A radiation shield that promises to protect the world from the still-dangerous radiation at the site of the Chernobyl Nuclear Power Plant is almost complete.

The 275 m by 108 m New Safe Containment dome is being moved over the grounds of reactor 4 using a system of hydraulic pumps to inch it over the site. The European Bank for Reconstruction and Development, which has led the project, expects this process to take about a week.

The giant shell was built away from the reactor because radiation levels above it are still extremely high. The construction took about 10 years.

The New Safe Containment dome replaces a steel and concrete structure called a sarcophagus that was built over the Chernobyl reactor 4 site months after the 1986 meltdown. Soviet scientists anticipated this sarcophagus would contain the site for 20 to 30 years before it needed restorative maintenance. By 1998, however, its structural integrity was compromised, necessitating a replacement.

On April 26, 1986, a combination of flaws in the reactor design at the No. 4 light water graphite moderated reactor and human error led to a catastrophic steam explosion and an open-air graphite fire. Plumes of radioactive material floated in the atmosphere for nine days after the disaster. Most of this material resulted in fallout over western Russia and Europe.  

The European Bank for Reconstruction and Development estimates the new containment shield cost about £1.3 billion.