Uranium's ability to split easily makes it the most common catalyst for nuclear power

Nuclear power relies on chain reactions involving uranium-235, but because the isotope's concentration in natural ores is too low to sustain these reactions, enrichment is needed to produce more highly concentrated fuel.

The oldest nuclear fission reactor on Earth formed naturally in West Africa about 2 billion years ago, where groundwater enabled atoms in uranium deposits to split, releasing energy.

In nuclear reactors, water acts as a coolant and moderator, slowing neutrons produced in nuclear reactions so they are more likely to interact with nuclear fuel and generate sustainable energy.

HALEU, or High-Assay Low-Enriched Uranium, is a next-generation nuclear fuel with higher energy density—three tablespoons of it are enough to supply the average person's electricity use for their entire lifetime.

Over a lifetime, the average American's nuclear power usage creates a hockey puck of nuclear waste

Spent nuclear fuel remains hot and highly radioactive for long periods, requiring submersion in cooling pools before being stored in dry casks and deep underground repositories. The potential recycling of nuclear waste is impeded by security concerns and dangerous reprocessing methods, particularly when obtaining fresh uranium is often easier.

See where the 94 nuclear reactors in the continental US are located

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.

The first nuclear reactor was built three years after nuclear fission was discovered

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.

Where radon comes from and why it may be the most dangerous source of radioactivity

Released from underground bedrock before passing through soil, this radioactive gas is produced from the decay of uranium, thorium, and radium and accounts for about half of all human exposure to radiation. It is the leading cause of lung cancer among nonsmokers and can build up in enclosed spaces such as buildings without proper ventilation to dilute the gas.

Visualize what happens to atoms during nuclear fission and how the process produces energy

Nuclear fission occurs when an unstable, often massive, atomic nucleus splits into smaller ones—daughter atoms—and releases energy. Within a nuclear reactor, these daughter atoms can collide and combine with neighboring atoms, destabilizing them and triggering a chain reaction of atomic splitting.

Methods for disposing of nuclear waste include melting it into a liquid to create glass, dumping it into graphite blocks, storing it in lead-lined rooms, and submerging it in deep pools of water.

While both are nuclear weapons, atomic bombs release nuclear energy by splitting large atomic nuclei, whereas hydrogen bombs derive most of their energy from fusing heavy hydrogen isotopes.

Nuclear fusion, where the nuclei of two atoms are combined, can produce near-limitless clean energy, but requires extreme conditions to kickstart because of the natural repulsion of atomic nuclei.

Helium formation, from radioactive decay inside Earth to nuclear fusion within stellar cores

Over the course of billions of years, uranium and thorium undergo alpha decay, producing helium nuclei—two protons and two neutrons—which become helium atoms after gaining two electrons. This helium becomes trapped in underground reservoirs along with other gases and can be recovered during natural gas extraction.

The 'Elephant's Foot' in Chernobyl is part of the largest documented mass of corium

The nuclear disaster produced around 200 tons of nuclear fuel that mixed with the surrounding melted reactor core materials. As of 2025, corium has been naturally formed four other times in history: once during the Three Mile Island accident and three times at the Fukushima Daiichi plant disaster.

Fusion reactions and radioactive decay produce elements inside stars

Hydrogen, present since the early universe, serves as fuel for the proton-proton chain, producing helium, which is then incorporated into the CNO cycle to produce carbon, nitrogen, and oxygen. Additional fusions of helium with these elements and subsequent decays via the alpha ladder produce elements up to iron and bismuth.

Nuclear power supplies almost half of US carbon-free energy

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.

Learn about the applications of radioactivity in medical, academic, and industrial settings

Besides their use for radiometric dating by archaeologists and researchers at museums and universities, radioactive materials are used in sensors that help track ocean currents and analyze pollution, soil, and petroleum products. Radioisotope-based sensors also help measure air in ice cream and prevent spillovers when soda bottles are filled in factories.

With less than 50 milligrams present in the top kilometer of Earth's crust at any given time, astatine is the rarest naturally occurring element on the planet.

View the most expensive materials on Earth, led by antimatter and other elements forged in particle accelerators.

