Natural sciences
Grade 8
Energy: electricity, heat and light
Module 4
Nuclear power
Activity:
To investigate the generation of nuclear power as a source of energy
[lo 1.2, lo 1.3, lo 3.1]
Assignment 1:
Do a project on “Nuclear power in South Africa”
Divide into groups for collecting information on nuclear power. Each group will answer the questions that follow and provide feedback in the form of a poster.
Where is South Africa's nuclear power station?
How much electricity is provided by this power station?
To whom is this electricity provided?
Which dangerous metal is used in the power-generating process?
Why is cooling an important component of this power-generating process?
Is it true that you need to burn 25 railway truckloads of coal to obtain the same amount of energy that is provided by a piece of uranium the size of one golf ball?
Visit:
www.eskom.co.za/nuclear.overview
Assessment of Information Gathering
Were you able to gather adequate information to answer the questions and provide feedback through the poster?
[LO 1.2; LO 1.3]
Assignment 2:
Have a class discussion on whether nuclear power has value or not.
Assessment of Class Discussion
Were you able to identify values?
[LO 3.1]
Assessment
LO 1: Scientific investigations:
The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.
This is evident when the learner:
- plans investigations;
- conducts investigations and collects data;
- evaluates data and communicates findings.
LO 3: Science, Society and the Environment
The learner will be able to demonstrate an understanding of the interrelationships between science and technology, society and the environment.
This is evident when the learner:
3.1 understands science as a human endeavour.
Memorandum
Assignment 1:
- Do a project on “Nuclear power in South Africa”
- The learners have to be divided into groups for collecting information on nuclear power. Each group is to address the questions that follow:
- Where is South Africa's nuclear power station? AT DUINEFONTEIN NEAR MELKBOS
- How much electricity is provided by this power station? 6% + TO OTHER COUNTRIES
- Which dangerous metal is used for the power-generating process? ENRICHED URANIUM
- Why is cooling an important component of this power-generating process? BECAUSE OF THE IMMENSE HEAT THAT IS GENERATED
- Is it true that you can burn 25 railway truckloads of coal to obtain a quantity of energy equal to that which is provided by an amount of uranium that is equal to the size of one golf ball?
- YES
- www.eskom.co.za/nuclear.overview
- Many people become quite concerned when they think of nuclear power because of the horror of the Second World War and Hiroshima, etc.
- The South African nuclear reactor is located north of Cape Town at Koeberg. It supplies roughly 6,5% of the country's electricity.
- The Koeberg power station is the only nuclear power station on the African continent. It has a pressure water reactor with two units, each of which develops 960 MW of power. This represents approximately six percent of the power of that is developed in South Africa.
- Koeberg supplies electricity to the whole of the Western Cape and exports surplus capacity to other parts of South Africa and to Namibia, our neighbour, during the summer.
- Although is the only nuclear power station in Africa, there are 438 nuclear power installations right across the world. Most of these, namely 118, are in Northern America and supply approximately twenty percent of America's electricity. In France, 76 percent of the total power development capacity come from nuclear power stations. More than seventeen countries depend on nuclear facilities to provide at least a quarter of their total electricity requirement.
- In spite of the perception that the use of nuclear power is being reduced, there are definite plans to extend the use of nuclear power in China, India, the Korean Republic and Japan. Six nuclear power installations were linked to electricity networks in 2000, and building was commenced on three new nuclear reactors – one in China and two in Japan. This has brought the number of nuclear reactors that are being built to 31.
A typical reactor comprises:
- Fuel – Uranium (U).
- A moderator – which slows down processes – almost like a system of brakes.
- Control rods – to stop a reaction.
- Cooling agent – which is able to cool down enormous heat.
- Protective covering to protect people from radioactive radiation – much concrete is frequently required in this regard.
The process is as follows:
- Enriched uranium is split (fission) under controlled conditions.
- Splitting of one atom of uranium provides 10 million times the amount of energy that is obtained from burning one atom of carbon!
- The nuclear reaction releases an enormous amount of heat.
- The heat converts to seam.
- The steam drives a turbine, which, in turn, drives a generator.
- The steam is condensed and pumped back to cool down for reuse.
A more detailed explanation of the process:
- The enriched uranium has the form of small particles coated with layers of carbon and silicon carbide. These layers create an inhibitor.
- The fuel comes in the form of balls, each containing 15 000 of these enclosed uranium particles. The reactor contains 440 000 balls, 310 000 of which are fuel balls.
- The heat that is generated during the nuclear reaction is borne away by means of helium gas, which enters the reactor at about 500°C, moves across the reactor fuel and leaves the reactor at about 900°C. This hot gas is directed through the closed-circuit gas turbine that drives a generator. From the turbine, the gas returns to the reactor and the cycle starts all over again.
