After the 1986 Chernobyl nuclear accident, reactor number 4, which was involved in the accident, was encased in concrete to contain the radiation and debris, creating a structure known as “the sarcophagus”. Other reactors in the plant however remained active until 2000, despite the radioactive nature of the area surrounding reactor 4.
Radiation continues to be emitted from a mass of material in reactor 4 known as “The Elephant’s Foot”. It’s made up of nuclear fuel, melted concrete and metal, and was formed during the initial accident.
The foot is still active. In ‘86 the foot would have been fatal after 30 seconds of exposure; even today, the radiation is fatal after 300 seconds. There were fears that due to the continued chemical reactions occurring within the mass that it may penetrate deeper into the ground, potentially connecting with ground water, but these have proven unfounded.