Radiation Notes
Radiation vs Radioactivity
· Radiation is a form of energy that can take the form of electromagnetic radiation (light, UV, Infrared) or fast moving particles (beta, alpha, neutrons)
· Radioactivity is a physical property of an element. If the element is radioactive, its nucleus is unstable and it will decay into smaller, more stable nuclei while giving off energy and/or other particles
Ionizing vs Non-ionizing
· If it has enough energy to make ions (remove electrons) than it can cause harm because ions are highly reactive and can react with other substances they aren’t meant to
o Examples: UV, x-rays, gamma rays, alpha & beta
· Non-ionizing is not dangerous but can be observed
o Visible light
o Infrared (heat)
Contamination vs irradiation
· Contamination is when you have a radioactive source on you, such that you are emitting radiation. If you are contaminated, then you can irradiate other things.
· Irradiation is when you have been exposed to a radioactive source but you do not have a piece of the radioactive source on you. You may get sick but you will not be able to expose others to radiation.
· Example: food irradiation
o The food is exposed to radiation but not contaminated. The bacteria in the food die as a result of the radiation but the food itself is not radioactive and no harm will come to you if you eat it (assuming you eat it in moderation, of course).
Units of radiation
· Bq (becquerel) 1 Bq/s tells you how many decays there are per second. This changes with time
· Rad: radiation-absorbed dose (tells the amount of energy absorbed per kg of tissue)
· Rem: Roentgen Equivalent of man (gives a measure of how dangerous it is for humans since not all radiation has the same biological effect, even for the same amount of absorbed dose.)
Safe and lethal doses of radiation
· Some argue over whether chronic radiation (consistent, long-term exposure to low energy radiation) is dangerous as most studies have been inconclusive
· 0.0005 rem (amount in average dental x-ray)
· 0.360 rem (average exposure due to life on Earth)
· 25 -50 rem results in temporary decrease in white blood cell population
· 100-200 rem, may cause nausea and vomiting for 1-2 days
· 500 rem, 50% chance of death w/in 30 days
Exposure to radiation
· Everyone is exposed to radiation throughout their lives
· On average: 360 mrem/year
· Sources of radiation come from
o Rocks, soil, radon
o Cosmic sources (UV)
o Your own body/food (Carbon-14)
o Medical sources (x-rays, bone scans, etc.)
o Power plants
o Other man made sources (tv, computers, etc.)
Protecting yourself from radiation
· distance (see graph pg 830)
· shielding (sunscreen, lead apron)
· time
Uses of radiation…there are many!
· Alpha
o Removes static charge
o Used on airplanes, copy machines, smoke detectors, space exploration, pacemakers
· Beta
o Used to gauge thickness
o Used in making paper, plastic, aluminum, glue on stamps, air whipped into ice cream, thickness of eggshells
· Gamma
o Food irradiation
o Sterilization of medical equipment (and our goggles!)
o Creation of different varieties of flowers (induces mutations)