In the late 1930s, we discovered that some particularly large atoms found in nature can be split into two (or fission), releasing a shocking amount of energy as heat. Because the energy emerges from the atomic nucleus, we call it nuclear energy.

When these atoms are arranged properly in a machine called a nuclear reactor, each splitting nucleus can induce its neighbors to split in turn, creating a controlled chain reaction. Reactors can convert the released nuclear heat into electricity, shaft horsepower (to power ships), building heating, desalinated water, hydrogen, and many other things useful to human civilization.

Today, about 430 commercial nuclear power plants worldwide produce around 400 GW of electricity, enough to power 400 million average households. About one-fifth of the USA’s electricity comes from nuclear power, which represents about half of the country’s zero-carbon electricity.

Nuclear energy is controversial due to concerns about radiation. Public support varies geographically, but nuclear is generally among the least popular forms of energy.

Why are some people so excited about nuclear energy?

Click on each of the headings for more details.

What are the downsides of nuclear energy?

Of course nothing’s perfect. Long-standing questions and concerns abound regarding nuclear energy. Click for details.

A nuanced reality

Nuclear fission’s ability to responsibly produce global-scale, 24/7, (nearly) carbon-free energy is unmatched among known technologies.

Next-generation reactor designs exist that can further reduce waste, improve safety, increase proliferation resistance, and reduce costs. Even if someone doesn’t support current nuclear, it is difficult for them to disregard all possible improvements. We humans have made impressive accomplishments before.

Of all the known energy resources, nuclear is perhaps the most passionately debated and least understood. Our goal is to explain what makes some people so excited and supportive, and what makes others so passionately opposed. There are many sides to each story. Let’s explore them deeper.

More intro: A primer on energy, greenhouse gas, intermittency, and nuclear

Fission and Fusion

There are two fundamental nuclear processes considered for energy production: fission and fusion.

• Fission is the energetic splitting of large atoms such as Uranium or Plutonium into two smaller atoms, called fission products. To split an atom, you have to hit it with a neutron. Several neutrons are also released which can go on to split other nearby atoms, producing a nuclear chain reaction of sustained energy release. This nuclear reaction was the first of the two to be discovered. All commercial nuclear power plants in operation use this reaction to generate heat which they turn into electricity.
• Fusion is the combining of two small atoms such as Hydrogen or Helium to produce heavier atoms and energy. These reactions can release more energy than fission without producing as many radioactive byproducts. Fusion reactions occur in the sun, generally using Hydrogen as fuel and producing Helium as waste (fun fact: Helium was discovered in the sun and named after the Greek Sun God, Helios). This reaction has not been commercially developed yet and is a serious research interest worldwide, due to its promise of nearly limitless, low-pollution, and non-proliferative energy. Read more at our fusion page.

Where to go from here

Take a look at the navigation bar on the top of the page (or click the line-icon if you’re on a small screen). You’ll find information on all sorts of relevant topics. To get started, check out the what is a nuclear reactor? page.

Other highlights include:

• Nuclear reactor development history
• Age of the Earth
• Radiation on flights

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