L9-Radiation and Radioactivity in the Environment
Page 1: Introduction to Radiation and Radioactivity
Overview of radiation and radioactivity in the environment.
Types, sources, and control measures discussed.
Page 2: Definition of Radiation
Radiation: Emission and propagation of energy in the form of waves or particles.
Types of Radiation:
Alpha (α): Heavy, positively charged particles.
Beta (β): Lighter, negatively charged particles or positively charged positrons.
Gamma (γ): No mass and no charge; high-energy electromagnetic radiation.
X-rays and UV Radiation: Forms of electromagnetic radiation.
Page 3: Electromagnetic Radiation: Sources and Properties
Electromagnetic Spectrum: Includes various types of radiation and their properties.
Types: Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
Penetration of Earth's Atmosphere: Y/N for different radiation types.
Wavelengths (m): Ranges from 10³ to 10⁻¹².
Frequency (Hz) and Temperature of Emission: Ranges from 10⁴ to 10²⁰ Hz.
Page 4: Sources of Ionizing Radiation
Common sources of ionizing radiation include radioactive materials emitting α, β, or γ radiation.
Page 5: Definition of Radioactivity
Radioactivity: Process where an unstable atomic nucleus loses energy by emitting radiation (α, β, γ).
Materials emitting radiation are considered radioactive.
Page 6: Nature of Radioactivity
Radioactivity involves the spontaneous decay of an unstable nucleus to a stable one by emitting radiation.
Radiation involves energy release from radioactive atoms.
Page 7: Environmental Sources of Radioactivity
Two main sources of environmental radioactivity:
Natural Radiation: Naturally occurring sources in the environment.
Man-Made Radiation: Human activities affecting radiation levels.
Page 8: Background Radiation Exposure Pathways
Various sources contribute to background radiation exposure:
Medical: 42%
Radon Gas: 15%
Food and Drink: 14% and 11% respectively.
Cosmic Rays: 14% and Buildings/Ground: 18%.
Page 9: Naturally Occurring Radioactive Materials (NORMs)
NORM: Naturally occurring radioactive materials in geological formations influence environmental radiation.
Sources: Mining, agriculture (phosphate), fossil fuel processing, building materials.
Page 10: Radiation from Building Materials
External Radiation: Originates from γ radiation of decay series (238U, 232Th, 40K).
Internal Radiation: Due to radon inhalation, leading to respiratory system deposition.
Page 11: NORM in Building Materials
NORM contributes to radiation exposure via external and internal radiation mechanisms.
Page 12: Uranium and Thorium Decay Series
Key isotopes of Uranium (U) and Thorium (Th) and their decay products.
Uranium-238 (4.5 billion years) and Thorium-232 (14.1 billion years).
Products include Radon-222 and other isotopes contributing to radioactivity.
Page 13: Natural Radioactivity in Reservoir Rock
Reservoir rocks contain small amounts of uranium, thorium, and radium.
Radium can precipitate with barium and calcium, creating slightly radioactive scales.
Materials with high NORM: Coal, crude oil sludge, phosphate rocks.
Page 14: Sources of Radiation Exposure
Natural Background Radiations (NBR):
Cosmic and terrestrial origins (238U-series, 232Th-series, 40K).
Technologically Enhanced Natural Radiation (TENR):
Altered due to mining, industrial activities, high radon concentrations, etc.
Man-Made Sources: Nuclear industry, medical, industrial, and research applications.
Page 15: NORMs and TENORMs
NORM: Natural radioactivity without human enhancement.
TENORM: NORM disturbed by human activity, leading to increased exposure risk.
Page 16: Mobility of Radiactivity
Sources of soluble/radiologically significant materials in water include Radium.
Accumulation can occur in waste materials and geological formations.
Page 19: Processing of Uranium
Yellow Cake: Material rich in U3O8, produced during uranium ore processing.
Composition: 0.7% of uranium is 235U; the rest is mainly 238U, unsuitable for fission.
Page 20: Enriched Nuclear Fuel
Achieving self-sustaining chain reactions requires uranium enriched in 235U.
Methods of enrichment include centrifugation, diffusion, and electromagnetic separation.
Page 22: Biological Effects of Ionizing Radiation
Deterministic Effects: Immediate and associated with cell death (e.g. lens injuries, infertility).
Stochastic Effects: Long-term effects like cancer, genetically affecting future generations.
Page 24: Radiation Interaction with Cells
Radiation interacts with DNA via excitations (energy consumption) and ionization (chemical bond disruption).
DNA damage types:
Direct Interaction: Breaks and cross-links occur directly.
Indirect Interaction: Through radical formation (e.g., OH-).
Page 26: Effects of Ionizing Radiation
Deterministic Effects: Dose threshold present; results in organ dysfunction and immediate effects.
Stochastic Effects: No threshold; probabilities of occurrence increase with dose, with longer latency periods.
Page 27: Principles of Radiation Protection
Justification: Positive net benefit from practices involving radiation.
Optimization (ALARA): Keep exposures as low as reasonably achievable.
Dose Limits: Recommended doses for public and workers, with specific doses specified.