Fission

Energy Mix

5% of world 🌎
(#5 resource)
9% of U.S. 🇺🇸
(#4 resource)

Electricity Generation

9% of world 🌎
(#4 resource)
18% of U.S. 🇺🇸
(#2 resource)

Number of Nuclear Reactors*

World 439 🌎

U.S. 94 🇺🇸
France 57 🇫🇷
China 58 (+32 under construction) 🇨🇳

Change in Global Nuclear Electricity Generation

Increase:
⬆<1%
(2019-2024)

Energy Density of Uranium*

33,000x more energy dense than oil

43,000x more energy dense than coal

37,000,000x more energy dense than natural gas

*energy densities by volume

Fissile vs Fertile

Fissile (e.g. U-235)
Capable of capturing a slow neutron, splitting apart, and releasing lots of energy and more neutrons, causing a chain reaction

Fertile (e.g. U-238)
Capable of becoming fissile, but takes a two-step process. It captures a neutron and goes through some radioactive decay to become fissile

Uranium Enrichment*

Natural uranium
0.7% U-235
99.3% U-238

Power plant grade
Enriched to 3-5% U-235

Weapons grade
Enriched to >90% U-235

*Natural uranium is enriched to have a higher proportion of U-235, a fissile isotope

Uranium Sourcing

Uranium mines 90%
Reprocessing*/stockpiles** 10%

Leading Producer

Kazakhstan 43% 🇰🇿
of the world’s uranium production from mines

Some countries (e.g., the U.S.) don't allow spent nuclear fuel reprocessing due to concerns about proliferation

Uranium Processing

Mined uranium converted to UF₆ (gaseous at low temp)
↓
UF₆ separated into U-235 and U-238 via centrifuge
↓
UF₆ recombined to 3-5% U-235
↓
UF₆ → UO₂ powder → fuel pellets

Largest Enrichment Capacity

Russia 43% 🇷🇺
27,000 tSWU/yr*** 
China 18% 🇨🇳
11,430-11,930 tSWU/yr

Other significant players
France, U.S., Netherlands, UK, Germany

Most Electricity Generation

U.S. 29% 🇺🇸
of global nuclear electricity

Highest Penetration

France 68% 🇫🇷
Slovakia 62% 🇸🇰
of country’s electricity generation comes from nuclear

Average Age of Reactors

World 31 years 🌎

U.S. 42 years 🇺🇸
France 37 years 🇫🇷
China 11 years 🇨🇳

Share of New Global Nuclear Capacity Additions

China 38% 🇨🇳
UAE 14% 🇦🇪
South Korea 11% 🇰🇷
(2019-2024)

Most Electricity Generation

Illinois 13%
of U.S. nuclear electricity

Highest Penetration

New Hampshire 64%
South Carolina 59%
Illinois 55%
Tennessee 51%
of state's electricity comes from nuclear

Capacity Factor*

92% in the U.S.
the highest of any energy resource used for electricity generation

Nuclear Installations are Retiring

19 U.S. reactors retired in the last 30 years

Number of U.S. reactors peaked at 112 in 1990

Average age is 42 years

New Nuclear is Expensive and Takes a Long Time to Build

Only 4 U.S. reactors added in the last 30 years

The two most recent reactors took 11 years and cost more than $30 billion (originally expected to cost $14 billion)

Existing Nuclear is Not Cost Competitive with Other Clean Energy Resources

Near-firm* wind
$14-21/MWh

Near-firm solar
$17-24/MWh

Existing nuclear
$34-49/MWh

*with 4 hours of battery storage

What Happened?

• Human error and faulty valves and sensors led to loss of coolant incident
• 70% meltdown of reactor core released a large amount of radiation within the containment building, but total radiation release to the atmosphere was small

Impact on Nuclear Industry

• Federal requirements were made more stringent, leading to higher costs and longer construction times
• Public opposition worsened
• Construction of new nuclear power plants in the U.S. stopped

What Happened?

