Nuclear Power in America: How It Works, Pros, Cons, Impact

Is U.S. Nuclear Power the Answer to Climate Change?

Nuclear Power Plant
••• Evening sets on the San Onofre atomic power plant December 6, 2004 in northern San Diego County, south of San Clemente, California. Photo by David McNew/Getty Images

The United States is the world's largest producer of nuclear power. In 2016, it generated 805 billion kilowatt hours (kWh) of electricity. That's more than 30 percent of the 2.4 trillion kWh of nuclear power produced worldwide. France is the second largest producer (418 billion kWh), followed by Russia (169.1 billion kWh), South Korea (149.2 billion kWh), China (123.8 billion kWh) and Canada (98.6 billion kWh).

(Non-U.S. figures are from 2014. Latest figures unavailable.)

The United State’s leadership came from its historic role as a pioneer of nuclear power development. The first commercial pressurized water reactor, Yankee Rowe, started up in 1960 and operated till 1992. (Source: "Nuclear Power in the USA," World Nuclear Association, April 2017.)

Nuclear Power Stations

There are 99 operating nuclear power plants in thirty states. Most are located east of the Mississippi River (see map). They generate around $40 - $50 billion each in electricity sales and create over 100,000 jobs. Every dollar spent by the average reactor generates $1.87 in the U.S. economy. (Source: "Nuclear Energy's Economic Benefits," Nuclear Energy Institute, April 2014.)

U.S. nuclear power plants generated 19.7 percent of the 4.079 trillion kWh of total U.S. electricity production in 2016. It was second to coal (30 percent) and natural gas (34 percent).

It's greater than hydroelectricity (6.5 percent) and other alternative sources including wind power (8.4 percent).

There are also 36 test reactors at research universities (see map). They are used to create small amounts of radiation for experiments. This is where scientists study neutrons and other subatomic particles, examine automotive and medical components and learn how to better treat cancer.

(Source: "Backgrounder on Research and Test Reactors," NRC, August 18, 2011.)

How Does Nuclear Power Work?

All power plants heat water to produce steam, which turns a generator to create electricity. In nuclear power stations, that steam is made by the heat generated from nuclear fission. It’s when an atom is split, releasing enormous amounts of energy in the form of heat. 

Uranium 235 is used as fuel because it breaks apart easily when it collides with a neutron. Once that happens, the neutrons from the uranium itself start colliding with its other atoms. This starts a chain reaction. That's why nuclear bombs are so powerful.

In a nuclear generator, the chain reaction is controlled by special rods that absorb excess neutrons harmlessly. These control rods are placed next to the fuel rods, which contain uranium fuel pellets. Over 200 of these rods are grouped into what is known as a fuel assembly. When the engineers want to slow down the process, they lower more control rods into the assembly. When they want more heat, they raise the rods. (Source: "How Do Nuclear Plants Work?" Duke Energy.)

The United States has two types of nuclear power plants. There are 65 pressurized water reactors and 34 boiling water reactors.

They differ in how the heat is transferred from the reactor to the generator. 

Pressurized water reactors use high pressure to keep the water in the reactor from boiling. This allows it to heat to super-high levels. The heat is then transferred through pipes to a separate container of water in the generator. It creates the steam that drives the electricity turbine. The water from the reactor then returns to be reheated. The steam from the turbine is cooled in a condenser. The resulting water is sent back to the steam generator. Here's an animated version of a pressurized water reactor.

Boiling water reactors on the other hand, use boiling water to directly create the steam to drive the generator. Here's an animated version of the boiling water reactor

What is most important is that the entire process takes place in a contained environment in order to protect the outside world from any contamination.

The power plants can be cooled down and even stopped quickly. (Source: "How Does Nuclear Energy Work?", UNAE.)


Nuclear power plants don't emit any greenhouse gasses, unlike coal and natural gas.

They create 0.5 jobs for every megawatt hour (mWh) of electricity produced. This is in comparison to 0.19 jobs in coal, 0.05 jobs in gas-fired plants and 0.05 in wind power. The only other power source that creates more jobs/mWh is solar photovoltaic, at 1.06 jobs/mWh. (Source: "Nuclear Energy's Economic Benefits," Nuclear Energy Institute, April 2014.)

