The sarcophagus encasing Chernobyl was built in haste and is crumbling. Despite strengthening work there are fears it could collapse, leading to the release of tonnes of radioactive dust.
The shelter will allow the concrete structure to be dismantled and for the radioactive fuel and damaged reactor to be dealt with.
Wild horse, boar and wolf populations are thriving, while lynx have returned to the area and birds have nested in the reactor building without any obvious ill-effects.