Is nuclear energy a good idea or not?

The Professional Development Service for Teachers is funded by the Department of Education and Skills under the National Development Plan SNN

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

Nuclear Fission



Nuclear fission

is 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

E



mc

2

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

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

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.

Nuclear Fusion

 Nuclear fusion is the joining together of two small nuclei to form a larger one. Two such reactions are the following

H

1 2 

H

1 2 

He

2 3 

n

1 0

H

1 2 

H

1 3 

He

2 4 

n

1 0  To overcome Coulomb repulsion, the nuclei must hit each other with enormous velocities.

 Nuclei reach these velocities when heated to temperatures of around 100,000,000 o C  Nuclear fusion in the interior of the sun is the principal source of the sun’s energy.

 video

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.

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

E



mc

2

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

Pros and Cons of Nuclear Energy

Pros Cons

Efficient – Produces a lot of electricity Reliable – not dependent on weather Clean – no carbon emissions Waste – radioactive waste is very dangerous Proliferation – some reactors produce plutonium (weapons) Cost – v. expensive to build Plentiful – a little uranium goes a long way Most concentrated type of energy – large quantities Terrorism – dangerous targets in war Danger of Nuclear Meltdown Chernobyl