video : Tsunami hits Japan
Radiation is a form of energy. It travels as rays, waves or energetic particles through air, water or solid materials.
Radioactive materials are composed of atoms that are unstable. As unstable atoms become stable, they release excess energy (called "radiation") through a process called radioactive decay or radioactivity. The time required for a radioactive substance to lose 50 percent of its activity by decay is called its half-life. (teringat tyme blajar fizik form 5 dlu, cikgu Surian)
The most common types of radiation emissions:
Alpha particles can be shielded by a sheet of paper or by human skin. But if materials that emit alpha particles are inhaled, ingested or enter your body through a cut in your skin, they can be very harmful.
Beta particles cannot be stopped by a sheet of paper. Some beta particles can be stopped by human skin, but some need a thicker shield (like wood) to stop them. Just like alpha particles, beta particles can also cause serious damage to your health if they are inhaled or swallowed. For example, some materials that emit beta particles might be absorbed into your bones and cause damage if ingested.
Gamma rays are the most penetrating of these three types of radiation. Gamma rays will penetrate paper, skin, wood, and other substances. Like alpha and beta particles, they are also harmful if inhaled, ingested or absorbed. To protect yourself from gamma rays, you need a shield at least as thick as a concrete wall. This type of radiation causes severe damage to your internal organs. (X-rays fall into this category, but they are less penetrating than gamma rays.)
Take the following action to reduce the effect:
Sheltering
Staying inside, with doors and windows closed, provides short-term protection from breathing in radioactive material in the air. It also gives protection from direct radiation from radioactive material in the air and on the ground.
Evacuation
Evacuation avoids relatively high, short-term exposure, by removing people from the affected area. As with other island communities, evacuation is unlikely to be an option for Jersey in these circumstances.
Stable iodine
Iodine collects in the thyroid gland. If it is appropriate taking stable (non-radioactive) iodine tablets prevents this happening with radioactive iodine released in reactor accidents. Taking stable iodine is combined with sheltering or evacuation.
Food
Radioactive material deposited on soil or grass, finds its way into food through crops and animals. It might be necessary to ban milk or other foods containing too much radioactive material.
Detection and monitoring
Radioactive material in an area can be measured in various ways, and there are a number of organisations and people with the specialist knowledge, skills and equipment to monitor these measurements.
source:
http://www.kingcounty.gov/healthservices/health/preparedness/radiation/facts.aspx
http://www.gov.je/StayingSafe/EmergencyPlanning/Pages/Radiation.aspx
pdf:
http://www.kingcounty.gov/healthservices/health/preparedness/radiation/%7e/media/health/publichealth/documents/radiation/facts.ashx
http://www.kingcounty.gov/healthservices/health/preparedness/radiation/facts.aspx
http://www.gov.je/StayingSafe/EmergencyPlanning/Pages/Radiation.aspx
pdf:
http://www.kingcounty.gov/healthservices/health/preparedness/radiation/%7e/media/health/publichealth/documents/radiation/facts.ashx
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