One week before the 25th anniversary of the nuclear power plant explosion at Chernobyl, world leaders pledged Tuesday to provide $780 million for the construction of a shelter designed to house the toxic remains for another century.

Rain, rust and snow have weakened the first shelter, built 25 years ago and designed to last 20.

Laurin Dodd, an American engineer who is directing the new containment project, described the condition of the existing shelter, often called the sarcophagus.

"The sarcophagus itself had very large openings in it the size of picture windows, with small creatures going in and out and birds flying in and out," Dodd noted.

Chernobyl suffered the what was then the world's worst nuclear power accident. The explosion sent a plume of contaminants one kilometer into the air over Ukraine. Winds carried radioactive clouds north over Russia and Belarus. 330,000 people had to be moved from their homes.

Today, millions of people live on contaminated land. A central core, is closed forever to human habitation. The governments of Belarus and Ukraine devote 5 percent of their national budgets to treating survivors and patrolling the no go zone.

Despite this legacy, there was little optimism back in February when the European Bank of Reconstruction and Development (EBRD) took reporters on a tour of Chernobyl, hoping to raise world interest in paying for the new containment shell.

Then on March 11, a wall of water crashed into the nuclear power plants in Fukushima, on the Pacific Coast of Japan. Balthasar Lindauer, deputy nuclear safety director at the European Bank, described the Fukushima factor.

"Today at the pledging conference, Fukushima was mentioned very frequently, and I think it certainly has drawn attention to Chernobyl," said Lindauer.

European Commission President Jose Manuel Barroso told the conference that Chernobyl and recent events in Fukushima, Japan, were a reminder that nuclear risks may not stop at a country's borders.

He pledged $156 million from the European Union to rebuild the Chernobyl containment shell. The United States delegation, led by former United States National Security Advisor Zbigniew Brzezinski made the largest single nation donation: $123 million.

By the end of the day, pledges had come in for three quarters of a final $1 billion needed to complete the project. All in all the new shell is to cost $2 billion and should be complete by the end of 2015.

Vince Novak, EBRD Nuclear Safety Director, led the foreign press group through the Chernobyl during the snows of February. Tuesday he told VOA from Kyiv:

"As a fund manager I am greatly relieved because that tells me that we can proceed full speed ahead with both of the large projects that we need to complete," said Novak.

Work has already started on the giant structure. To protect workers' health, it is being built 300 meters away from the Chernobyl plant, which still holds 200 tons of radioactive fuel and material.

Laurin Dodd explains that it will be built on rails.

"When it is actually ready to be slid into place it will be, I am told, one of the largest structures ever moved on land," noted Dodd.

The new shell will be two football fields wide and two and a half football fields long. 

"The new safe confinement shell will be something like 16 or 17 stories high. You could fit the Statue of Liberty quite comfortably inside of it," added Dodd.

Inside, a central beam will hold a remote controlled moveable crane. This will be used to pick apart the old shell and then remove the molten radioactive mass from the bowels of the old plant. Special ventilation systems will filter air for release to the atmosphere and a heating systems will prevent the buildup of condensation.

"It's being designed for a 100 year life, which means that we have to maintain corrosion control over that period of time.  Basically, we have to prevent rusting. So there will be extensive heating and ventilation systems," Dodd said.

On Sunday Tokyo Electric Power, operator of the damaged reactors at Fukushima, announced that it plans to build its own concrete and steel containment structure with an air filter. It expects to have this shell in place by the end of this year. It did not say how long that structure is designed to last.

Source: VOANews.com