Artificial Radioactivity Presented by Mr Y N Chan

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

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

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.

Artificial Radioactivity Vs Natural Radioactivity Artificial Radioactivity • Fission occurs immediately • Reaction products are various Natural Radioactivity • Have a unique halflife • Fission products are unique depends on the parent nucleus.

Nuclear Fission

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

Chain Reaction

Control and Uncontrol Fission • 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

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

The nuclear debate (2) AGAINST the nuclear energy • 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.

Artificial Radioactivity END