Hours of research by our editors, distilled into minutes of clarity.
While today's nuclear reactors rely on fission, which releases energy by splitting heavy atoms, nuclear fusion releases energy by combining atoms together to form more massive ones. Fusion involves overcoming repulsive forces between the centers, or nuclei, of atoms, and, as of 2026, overcoming this repulsion takes more energy than is produced.
As of 2023, nearly 20% of US electricity comes from nuclear power, but most reactors were built from 1971 to 1990. Expansion slowed due to safety concerns, high costs, and competition from natural gas.
In 2023, these reactors—located in 53 plants across 28 states—prevented 437 million tons of carbon dioxide emissions. A single fingertip-sized uranium pellet generates as much electricity as a ton of coal, enough for one household's annual electricity.
After learning that large atomic nuclei release energy upon being split apart, scientists quickly researched how to control the reaction to make electricity. Fusion—combining small atomic nuclei—generates massive energy in stars and hydrogen bombs.
The discovery of the neutron provided scientists with a particle that could penetrate the nucleus and advance atomic physics. Otto Hahn was the sole Nobel recipient for the discovery of fission, despite collaborating with Lise Meitner and Fritz Strassmann.
Uranium is commonly found in rocks, water, and soil worldwide, but significant industrial processes are needed to process and enrich it for efficient reactor usage. After being irradiated in reactors, it must be cooled down before disposal.
When a neutron collides with an atom, it is absorbed into the nucleus. If the resulting nucleus is unstable, it can undergo a series of decays that turn it into a less massive nucleus while releasing energy and other particles.
Nuclear reactions within a containment structure boil water into steam, which drives a turbine that generates electricity. This water is then recirculated via pumps back into the containment structure to repeat the process, with reaction rates lowered by the insertion of control rods that absorb neutrons, which trigger reactions.
All nuclear waste would have been stored at Nevada's Yucca Mountain, but the Obama administration indefinitely stalled the project after intense community backlash. Spent fuel is now stored at more than 80 locations in 36 states, raising safety concerns.
A reactor explosion during a safety test resulted in a series of evacuations and resettlements that displaced over 300,000 people and left areas uninhabitable for up to 20,000 years. The Soviet government initially tried to hide the disaster, but rising radiation levels were identified by detectors in Sweden.
Nuclear meltdowns occur when a reactor overheats and radioactive materials leach into the surrounding environment. While rare, the reasons for each occurrence—as detailed in this piece—can help establish new safety protocols for future reactors.
Dive into the dynamic world of science and technology, where curiosity has brought about extraordinary understandings of the universe and creativity has led to the breakthroughs and innovations that have transformed our world. Explore a wide range of topics, from the natural and physical sciences to cutting-edge technologies and the people who shaped them, each of which is accompanied by carefully curated resources meant to inform, engage, and inspire those eager to uncover the nature of reality.