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Radiation-pollution, measurement & application

Radiation

TOPICS COVERED

  1. Types of Radiation Pollution
  2. Sources of Radiation Pollution
  3. Radioactive pollution
  4. Measurement of radioactivity
  5. Application of radiation
  6. Research Reactors in India

 

  1. Types of Radiation Pollution
  2. Ionizing radiation
  3. Short-wavelength
  4. Particulate radiation.
  5. Non-ionizing radiation

Ionizing radiation

Ionizing radiation is the short wavelength radiation or particulate radiation emitted by certain unstable isotopes during radioactive decay

  1. Short-wavelength

E.g. Gamma Radiation & X-Ray radiation

  1. Particulate radiation: e.g. alpha particles, beta particles, neutrons & protons.

Impact of ionizing radiation

  • Ionizing radiation can ionize the atoms or molecules with which it interacts. In other words, ionizing radiation can cause other atoms to release their electrons, thus forming free radicals.
  • Radioactivity is considered toxic because these free electrons can damage many bio-chemicals, such as proteins, lipids, and nucleic acids (including DNA)
  • In case of intense radiation, this damage can cause severe human health problems, including cancers, birth defects and even death

Non-ionizing radiation

  • It is relatively long-wavelength electromagnetic radiation,  such as radio waves, microwaves, visible radiation & UV radiation
  • Non-ionizing radiation is generally considered less dangerous than ionizing radiation because it does not produce free radical in living cells.
  • However, some forms of non-ionizing radiation, such as ultraviolet, can damage biological molecules and cause health problems.

 

  1. Sources of Radiation Pollution
  2. Natural
  3. Man made
  • On average, 82% of ionizing radiation comes from natural sources and 18% from anthropogenic sources
  • The major natural source of radiation is radon gas which accounts for about 55% of the total radiation dose.
  • The principal anthropogenic sources of radioactivity are medical X-rays, nuclear medicine, nuclear weapons & nuclear power plant.
  1. Radioactive pollution
  • Nuclear weapons release enormous amounts of radioactive materials when they are exploded.
  • Most of the radioactive pollution from nuclear weapons testing is from iodine -131, cesium-137, and strontium-90.
  • Iodine-131 is the least dangerous of these isotopes. Iodine-131 accumulates in the thyroid gland , and large doses can cause thyroid cancer.
  • Cesium-137 has a half-life of about 30 years. It is chemically similar to potassium, and is distributed throughout the human body.
  • Strontium-90 has a half-life of 38 years. It is chemically similar to calcium and is deposited in bones. Strontium-90 is expelled from the body very slowly, and the uptake of significant amounts increases the risks of developing bone cancer or leukemia.
  • At high altitude, people are exposed to higher doses of radiation because the atmosphere is thinner at higher elevations
  • Exposure to cosmic radiation is also high while people are flying in an airplane, so pilots and flight attendants have an enhanced, occupational exposure.
  • Miners, who spend a lot of time underground, are exposed to relatively high doses of radon-222 and consequently have relatively high rates of lung cancer.
  • Cigarette smokers expose their lungs to high levels of radiation, since tobacco plants contain trace quantities of polonium-210, lead-210, and radon-222.

 

  1. Measurement of radioactivity
  • A Curie (Ci) represents the rate of radioactive decay.
  • A rad is a unit representing the absorbed dose of radioactivity.
  • A rem is a unit that measures the effectiveness of radioactivity in causing biological damage.

 

  1. Application of radiation
  2. Agriculture: Development of High Yield Variety Seeds by inducing mutation through gamma radiations. It helps to promote early maturity, withstand biotic & abiotic stress and enhance nutritional quality.

BARC has developed over 40 such seeds for commercial use.

  1. Preservation of food: food irradiation by controlled doses of ionizing radiation kills bacteria. This technique is called Food Irradiation. It helps to extend the shelf life of food.

KRUSHAK: Krushi Utpadan Sanrakshan Kendra is the technology demonstration plant set up by BARC at Lasalgaon, district Nashik, Maharashtra. It uses gamma radiation from cobalt-60 source.

 

Benefits of Food Irradiation

  • Preservation – destroy or inactivate organisms that cause spoilage and decomposition and hence extend the shelf life of foods.
  • Control of Insects & help in reducing the use of insecticides
  • Decreases the use of pesticides
  • Prevention of Food borne Illness
  • Delay of Sprouting and Ripening –inhibit sprouting (e.g., potatoes, garlic, etc.) and delay ripening of fruit to increase longevity.
  1. Sterilization: Radiation is a safe and cost-effective method for sterilizing single-use medical devices such as syringes and surgical gloves. One of its key advantages is that it allows already-packaged products to be sterilized. Radiation kills germs that can cause disease and neutralizes other harmful organisms. Sterilization with ionizing radiation inactivates such microorganisms.
  2. Water desalination: it provides cheap and low energy consuming water desalination technology using radioisotopes. Radiator of ultrasonic waves and source of alpha-particles are suggested to use as the evaporator and ioniser of water aerosols, respectively.

Moreover, ultraviolet light (a form of radiation) is used to disinfect drinking water.

  1. Health care applications: radio-isotopes find wide applications in medical diagnosis, therapy and medicines.
  2. Medical imaging
  • Radiography
  • MRI
  • Tomography
  • CT scan
  • PET
  • Photo Acoustic Imaging
  • Ultrasound
  1. Nuclear medicines
  • Hydrogen- Treating wounds and Leprosy
  • Holmium 166 & Samarium 153- Arthritis treating
  • Lutetium – 177- Skeletal pain treatment
  • Cesium – 137- Brachy therapy, Cancer treatment
  • Cobalt – 60- Cancer treatment
  • Phosphor – 32 & Samarium – 153- Treating bone cancer
  1. Treatment of cancer through therapy
  2. Industrial application: Radiationis is used to create high-performance polymeric materials.  Radiation can cause cross-linking of some molecules to form giant molecules which have higher heat, chemical and mechanical resistance. This helps harden plastics.
  3. Space exploration: power- plutonium batteries
  4. Environmental application – radiation is used to help remove toxic pollutants, such as exhaust gases from coal-fired power stations and industry. It also does accurate measurement of the movement of pollutants in the environment
  5. Archaeology: Archaeologists also use radioactive substances to determine the ages of fossils and other objects through a process called carbon dating. For example, in the upper levels of our atmosphere, cosmic rays strike nitrogen atoms and form a naturally radioactive isotope called carbon-14. Carbon is found in all living things, and a small percentage of this is carbon-14.

 

  1. Research Reactors & radio isotope centers in India

Radio Isotopes Production Centers

  1. Research Reactors Trombay
    2. Atomic Power Reactor of NPCIL
    3. Cyclotron of VECC Kolkata

RESEARCH REACTORS

  • Apsara –(from UK) –Trombay (Shut down permanently in 2010)
  • CIRUS –(from Canada)-Trombay (Shut down permanently in 2010)
  • Zerlina- (from USA)-Trombay (decommissioned)
  • Purnima I – III –(indigenous)-Trombay (decommissioned)
  • Dhruva – Trombay
  • Kamini- Kalapakkam
  • FBTR – Kalpakkam
  • Zerlina was decommissioned in 1984 and Purnima series made way for Kamini.
  • Dhruva, Cirucs and Apsara are used for producing radioisotopes.
  • Kamini is used mainly for radiography of various materials.
  • FBTR is the test bed for the development of fuel, blanket and structural materials for FBR program.
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