Nuclear power plants use uranium fuel to generate clean, safe, reliable electricity. The uranium fuel is compressed into pencil-eraser-sized pellets and then placed in rods that are bundled into "fuel assemblies" for use in the reactor.
When the uranium fuel no longer contains enough energy to produce electricity efficiently, the used fuel assemblies are removed from the reactor and safely contained in stainless steel-lined concrete pools of water on the plant site, in a process called "wet storage." The water helps cool the fuel as it becomes less radioactive over time.
In the United States, the U.S. Department of Energy holds the ultimate legal responsibility for the disposal of used nuclear fuel. However, the approval and construction of a federal waste disposal site is years behind schedule. Because of this delay, nuclear power plants across the country are supplementing wet storage with "dry storage" - a safe, secure and well-proven technology that has been used for more than 20 years at more than 55 nuclear plant locations in the United States.
Instead of water, dry storage containers use such materials as steel, concrete and lead as a radiation shield. The U.S. Nuclear Regulatory Commission (NRC), which issues 20-year licenses for the containers, has approved several designs and maintains strict regulatory oversight of dry storage.
Dry storage facilities are heavily secured through a variety of proven measures, including high-tech security and surveillance systems, radiation monitoring and regular security patrols, as well as multiple layers of physical barriers. They are also built to withstand such natural disasters as hurricanes, tornadoes, and earthquakes.
All of the used nuclear fuel produced by the U.S. nuclear energy industry in 50 years of operation would, if stacked end-to-end, only cover an area the size of one football field to a depth of about 7 yards.
(Source: Nuclear Energy Institute)