Several hundred builders are working on a crowded construction site, day and night. The workers come from all around the world: Ukraine, Turkey, France, Germany, Russia, Italy, Philippines and Azerbaijan. At first glance, things here don't look much different from at any other building site. But, if you look closer, you then see the radiation gauges that everyone wears around their necks, and the world-famous silhouette of Chernobyl's covered former nuclear reactor.

The construction of the New Safe Confinement (NSC), a protective cover, or sarcophagus, over the radioactive ruins of the Chernobyl nuclear power plant, looks deceptively routine. In reality, things could become life-threatening here at any time. Just in case, everyone here has a breathing mask.

Chief engineer Viktor Salisezki has to have an eye on safety at the Chernobyl site all the time

An accident in February this year near the site showed the extent of the risk of radioactive contamination. Only about 100 meters away from the building site, masses of snow caused a 600-square-metre section of a roof in a machinery hall to cave in.

''We were lucky, the wet weather prevailed and no significant emissions resulted,'' Viktor Salisezki, chief engineer of the NSC project, told DW.

A unique building site

The level of radioactivity around the former Chernobyl nuclear reactor these days is much less than straight after the nuclear reactor accident in 1986. However, it is still considerably higher than the maximum normal permissible level of radiation. Each worker is only allowed to be on duty here up to 15 days a month.

In an area the size of eight football fields, a layer of radioactively contaminated earth several meters thick is currently being dug up and removed. The area, in which the new protective cover will be installed, is protected against the radiation coming from the ground by a layer of thick concrete.

The workers are exposed to the highest levels of radiation when they work directly on the walls of the old sarcophagus. They can only work there for a maximum of two to three hours at a time. There, they are laying the foundations of a building, from which experts will oversee the functioning of the new protective shell.

The 100 year solution

Construction work beside the old sarcophagus

So far, experts have managed to formulate a plan of how the old sarcophagus can be dismantled, according to Viktor Salisezki. But it is still unclear how it will be financed.

"The dismantling of the unstable structure of the sarcophagus as well as further work under the new protective shell will have to be financed by the Ukrainians themselves,"says Salisezki. When that is due to happen, depends on the economic situation in the country.

Proposals for the construction of new sarcophagus have ranged from building a huge concrete pyramid above the site, to burying the reactor block many kilometers underground.

In the end though, engineers have opted for an arch-shaped steel structure, with a height of nearly 100 meters. The new protective shell is expected to last 100 years, meaning it's just a temporary solution:

''Leaving the radioactive material on the site forever – irrespective of what form it is in – means that it becomes a permanent nuclear waste storage facility," explains Norbert Molitor, the German coordinator of the expert group which has helped develop the NSC project.

"Building a permanent nuclear waste dump site involves meeting specific criteria. So far, no-one has shown me that this can be done here."

International donors required

Norbert Molitor says that the Chernobyl problem won't be solved any time soon

Norbert Molitor knows how difficult it is to raise money to clear the aftermath of the Chernobyl catastrophe. He helped organize the conference in 2011, in which $980 million (750 million euros) was raised for the NSC from donors across the globe.

The experts dare not predict when the Chernobyl problem will finally be solved, but Molitor predicts its cost will run into the billions of euros.

Politicians tend to not think so far ahead to financially plan something that big, Molitor says. The money for the new protective shell only came together as it became obvious that the old sarcophagus could collapse at any time.

Following the planned completion of the NSC in autumn 2015, the Ukrainian government will face new responsibilities for its maintenance. How that will be funded though is still uncertain. To date, donors have only agreed to pay for the construction of the facility.