Radiation Protection :Radiation Protection A Course in Radiation Safety


Background Radiation Exposure :Background Radiation Exposure All individuals living on the Earth are exposed to radiation from natural and man-made sources.


Major Sources of Exposure to Ionizing Radiation :Major Sources of Exposure to Ionizing Radiation Natural Background Radiation Technologically Modified Sources Modified Natural Sources Technologically Modified Sources


Natural Background Radiation Sources :Natural Background Radiation Sources Cosmic Sources Cosmogenic Sources Terrestrial Sources


Cosmic Radiation :Cosmic Radiation Radiation that originates in space Primarily composed of: Protons – 85% Alpha particles – 14% Misc. atomic nuclei – 1%


Cosmic Radiation :Cosmic Radiation Cosmic radiation is highly penetrating Much of the it is deflected back into space by the Earth’s magnetic field Much of it is attenuated by the Earth’s atmosphere


Cosmogenic Radionuclides :Cosmogenic Radionuclides Radionuclides are produced by the action of cosmic radiation on atmospheric gas atoms Major contributors include: C14 Half-life: 5730 yrs H3 Half-life: 12.3 yrs Na22 Half-life: 2.6 yrs Radiation exposure from cosmogenic sources results from inhalation & ingestion due to their presence in the air, soil, & water


Terrestrial Sources :Terrestrial Sources Results from the presence of primordial radionuclides and their decay products: Uranium Series (238U) 226Ra (bone seeking ? emitter) 222Rn (?-emitting gas) Thorium Series (232Th) Actinium Series (235U)


Terrestrial Sources :Terrestrial Sources Radiation exposure from terrestrial sources can vary significantly from country to country:


Terrestrial Sources :Terrestrial Sources Radiation exposures also vary from state to state:


Technologically Modified Sources :Technologically Modified Sources Radiation exposure from modified natural sources or man-made sources Modifications of natural sources Fossil fuels Phosphate fertilizers Enhanced exposure as a result of air travel Consumer products


Modifications of natural sources :Modifications of natural sources Fossil fuels: Exposure comes from the burning of fossil fuels releasing primordial radionuclides and K40 into the air Phosphate fertilizers: Phosphate rock contains U238 decay products; byproduct (gypsum) can increase radon levels when used in buildings Increased air travel: Exposure from cosmic radiation doubles every 1500-2000 m above sea level Consumer Products: Luminous Dials (H3, Ra226) Anti-Static Devices (Po210) Smoke Detectors (Am241) Tobacco Products (Pb210, Po210)


Slide 14:Annual Dose Equivalents from Selected Consumer Products


Technologically Modified Sources: :Technologically Modified Sources: Fallout: As a result of atmospheric and under-ground nuclear testing; results from ingestion and inhalation of products such as C14, Cs137, Sr90, and H3 Nuclear Power Production: Primary exposures include those occupationally exposed during: mining fuel fabrication reactor operation waste storage


Technologically Modified Sources: :Technologically Modified Sources: Occupational Exposure: Occurs with individuals industry medical research nuclear power diagnostic medicine therapeutic medicine Medical Exposure: Results from exposures from nuclear medicine radiation therapy radiology


Estimated Annual Dose Equivalent (mrem) From Natural Sources :Estimated Annual Dose Equivalent (mrem) From Natural Sources


Slide 18:According to latest estimates we receive on average approximately 300 mrem annually from natural background and other radiation sources Remember: the sources of radiation exposure to a population vary from one country to another, and even from state to state


Remember: :Remember: Medical exposures contribute more to a population’s exposure in a technologically developed nation.