Lenin Square today in Pripyat, Ukraine, the
city nearest to the Chernobyl Nuclear Power Plant.
Certain radioactive elements (such as plutonium-239) in “spent” fuel will remain hazardous to humans and other creatures for hundreds of thousands of years. Other radioisotopes remain hazardous for millions of years. Thus, these wastes must be shielded for centuries and isolated from the living environment for millennia.