Radioactivity – UPSC Prelims

  • Radioactivity is the phenomenon of spontaneous emission of particles or waves from the unstable nuclei of some elements.
  • There are three types of radioactive emissions: Alpha, Beta and Gamma.
  • Alpha particles are positively charged He (Helium) atoms, beta particles are negatively charged electrons and gamma rays are neutral electromagnetic radiations.
  • Radioactive elements are naturally found in the earth’s crust.
  • Uranium, thorium and actinium are three NORM (Naturally Occurring Radioactive Materials) series that contaminate water resources.
  • A small amount of radiation is found in nature but the extended amount of radiation is harmful to human health.
  • Radioactivity is measured in Becquerel (SI unit) or in Curie.
  • The unit Sievert measures the quantity of radiation absorbed by human tissues.
Sources of Radioactivity:
  • Natural Sources:
    • Radiotoxic Elements in Aquatic System: Radium, a descendant of the NORM series, is one of the radiotoxic elements found in aquatic systems and can be penetrated into groundwater via:
      • aquifer rock dissolution
      • decaying of 238U and 232Th,
      • desorption processes.
      • Radium is a radionuclide formed by the decay of uranium (U) and thorium (Th) in the environment.
    • Magma: Sometimes, magma also releases radioactive gases into the environment.
    • Soil Sediments: Percolation of NORM from the soil sediments to the aquifer causes groundwater contamination.
    • Atmospheric Deposition of Cosmogenic Radionuclides:
      • Atmospheric deposition (both dry and wet) of cosmogenic radionuclides add radioactive nuclei in the surface water.
      • Cosmogenic radionuclides are radioactive isotopes which are produced by natural processes and distributed within the Earth system.
  • Anthropogenic:
    • Nuclear Reactors and Warheads:
      • Nuclear reactors and nuclear warhead experiments are the key sources of human-induced radionuclides discharge.
      • Nuclear reactors produce radioisotopes (Cobalt-60, Iridium-192, etc) that hand out as sources of gamma radiation in radiotherapy and numerous industrial appliances.
      • Nuclear power plants placed at the coastal regions add to the radiological contaminants in the marine water by releasing atomic wastes.
      • Water is also used as coolants in these powerhouses, which also get contaminated.
    • Dumping of Radioactive Waste:
      • The application of radioactive elements in nuclear weapons, X-rays, MRI and other medical equipment causes their exposure to human beings. Dumping of these radioactive wastes in surface water bodies causes water pollution.
    • Mining:
      • Mining activities of radioactive elements like uranium and thorium also pollute surface and groundwater.
    • Nuclear Accidents:
      • Radioactive pollution due to nuclear submarine accidents and sinking have been reported.
      • The Rocky Flats plant in Colorado, Fukushima and the Chernobyl nuclear disaster are some examples of such nuclear accidents.
Effects of radioactive pollution on health:
  • Radiation Syndrome:
    • Human tissues absorb radiation through polluted water and foodstuff, which can cause serious health risks.
    • High doses of radiation can cause acute radiation syndrome or dermal radiation injury.
  • Disorders in Human Physiology:
    • Exposure to radiation causes various disorders in human physiology, including cancer, leukaemia, genetic mutations, cataracts, etc.
  • Mutation and Structural Alteration:
    • Genetic effects ionizing radiation induces mutations in germ cells (male sperm cells and female egg cells), resulting in structural alteration in germ cell DNA that is passed onto offspring.
  • Hereditary disorders can lead to premature death and severe mental illness.
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