A single uranium fuel pellet the size of a fingertip contains as much energy as 17,000 cubic feet of natural gas, 1,780 pounds of coal or 149 gallons of oil.
Nuclear power plants do not burn any fuel. Instead, they use uranium fuel, consisting of solid ceramic pellets, to produce electricity through a process called fission.
The yellowcake then goes to a conversion plant, where chemical processes convert it to uranium hexafluoride. The uranium hexafluoride is heated to become a gas and loaded into cylinders. When it cools, it condenses into a solid.
Uranium hexafluoride contains two types of uranium, U-238 and U-235. The percentage of U-235, which is the type of uranium that fissions easily, is less than 1 percent. To make the uranium usable as a fuel, its U-235 content is increased to between 3 percent and 5 percent. This process is called enrichment. The concentration of U-235 is so low in enriched uranium that an explosion is impossible.
After the uranium hexafluoride is enriched, a fuel fabricator converts it into uranium dioxide powder and presses the powder into fuel pellets. The fabricator loads the ceramic pellets into long tubes made of a noncorrosive material, usually a zirconium alloy. Once grouped together into a bundle, these tubes form a fuel assembly.
For more information, see the U.S. Nuclear Regulatory Commission's website pages on "Stages of the Nuclear Fuel Cycle," "Uranium Conversion," and "Fuel Fabrication."
Size of Nuclear Fuel Assemblies
A single fuel assembly for a boiling water reactor (BWR) is approximately 14.5 feet high and weighs approximately 704 pounds. A single fuel assembly for a pressurized water reactor (PWR) is approximately 13 feet high and weighs approximately 1,450 pounds. The PWR fuel assembly weighs more because it contains 264 fuel tubes, while the BWR fuel assembly contains 63.
Watch NEI's easy-to-understand video tutorial below on fuel assemblies in a nuclear reactor. (Note: Select "Full screen" at the bottom right of the video to see an enlarged version of the video.)
The utility industry is confident that the fuel supply industry will respond to increasing demand. Bolstering confidence in future supply is the fact that some of the world’s richest deposits of uranium are in politically stable countries. Canada and Australia account for 40 percent of global uranium production; the United States accounts for 3 percent.
In 2009, uranium of U.S. origin accounted for 14 percent of the material used by the owners and operators of U.S. nuclear power plants. The remainder (49.8 million pounds) came from other sources, according to the U.S. Energy Information Administration. The U.S. uranium production industry is working to increase domestic supplies. For example, 2008 expenditures for uranium exploration and mine development in the United States were up 673 percent from 2004. Revitalization of the U.S. uranium production industry also brightens the job market. Although the industry remains comparatively small, employment has more than doubled since 2004.
'Megatons to Megawatts' Program A U.S.-Russian program to eradicate weapons provides the uranium to generate 10 percent of America’s electricity. The “Megatons to Megawatts” program involves the conversion, dilution and recycling of highly enriched uranium fuel from former Soviet nuclear warheads into low-enriched fuel for nuclear power plants. USEC Inc. purchases the uranium and then markets the fuel to its electric industry customers. The program implements a 1993 agreement between the United States and Russia calling for Russia to recycle 500 metric tons of weapons-grade uranium from dismantled warheads. USEC reported that as of December 31, 2010, the program had recycled 412 metric tons of highly enriched uranium into 111,905 metric tons of low-enriched uranium—equivalent to 16,494 warheads eliminated. For more information, visit the USEC Inc. Web site.