, but the reality is somewhat more practical. In most buildings the slight movements in the ground caused by swelling of the soils beneath would not cause any significant problem. But in the case of the synchrotron, even tiny movements in experimental areas could render the whole machine useless.

The team established a solution where the whole of the experimental floor and storage rings is built upon an isolated slab raised above ground level.This was achieved by drilling into the chalk deep below the site and forming 1,500 reinforced concrete piles.Held in the chalk, these restrict movement of the building caused by shifts in the clay and gravel that lie over the chalk.

The piles are connected to a single slab for the experimental hall and storage ring which was cast above ground on top of a honeycomb layer of clayboard.Once the concrete was cured this layer could be washed away, leaving the slab propped 60 mm above the ground.

The team has completed the storage ring and closed off the ring of structural steelwork that forms the building's skeleton. Some 1,350 10tonne concrete slabs that will form the roof of the storage ring are in the process of being fitted. Each one has been individually designed and produced by Nottinghamshire concrete beam specialist Precon to an accuracy of a single millimetre.Around 55 per cent are now in place, coursed like brickwork to prevent any radiation escaping.

One of the key challenges Costain now faces is installing all of the mechanical and electrical services required to serve the experimental halls, linear accelerator and storage rings.The pressures come both from the large number of services that need to be fitted and also the fact that this must be carried out in sequence to allow installation of the synchrotron machinery itself to be carried out.

'We are installing £10 million-worth of M&E systems, ' says Costain deputy project director and M&E lead Jim Gamble.'What makes it interesting is that we have to hand over part of the building early. But the prime plant that supports that area is on the other side of the building, so the construction sequence has to take that on board.'

The building features two large rings of services, one of which is inside the storage ring, with the second running around the perimeter of the building.

The services to be plumbed in include air conditioning, cooling water, liquid nitrogen and compressed air to meet the demands of the experimental floor.

This is before you even begin to consider the miles of electrical cable that must be installed in cable trays to provide power and building control systems. Space must be left to add further services as the synchrotron has the capacity to expand from seven up to potentially 48 beamlines.

'It is not like an office building where you know what you are doing from the start, ' says Mr Scott.'People are still making equipment for the building and understanding how it will work as we build it, so we need to be able to react to changes.We haven't had a fixed brief and that has made it an interesting job to work on.'

Despite this fluidity of scheduling, the installation of the machinery inside the synchrotron is expected to start in September this year and will carry on in parallel with construction until Costain finishes on site in late 2005.

In 2007 the synchrotron's beamlines will be fully commissioned and the first scientists will enter the structure, ready to boldly go where no man has gone before.

The Diamond Synchrotron

What is Diamond?

Diamond will be the first third-generation synchrotron light source in the UK, a doughnut-shaped supermicroscope the size of several football fields. It will produce incredibly intense light beams, mainly as X-rays, that will be able to penetrate deep inside all kinds of matter, from proteins to plastics.

What is it for?

Diamond will enable scientists to investigate the structure of matter such as biological tissues, polymers and catalysts at the atomic and molecular level.

These studies will help them, for example, to design new medicines and high-tech materials, as well as to investigate environmental issues such as climate change.

Who is behind it?

Diamond Light Source Ltd is the joint venture company set up to build, commission and run the Diamond Synchrotron Light Source. It was established in March 2002 and is led by Professor Gerhard Materlik.The company's shareholders are the Council for the Central Laboratory of the Research Councils, which holds 86 per cent of the shares and the Wellcome Trust, which holds the remaining 14 per cent of the shares.

Project details

Diamond Synchrotron Light Source

Completion date: beginning of 2007

Cost: (including the construction of the first seven experimental beamlines) is £235 million at September 2001 prices

Client: Diamond Light Source

Main contractor: Costain

Project manager: Capita Symonds

Design team: JacobsGIBB

Quantity surveyors: Franklin Andrews

Planning supervisor: Gleeds

Mechanical and electrical works: Haden Young

Envelope: Lakesmere

Steel frame: William Hare

Reinforced concrete: Byrne Bros

Construction period: 97 weeks