Lecture 3-Sources of Radiation

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Lecture 3-Sources of Radiation

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Lecture 3-Sources of Radiation

  1. 1. Sources of Radiation Jump to first page
  2. 2. Objectives List at least three different sources of naturally occurring radiation Estimate your radiation dose from natural and artificially produced radiations Explain how radiation varies on earth Jump to first page
  3. 3. Principal Components of Background Radiation Everyone is exposed External sources Solar and cosmic rays Soils, rocks, building materials Inhaled sources Radon Ingested sources Foodstuffs Jump to first page
  4. 4. Solar Flares High energy protons and electrons streaming from the sun and hit the earth’s outer atmosphere Jump to first page
  5. 5. Cosmic Radiation High energy particles Protons Electrons Muons Heavy particles (Z<26) Interact with earth’s atmosphere Jump to first page
  6. 6. Radiation From the Earth Naturally occurring radionuclides present in rocks, soils, plants, water, air, and building material Major nuclides include Uranium (U) Thorium (Th) Radium (Ra) Radon Jump to first page
  7. 7. Inhaled Radioactivity Primarily radon and progeny, from Buildings Smoking Rocks, soils Jump to first page
  8. 8. Ingested Radioactivity Naturally occurring radionuclides are present in food 40 K is a major contributor Jump to first page
  9. 9. Variations in Dose Northeaster, Eastern Central, and Far Western Areas, Range 35 to 75 mrem/yr Average:46 mrem/yr Colorado Plateau , Range 75 to 140 mrem/yr Average: 90 mrem/yr Atlantic and gulf coastal plain, Range 15 to 35 mrem/yr Average:23 mrem/yr Jump to first page
  10. 10. Artificially Produced & Enhanced Radiation X-rays Nuclear medicine Televisions Nuclear power plants Smoke detectors Radium dials Nuclear waste Air travel Jump to first page
  11. 11. Where Your Dose Comes From 4% 3% 1% Contributors to Dose Radon, 55% Cosmic, 8% 11% Terrestrial, 8% Internal, 11% Medical X-rays, 11% 11% Nuclear Medicine, 4% 55% Consumer Products, 3% Other, <1% 8% 8% Occupational 0.3% Fallout, <0.3% Nuclear Fuel Cycle, 0.1% Miscellaneous 0.1% Contribution of various sources to the total U.S. average effective dose equivalent Jump to first page
  12. 12. U.S. Annual Average Dose Annual average total effective doses to the U.S. Population Natural background, 2 mSv 200 mrem radon Natural background, 1 mSv 100 mrem other Medical diagnostic, 0.39 mSv 39 mrem x-rays Nuclear medicine 0.14 mSv 14 mrem Consumer Products 0.12 mSv 12 mrem Rounded Total 3.6 mSv 360 mrem Jump to first page
  13. 13. Summary Everyone is exposed to radiation from Natural sources Enhanced natural sources Artificially produced sources Jump to first page
  14. 14. Summary, cont’d Natural background radiation comes Earth’s crust Cosmic rays and solar flares Inhaled Ingested radioactivity Cosmic rays vary with altitude and position relative to equator Jump to first page
  15. 15. Summary, continued Terrestrial radiation varies with locality, altitude, and soils Radon and its progeny result in irradiation of lung tissue with alpha particles - this is the largest source of natural radiation Diagnostic radiation is the largest man-made source of radiation contribution to U.S. population dose Jump to first page

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