Date post: | 18-Dec-2014 |
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Sources of Radiation
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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
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Principal Components of Background Radiation
Everyone is exposed External sources
Solar and cosmic rays Soils, rocks, building
materials Inhaled sources
Radon Ingested sources
Foodstuffs
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Solar Flares
High energy protons and electrons streaming from the sun and hit the earth’s outer atmosphere
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CosmicRadiation High energy particles
Protons Electrons Muons Heavy particles
(Z<26) Interact with earth’s
atmosphere
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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
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Inhaled Radioactivity
Primarily radon and progeny, from Buildings Smoking Rocks, soils
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Ingested Radioactivity
Naturally occurring radionuclides are present in food
40K is a major contributor
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Variations in Dose
Atlantic and gulf coastal plain, Range 15 to 35 mrem/yrAverage:23 mrem/yr
Colorado Plateau , Range 75 to 140 mrem/yrAverage: 90 mrem/yr
Northeaster, Eastern Central, and Far Western Areas, Range 35 to 75 mrem/yrAverage:46 mrem/yr
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Artificially Produced & Enhanced Radiation
X-rays Nuclear medicine Televisions Nuclear power plants Smoke detectors Radium dials Nuclear waste Air travel
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Where Your Dose Comes FromContributors to Dose
55%
8%
8%
11%
11%
4% 3% 1% Radon, 55%
Cosmic, 8%
Terrestrial, 8%
Internal, 11%
Medical X-rays, 11%
Nuclear Medicine, 4%
Consumer Products, 3%
Other, <1%
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
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U.S. Annual Average Dose
Annual average total effective doses to the U.S. Population
Natural background, radon
2 mSv 200 mrem
Natural background, other
1 mSv 100 mrem
Medical diagnostic, x-rays
0.39 mSv 39 mrem
Nuclear medicine
0.14 mSv 14 mrem
Consumer Products
0.12 mSv 12 mrem
Rounded Total 3.6 mSv 360 mrem
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Summary
Everyone is exposed to radiation from Natural sources Enhanced natural sources Artificially produced sources
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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
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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