In a nuclear power plant, the process of nuclear fission results in the production of large amounts of heat. The heat is then used to produce steam that can turn a turbine to generate electricity. One issue surrounding nuclear power is what to do with the spent nuclear fuel which is still radioactive.
|Applications and implications of science||4a. about the use of contemporary scientific and technological developments and their benefits, drawbacks and risks|
|4b. to consider how and why decisions about science and technology are made, including those that raise ethical issues, and about the social, economic and environmental effects of such decisions|
|4c. how uncertainties in scientific knowledge and scientific
ideas change over time and about the role of the scientific
community in validating these changes.
Energy, electricity and radiations
In their study of science, the following should be covered:
|7a. energy transfers can be measured and their efficiency calculated, which is important in considering the economic costs and environmental effects of energy use|
|7c. radiations, including ionising radiations, can transfer energy d radiations in the form of waves can be used for communication.|
|Science - Curriculum for Excellence level 4||SCN 4-04a.||Planet Earth - Energy Sources and sustainability: By contributing to an investigation on different ways of meeting society's energy needs, I can express an informed view on the risks and benefits of different energy sources, including those produced from plants.|
|SCN 4-11b.||Forces, electricity and waves - Vibrations and waves: By carrying out a comparison of the properties of parts of the electromagnetic spectrum beyond the visible, I can explain the use of radiation and discuss how this has impacted upon society and our quality of life|
|SCN 4-20a.||Topical Science: I have researched new developments in science and can explain how their current or future applications might impact on modern life|
|Chemistry National 4 & 5||Potentially relevant to modules: Chemistry in Society (energy sources)|
|Environmental Science National 4 & 5||Potentially relevant to modules: Sustainability (energy and waste management), Earth's resources (Earth's materials).|
Physics National 4 & 5
|Potentially relevant to modules: Energy (heat and electricity)|
|Science National 4||
Potentially relevant to modules: Fragile Earth (metal extraction, environmental issues)
Why is investigating nuclear power important?
How is nuclear power produced?
An atom of a particular element can have a different number of neutrons and this is called an isotope. For example most carbon (C) atoms have 6 protons and 6 neutrons and can be written as C-12, but some carbon atoms have 7 or 8 neutrons. These isotopes of carbon are written as C-13 and C-14 where the number represents the total number of protons and neutrons. These additional neutrons do not last forever and the loss of neutrons is called radioactive decay.
Uranium (U) atoms have 92 protons and between 141 and 146 neutrons making six different isotopes of Uranium. The isotope U-235 is the one used in generating nuclear energy. Uranium is a metal that is mined in different parts of the world (including Canada, Australia and Kazakhstan) however most of the uranium found on Earth is U-238. Only a small amount of natural uranium (<1%) is U-235 which is needed in a nuclear reactor. U-238 is often made into plutonium (P)-239 which can also be used in a nuclear reactor.
At a nuclear power plant, neutrons smash into the nucleus of the uranium or plutonium atom which splits in half to produce two smaller nuclei, some more neutrons and heat. The neutrons released are able to collide with other uranium atoms causing a chain reaction.
The heat is used to produce steam that can turn a turbine to generate electricity. Other ways of heating water to produce steam include burning 'fossil fuels' such as coal, oil or gas. The nuclear reaction does not lead to carbon dioxide, sulphur dioxide or nitrogen oxides which are emitted by other power plants, but there are emissions associated with mining, treating and transporting the fuel and with constructing and operating the plant.
Every two years or so, the nuclear power plant shuts down to replace the "spent" uranium (or plutonium) fuel that has now released most of its energy through fission. It is now radioactive waste. Nuclear waste can emit ionizing radiation (high energy particles that can strip electrons from atoms so they become ions) for thousands of years and safe disposal of this is a highly controversial topic. Ionizing radiation can damage living tissues and can cause radiation sickness, cancer and death.
Many countries are expanding their nuclear power programmes to help meet their climate change and energy needs. Nuclear reactors produce large quantities of ionizing radiation as a by-product of fission during operation. One issue surrounding nuclear power is what to do with the spent fuel which is still radioactive. There are also concerns that this waste could be stolen or used to develop nuclear weapons.