A temporary structure was quickly built over reactor number 4 to contain radioactive material. A more permanent solution was needed. About two decades in the making, a massive steel structure called the New Safe Confinement was built to seal in the site.

Segments of the structure were pre-assembled in Italy and shipped to Ukraine. To prevent exposure to radiation for the workers, the structure was erected 300 m away from the site. The framework was completed in 2014, and the entire structure was moved into place in November 2016. Notice the difference in its location between these 2015 and 2018 images from Sentinel-2.

Considered the world’s largest moveable structure, the new covering weighs 40,000 tons and is 843 feet across, 355 feet high, and 492 feet long. It’s tall enough for the Statue of Liberty to fit inside. At Sentinel’s 10-meter resolution, the huge structure appears as a bright set of pixels at the accident site.

The New Safe Confinement is expected to securely contain the radiation for 100 years.