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

Is Nuclear Power Bad?

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. Electric companies are reportedly saying that nuclear energy could disappear from California within a decade if the state rejects plans to spend $1.4 billion repairing the aging generators at the San Onofre and Diablo Canyon nuclear power plants. Photo by David McNew/Getty Images

The United States is the world's largest producer of nuclear power. In 2014, it generated 798.6 billion kilowatt hours (kWh) of electricity. That's more than 30% of the 2.4 trillion kWh 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).

U.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 until 1992. (Source: World Nuclear Association, Nuclear Power in the USA, May 2015)

Nuclear Power Stations

There are 99 operating nuclear power plants in thirty states. Most are located east of the Mississippi (see map) They create $40 - $50 billion each in electricity sales and 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)

U.S. nuclear plants generated 19.6% of the 4.092 trillion kWh of total U.S. electricity production in 2014. That was second to coal, (37.7%) and natural gas (28%), but greater than hydro (6.6%) or alternative sources such as wind power (8.1%).

There are also 36 test reactors at research universities (see map). They are used to create small amounts of radiation for experiments.

That 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)

How Does Nuclear Power Work?

All power plants heat water to produce steam, which turns a generator to generate electricity.

In nuclear power stations, that steam is made by the heat generated from nuclear fission. That'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, starting a chain reaction. That's why a nuclear bomb is so powerful.

In a nuclear generator, this 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 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. That allows it to heat to super-high levels. That heat transfers through pipes to a separate container of water in the generator. That creates the steam that drives the electricity turbine. The water from the reactor returns to be reheated. The steam from the turbine is cooled in a condenser. The resulting water is sent back to the steam generator. (Source: "How Does Nuclear Energy Work?", UNAE) Here's an animated version of a pressurized water reactor.

Boiling water reactors use boiling water to directly create the steam the that drives the generator. Here's an animated version of the boiling water reactor

Most important, the process takes place in a contained environment to protect the outside world from any contamination. Power plants can be cooled down and even stopped quickly. 


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

They create .5 jobs for every megawatt hour (mWh) of electricity produced. That compares to .19 jobs in coal, .05 jobs in gas-fired plants, and .05 in wind power. The only source that creates more jobs/mWh is solar photovoltaic, at 1.06 jobs/mWh. (Source: "Nuclear Energy's Economic Benefits," NEI)

For decades, nuclear power has had the cheapest operating costs. At 1.87 cent/kWh (2008 figures), it's 68% of the cost of coal and, for years, just 25% the cost of natural gas. 

Fears about global warming inhibited new construction of coal-fired plants. As a result, from 1992 to 2005, some 270,000 MWe of new gas-fired plants were built. At the time, gas plants seemed to have the lowest investment risk. As a result, only 14,000 MWe of new nuclear and coal-fired capacity came online. That helped drive up natural gas prices, forcing large industrial users of it offshore and pushing gas-fired electricity costs towards 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 gasses and particles. Radioactive particles are then inhaled or ingested by people and animals, or deposited on the ground. These particles are composed of unstable atoms that give off excess energy, called radiation until they become stable. In low doses, radiation is harmless, but after a nuclear meltdown, 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 likelihood is rare. The only U.S. nuclear disaster was at Three Mile Island in 1979 when the radioactive fuel rods partially melted. Only a bit of radioactive gas was released, without any measurable health effects. Nevertheless, no new nuclear power plants were built for 30 years.

Nearly three million Americans live within ten miles of an operating plant, where 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 it 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 and takes hundreds of thousands of years to deactivate. Currently, 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 (NRC) to design, construct, operate, and eventually decommission a permanent geologic repository for the disposal of high-level waste at Yucca Mountain, Nevada. However, 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: NRC, High-Level Waste Disposal)

The Future of U.S. Nuclear Power

Annual U.S. electricity demand is projected to rise 28% 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 plants. There were also three regulatory initiatives that eased the way:

  1. A streamlined design certification process.
  2. Provision for early site permits.
  3. Combining 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," WSJ , October 29, 2015)

Fracking of domestic shale oil and natural gas has made gas an affordable alternative to modernizing old nuclear plants. As a result, four plants have closed in the last two years. Keeping the old nuclear plants running costs more than building new gas-fired plants, or refurbishing old coal 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: Christina Nunez, "​Another Reactor Closes, Punctuating New Reality for U.S. Nuclear Power, National Geographic.)

Continue Reading...