Understanding the Difference Between Nuclear Fission and Fusion Technologies
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What is Nuclear Fission?
Nuclear fission is the process used in today's nuclear power plants. It occurs when the nucleus—the central core of an atom—typically of a heavy element, such as uranium or plutonium, splits into two smaller nuclei. This splitting releases a large amount of energy, as well as additional neutrons, which can go on to split more atoms in a chain reaction. This chain reaction is what allows nuclear reactors to produce a steady supply of energy.
Key Characteristics of Fission Technologies:
- Relies on heavy elements like uranium or plutonium.
- Produces energy through a chain reaction.
- Generates long-lived radioactive waste.
- Can be controlled in nuclear reactors to generate electricity.
While fission has been a reliable energy source for decades, it also requires careful regulation to ensure safety, security, and environmental protection.
What is Nuclear Fusion?
Nuclear fusion is the process that powers the sun and stars. Instead of splitting atoms, fusion combines two atomic nuclei—typically forms of hydrogen—into a heavier nucleus, releasing a large amount of energy in the process. Scientists and engineers are working to recreate the extreme temperatures and pressures that cause fusion in stars in specialized machines on Earth.
Key Characteristics of Fusion Technologies:
- Relies on light elements like hydrogen isotopes.
- Requires extreme temperatures and pressures to initiate.
- Does not rely on a chain reaction.
- Expected to produce minimal long-lived radioactive waste.
Because fusion technologies would not produce the same long-lived waste as fission power and carries a lower risk of uncontrolled chain reactions, it has long been considered a potential energy source for the future.
How Are Fusion and Fission Different?
| Feature |
Fission Technology |
Fusion Technology |
| Reaction Type |
Splitting heavy atoms |
Combining light |
| Fuel Source |
Uranium, plutonium |
Hydrogen isotopes (deuterium, tritium) |
| Chain Reaction |
Yes, requires control mechanisms |
No, reaction stops if conditions are not maintained |
| Radioactive Waste |
Produces long-lived waste |
Long-lived waste not expected |
| Safety Concerns |
Requires safety features to prevent overheating or radiation release |
Minimal risk of meltdown; requires continuous energy input to sustain reaction |
The NRC’s Role in Fusion
The U.S. Nuclear Regulatory Commission (NRC) regulates the use of radioactive materials and nuclear technology to ensure public health and safety and protection of the environment. While traditional nuclear fission reactors are licensed and regulated under well-established frameworks, fusion presents new considerations.
Unlike fission reactors, fusion machines do not rely on a self-sustaining chain reaction and are not expected to generate the same kind of long-lived radioactive waste. As fusion technology progresses, the NRC is working with stakeholders, including researchers, industry leaders, and policymakers, to determine how best to regulate fusion in a way that ensures safety while supporting innovation.
The NRC’s approach is focused on:
- Public Safety and Security – Ensuring fusion facilities operate safely and securely.
- Environmental Protection – Evaluating the impact of fusion technology on people and the environment.
- Stakeholder Engagement – Collaborating with experts to develop a regulatory framework that reflects the unique characteristics of fusion.
As fusion research and development continue, the NRC remains committed to its mission of protecting people and the environment while adapting to emerging technologies.
For more information about the NRC’s role in fusion, visit the Vision and Strategy page.