Nuclear Fission

✅ Definition:

Nuclear fission is a nuclear reaction or process where the nucleus of a heavy atom (such as uranium-235 or plutonium-239) splits into two or more smaller nuclei, releasing a large amount of energy, neutrons, and gamma radiation. The total mass of the resulting fragments is less than the original nucleus, and this mass difference is converted into energy according to Einstein’s equation, E=mc².

📜 History of Discovery:

• Nuclear fission was discovered in 1938 by German chemists Otto Hahn and Fritz Strassmann.

• The physical explanation of the process was provided by Austrian physicist Lise Meitner and her nephew Otto Frisch.

• This discovery led to the development of nuclear reactors and atomic bombs.

• The first controlled nuclear chain reaction was achieved in 1942 under the leadership of Enrico Fermi.

🔬 How Fission Works:

1. Neutron absorption:
   A heavy nucleus like uranium-235 or plutonium-239 absorbs a neutron and becomes unstable.

2. Nucleus splitting:
   The unstable nucleus splits into two (or sometimes more) smaller nuclei, called fission fragments, which are usually radioactive.

3. Energy release:
   A large amount of energy is released (around 200 million electron volts, MeV, per fission event).

4. Emission of neutrons:
   2 to 3 neutrons are released, which can trigger further fission events, causing a chain reaction.

⚙️ Types and Characteristics:

• Thermal neutron fission:
  Most common in nuclear reactors, where neutrons are slowed down (thermalized) to increase the probability of fission.

• Fast neutron fission:
  Occurs without slowing neutrons, used in fast breeder reactors.

🏭 Applications:

• Nuclear power plants:
  Use controlled fission reactions to produce heat, which generates steam and drives turbines to produce electricity.

• Nuclear weapons:
  Uncontrolled chain reactions cause massive explosions.

• Medical isotopes production:
  Radioactive isotopes used in diagnostics and cancer treatments are produced via fission.

• Scientific research:
  Studies in nuclear physics and material science.

⚠️ Risks and Challenges:

• Radioactive waste:
  Fission products remain radioactive for thousands of years and require careful long-term storage.

• Nuclear accidents:
  Loss of control over chain reactions can cause disasters (e.g., Chernobyl, Fukushima).

• Nuclear proliferation:
  The spread of fission technology poses security risks.

• Environmental impact:
  Radioactive contamination can affect ecosystems and human health.

🔮 Future Perspectives:

• Development of safer reactors with passive safety features and better fuel utilization (e.g., fast reactors).

• Improved methods for radioactive waste management and recycling.

• Exploration of alternative nuclear energy sources such as nuclear fusion, which promises cleaner and safer energy.