Radiation

• Nuclear radiation is used in medicine to diagnose internal disorders in patients and to treat them
• Examples of the use of nuclear radiation in medicine include:

  • Radioactive tracers to trace the flow of a substance through an organ
  • Gamma cameras to take images of internal organs
  • Gamma radiation in a narrow beam to destroy cancerous tumors
  • Radioactive implants to destroy cancer cells in some tumors
• Radioactive tracers contain a radioactive isotope that emits gamma radiation and can be detected outside the system
• Radioactive iodine is used to test for blocked kidneys because:

  • Its half-life is 8 days
  • It emits gamma radiation
  • It decays into a stable product
• Gamma cameras are used to take images of internal organs by detecting gamma radiation emitted by a gamma-emitting radioactive isotope absorbed by the organ
• Gamma radiation in a narrow beam is used to destroy cancerous tumors because it can penetrate deeper in the body than beta or alpha radiation
• Radioactive implants with beta or gamma-emitting isotopes are used to destroy cancer cells in tumors
• Workers who use ionizing radiation need to reduce their exposure by wearing personal radiation monitors and following safety rules
• Background radiation is caused by radioactive substances found naturally all around us
• A Geiger counter clicks even with a radioactive source near it due to background radiation
• A Geiger counter is used for detecting and measuring ionising radiation
• Radiation dose in YSv:

  • Cosmic rays: 238 YSv
  • Ground and buildings: 332 YSv
  • Food and drinks: 274 YSv
  • Natural radioactivity in the air: 1190 YSv
  • Medical applications: 332 YSv
  • Nuclear weapon tests: 5 YSv
  • Air travel: 5 YSv
  • Nuclear power: 2 YSv
• Radiation from radioactive substances is hazardous because it ionises substances it passes through
• The numbers in the radiation dose table are measured in sieverts (SV) and indicate the average annual radiation exposure from each source
• Medical sources of radiation include x-rays and radioactive substances due to their ionising effect
• Background radiation in the air is mainly caused by radon gas seeping through the ground from radioactive substances deep underground
• Radon gas emits alpha particles and can be a health hazard if it seeps into buildings
• In some locations, pipes under buildings can be installed with a suction pump to draw radon gas out of the ground before it enters the building
• Used fuel rods are stored in big tanks of water for approximately a year after being removed from a reactor to cool down the rod
• Remote-control machines are used to open fuel rods
• Unused uranium and plutonium are removed chemically from the used fuel
• Unused uranium and plutonium are stored in sealed containers for future use
• The material left after removing uranium and plutonium contains radioactive isotopes with long half-lives
• This radioactive waste must be secured in safe conditions for many years to prevent radioactive contamination of the environment
• Most of the world's nuclear reactors will need to be replaced in the next 20 years with new third-generation nuclear reactors
• New third-generation nuclear reactors could have:

  • A standard design to reduce costs and construction time
  • A longer operating life which lasts for approximately 60 years
  • Much less effect on the environment
  • More safety features
• Radioactive isotopes have a wide range of half-lives
• Some radioactive isotopes have half-lives of a fraction of a second
• Others have half-lives of more than a billion years
• Isotopes with the shortest half-lives have the most unstable nuclei
• Isotopes with short half-lives emit a lot of radiation in a short time
• The half-life of a radioactive source indicates how quickly its activity decreases
• As the activity decreases, the rate of radiation emission decreases
• Hazards from radiation decrease with time according to the half-lives of isotopes
• The effect of radiation on living cells depends on:

  • The type or amount of radiation received (the dose)
  • Whether the source of radiation is inside or outside the body
  • How long the living cells are exposed to radiation
• The bigger the radiation dose someone gets, the higher the risk of cancer because higher doses kill living cells
• Count rate of a radioactive substance is the number of decays recorded each second
• A Geiger-muller counter is used to measure count rate
• Nuclei can emit alpha/beta particles, protons/neutrons, and gamma waves
• Sometimes nuclei can emit more than one type of radiation