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Nuclear Power

What are the advantages of nuclear energy?

Nuclear energy is:

  • Safe and secure. Nuclear power plants are designed, built and operated with extensive safety and security measures to protect the public, plant workers and the environment. To ensure the safety of nuclear power plants, the U.S. nuclear industry is heavily regulated with strict guidelines from the Nuclear Regulatory Commission (NRC).
  • Clean. Nuclear energy is one of the cleanest power sources today. Nuclear power plants produce no greenhouse gases and are America’s largest source of carbon-free electricity.
  • Reliable and affordable. Nuclear energy can reliably generate large amounts of electricity around-the-clock to meet customers’ energy needs. In fact, nuclear power provides electricity to one in five businesses and homes in the U.S. Nuclear power plants are also the lowest-cost provider of large-scale electricity, producing baseload electricity for about 2.14 cents per kilowatt-hour.

Why are nuclear power plants considered among the safest and most secure facilities in the world?

Safety and security are the highest priority of the nuclear industry. To protect our nuclear power plants, each nuclear station has strictly controlled safety and security programs and features, including the following:

  • Redundant engineered safety systems are maintained in operable condition and frequently tested to ensure the safe operation and condition of the plants at all times.
  • Plant personnel are trained extensively to cope with abnormal situations that might arise, including “what if” scenarios.
  • Detailed and comprehensive emergency plans are practiced throughout the year in coordination with local, state and federal emergency management officials to ensure plans, equipment and personnel can appropriately respond to an emergency or abnormal event.
  • Reactor operators are rigorously trained and are subjected to careful screening. Operators have stringent standards on continuing training, which is one week out of every five weeks.
  • Well-trained, armed security forces protect all U.S. plants 24 hours a day.
  • Multiple physical intrusion barriers consisting of concrete structures and razor wire fences surround the plants.
  • Advanced surveillance equipment continuously monitors areas around the plants.
  • Safety system functions protect plants from cyber-security attacks.
  • Low concentration of fuel (uranium-235) makes it physically impossible for a commercial nuclear power plant in the U.S. to explode like a nuclear bomb.

Additionally, all nuclear plants are built to withstand a wide variety of external forces, including hurricanes, tornadoes, fires, floods and earthquakes.

What role does nuclear power play in Duke Energy’s generating portfolio?

Duke Energy operates 11 nuclear units in the Carolinas at six plant sites. Affordable, reliable and clean nuclear energy has been part of Duke Energy's generation mix for 40 years. And, with zero carbon emissions, it is an important clean-energy resource for the future.

Safety and security have always been the highest priority in Duke Energy’s nuclear program, which began in the 1960s with the construction of Robinson Nuclear Plant. Our plants are designed, built and operated for safety, with multiple barriers and redundant and diverse safety systems to protect the public, plant workers and the environment.

Are Duke Energy’s nuclear power plants designed to withstand natural forces?

Nuclear plants operated by Duke Energy, like all U.S. nuclear power plants, are built to withstand a wide variety of external forces, including hurricanes, tornadoes, fires, floods and earthquakes.

  • Each nuclear unit can be safely shut down in the event of severe natural occurrences, such as an earthquake, as part of the plant design.
  • Plants are built to withstand earthquakes of the magnitude equivalent to or greater than the largest known earthquake for the region where they are located.
  • Key safety systems in the plant are designed to withstand the ground motion that would result from a design basis earthquake. Engineers and scientists calculate the potential for earthquake-induced ground motion using a wide range of data. They review the impacts of historical earthquakes up to 200 miles away from each plant site, with careful study given to those within 25 miles. All of this information is used to determine the maximum potential earthquake that could affect the site.
  • Each plant has sensitive instrumentation to detect seismic activity and alert operators if it is necessary to shut down the plant or take other precautionary measures.
  • Safety at nuclear plants in the U.S. is based on the defense in depth philosophy, where multiple barriers and redundant safety systems ensure the safe operation and condition of the plants at all times.
  • Detailed and comprehensive emergency plans are practiced throughout the year in coordination with local, state and federal emergency management officials to ensure our plans, equipment and personnel can appropriately respond to an emergency or abnormal event.

