KIEV, Ukraine - Twenty-two years after the Chernobyl nuclear disaster, work is under way on a colossal new shelter to cover the ruins and deadly radioactive contents of the exploded Soviet-era power plant.
For years, the original iron-and-concrete shelter that was hastily constructed over the reactor has been leaking radiation, cracking, and threatening to collapse.
The new one, an arch of steel, would be big enough to contain the Statue of Liberty.
Once completed, Chernobyl will be safe, said Vince Novak, nuclear safety director at the European Bank for Reconstruction and Development, which manages the $505 million project.
The new shelter is part of a broader $1.4 billion effort financed by international donors that began in 1997 and includes shoring up the current shelter, monitoring radiation, and training experts.
The explosion at reactor No. 4 on April 26, 1986, was the world's worst nuclear accident, spewing radiation over a large swath of the former Soviet Union and much of northern Europe. It directly contaminated an area roughly half the size of Italy, displacing hundreds of thousands of people.
In the two months after the disaster, 31 people died of radioactivity, but the final toll is still debated.
The U.N. health agency estimates that about 9,300 eventually will die from cancers caused by Chernobyl's radiation. Groups such as Greenpeace insist the toll could be 10 times higher.
The old shelter, called a sarcophagus, was built in just six months. But intense radiation has weakened it, according to the U.S. Nuclear Regulatory Commission, and rain and snow are seeping through cracks.
Officials say a tornado or earthquake could bring down the shelter, releasing clouds of poisonous dust.
The first step, shoring up the sarcophagus, is almost complete, Ukrainian and European Bank for Reconstruction and Development officials say.
Later, the 20,000-ton arch - 345 feet tall, 840 feet wide, and 490 feet long - will be built next to the old shelter and slid over it on rail tracks.
Construction is to begin next year and be completed in 2012, and it is designed to last 100 years.
It is designed and built by Novarka, a French-led consortium.
Workers will wear protective suits and masks and those needing to be closer to the radioactivity will work in shifts as short as several minutes.
Once the arch is up, the least stable parts of the old shelter and the reactor will be dismantled and removed.
In 50 years, the nuclear fuel will be extracted.