In the late 1930s, we discovered that some particularly large atoms found in nature can be split into two, 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 and over time, but as of 2023, polls show that a majority of people support expanding nuclear power.
(Click on each of the headings for more details.)
|Energy Density (MJ/kg)
|100W light bulb time (1kg)
|Natural Uranium (LWR)
|Reactor Grade Uranium (LWR)
|Natural Uranium (breeder)
Splitting atoms is a carbon-free process, so nuclear power is a global solution to climate change. While some processes in the overall lifecycle are currently carbon-emitting, the net result is that nuclear is nearly as low-carbon as you can get. Once we electrify construction and mining equipment and power it all with nuclear and other zero-carbon processes, the overall carbon will trend to zero.
We have enough nuclear fuel resources to power the world for literally billions of years with advanced reactors. Even with conventional reactors, peak uranium is far off.
Humans use a lot of energy, and we’re using more every day. Between 2000 and 2010, the world total energy consumption rose by an astounding 29% . Choices about our consumption of energy are fundamental to the primary geopolitical and environmental struggles of our day. Nuclear energy is a strong candidate for supplying our energy while alleviating these struggles.
Of course nothing’s perfect. Long-standing questions and concerns abound regarding nuclear energy. Click for details.
When heavy atoms split and release energy, the two smaller atoms remaining (called fission products) are often left with some extra energy to give off. This energy is released over a period of time (the longest-lived waste lasting 100,000+ years) in the form of energetic particles called radiation. The high radiation is hazardous and must be kept isolated from the biosphere. We have not yet agreed on what should be done with this high-level nuclear waste.
We know how to deal with nuclear waste safely. The Finns simply chose to go ahead and solve their nuclear waste issue and built the repository at Onkalo. We have good experience with deep geologic disposal in salt deposits that have been stable for 250 million years. Research in deep borehole technology is also looking promising. Finally, if we close the fuel cycle and recycle spent fuel, then it decays to safe levels in several hundred years rather than hundreds of thousands. Furthermore, despite the fear, few people, if any, have ever been injured by stored commercial nuclear waste.We have a detailed page dedicated to nuclear waste here.
The radioactive fission products are hottest when a reactor first shuts down. In effect, you can’t shut a reactor completely off. This decay heat must be cooled or else the containment structures that hold the fuel and waste can breach, releasing radiation into the biosphere. Accidents at Fukushima and Three Mile Island were caused by this effect. Unstable reactor design and operation at Chernobyl led to a power excursion and widespread dispersal of radioactive material. So, people worry about reactor safety.
Nuclear energy has actually saved over 1.8 million lives by displacing air-pollution related deaths that would have occurred had fossil or biofuel plants been built instead of the clean-air nuclear ones . This includes the health effects of the nuclear accidents. So they’re like airplanes; when one goes down, it is a major disaster and huge story, but when you look at the data, it is clear that nuclear reactors are one of the safest ways known to produce energy. And advanced designs can make them even safer.Nuclear safety and risk details
The first application of fission was as an atomic bomb. While nuclear reactors and atomic bombs are significantly different machines, there is some technology overlap, especially in fuel cycle facilities like enrichment and reprocessing plants. So, some people argue that having reactors around might make it easier to spread nuclear weapons.
It is important for nuclear facilities to monitor nuclear material. That said, advanced designs are being developed that reduce reliance on enrichment. Actually, nuclear reactors are useful for peacefully destroying nuclear weapons, and between the late 1990s and 2013, fully 10% of the US electricity was generated in nuclear reactors using dismantled ex-Soviet nuclear warheads in the Megatons-to-Megawatts program.
Nuclear reactors are generally large and complex, with lots of reinforced concrete and nuclear-grade quality assurance programs. As a result, they tend to be expensive to build. Once they’re built, the fuel and operating costs are relatively cheap, but the capital cost is a major hurdle.
If carbon dioxide is ever treated as a pollutant, then nuclear reactors will become much more competitive. But there is definitely room to improve! Research is ongoing in many venues to reduce the cost of nuclear reactors. Countries that chose a standard design and built many of the same have succeeded in bringing costs down.
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.
There are two fundamental nuclear processes considered for energy production: fission and fusion.
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.
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