Sources of Atmospheric Radiation Release: Natural & Anthropogenic

Radiation enters the atmosphere from both natural processes and human activities. Major sources:

Anthropogenic (Human-Caused)

1. Nuclear Accidents: Chernobyl (1986), Fukushima (2011) — massive Cs-137, I-131, Sr-90 releases.
2. Nuclear Weapons Testing (1945–1980): 500+ atmospheric tests (US, USSR, UK, FR, CN) — global fallout (C-14, Sr-90, Cs-137, Pu-239).
3. Nuclear Fuel Cycle: Uranium mining/milling (radon, tailings), enrichment, reprocessing (La Hague, Sellafield — authorized discharges), waste storage.
4. Radioactive Material Accidents: Transport crashes, lost sources (e.g., Goiânia 1987), medical/industrial mishandling.
5. Coal Combustion: Fly ash releases U, Th, Ra, Rn, Po-210 — collectively > nuclear power per TWh.
6. Industrial/Medical: Improper disposal of gauges, smoke detectors (Am-241), radiotherapy sources.

Natural Sources

• Radon (Rn-222): Decay of U-238 in soil/rock; #1 natural radiation exposure (indoors).
• Cosmic Radiation: Galactic cosmic rays + solar particles; increases with altitude/latitude.
• Volcanic Eruptions: Release trapped magmatic gases (Rn, CO2, SO2) and ash with K-40, U/Th series.
• Terrestrial Gamma: K-40, U/Th decay in crust — external exposure.
• Internal Exposure: K-40, C-14, Pb-210, Po-210 in food/water/body.

Regulatory Framework

• IAEA Safety Standards (GS-R-3, GSR Part 3).
• UNSCEAR — scientific assessments.
• National regulators (NRC, ONR, CNSC, etc.) — discharge limits, monitoring.
• CTBTO — verifies test ban via radionuclide stations.

Natural sources dominate global collective dose; anthropogenic spikes are localized or historical (fallout peak 1963).