What additional safeguards protect nuclear power plants from extraordinary events?

The physical attributes of nuclear power plants, along with well-trained and highly-skilled security forces, are integrated into the overall station design to ensure the safe operation of the plant and to protect against extraordinary events.

Additionally, the U.S. nuclear industry has implemented a program of continuous improvement based on lessons learned from worldwide operating experience to better protect our plants in the event of an emergency.

  • After the 1979 Three Mile Island accident, significant changes were made to emergency planning requirements and emergency operating procedures. Human factor issues were addressed by now requiring every nuclear station to have a replica of its control room for training purposes. New requirements for hydrogen control were added to help prevent explosions inside of containment, along with new requirements for enhanced control room displays of the status of pumps and valves. Modifications were also made to the Resident Inspector Program, which now requires at least two full-time NRC inspectors to be on site at each nuclear power plant.
  • Since the events of Sept. 11, 2001, the NRC required U.S. nuclear operators to revamp their disaster plans to deal with the potential loss of large areas of the plant after extreme events. The NRC now requires licensees to have important equipment available and staged in advance, in addition to new procedures and policies to deal with an emergency. It was also proved, using sophisticated computer modeling by some of the world’s leading structural engineers, that critical structures at nuclear plants can withstand a jetliner impact without releasing radiation.

How will the Fukushima Daiichi nuclear accident in Japan affect the U.S. nuclear industry?

On Friday March 11, 2011, Japan was struck by a magnitude-9 earthquake. Fukushima Daiichi’s safety systems survived the earthquake, but the ensuing tsunami caused the site to lose normal and emergency power, resulting in the site losing cooling system capabilities.

Our industry takes our commitment to the safe operation of nuclear energy facilities very seriously, and as the full extent of Fukushima events are learned, more long-term corrective measures and assessments will be taken to further protect nuclear plants in the U.S.

To ensure that reactors in the U.S. could respond to an event similar to what occurred at Fukushima, the U.S. nuclear industry has already taken the following actions.

  • Re-assessed each plant’s ability to maintain safety during extreme events, including the loss of significant operational systems caused by natural events, fires, aircraft impact or explosions.
  • Re-assessed each plant’s ability to respond to a total loss of off-site power by confirming that we have adequate materials and procedures in place.
  • Re-assessed each plant’s ability to respond to floods, including their impact on systems inside and outside the plant.
  • Performed walk-downs and inspection of important equipment needed to respond successfully to fires and floods.
  • All U.S. nuclear stations underwent detailed inspections by the NRC as follow-up to the Fukushima event. Information from this review will also be used to evaluate the readiness of U.S. nuclear plants to respond to similar events.

For more information on the situation in Japan, please visit the Nuclear Energy Institute and U.S. Nuclear Regulatory Commission websites

How do nuclear power plants prevent cyber-security attacks?

Cyber security has been an area of increased activity over recent years, and Duke Energy has completed many tasks and projects related to cyber security as part of its nuclear security programs. Since the terrorist attacks of Sept. 11, 2001, U.S. nuclear stations have been subject to several NRC orders related to cyber security, including 10 CFR 73.54, "Protection of digital computer and communication systems and networks,” which is currently being implemented. It requires each licensee to provide high assurance that digital computer and communication systems and networks are adequately protected against cyber attacks.

  • Duke Energy has a detailed cyber security plan for its nuclear stations and continues to perform plan assessments, update the plan and implement new standards/controls as necessary.
  • Duke Energy complies with all cyber security orders and programs related to nuclear operations and, through national and industry networks, remains abreast of new information related to cyber security.
  • Safety and control systems at U.S. nuclear power plants are not connected to the Internet.
  • Nuclear power plants have security attributes (technologically advanced detection, insider mitigation programs and behavior testing) not found at other critical infrastructure, and safety system functions are securely protected from cyber attack.
  • Unlike industries for which two-way data flow is critical (e.g., banking), nuclear power plants do not require incoming data flow.
  • Nuclear plants are protected from grid instability with backup power supplies that provide for safe reactor shut down in the event of a blackout.

