Activity 3.4 - Radiation exposure

Learning Aims:

To understand that radiation origins from natural and from artificial (man-made) sources
To give examples of radiation from natural and man-made source
To measure the radiation background and the radiation from naturally occurring radioactive substances.
To observe the random nature of the radiation process
To explain the way the effective exposure dose is calculated
To calculate a personal annual radiation dose
To explain effects of radiation

Materials:

A computer with internet connection
Sources of natural radiation
A detection device: a Geiger-Müller counter or data-logger with a radiation sensor and software (Coach 6)

Suggestions for use:

Here students learn to which radiations people are exposed, how an annual radiation dose is calculated and what are effects of radiation on humans.

In activity 1 students analyse the sources of ionising radiation on Earth. Ionising radiation in our direct environment arises from natural processes (e.g. cosmic radiation, radioactivity in the body, inhalation of radon gas, radionuclides in food and drink) and from artificial process (such as medical X-rays, fallout from nuclear weapons tests, and discharges of radioactive waste).

In activity 2 students investigate the radiation of their environment, they measure background radiation in different places and measure the radiation of some natural materials. In this activity they observe the random nature of the radiation process.
Exemplary data:
Background radiation, Number of measurements: 30, Max: 18.00, Min: 3.00,
Average: 8.00, Standard deviation: 3.97

In activity 3 they learn how absorbed radiation doses by the human body are calculated and in which units they are measured.
In activity 4 students realise that the personal annual radiation dose exposure depends on many factors (the amount of natural radioactivity depends on the location on earth, the amount of artificial radiation depends on the dose of medical radiation, etc.). They calculate the annual personal radiation dose. For this they use the provided chart (origin American Nuclear Society).
Such an annual personal dose can also be calculated via computer for example at: http://firstyear.chem.usyd.edu.au/calculators/radiation_dose.shtml, or

http://www.epa.gov/rpdweb00/understand/calculate.html

In activity 5 the students find out and discuss the effects of radiation on the human body and cells.

Possible questions:

What are natural sources of radiation?
What are man-made sources of radiation?
What is the most significant natural source of radiation?
What is the background radiation in your environment?
How do you measure the background radiation?
What does it mean that background radiation has a random nature?
What is the absorbed radiation dose and in which units is it measured?
What is the equivalent radiation dose and in which units is it measured?
What is the effective radiation dose and in which units is it measured?
What is your personal annual radiation dose and how is it calculated?
What are the biological effects of radiation?