April 1, 2019
Detection of Ionizing Radiation
- Photographic film: The more radiation absorbed by the photographic film, the darker the film becomes. This is worn by people who work with radiation to monitor the level of radiation exposure.
- Geiger-Müller tube: Gas is stored in the tube at low pressure. When ionizing radiation enters the tube, gas particles will become ionized, making it possible to flow a pulse of current in the electrode. Counting circuit measures the level of radiation entering the tube.
Background Radiation
Background radiation is radiation present in the environment which is not due to intentional introduction of radiation. Some sources of background radiation are:
- Cosmic rays travelling from space to Earth
- Some rocks that give off radioactive radon gas
- Radioactive food and drinks
- Buildings and the ground
- Nuclear power and weapons test
- Medical sources such as X-rays
Uses of Radioactivity
- Archaeological dating: Living plants absorb small amount of radioactive carbon-14, and carbon-14 starts to decay after the plant dies. By measuring the activity of carbon-14 in an ancient relic, scientists can estimate the age.
- Sterilization: Gamma rays are used to kill any bacteria or parasites and sterilize equipment or food.
- Cancer treatment: Cobalt-60 decays by emitting gamma rays, and gamma rays can kill cells in malignant tumors.
- Thickness monitoring: Beta particles can be used to monitor thickness of thin metal sheets.
- Tracers in medicine: Using radioactive isotopes of elements that easily accumulate in a specific site of the body can help to monitor the functions of the body.
Dangers of Radioactivity
- Contamination occurs when a radioactive source is introduced into the object. The contaminated object will become radioactive.
- Irradiation occurs when an object is exposed to a radioactive source outside of the object. The object does not become radioactive in this case.
- Exposure to radiation can cause mutations in the DNA, causing cancer, or damage and kill cells by ionizing the cell membrane.
Reducing Risks of Radiation
- Always wear protective clothing, such as lead-lined suits and gloves, when working with radiation.
- Wear film badges containing photographic film to monitor the level of exposure to radiation.
- Nuclear power plants produce waste that may remain radioactive for thousands of years. These waste are tightly sealed in lead-lined containers and then buried deep underground. The site for burial should be impereable to water and have no earthquake or volcanic activity.