How long can nuclear power plants operate?

The NRC initially licenses U.S. nuclear power plants to operate for 40 years.

After the initial operating license, current federal regulations permit nuclear plant owners to renew their plants’ license for an additional 20 years. To renew a license, the NRC must be satisfied the plant can operate safely for an additional 20 years. Learn more about the NRC license renewal process.

Since no nuclear plant has operated long enough to explore renewal after the additional 20 years, there is still a possibility for further license extension.

How does Duke Energy store its used nuclear fuel?

The federal government has responsibility for permanently disposing of high-level waste (used nuclear fuel). Until a permanent disposal facility is licensed, used nuclear fuel is safely and securely stored at plant sites in storage pools or specially designed dry storage containers.

Duke Energy has more than 40 years of experience handling used nuclear fuel. Our employees are well-trained, environmentally conscious professionals who take pride in their work.

If all the used fuel produced in nearly 50 years of U.S. nuclear power plant operations was stacked end to end, it would cover a football field to a depth of less than 10 yards. Ninety-six percent of this “waste” could be recycled.

President Obama appointed a Blue Ribbon Commission to re-evaluate fuel storage, and Duke Energy continues to support the government's efforts to fulfill its obligation to accept and manage used nuclear fuel. Until a national repository or recycling is available, utilities will continue to safely and securely store used fuel at nuclear stations.

What is radiation and is it emitted from nuclear power plants?

Radiation is a natural part of our environment. We receive radiation from the sun, minerals in the earth, the food we eat and building materials in our houses. Even our bodies give off small amounts of radiation. Some radiation also comes from manmade sources such as medical and dental X-rays, televisions and smoke detectors.

The amount of radiation a person gets is measured in millirems. The average person receives about 360 millirems of radiation each year — about 80 percent comes from natural sources and the rest from manmade sources.

Nuclear power plants contribute a very small amount of radiation to the environment which is carefully monitored, meets established regulations and is reported to the appropriate local, state and federal agencies. A person living next to a nuclear plant will receive less than one additional millirem per year due to plant operations.

Visit the U.S. Environmental Protection Agency’s website to enter RadTown USA, an interactive tool used to explore a virtual community of houses, schools, laser light shows, construction equipment, flying planes and moving trains. Each place in RadTown helps you learn about radiation sources or radiation-treated items you might find there.

What is the white cloud seen coming from some nuclear plants?

The white cloud — or plume — is simply water vapor being released from the plant's large cooling towers. Some of Duke Energy's plants use lakes to cool the water, so the large cooling towers are unnecessary. Lake or river water flows through thousands of tubes to cool steam and turn it back into water. It is then discharged down a long canal (for further cooling) and eventually enters the main part of the lake or river.

At other plants, the cooling water is circulated through cooling towers to remove the extra heat it has gained. The water is pumped to the top of the cooling towers and pours down through the structure. At the same time, a set of fans at the top of each tower pulls air up through the condenser water to cool it even more. The condenser water then flows back into the turbine building to begin condensing steam again.

Why are new nuclear power plants necessary? Can't we just use wind or solar power?

Although renewable energy sources, like wind and solar power, are important resources for the country’s energy mix, only nuclear power is capable of producing large amounts of electricity 24 hours a day, 365 days a year.

While Duke Energy is also investing in wind and solar farms, large baseload plants — like nuclear — are an important part of our mission to provide clean, affordable, reliable electricity.

Duke Energy New Nuclear Generation

What are Duke Energy’s plans for new nuclear generation?

Duke Energy submitted combined construction and operating license (COL) applications to the Nuclear Regulatory Commission (NRC) for the proposed Lee Nuclear Station Gaffney, S.C., the Levy County site in Florida, and for two new units at its Harris site in New Hill, N.C.

Duke Energy selected the Westinghouse AP1000® for the proposed new nuclear stations. The Westinghouse AP1000 reactor is an advanced passive pressurized water reactor (PWR), featuring innovative passive safety systems and proven Westinghouse PWR technology — which is currently in use at several of our nuclear facilities.

