Frequently Asked Questions on Nuclear Power

How does nuclear power affect the environment?
Clean-Air Benefits of Nuclear Energy
Nuclear power plants aid compliance with the Clean Air Act of 1970, which set standards to improve the nation's air quality. Using more nuclear energy gives states additional flexibility in complying with clean-air requirements.

Climate Change Initiatives
Federal, state and local policymakers increasingly recognize nuclear energy's contribution to meeting growing electricity demand while reducing greenhouse-gas emissions.

Life-Cycle Emissions Analysis
Nuclear power plants do not emit criteria pollutants or greenhouse gases when they generate electricity. The life-cycle emissions from nuclear energy are comparable to other non-emitting sources of electricity like wind, solar and hydropower.

Clean Electricity for Transportation
Research is under way to reduce air emissions from the transportation sector by developing electric vehicles that can run farther and longer between charges. Clean electricity from nuclear plants can make these vehicles truly "clean."

Nuclear energy has one of the lowest impacts on the environment of any energy source because it does not emit air pollution, isolates its waste from the environment and requires a relatively small amount of land.

Sustainable Development
Nuclear energy has a vital role to play in providing clean energy for sustainable economic development around the world.
What are nuclear reactors?
Reactors use fission to make electricity rather than burn fossil fuels. A nuclear power plant generates electricity using a "reactor," which is a device designed to use the fission process (splitting of atoms) to turn a small amount of mass into energy in a controlled way. Each fission produces energy, neutrons, and waste fission products.

The energy from the fission reaction is removed from the reactor by a coolant to produce steam to drive the turbines of the electric generators. Thus, in a nuclear power plant, fission of nuclear fuel plays the same role as burning of coal, natural gas, or oil plays in fossil fuel power plants. The neutrons cause more fission reactions. There are two types of reactors: thermal spectrum and fast-spectrum, or simply "thermal" or "fast" for short. The difference has to do with the energy level of the neutrons. The Global Nuclear Energy Partnership includes both.
What are thermal reactors?
In a thermal reactor, the neutrons created by fission are slowed down, or moderated, before they cause more fission reactions. Thermal reactors typically use a special type of uranium, called "enriched" in the isotope uranium-235 and certain isotopes of the transuranic elements, called "fissile." Virtually all of the world's 441 operating nuclear power plants are thermal reactors. Most of these are Light Water Reactors (LWRs), which use water to cool the reactor and to moderate (slow-down) neutrons. The two LWR types, boiling water reactors (BWRs) and pressurized water reactors (PWRs), result from early U.S. reactor development programs. LWRs dominate world nuclear energy because their technology is well proven and they have favorable economics compared to other options currently available.
What does nuclear fuel look like?
Nuclear fuel is a solid material like coal or wood. It is not a liquid or a gas like oil or propane. For U.S. nuclear power plants, uranium oxide fuel is made into pellets. The pellets are stacked into long tubes, typically made of an alloy of zirconium metal, to form fuel rods. The fuel rods are bundled together and structurally reinforced to form a fuel assembly. These assemblies are installed in a nuclear reactor. The size and form of a nuclear fuel assembly depends on the type of reactor in which it will be used. There are typically hundreds of fuel assemblies in a single nuclear power plant.
How does a nuclear power plant work?
Power plants, whether they are coal, gas, oil or nuclear, use steam to make electricity. They operate like a giant tea kettle, turning water into steam which spins giant turbines that power generators to make electricity. The primary difference between fossil and nuclear power plants is that nuclear plants use uranium as the fuel to produce steam instead of burning fossil fuels.

In a nuclear power plant reactor, water is heated by a process called nuclear fission.
  • Uranium atoms are split when they are struck by neutrons.
  • When the atoms split, they release heat, along with two or three more neutrons.
  • These neutrons then strike other uranium atoms, again causing the atoms to split, release heat and again, two or three more neutrons. This is called a chain reaction.
The steam then spins the turbines that are connected to the generators to produce electricity.
Can a nuclear plant explode?
No, a nuclear explosion cannot occur at commercial nuclear plants.

Fuel for nuclear plant uranium is mined from the earth and then goes through the process of "enrichment." From that process, comes uranium-235 (which makes up approximately 4% of nuclear fuel used at a commercial facility) and uranium-238 (which makes up the other 96% of the fuel). In order to have an explosion, unranuim-235 must make up nearly 100% of the fuel. Scientifically speaking, an explosion at a nuclear facility in the U.S. would counter the laws of physics.