"The “elephant’s foot,” a two metric ton slab of materials from Chernobyl’s melted reactor core. The slab is melted 2 meters deep into concrete and cannot be approached; to obtain samples, scientists use AK-47s to shoot off pieces. The Chernobyl reactor today is covered in a huge concrete box called the sarcophagus. As of 1998, the debris inside the sarcophagus was emitting radiation levels as high as 10,000 rontgens (average city background radiation is about 35 microrontgens). The sarcophagus is predicted to collapse; rain water corrosion is already threatening the roof and leaking radioactive material into the soil. A new confinement system will be installed in 2013. Interestingly, the inside of the reactor is covered in black radiotrophic fungus, which uses melanin to convert gamma radiation into energy."
The first claim, that this lump weighs hundreds of tons, sounds way off.