Westinghouse is partnering with The Shaw Group Inc., a global engineering, design, construction and operations firm, on engineering work for this project. See our Technology section for more information.

Will the Fukushima Daiichi accident affect new nuclear plant construction in the U.S.?

It's premature to draw conclusions about the impact of the Fukushima accident on the U.S. new nuclear plant construction. New reactor projects are in the early stages and there is sufficient time to incorporate lessons learned from the events in Japan as more is learned. Projects awaiting their COLs from the NRC are expected to proceed.

Nuclear energy has and will continue to play a key role in meeting America’s energy needs. Duke Energy is continuing with development activities for its proposed nuclear plants.

Nuclear Glossary

Here are a few commonly used words in the nuclear industry. Visit the NRC website for additional words and phrases.

Atom: The smallest particle of an element that cannot be divided or broken up by chemical means. It consists of a central core called a nucleus, which contains protons and neutrons. Electrons revolve in orbits in the region surrounding the nucleus.

Atomic Energy: Energy produced in the form of heat during the fission process in a nuclear reactor. When released in sufficient and controlled quantity, this heat energy may be used to produce steam to run a conventional turbine generator to produce electrical power. Atomic energy is more correctly called nuclear energy.

Background Radiation: Radiation in the environment from cosmic rays and radioactive material that naturally exists in soil, water and air. The amount of radiation a person gets is measured in millirems, and the average person receives about 360 millirems of radiation each year — about 80 percent from natural sources and the rest from manmade sources.

Boiling Water Reactor (BWR):  A kind of commercial power reactor Duke Energy operates. The water flows upward through the core, where it is heated by fission and allowed to boil in the reactor vessel. The resulting steam then drives turbines, which activate generators to produce electrical power.

Capacity Factor: A measure of reliability, reflecting the amount of electricity a generating unit provides versus how much it could provide if operating at all times.

Combined Construction and Operating License (COL): A license issued by the NRC authorizing a licensee to construct and operate a nuclear power plant at a specific site, in accordance with established laws and regulations. A COL is valid for 40 years, with the possibility of a 20-year renewal.

Containment Building: The structure housing the nuclear reactor, pressurizer, reactor coolant pumps, steam generators and other associated piping and equipment. It is an airtight structure, steel-lined, with heavily reinforced concrete walls several feet thick. It is designed to withstand tremendous physical forces.

Control Rods: Rods made of material that absorbs neutrons. When inserted into the nuclear fuel, the rods stop the fission process, thereby shutting down the reactor.

Cooling Tower: A heat exchanger designed to aid in the cooling of water that was used to cool exhaust steam leaving the turbines of a power plant. Cooling towers transfer exhaust heat into the air, instead of into a body of water.

Core: The central portion of a nuclear reactor, which contains the fuel assemblies, moderator, neutron poisons, control rods and support structures. The reactor core is where fission takes place.

Fission: The splitting of the atom, which releases tremendous amounts of heat energy.

Fuel Rod: A long, slender, zirconium metal tube containing pellets of fissionable material, which provide fuel for nuclear reactors. Fuel rods are assembled into bundles called fuel assemblies, which are loaded individually into the reactor core.

Pressurized Water Reactor (PWR): The kind of commercial power reactor Duke Energy operates. The reactor heats water in a closed system that then transfers its heat to another closed system in the steam generators to produce steam for a turbine generator.

Radiation: Particles and/or energy given off by unstable atoms as they undergo radioactive decay to stability.

Reactor: A cylindrical, steel vessel that contains the core, control rods, coolant and structures that support the core.

Steam Generator: A large heat exchanger. In a pressurized water reactor, it’s the large steel tank where steam is produced. It is located inside the containment building.

Turbine Generator: A structure housing the steam turbine, electric generator and much of the feedwater system.

Uranium: A critical element used in nuclear power reactors because of the ability of its atoms to undergo fission when it absorbs neutrons.