Thirty years ago, areas within 30 kilometers of Chernobyl were sealed off. But since 2011, the Ukrainian government has opened up a tour route for visitors, though strictly controlled.

Entering a once forbidden area. Visitors are warned not to deviate from the guided route, nor touch anything. They must tread carefully so as not to unsettle the dusty earth containing high radiation. A prolonged exposure to around 500 roentgen is potentially lethal to humans. Here, it's 1,000 roentgens in some areas.

"I move the counter to the right, the radiation index here is 960 roentgen. And here, the index reaches 1,000. Here is 2,000," Tour guide Alexander said.

3 kilometers away from the nuclear site, the once lively Pripyat city used to house many of the plant's workers and their families,
With a hasty evacuation following the catastrophe, the city has remained eerily deserted ever since.

On the way to the heart of the nuclear disaster - the 4th reactor, radiation levels spike from 700 to 1100 roentgen, even interfering with filming.

Maintenance work is being done under the watch of more than 1,000 scientists and technicians. But they're strictly banned from shifts of more than five minutes on site.

Chernobyl’s 4th reactor which exploded 30 years ago was encased in a thick concrete ‘tomb’ following the disaster, but now cracks are appearing on the structure. The Ukrainian government has pledged to build a new, stronger shield to keep the nuclear fuel contained.