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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