Uranium (nuclear) Basics
Did you know?
All nuclear power in the United States is used to generate electricity.
Nuclear energy is energy in the core of an atom
Atoms are the tiny particles in the molecules that make up gases, liquids, and solids. Atoms themselves are made up of three particles called protons, neutrons, and electrons. An atom has a nucleus (or core) containing protons and neutrons, which is surrounded by electrons. Protons carry a positive electrical charge and electrons carry a negative electrical charge. Neutrons do not have an electrical charge. There is enormous energy present in the bonds that hold the nucleus together. This nuclear energy can be released when those bonds are broken. The bonds can be broken through nuclear fission, and this energy can be used to produce electricity.
In nuclear fission, atoms are split apart, which releases energy. All nuclear power plants use nuclear fission, and most nuclear power plants use uranium atoms. During nuclear fission, a neutron hits a uranium atom and splits it, releasing a large amount of energy in the form of heat and radiation. More neutrons are also released when a uranium atom splits. These neutrons go on to hit other uranium atoms, and the process repeats itself over and over again. This is called a nuclear chain reaction. This reaction is controlled in nuclear power plant reactors to produce a desired amount of heat.
Nuclear energy can also be released in nuclear fusion, in which atoms are combined or fused together to form a larger atom. This is the source of energy in the sun and stars. Nuclear fusion is the subject of ongoing research as a source of energy for heat and electricity generation, but it is not yet clear whether or not it will be a commercially viable technology because of the difficulty of controlling a fusion reaction.
Uranium is the fuel most widely used by nuclear plants for nuclear fission. Uranium is considered to be a nonrenewable energy source, even though it is a common metal found in rocks worldwide. Nuclear power plants use a certain kind of uranium, referred to as U-235, for fuel because its atoms are easily split apart. Although uranium is about 100 times more common than silver, U-235 is relatively rare.
Most U.S. uranium ore is mined in the western United States. Once uranium is mined, the U-235 must be extracted and processed before it can be used as a fuel.
Nuclear Power Plants
Nuclear power comes from nuclear fission
Many power plants, including nuclear power plants, heat water to produce electricity. These power plants use steam from heated water to spin large turbines that generate electricity. Nuclear power plants use heat produced during nuclear fission to heat water.
In nuclear fission, atoms are split apart to form smaller atoms, releasing energy. Fission takes place inside the reactor of a nuclear power plant. At the center of the reactor is the core, which contains uranium fuel.
The uranium fuel is formed into ceramic pellets. Each ceramic pellet produces roughly the same amount of energy as 150 gallons of oil. These energy-rich pellets are stacked end to end in 12-foot metal fuel rods. A bundle of fuel rods, sometimes hundreds, is called a fuel assembly. A reactor core contains many fuel assemblies.
The heat produced during nuclear fission in the reactor core is used to boil water into steam, which turns the turbine blades. As the turbine blades turn, they drive generators that make electricity. Afterward, the steam is cooled back into water in a separate structure at the power plant called a cooling tower. The water can then be reused.
Nuclear power plants generate about 20% of U.S. electricity
The United States has 99 nuclear reactors at 61 operating nuclear power plants located in 30 states. Thirty-five of the plants have 2 or more reactors. Nuclear power has supplied about one-fifth of annual U.S. electricity since 1990.
The United States generates more nuclear power than any other country
Of the 31 countries in the world that have commercial nuclear power plants, the United States has the most nuclear capacity and generation. France has the second-highest nuclear electricity generation and obtains about 75% of its total electricity from nuclear energy. Fifteen other countries generate more than 20% of their electricity from nuclear power.
Nuclear electricity generation by top five countries, 2014
Types of Nuclear Reactors
Nuclear reactors are machines that contain and control nuclear chain reactions while releasing heat at a controlled rate.
A nuclear power plant uses the heat that a nuclear reactor produces to turn water into steam, which then drives turbine generators that generate electricity.
U.S. nuclear power plants use two types of nuclear reactors
Nuclear power plants in the United States have either a boiling-water reactor or a pressurized-water reactor.
Boiling-water nuclear reactors
In a boiling-water reactor, the reactor core heats water, which turns directly into steam in the reactor vessel. The steam is used to power a turbine generator.
Pressurized-water nuclear reactors
In a pressurized-water reactor, the reactor core heats water and keeps it under pressure to prevent the water from turning into steam. This hot radioactive water flows through tubes in a steam generator.
A steam generator is a giant cylinder filled with nonradioactive water (or clean water). Inside the giant water-filled cylinder are thousands of tubes filled with the hot radioactive water from the reactor core that eventually bring the clean water to a boil and turn it into steam.
The radioactive water flows back to the reactor core to be reheated, and once reheated, returns to the steam generator. The clean water may come from one of several sources like oceans, lakes, or rivers.
What are small modular reactors?
The U.S. Department of Energy is supporting the design, certification, and commercialization of small modular reactors (SMRs). SMRS are about one-third the size of the reactors that are operating and under construction in the United States. SMRs have simple, compact designs that can be assembled in a factory and transported by train or truck to the power plant site. The size and simplicity of the SMRs could reduce the time it takes to construct a new nuclear power plant.
Getting (Producing) Uranium
Uranium is the fuel most widely used by nuclear power plants for nuclear fission. In nuclear fission, energy is released when atoms are split apart to form smaller atoms. Nuclear power plants use the heat from nuclear fission to produce electricity.
Uranium is a common metal, but it must be processed into a fuel
Uranium is a common metal found in rocks all over the world. Uranium occurs in combination with small amounts of other elements. Economically recoverable uranium deposits have been discovered primarily in the western United States, Australia, Canada, Central Asia, Africa, and South America.
Nuclear power plants use a certain type of uranium, U-235, as fuel because its atoms are easily split apart. Although uranium is about 100 times more common than silver, U-235 is relatively rare.
After uranium is mined, the U-235 must be extracted and processed before it can be used as a fuel. Mined uranium ore typically yields one to four pounds of uranium concentrate (U3O8 or yellowcake) per ton, or 0.05% to 0.20% yellowcake.