How Nuclear Power Works

Nuclear power is usually associated with the major disasters of Chernobyl, Fukushima and Three Mile Island. While these disasters make nuclear power plants seem like a dangerous source of energy ready to blow at any moment, there have only been three major accidents across over 16,000 cumulative reactor-years of operation in 32 countries, according to the World Nuclear Association. In fact, nuclear power is actually a more common source of energy than you may believe.

According to the U.S. Nuclear Regulatory Commission, there are currently 100 nuclear power plants in the U.S. licensed to operate. You may have spotted them by their massive hourglass-shaped towers.

To help you get to the “core” of the nuclear power process and understand its true potential, we’ve visualized everything from the molecular level to the large hourglass cooling towers that are the most iconic symbol of nuclear power plants.

The nucleus of the Uranium atom is bombarded with neutrons which causes it to split apart and collide with other atoms in a chain reaction.

Uranium undergoes spontaneous fission at a slow rate naturally, making it perfect to use as a fuel source for nuclear power plants. Nuclear power plants induce fission and use the energy given off as the source of its power.

Inside the reactor, enriched Uranium pellets are arranged in long rods. The rods are put in bundles and submerged in water.

The uranium used in the plants is found naturally in the earth’s crust in the form of uranium-238 (U-238) and uranium-235 (U-235). The numbers refer to the amount of protons and neutrons found in the atom. The natural uranium mined is then formed into pellets at processing plants. The pellets used in the reactor core are the fuel form.

Image of containment structure showing enriched Uranium submerged into water in the reactor core. Then water heats to 570˚F then pressurizes. This pressurized water feeds into a steam generator and turns to steam. A second image of a turbine/generator shows steam generator powering turbine. The turbine powers the generator. Steam then condenses into water and pumps into the cooling tower. The third image is of the cooling tower which cools water. Fresh water pumps in to get cooled. Then cool water cycles back through.

There are two types of nuclear power plants: pressurized water reactors and boiling water reactors. Since two-thirds of U.S. nuclear plants are pressurized water reactors, we’ve focused on that here. From the outside, the large containment structure and cooling towers might be all that you can see to distinguish it from other types of power plants. But, what’s on the inside of the containment structure is where the real action happens. This concrete structure houses the steel containment vessel that shields the reactor core and protects the outside world from the radioactive steam.

So what is it about nuclear power plants that makes them so different than other types of power and potentially dangerous? Despite their stigma, nuclear power plants work very similarly to other power plants in that they heat water into steam that powers a turbine generator. However, instead of burning coal, they harness the power of nuclear fission using uranium to heat the water. Any negative associations with nuclear power stem from these highly radioactive nuclear reactors that house the heated uranium. The radioactive materials, if released, can be harmful and potentially deadly to those exposed. But, as long as proper safety measures are in place and properly followed, all potential problems with nuclear power can be avoided.

Chernobyl’s safety systems were deliberately turned off during a test, which lead to an overheating of the system. Fukushima’s electricity, which helps cool a reactor, was knocked out during an earthquake and subsequent tsunami. But these risks were known, and certain safety precautions that could have been taken to prevent problems were ignored by the plant’s owner. After an electrical or mechanical failure, the Three Mile Island incident was caused by the way the workers misread the situation.

A mix of high construction costs, high energy prices and public scrutiny halted the growth of nuclear power plants in the 1970s. Despite this, the U.S. accounts for 30% of the world’s nuclear power generation. And according to the World Nuclear Association, U.S. reliance on nuclear is on the rise. There are plans for at least four more plants as of 2021, with the first new nuclear plant of the 21st century completed in October 2016. Control of nuclear power plants has come a long way since the Chernobyl days, but nuclear power will always be a powerful energy source that requires constant vigilance.

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