“The World We Create” NATS 101 Section 6 Don’t forget to turn in your homework! 02/02

UNIT 1: Energy Sources, Conventional or Alternative? Nuclear Energy

Ionizing Radiation It has enough energy to affect the structure of the atoms. Particularly, to remove electrons (ionize) and break bonds in molecules.

Radioactivity Some substances, such as uranium and plutonium, emit ionizing radiation spontaneously (you don’t need to split them). This property is called Radioactivity Geiger Counter

 Identify common sources of ionizing radiation in your surroundings.  Make better judgments about the risks of exposure to different sources of ionizing radiations;  Evaluate the truthfulness and implications of statements about radioactive materials. How much are we exposed?

True or False? 1. Human senses can detect radioactivity. 2. Elements such as Uranium and Radium are radioactive, but others such as Carbon and Lead are not. 4. Radioactive waste has very high temperatures. 3. Cancer cells are more sensitive to radiation than healthy cells. 5. Smokers are exposed to a highly dose of radioactivity than non-smokers. 6. The human body naturally contains small quantities of radioactive substances. 7. Exposure to radioactive materials causes serious burns. 8. Radioactive materials glow in the dark.

Radioactive Decay Radioactive isotopes are unstable and “decay” by emitting particles or energy. In this process, the chemical nature of the atoms can change (they may lose or gain protons). Radioactive decay can occur through three different types of processes, each of which generates a different type of ionizing radiation. Alpha decay Beta decay Gamma decay

Alpha Decay What is emitted? What happens to the nucleus?

Beta Decay =electron What is emitted? What happens to the nucleus?

Gamma Decay What is emitted? What happens to the nucleus?

Low Energy – Non-Ionizing High Energy – Ionizing (changes structure of matter) Low E- Non-Ionizing Electromagnetic Radiation High E- Ionizing

In Your Groups List ways you have been exposed to ionizing radiation today (in the form of either waves or particles). You have 2-3 minutes

Isotopes in Nature Most elements in nature are a mixture of isotopes. Some of them are radioactive, although most of them are not. Some Natural Radioisotopes NameSymbolAbundance (%) Hydrogen-3H31H Carbon-14C 14 6 Trace Potassium-40K Platinum-190Pt Thorium-232Th Uranium-238U

Background Radiation In our everyday lives, we are exposed to some amount of ionizing radiation. This amount varies by person, depending on your lifestyle and living conditions. Scientists call this type of radiation Background Radiation.

How Do We Measure Radiation? Because of its effect on living tissue, the amount of ionizing radiation to which people are exposed over time must be monitored. In the US, the radiation dose is measured using two basic units: RAD- measures the absorbed dose of radiation REM- measures the ionizing effect on living organisms Normal human exposures are measured in milirems 1 mrem = rem

Your Annual Dose  Calculate your individual annual ionizing- radiation dose (handout).  Compare your annual dose with the dose calculated by the other members of your team. Calculate the group average.  Compare the amount of radiation from natural sources (radon, cosmic, terrestrial, internal) to that from man-made sources? You have 10 minutes To convert your answer to rems from mrems: divide your value by 1000.

Sources of Ionizing Radiation US average yearly dose: 0.36 Rems.

Internal Sources Thyroid Iodine-131 Lungs Radon-222 Uranium-238 Plutonium-239 Krypton-85 Muscles Potassium-40 Cesium-137 Liver Cobalt-60 Bones Radium-226 Strontium-90 Phosphorus-32 Carbon-14

How Much Would It Take? DoseBodily Effect 0-25 remsNo noticeable effect 25-50Slight decrease in white blood cell count Significant decrease in white blood cell count Nausea, loss of hair Hemmoraging, ulcers, possible death >500Death

Biological Damage from Radiation Rapidly dividing cells, such as blood cells and sex cells, are more susceptible to radiation damage that are slowly dividing or non-dividing cells, such as nerve cells. Fetuses and children are more susceptible to radiation damage than are adults. Tissue type Most scientists assume that an increase in radiation dose produces a proportional increase in risk. Dose The more a given dose is spread out over time, the less harm it does. Exposure time The larger the body area exposed, the greater the damage. Area exposed

The Benefits Medical uses Diagnosis: - Tracers - PET scans Treatment: Cancer patients are “shot” with a beam of radiation in a localized area, killing most of the cells in the area.

“ The average radiation dose to people living within ten miles of the Three Mile Island Nuclear Plant was 8 mrem, and no more than 100 mrem to any single individual. ” American Nuclear Society “ Some 350,000 people involved in the initial clean-up of the Chernobyl nuclear plant in received average total body radiation doses of the order of 10 rems. ” International Atomic Energy Agency What is this telling you? What would your reaction be? “ The study of 120,000 Hiroshima survivors indicates that the risk of cancer increases linearly with the radiation dose. The dose at 1000 meters at Hiroshima is estimated at 400 rems. ” Hyperphysics (on-line resource)

True or False? 1. Human senses can detect radioactivity. 2. Elements such as Uranium and Radium are radioactive, but others such as Carbon and Lead are not. 4. Radioactive waste has very high temperatures. 3. Cancer cells are more sensitive to radiation than healthy cells. 5. Smokers are exposed to a highly dose of radioactivity than non-smokers. 6. The human body naturally contains small quantities of radioactive substances. 7. Exposure to radioactive materials causes serious burns. 8. Radioactive materials glow in the dark.

True or False? Human senses can detect radioactivity. Elements such as Uranium and Radium are radioactive, but others such as Carbon and Lead are not. Radioactive waste has very high temperatures. Cancer cells are more sensitive to radiation than healthy cells. Smokers are exposed to a highly dose of radioactivity than non-smokers. The human body naturally contains small quantities of radioactive substances. Exposure to radioactive materials causes serious burns. Radioactive materials glow in the dark.