Nuclear Energy

1. Nuclear Energy Is nuclear energy a good idea or not? SNN

2. What is Nuclear Energy? • Nuclear energy is the energy that comes from the core or the nucleus of an atom. • Massive amounts of it are available to make electricity. • It is released in 2 ways: • Fission • Fusion

3. Nuclear Fission • Nuclear fissionis the splitting of a nucleus into two roughly equal parts, usually caused by the bombardment of neutrons. more • It is usually accompanied by the release of large amounts of energy if the mass after the split is less than the mass before. • Energy is calculated through

4. Chain Reaction • During fission, a nucleus is split into two roughly equal fragments producing 2 or 3 neutrons. • If these neutrons are slowed down, they may produce further fissions producing more neutrons. • This is a chain reaction . It only occurs if a critical mass of material is available. video

5. Nuclear Reactor The reactor consists of • Fuel rods – enriched Uranium • Moderator - slow down the neutrons • Control rods - to absorb neutrons. (slow/stop reactions) • Shielding – thick concrete walls surround it. Lead is also used. • Coolant – the nuclear energy is converted to heat. The reactor core is cooled using water . • Heat exchanger – takes the heat to a turbine which drives an electrical generator

6. Nuclear Bomb • If a chain reaction continues uncontrolled, a nuclear explosion (video)occurs. • A certain mass (critical mass) of fissile material is required. • In the nuclear bomb, two masses of fissile material, each less than the critical mass, are brought quickly together to produce a nuclear explosion.

7. Nuclear Fusion • Nuclear fusion is the joining together of two small nuclei to form a larger one. Two such reactions are the following • To overcome Coulomb repulsion, the nuclei must hit each other with enormous velocities. • Nuclei reach these velocities when heated to temperatures of around 100,000,000oC • Nuclear fusion in the interior of the sun is the principal source of the sun’s energy. • video

8. Nuclear Fusion – an alternative? • Advantages of fusion over fission • Less radioactive • No chance of a runaway chain reaction • The fuel, deuterium, is readily available and cheap (in the oceans) • It is anticipated that a fusion reactor will be available in the future. Much research is currently being undertaken in this field.

9. Mass–Energy • Einstein’s Special Theory of Relativity: mass and energy are equivalent– mass can be converted to energy and energy to mass. • This is the law of Conservation of Mass-Energy • A small quantity of mass can create a large amount of energy – according to the formula

10. Hazards & Precautions of Ionising Radiation • Hazards: • Ionisation causes atoms to lose electrons. • In human tissue, this can affect the normal operation of body cells. • This can cause skin burns, cancer, genetic defects or death. • Precautions: • Use protective clothing • Minimise the time spent using them • Make sure sources are properly shielded • Do not eat, drink or smoke in their vicinity • Use tongs for handling sources • Keep sources in a safe place

11. Pros and Cons of Nuclear Energy