Page 247 - Radiation Safety

2. Terrestrial Radiation

• Emitted from the radioactive nuclides present in varying

amounts in soils and rocks, the atmosphere and

hydrosphere, and from those radionuclides that are

transferred to man through the food chains or by inhalation.

• Leads to both external and internal exposures.

U-238,U235,Th-232,K-40,Rb-87

Three main natural decay chains: Th-232, U-235 and U-238

Each of the 3 decay chains producer a radiactive gas (e.g.Rn-

222 from U-238 decay chain

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