Nuclear Fission vs. Nuclear Fusion: What's the Difference?
Read the comparison below, or explore it visually. Create a visual lesson comparing nuclear fission and nuclear fusion using available credits or plan allowance.
Both release enormous energy from the atomic nucleus, but in opposite ways. Fission splits a heavy atom (like uranium) into smaller pieces. Fusion joins light atoms (like hydrogen) into a heavier one. Fission powers today's nuclear plants and atomic bombs; fusion powers the Sun and stars — and is the holy grail of clean-energy research.
At a glance
| Nuclear Fission | Nuclear Fusion | |
|---|---|---|
| What happens | A heavy atom splits apart | Light atoms join together |
| Fuel | Heavy elements (uranium, plutonium) | Light elements (hydrogen isotopes) |
| Used in | Nuclear power plants today | The Sun; experimental reactors |
| Waste | Long-lived radioactive waste | Little long-lived waste |
| Difficulty | Proven and in use now | Extremely hard to sustain on Earth |
Which should you use?
Fission is the practical, proven process: it runs every commercial nuclear reactor on Earth, splitting uranium to boil water and drive turbines — but it leaves radioactive waste.
Fusion is the cleaner dream: it powers the stars and could give near-limitless energy with little waste, but recreating the Sun's heat and pressure on Earth remains a huge engineering challenge.