L9-Radiation and Radioactivity in the Environment

Radiation and Radioactivity in the Environment

• Overview of types, sources, and control methods of radiation and radioactivity.

Types of Radiation (Page 2)

• Radiation: Emission and propagation of energy in waves or particles.

  • Types include:

    • Alpha (α)

    • Beta (β)

    • Gamma (γ): No mass and no charge.

    • X-rays and UV Radiation

Electromagnetic Radiation (Page 3)

• Radiation penetration through Earth's atmosphere varies:

  • Types and Properties:

    • Radio

    • Microwave

    • Infrared

    • Visible Light

    • Ultraviolet

    • X-ray

    • Gamma ray

  • Wavelength:

    • Ranges from 10³ m (radio) to 10⁻¹² m (gamma)

  • Frequency:

    • Ranges from 10⁴ Hz (radio) to 10²⁰ Hz (gamma)

  • Representations from large (buildings) to small (atomic nuclei).

Sources of Ionizing Radiation (Page 4)

• Common sources:

  • Radioactive materials emitting α, β, or γ radiation.

Understanding Radioactivity (Page 5 and 6)

• Radioactivity: Process of unstable nucleus losing energy through radiation emission.

  • Key points:

    • Includes α particles, β particles, and γ rays.

    • Any material that emits radiation is considered radioactive.

Environmental Radioactivity Sources (Page 7)

• Types:

  • Natural Radiation

  • Man-Made Radiation

Environmental Radiation Exposure (Page 8)

• Sources of background radiation:

  • Radon gas: 18% exposure.

  • Nuclear Power: ~1%.

  • Medical sources: 42%.

  • Cosmic Rays: 14%.

  • Overall Breakdown:

    • 15% from artificial sources.

    • 14% from food and drink.

Naturally Occurring Radioactive Materials (NORM) (Page 9 and 11)

• Sources include:

  • Mining, agricultural fertilization, use of fossil fuels, and building materials.

• Health Impact:

  • External radiation from decay series of isotopes (238U, 232Th, 40K).

  • Internal radiation from radon inhalation.

Uranium and Thorium Decay Series (Page 12)

• Decay processes of:

  • Uranium (238U, 234U)

  • Thorium (232Th)

  • Resultant isotopes and their half-lives vary considerably, impacting natural radioactivity.

NORM and TENORM (Page 13 to 15)

• NORM: Naturally occurring without human enhancement.

• TENORM: Enhanced by human activities, increasing exposure pathways and environmental contamination risks.

Sources of Radiation Exposure (Page 14)

• Natural Background Radiations (NBR) include:

  • Cosmic rays, terrestrial origins, and decay series of specific isotopes.

• Technological Enhanced Radiation includes:

  • Mining, nuclear industries, medical sources, and radioactive waste.

Practicalities of Enriched Nuclear Fuel (Page 19 and 20)

• Processing uranium to produce enriched fuel necessary for nuclear power generation.

  • Enrichment Step: Involves increasing 235U concentration from 0.7% to 2-3% or higher for reactors.

• Methods include centrifugation, diffusion, and isotopic separation.

Biological Effects of Ionizing Radiation (Page 22 to 27)

• Deterministic Effects:

  • Result from a direct hit on tissues resulting in immediate physiological impacts (e.g., cell death).

• Stochastic Effects:

  • Cancer and hereditary effects depending on dose and exhibited in populations.

• Cellular Interactions:

  • Direct & indirect DNA damage leads to repair or erroneous repair pathways that may lead to cancer development.

Radiation Safety Principles (Page 27)

• Justification Principle: No radiation practice shall be adopted unless it produces a net benefit.

• Optimization Principle (ALARA): All exposures must be kept as low as reasonably achievable.

• Dose Limits: Specific thresholds established for the public and radiation workers (1,000 mSv/y for the public, 20,000 mSv/a for workers).