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Key Knowledge and Skills

Effects of Radiation. Key Knowledge and Skills. describe the effects of α, β and γ radiation on humans, including short- and long term effects from low and high doses, external and internal sources, including absorbed dose (Gray), dose equivalence (Sieverts) and effective dose (Sieverts);

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Key Knowledge and Skills

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  1. Effects of Radiation Key Knowledge and Skills • describe the effects of α, β and γ radiation on humans, including short- and long term effects from low and high doses, external and internal sources, including absorbed dose (Gray), dose equivalence (Sieverts) and effective dose (Sieverts); • describe the effects of ionising radiation on living things and the environment; • describe the risks for living things and/or the environment associated with the use of nuclear reactions and radioactivity.

  2. The effects of radiation on humans depends on • The amount of radiation (activity) • The type of radiation • The length of time of exposure • The parts of the body that are exposed

  3. Exposure Coulombs/kilogram[C/kg] - SI unit of exposure: the number of rays required to produce 1 coulomb of electrical charge in 1 kilogram of air. Roentgen [R] - Historical unit of exposure: the number of  required to produce 2.58x10-4 coulombs of electrical charge in 1 kilogram of air. 1[R] = 2.58x10-4[C/kg]

  4. Absorbed Dose Gray [Gy] - SI unit of absorbed dose. It is a measure of the amount of energy received. absorbed dose = energy absorbed mass 1 Gy = 1 joule/kg. The historical unit of rad is sometimes used. 1 rad = 0.01 Gy

  5. Dose Equivalent Sievert [Sv] - SI unit of dose equivalent. This measure of the amount of radiation takes into account the different styles of damage caused by various forms of ionising radiation. dose equivalent = absorbed dose x quality factor Quality factor Type of Radiation 1 beta particles, gamma rays 2 - 10 neutrons & protons 10 - 20 alpha particles

  6. Summary Unit Definition Source activity Bequerel (Bq) 1 disintegration per second Exposure Coulombs/kg (C/kg) 1 coulomb of electrical charge in 1 kgof air Absorbed Dose Gray (Gy) 1 J/kg Biologically Sievert (Sv) quality factor x absorbed dose Equivalent Dose

  7. Apart from the dose equivalent, there are also different risk-weighting factors for different parts of the body. A given dose equivalent is four times more likely to cause fatal cancer in the lungs than in the thyroid.

  8. The average radiation dose per person per year is 2300 Sv (0.023 Sv). A dose of as little as 1 Sv is enough to cause radiation illness such as nausea and vomiting in a few days. Anything above 3 - 5 Sv causes death.

  9. Radioactive radiations can cause severe damage to living organisms. The exact mechanism for this is not fully understood. It seems that when radiation is absorbed by a complex organic molecule, instead of a straightforward excitation of the molecule, re-organisation of the molecule may take place. This can have drastic effects, particularly in the DNA of cells where an upset in the genetic coding this might give rise to mutations or may cause cells to continue dividing without any check, resulting in cancer.

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