Nuclear Fission: A Complete Explanation
1. Introduction to Nuclear Fission
Nuclear fission is the process where a heavy atomic nucleus splits into smaller nuclei, releasing a
large
amount of energy. It was discovered in 1938 by Otto Hahn and Fritz Strassmann, with an
explanation provided by
Lise Meitner and Otto Frisch.
2. The Process of Nuclear Fission
A heavy nucleus (e.g., Uranium-235) absorbs a neutron, becomes unstable, and splits into smaller
nuclei,
releasing:
- Fission products (smaller nuclei).
- Free neutrons (which continue the reaction).
- Energy (heat and radiation).
Example reaction:
U-235 + neutron -> Ba-141 + Kr-92 + 3 neutrons + Energy
3. Chain Reaction and Critical Mass
A chain reaction occurs when released neutrons cause further fission reactions. The reaction
depends on:
- Subcritical Mass: Too little material to sustain fission.
- Critical Mass: Just enough material to sustain fission.
- Supercritical Mass: Excess material causing an accelerating reaction.
Controlled Chain Reaction (in Nuclear Reactors):
- Control Rods absorb excess neutrons.
- Moderators slow down neutrons to increase efficiency.
4. Energy Released in Fission
The energy comes from the mass defect, explained by Einstein's equation:
E = mc^2
Each uranium-235 fission releases about 200 MeV of energy.
1. Introduction to Nuclear Fission
Nuclear fission is the process where a heavy atomic nucleus splits into smaller nuclei, releasing a
large
amount of energy. It was discovered in 1938 by Otto Hahn and Fritz Strassmann, with an
explanation provided by
Lise Meitner and Otto Frisch.
2. The Process of Nuclear Fission
A heavy nucleus (e.g., Uranium-235) absorbs a neutron, becomes unstable, and splits into smaller
nuclei,
releasing:
- Fission products (smaller nuclei).
- Free neutrons (which continue the reaction).
- Energy (heat and radiation).
Example reaction:
U-235 + neutron -> Ba-141 + Kr-92 + 3 neutrons + Energy
3. Chain Reaction and Critical Mass
A chain reaction occurs when released neutrons cause further fission reactions. The reaction
depends on:
- Subcritical Mass: Too little material to sustain fission.
- Critical Mass: Just enough material to sustain fission.
- Supercritical Mass: Excess material causing an accelerating reaction.
Controlled Chain Reaction (in Nuclear Reactors):
- Control Rods absorb excess neutrons.
- Moderators slow down neutrons to increase efficiency.
4. Energy Released in Fission
The energy comes from the mass defect, explained by Einstein's equation:
E = mc^2
Each uranium-235 fission releases about 200 MeV of energy.