Similarities in reactivity complicate separating rare earths from ores

The proximity of these elements in the periodic table mean they have similar electron structure and require complex separation processes during processing. However, their uncommon magnetic, luminescent, and electrical properties make them invaluable for critical industrial applications.

View the periodic table of radioactive elements, and a list of each's most stable isotopes

Technetium is the lightest artificial radioactive element, which is produced primarily as a byproduct of nuclear fission. Several unstable isotopes are commercially available to medical professionals and scientists, despite their radioactivity risks.

Radioactivity was accidentally discovered when uranium left marks on photographic plates

In 1896, Henri Becquerel had been exploring phosphorescence—the emission of light of one color after an object is exposed to another color. He expected these emissions to come from objects exposed to sunlight, but he observed emissions after an overcast day.

Small modular reactors can provide nuclear power with reduced risks and logistics

Their factory-built design allows them to be quickly installed underground, reducing their exposure to future extreme weather. They can provide power to small towns and major cities with much smaller start-up costs and reduced siting requirements.

Turning nuclear waste into cancer medications

This video explores Terrapower, a company transforming nuclear waste into lifesaving cancer treatments. This is accomplished through the production and use of Actinium 225, a rare isotope derived from thorium, which is used in targeted alpha therapy to treat cancer.

Distinguishing between natural and artificial, or induced, radioactivity

Naturally occurring radioactivity comes from radioactive elements underground, cosmic radiation from the sun and other objects in space, and radioactive atoms that make up the molecules we breathe, eat, and drink. Artificial radioactivity is predominantly generated for medical applications and industrial activities.

Clean energy technologies are more mineral-intensive than burning fossil fuels

Solar panels use silver due to its high conductivity, hydropower plants use chromium in their steel alloys, and geothermal plants need titanium to withstand abundant heat and pressure. Lithium—used in energy storage—is expected to see over 500% increased demand from 2020 to 2025.

Rare earth elements may be extracted from mine waste and coal ash

Rather than focusing solely on new mining operations, which can take decades to establish, some startups are developing methods to extract these metals from the toxic waste of existing operations and thereby minimize environmental impacts. (Some readers may experience a paywall.)

As of 2024, there are 90,000 tons of nuclear waste stored at 100+ sites in 39 states

Over 315,000 bundles of spent nuclear fuel rods are stored in water pools and over 3,800 dry storage casks in concrete vaults above ground. Corrosion from saltwater spray threatens waste containers of reactors near oceans.

Visualizing the chemistry of nuclear weapons

Nuclear weapons have devastating effects, but the science of how they work is atomically small. There are two main types of nuclear reaction: fission and fusion. The fission bomb produces immense energy by splitting an atom, the result of firing a...

Before 1932, when particle accelerators were first used for nuclear research, scientists relied on naturally radioactive substances to advance their understanding of the atomic nucleus.

An overview of radioactivity, which can spontaneously change one element into another

Unstable atomic nuclei can transmute into a new element—an atom with a different number of protons—by emitting an alpha particle (two protons and two neutrons) or a beta particle (an electron). The electron can emerge from the nucleus when a neutron, which has no charge, suddenly transforms into a proton and an electron, thereby maintaining zero charge before and after the transformation, but altering the original element.

Why everyone is racing to get rare earth minerals

Rare earth minerals are crucial for high-tech electronics and transitioning to new energy sources. China currently dominates rare earth processing capacity, but the US is seeking to increase its mineral production by using its geopolitical influence to strike international mineral agreements with nations like Ukraine.

The continuous decay of radioactive elements regenerates geothermal energy reserves

Geothermal power is a renewable energy source derived from Earth's interior, where the core reaches temperatures exceeding 5,000 degrees Celsius (9,000 degrees Fahrenheit). These temperatures result from leftover energy from collisions during planetary formation, with radioactive decay in the core releasing additional energy that travels to the surface.

Build atomic nuclei to explore their instability and resulting radioactive decay

In this simulation, users can add protons and neutrons to create an atomic nucleus, view its half-life and decay options, and identify patterns in how specific combinations of particles create extremely stable nuclei, from which the nuclear shell model of stability emerged.