For decades, nuclear power has had the cheapest operating costs. At 1.87 cent/kWh (2008 figures), it's 68 percent of the cost of coal. And until recently, it was just 25 percent of the cost of natural gas. 

Fears about global warming inhibited new construction of coal-fired power plants. As a result, from 1992 to 2005, some 270,000 megawatts of enerfy of new gas-fired power plants were built. At the time, those plants seemed to have the lowest investment risk. As a result, only 14,000 MWe of new nuclear and coal-fired capacity came online. It helped drive up natural gas prices, forcing large industrial users offshore and pushing gas-fired electricity costs toward 10 cents/kWh.


There are two huge disadvantages to nuclear power, thanks to the radioactive nature of its fuel source. 

1. An accident at the plant could release radioactive material into the environment as a plume (cloud-like formation) of radioactive gases and particles. These particles are then inhaled or ingested by people and animals or deposited on the ground. The particles are composed of unstable atoms that give off excess energy, called radiation, until they become stable. In low doses, radiation is harmless. After a nuclear meltdown though, the large doses destroy living cells and can cause mutations, illness and death. 

The potential impact of a nuclear meltdown can be catastrophic, as seen in Chernobyl and Fukushima, even though the chances of such an incident happening is rare. The only U.S. nuclear disaster was at Three Mile Island in 1979 when the radioactive fuel rods partially melted. Only a small amount of radioactive gas was released. There were no measurable health effects. Nevertheless, no new nuclear power plants were built for 30 years.

Almost three million Americans live within 10 miles of an operating plant. They risk direct radiation exposure in case of an accident. If you are one of those people, here's how to prepare for an accident.

2. Disposal of nuclear waste is a huge disadvantage. Low-level waste comes from contact with the nuclear fuel in day-to-day operations. It is disposed of on-site or is sent to a low-level waste facility in one of 37 states. (Source: "Low-Level Waste," U.S Nuclear Regulatory Commission.) 

High-level waste consists of spent fuel. It takes hundreds of thousands of years to deactivate. At the moment, 70,000 tons of this fuel is stored at the power plants themselves. (Source: "Faff and Fallout," The Economist, August 29, 2015.)

In the Nuclear Waste Policy Act of 1982, Congress told the U.S. Nuclear Regulatory Commission to design, construct, operate and in the end decommission a permanent geologic repository for the disposal of high-level waste in Yucca Mountain, Nevada.

Local officials don't want the hazard in their state. They delayed its development until 2013 when the NRC won its case in the U.S. Court of Appeals. In 2015, the NRC completed a safety assessment and began work on an Environmental Impact Statement. (Source: "High-Level Waste Disposal," U.S. Nuclear Regulatory Commission.)

The Future of U.S. Nuclear Power

Annual U.S. electricity demand is projected to rise 28 percent by 2040. With rising oil and gas prices and concern about global warming, nuclear power has started to look attractive again. In the late 1990s, nuclear power was seen as a way to reduce dependency on imported oil and gas. This policy change paved the way for significant growth in nuclear capacity.

The Energy Policy Act of 2005 provided financial incentives for the construction of advanced nuclear power plants. There were also three regulatory initiatives that eased the way:

  • A streamlined design certification process.
  • The provision for early site permits.
  • The combining of the construction and operating license process.

Since 2007, companies have applied for 24 licenses for new nuclear reactors. There are four new plants under construction. Westinghouse is building two in Georgia and two in South Carolina. (Source: "Westinghouse Buys CB&I's Nuclear Unit," The Wall Street Journal, October 29, 2015)

On the other hand, fracking of domestic shale oil and natural gas has made gas an affordable alternative to modernizing old nuclear power plants. As a result, four plants have closed in the last two years. Keeping old nuclear power plants running costs more than building new gas-fired plants. It is even more expensive than refurbishing old coal-fired power plants to natural gas.

Therefore, the future of expanding nuclear power in America depends on natural gas prices. If they rise again and stay high, expect attention to return to nuclear power generation. (Source: "Another Reactor Closes, Punctuating New Reality for U.S. Nuclear Power," National Geographic, January 1, 2015.)