Lecture Notes: Irradiation and Radioactive Contamination

Learning Objectives

• Understand the concepts of irradiation and radioactive contamination.
• Describe the hazards associated with these concepts.
• Learn the precautions to mitigate these hazards.

Review of Radioactive Isotopes

• Radioactive isotopes decay and emit radiation.
• Radiation can be ionizing, meaning it can create ions (charged atoms).
• Ionizing radiation increases the risk of cancer in humans.

Irradiation

• Definition: Exposing an object to nuclear radiation (alpha, beta, gamma radiation, or neutrons).

  • Example: Sterilization using gamma radiation.
    • Medical equipment is sterilized using heat, but some objects require gamma radiation.
    • Gamma radiation is produced by radioactive isotopes.
    • Object example: Sterilizing a syringe inside a sealed plastic wrapper.
    • The object is near a radioactive isotope emitting gamma radiation.

• Key Point: An irradiated object does not become radioactive.

  • The object is only exposed to radiation, not the radioactive isotope.

Hazards of Ionizing Radiation

• Increases risk of cancer.
• Precautions:
  • Shielding: To stop the radiation.
    • Alpha Radiation: Low penetrating power; stopped by gloves.
    • Beta and Gamma Radiation: More penetrating; stopped by lead (e.g., lead apron).
    • High levels of radiation require lead walls/screens.
  • Radiation Meters: Measure radiation exposure.
    • Stops work if radiation exposure is too high.

Radioactive Contamination

• Definition: Unwanted radioactive isotopes on other materials.

  • Radioactive atoms decay and emit ionizing radiation.
  • Contamination means having the radioactive source on/in you.

• Hazards:

  • Alpha Emitters: Strongly ionizing, dangerous if inhaled/swallowed.
    • Penetrate living cells and damage DNA.
  • Beta Particles: Less ionizing than alpha but penetrate into the body.
  • Gamma Rays: Weakly ionizing, pass in and out of the body.

Scientific Studies and Peer Review

• Studies on radiation effects are published and peer-reviewed.
  • Ensures findings are checked and validated by other scientists.

Additional Resources

• Revision workbook for practice questions on irradiation and contamination.
• Link provided for accessing the workbook.