• Caused by poor design (graphite instead of water as a moderator), lack of safety features, poor containment, and inadequately trained workers
• Explosion blew the top off the containment building, started a huge fire, and released large amounts of radiation to the atmosphere
• 20 people were killed immediately
• ~8,000 deaths have occurred since the accident
• Impact on mortality was likely worsened due to poor and delayed governmental response
• Total estimates of expected cancer deaths range from 20,000 to 475,000

Impact on Nuclear Industry

• Greater emergency planning, preparedness, and management for nuclear accidents in many nations
• Development of international nuclear safety systems
• Brought to light how nuclear accidents in one nation could have widespread effects
• The Chernobyl reactors were Soviet-designed graphite moderated reactors. Today, only Russia (10), China (1), and the UK (8) have graphite moderated reactors
• First containment building was hastily completed in October 1986, but was not built to last. A new containment building was completed in 2017. Future efforts will prioritize the removal of the fuel-containing material from the site

What Happened?

• A 45-foot tsunami hit the Fukushima Dai-ichi Nuclear Power Plant, flooding the entire facility
• The flooding swamped the diesel pumps that supplied water to the reactors, causing all of them to fail at the same time and effectively eliminating the safety systems for the nuclear reactors
• 4 of the 6 reactors exploded
• The explosions breached containment and released radioactive material into the atmosphere and ocean that was detected as far away as California

Impact on Nuclear Industry

• Japan shut down all 48 of its operable reactors. Today, only 14 reactors have been restarted, due to a lengthy review process implemented since 2011
• Other countries reconsidered the role of nuclear power in their energy mix. Notably, following Fukushima, Germany announced plans to shut down all of its reactors due to increased fear towards nuclear energy. Today, Germany has no operating nuclear reactors
• Greater safety measures have been implemented globally, particularly the development of more independent safety systems and strengthened protections against natural disasters. These measures have increased the costs of operating nuclear power plants

Half Lives* of Main Radioactive Nuclear Waste Isotopes

Strontium-90: 29 years
Cesium-137: 30 years
Plutonium-239: 24,000 years**

Amount of Global Nuclear Waste

400,000 metric tons
(about the same weight as the Empire State Building)

11,000 metric tons
generated annually

Methods for Nuclear Waste Storage

1. Temporary: pools (~10 years); dry casks (<100 years)
2. Reprocessing the fuel (reduces overall amount of nuclear waste)
3. Burying the waste in a geologically safe location***

No proven method to store for 200,000+ years

Drivers

• Zero-carbon
• No air pollution
• High capacity factor (92% in the U.S.)
• Extremely energy dense fuel
• Facilities require relatively low land use per MWh produced
• Uranium is an abundant resource
• Investment and growing interest in small modular reactors

Barriers

• Low-probability, high consequence accidents
• Produces radioactive waste that must be safely stored for hundreds of thousands of years
• Risk of nuclear proliferation and the spread of nuclear weapons capabilities to more countries, with geopolitical consequences
• Large baseload power plants that are not flexible for integration of renewables or load following
• Extremely expensive to build and insure relative to other sources of electricity
• Takes a long time to plan, permit, and build (~10 years just for building)
• U.S. nuclear power plants are old and require upgrades and new licensing
• Decommissioning of nuclear power plants can take 50+ years and is expensive
• NIMBY issues; community opposition to siting nuclear power plants and waste repositories
• Operations are water intensive
• Uranium mines can contaminate water

Climate Impact:
Low

• Zero greenhouse emissions when operating

Environmental Impact:
Low to Medium

• Radioactive waste is toxic for hundreds of thousands of years
• Risk of radiation leaks from nuclear meltdowns or terrorism
• Nuclear proliferation raises the risk of nuclear weapons use
• Significant environmental impact if atomic weapons or dirty bombs are detonated
• Large amounts of water used for cooling, potential thermal pollution of water

Updated July 2025