EDIT
In the weeks following the explosion, thousands of people risked their lives building the sarcophagus around Reactor Four. Only ever meant to be temporary, today this ramshackle arrangement of concrete walls and corrugated iron panels is held together with scaffolding. "This particular scaffolding structure is to help hold up the west wall," Mr Dodd explained.
"After the accident, the west reactor wall was cracked all the way across. It is actually tilted outwards and there was concern that it could collapse and expose the almost 200 tonnes of radioactive fuel that's still inside the shelter to the atmosphere. The area beneath the west wall is now a construction site. Resembling a giant arch and billed as large enough to contain St Paul's Cathedral, the new shelter is being built some distance from the reactor so it can be slid over the top of the existing sarcophagus.
Simon Evans from the European Bank for Reconstruction and Development (EBRD) is overseeing the project: "Radiation levels as you get closer to the sarcophagus get higher and higher, so the difficulties of building something nearer, multiply. So, if you can build it as far away as possible it makes it easier."
EDIT
The total cost of this ambitious scheme is 1.6 billion euros (£1.37bn; $2.21bn) but despite promises from G8 conferences, the bank is still 740 million euros short. It's also notable that the largest contributor is Europe; Russia - where the reactor was designed and built in Soviet times - is the tenth. President of the EBRD Thomas Mirow admitted it was a difficult time to raise funds but told the BBC that countries should think beyond the current economic climate. "This is such an exceptional case," he said. "I think with all the major players in the international community being involved, it should be possible to get the money."
EDIT
http://www.bbc.co.uk/news/science-environment-12335595