Nuclear Fission and Fusion

Introduction

• Objective: Understand nuclear fission, chain reactions, and nuclear fusion.
• Target Audience: Triple Physics students.

Nuclear Fission

• Definition: The process where the nucleus of a large, unstable atom splits.
• Key Elements: Uranium and plutonium (specific isotopes, naming not required for exams).
• Process:
  • Nucleus absorbs a neutron to trigger fission.
  • Rarely happens spontaneously.
• Outcome:
  • Splits into two smaller nuclei, called daughter nuclei.
  • Emits 2-3 neutrons and gamma radiation.
  • Releases energy (products have kinetic energy).

Chain Reaction

• Definition: A self-sustaining series of reactions.
• Mechanism:
  • Neutrons from one fission event trigger further fission in other nuclei.
  • Results in a rapid increase in the number of fission events and energy release.
• Control:
  • Controlled in nuclear reactors for electricity generation.
  • Uncontrolled chain reactions result in nuclear explosions.

Nuclear Fusion

• Definition: The process where two light nuclei (e.g., hydrogen) fuse to form a heavier nucleus.
• Energy Conversion: Some mass is converted into energy, released as radiation.
• Occurrence:
  • Powers stars, including the sun.
• Key Difference: Not a chain reaction, unlike fission.

Conclusion

• Understand the differences between nuclear fission and fusion.
• Grasp how fission can be controlled or uncontrolled and the implications of each.

Additional Resources

• Practice questions available in the revision workbook (link provided in the presentation).