GOVERNMENTS from around the world have pledged 550m euros to seal the stricken nuclear reactor at Chernobyl within a 20,000-tonne steel shield that would be large enough to enclose St Paul's Cathedral in London. The huge arch is designed to prevent any further radiation from escaping for 100 years.

The pledges, made at a conference in Kiev ahead of the 25th anniversary of the disaster on April 26, 2011, bring the total raised for the Chernobyl safety works to $1.8bn and will enable efforts to finally secure the reactor which caught fire in April 1986.

Twenty-eight governments have so far offered money. The European commission was the biggest contributor with 110m euros.

The US pledged 86m euros and Britain — which still has more than 300 hill farms in Wales under radiation restrictions following fallout from Chernobyl — will contribute 35m euros. The European Bank for Reconstruction and Development announced an extra 120m euros. Japan, Italy and Canada are considering whether to contribute to the fund.

The planned arch-shaped structure, which at 190 metres wide and more than 100 metres tall, will take five years to build. It will replace a hastily built concrete 'sarcophagus' erected around the reactor in 1987. This now has serious cracks in it, raising fears that 95 per cent of the original nuclear material which is left inside the reactor could escape.

Radiation levels directly over the sarcophagus are too high for the arch to be built over it, so it will be constructed in two halves and then moved over it on rails. It is designed so that authorities could start dismantling the reactor from inside in 100 years' time. The shield is intended to stay in place until either the radiation threat decreases or the Ukrainian government finds a permanent storage facility for the 200 tonnes of uranium and one tonne of radioactive plutonium still inside the ruins.

World governments, which had already raised more than 1.1bn euros in international funding for the shelter, as well as for a permanent nuclear fuel store for other reactors on the Chernobyl site, said that the current crisis at the Fukushima plant in Japan persuaded them to respond to the appeal by Ukraine, which estimates the accident has so far cost the nation more than $12bn. n

But Mikhail Gorbachev, president of the Soviet Union at the time of the Chernobyl disaster, says nuclear power was not the answer to the world's energy problems or to climate change. — The Guardian, London