2. Artificial Radioactivity Presented by Mr. Y. N. Chan LIU PO SHAN MEMORIAL COLLEGE

3. Artificial Radioactivity (1) Stable nucleus will become UNSTABLE when it is collided with neutrons or particles. Example :

4. Artificial Radioactivity (2) Neutrons are used to bombard the nuclei because they are neutral and more easily to enter into the nuclei. Energy will be released during the process.  Nuclear Energy Nuclear fission are adopted to generate nuclear energy.

5. Artificial Radioactivity Vs Natural Radioactivity Fission occurs immediately Reaction products are various Have a unique half- life Fission products are unique depends on the parent nucleus. Artificial RadioactivityNatural Radioactivity

6. Nuclear Fission

7. Features of U-235 fission U-235 splits into two smaller nuclei and two neutrons Energy is released. The fission neutrons collide with other U-235 nuclei and cause further fission.  CHAIN REACTION

8. Chain Reaction

9. If the chain reaction is not controlled, very large amount of energy is released in a short time  ATOMIC BOMB If the fission is controlled so that only one fission neutron start another fission (other fission neutrons being absorbed). Reaction rate become steady  NUCLEAR POWER PLANT Control and Uncontrol Fission

10. The nuclear debate (1) Oil and coal are running out Nuclear energy has a low running cost Clean and less polluted FOR the nuclear energy

11. The nuclear debate (2) Other possible sources of energy e.g. solar energy, wind energy, tidal energy Capital Investment is High Treatment of nuclear waste is a problem In case of accident, the damage to the public may be immense. AGAINST the nuclear energy

12. Artificial Radioactivity END