Nuclear energy originates from the splitting of uranium atoms in a process called fission. In the plant’s nuclear reactor, neutrons from uranium atoms collide with each other and split into smaller particles, releasing heat and neutrons in a chain reaction. This energy can be used to make steam, which is used in a turbine to generate electricity.
Two types are used in the United States: boiling-water reactors and pressurized-water reactors.
- In a boiling-water reactor, the water heated by the reactor core turns directly into steam in the reactor vessel and is then used to power the turbine-generator.
- In a pressurized-water reactor, the water heated by the reactor core is kept under pressure so that it remains liquid. This hot radioactive water flows through a piece of equipment called a steam generator.
A steam generator is a giant cylinder with thousands of tubes in it that the hot radioactive water can flow through and heat up. Outside these hot tubes in the steam generator is nonradioactive water, which eventually boils and turns to steam.
The fuel most widely used by nuclear plants for nuclear fission is uranium. Though uranium is quite common, about 100 times more common than silver, the U-235 used in nuclear power plants is relatively rare.
- The pellets are about the size of your fingertip, but each one produces roughly the same amount of energy as 150 gallons of oil.
- Unlike fossil fuel-fired power plants, nuclear reactors do not produce air pollution or carbon dioxide while operating.
- In 2008, U.S. uranium ore reserves were estimated at one billion, 227 million pounds. These reserves are located primarily in Wyoming and New Mexico.
- Nuclear power generates a number of radioactive by-products, including tritium, cesium, krypton, neptunium and forms of iodine. These materials can remain radioactive and dangerous to human health for thousands of years.
- Uranium is a nonrenewable resource that cannot be replenished on a human time scale. Uranium is extracted from the earth through traditional mining techniques or chemical leaching.
- Every 18 to 24 months, nuclear power plants must shut down to remove and replace the “spent” uranium fuel. This spent fuel has released most of its energy as a result of the fission process and has become radioactive waste.
- Nuclear reactors and power plants require complex and costly security measures.
Nuclear power accounted for almost 20% of the total net electricity generated in the United States in 2010, In 2010, there were 65 nuclear power plants (composed of 104 licensed nuclear reactors) throughout the United States. Most of the reactors are east of the Mississippi.
Nuclear fusion, combining rather than splitting atoms, is the subject of ongoing research; but it is not yet clear that it will ever be a commercially viable technology for electricity generation.