A nuclear reactor's characteristic blue light is produced from superluminal particles

When light travels through water, its effective speed is 25% lower than its speed in a vacuum. Just as sound waves bunch up and produce a sonic boom when objects move faster than the speed of sound, particles moving faster than this reduced speed generate a shock wave of light, visible as a blue hue.

Watch a visualization of a fission chain reaction

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.

Learn about ionizing radiation and see the most radioactive places on Earth

The average person is exposed to radiation every day, though most of it is either harmless non-ionizing radiation or ionizing radiation at doses too small to significantly affect an individual. The highest doses of ionizing radiation are received by smokers due to the radioactive polonium and radioactive lead in tobacco products.

Geothermal power can reduce the dangerous mining of rare earth elements

Geothermal brines—mineral-rich underground fluids extracted for use in geothermal plants—contain small concentrations of REEs that can be recovered after energy generation. Although researchers suggest that this retrieval requires complex extraction methods at a significant scale to account for high flow rates, the chemical processes also occur in traditional REE processing.

Mining of rare earth elements risks leaking radioactive wastewater

The extraction and processing of REEs requires significant amounts of water, and poorly regulated projects can contaminate groundwater with acids and heavy metals. Toxic waste spills have paused work in several US mines since the 1980s, despite growing REE demand.

Unusually stable, undiscovered elements may exist near atomic number 126

While heavier elements like uranium and plutonium are unstable and decay quickly, simulations suggest a pocket of stability exists for elements with approximately 126 protons and 184 neutrons. Such elements may have practical applications, such as americium, a synthetic element used in smoke detectors.

Nuclear batteries generate electrical currents using radioactive materials

Rather than using electrochemical reactions to produce the electrons that flow through a circuit, isotopes like nickel-63 undergo beta decay—emitting electrons—which a semiconducting material can absorb to establish a charge imbalance that generates current. Such batteries could provide low-power energy for decades.

Microreactors are 100 to 1,000 times smaller than traditional nuclear reactors but still generate thermal energy for heating or electricity by splitting atomic nuclei.

More than 97% of the world's particle accelerators are used for commercial purposes

Only a few hundred of the over 30,000 particle accelerators worldwide are used for research. Most are involved in medical imaging and treatment, food sterilization, semiconductor processing, cargo screening, and radioisotope production. They're also used to modify the properties of polymers.

How gold, platinum, and many rare earth elements form during neutron star mergers

While massive stars naturally fuse elements as heavy as iron, an analysis of gravitational waves from the collision of two neutron stars revealed that more massive elements are created in this environment via rapid neutron capture—the r-process. This phenomenon sees existing iron nuclei absorb plentiful free neutrons, many of which decay into protons, creating new elements.

Explore an interactive database of critical minerals and their uses

Columbia University's Critical Materials Monitor identifies 56 elements required for the clean energy transition. The tool provides details on the reserves, production, and trade of each element, alongside what materials are needed for each technology (desktop only).

Experiments suggest nuking a metal-rich asteroid may strengthen it

Scientists exposed meteorite samples to proton irradiation at CERN to mimic the effects of a nuclear detonation. The material exhibited greater resistance to breaking after the exposure, suggesting nuclear weapons may better serve to deflect asteroids, not break them.

More than 90% of the atoms in the human body were forged by stars, with almost three-quarters originating from the explosion of massive stars.

What fuels the sun?

The sun is our biggest source of heat and light, but how does this massive powerhouse continue to produce such amazing energy? Basically, it's a fusion reactor. At its core the sun produces all that solar energy through hydrogen fusing and converting into helium, over and over again. Learn more about the entire amazing and explosive process here.

View summaries of the most common types of radioactive decay and their associated particles

The alpha particle has the strongest ability to ionize other atoms it strikes, but it also does not travel very far before colliding with something and being absorbed. Gamma particles—high-energy photons—do not interact with matter as easily and therefore possess the greatest penetrating power, though this also makes their ionizing potential the smallest.

The Manhattan Project operated at three key sites, each with a distinct role in building the first atomic bomb.