Sources and effects of radiation

Overview

Click on the links above for teaching schemes, activities and web links and other resources related to this topic.

Introduction
This topic will require a substantial amount of teaching time as it includes both new science and several different important ideas about science. The model of the atom and radioactivity are introduced and it will also be necessary to review the radiation model of action at a distance. Most of the important aspects of risk can be covered in this topic and there are many opportunities to develop understanding of both causal links and decision making.

A suggested route through the topic

1 Setting the scene
One could start with a selection of newspaper articles that mention radiation risks, easily found in a search of any newspaper web site. The Daily Mail and the Guardian are free. Discuss with the class what image of radiation they present. Do they understand all the terms used?

Another start would be to use a Geiger counter to count background radiation and compare this with radiation from some rock samples.

2 The Science and uses of radioactivity

• Review the basic model of the atom and introduce isotopes, nuclear stability and and radiation. Animations available in physics CD teaching resources would help explain. See text book page 169 and 171.
• Why does ionising radiation cause cancer? Why do we need the concept of the effective dose, the Sievert?
• Do the activity, Uses of radioactivity (56 KB) which will give students more familiarity with the different types of radiation and with half lives.

3 Natural and artificial sources of ionising radiation

This section is useful in developing a balanced awareness of the relative risks posed by different sources and may encourage a more critical understanding of some media reports.

• Do the activity 'Estimating your radiation dose' (217 KB).
• Discuss the balance between natural and artificial radiation. Are they surprised?
• The activity introduces the idea of risk and a balance of risks and benefits.

4 Routes by which radioactive materials can enter and move through the environment, methods of handling storing and disposing of waste

• Students could look again at the activity 'Estimating your radiation dose' (217 KB). They could construct a flow chart similar to that on page 174 of the text book showing the routes by which someone living near Sellafield would receive a slightly increased radiation dose, distinguishing the routes for doses from irradiation and contamination.
• A discussion of the Chernobyl accident would include lots of examples of how radioactive materials move through the environment.
• The HPA has an animation on the movement of radioactive discharges.
• The activity Nuclear waste disposal (37 KB) allows students to consider the decision making involved and the different perspectives of different groups.

5 Risks from radiation and principles underlying radiation protection

This section develops ideas about risk, particularly from low doses of radiation. It should develop an understanding of some of the difficulties involved in establishing clear causation. It also considers decision making and the ALARA principle.

• The activity 'Risks of radon' (24 KB) and the textbook pages 181 to 183 introduce some of the data used to reach conclusions on the risks from radon and show how contradictory the evidence is. They demonstrate well the uncertainties involved in risk assessment.
• No one disputes that there are leukaemia clusters around Sellafield. However there is ongoing dispute about the cause. This topic would provide a good question for a project or for a class exercise in research. The textbook, page 183 to 185, describes the conclusions available as of 2000 but new information has been published since. A report from COMARE provides one recent view.
• The Health Protection Agency, formerly NRPB, has set dose limits for exposure. These vary depending on circumstances. the general public and nuclear workers have different limits, but medical procedures may exceed these. A comparison of these different limits and their reasons would provide a good way of exploring the ALARA principle and the balance between risk and cost.
• Risks from non-ionising radiation present even more uncertainty. Power lines and mobile phones have been suggested as presenting significant risks but the evidence is far from clear. The activity on Mobile phones and the precautionary principle provides one way of learning about some of these issues.
• A comparison of different media stories on the same issue would be a useful exercise and could draw on ideas developed in argument skills activities. It would also raise points about public acceptability of different risks
• Stories about increased risk due to a radiation source would also give the opportunity to consider the difference between absolute and relative risk. Media stories usually fail to do this. 'Risk doubled' is not important if it is a very low risk.