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Biological Effects

Biological Effects. Chemical changes vs Nuclear changes. Chemical – atoms rearrange, but do not change atomic identity . Nuclear – nuclear change, change in atomic identity possible across nuclear change. Chemical Change vs Nuclear Change.

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Biological Effects

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  1. Biological Effects

  2. Chemical changes vs Nuclear changes • Chemical – atoms rearrange, but do not change atomic identity. • Nuclear – nuclear change, change in atomic identity possible across nuclear change.

  3. ChemicalChange vsNuclearChange 4C7H2(NO2)3CH3 +25O2 32CO2 + 10H2O + 6 N2 10n + 23592U 14156Ba + 9236Kr + 3 10n 10n + 23592U 13752Te + 9740Zr + 2 10n

  4. What does radiation do to you? Ionizing radiation – the high energy alpha, beta or gamma radiation can knock an electron out of a chemical bond: ionizing radiation + H2O  H2O+ + e-

  5. 7.7

  6. What units are used to measure radiation? Given Off by Sample Absorbed by Tissue Ci 1 Ci = 3.7 X 1010disintigrations/sec (Geiger counter) rad rem Sv 1 Sv = 100 rem (special paper)

  7. Fig. 7.20 Linear Non Threshold Model Threshold Model

  8. Where does radiation come from? • Unstable radioisotopes • Naturally found in environment • Made by humans for medical, energy, defense purposes

  9. Fig. 7.19 BACKGROUND RADIATON

  10. U-238 Radioactive Decay Series Radioactive isotopes undergo decay until they reach a stable species. All isotopes of all elements with atomic number 84 (Po) and higher are radioactive. 7.5

  11. Tab. 7.3

  12. Average annual dose 3600 μSv μ is a prefix meaning 1 x 10-6

  13. Radioisotopes have varying rates of decay

  14. Half-life: the time required for the level of radioactivity to fall to one-half of its value. Example of decay of Pu-239. 7.8

  15. Half-life: the time required for the level of radioactivity to fall to one-half of its value. 7.8

  16. Box. 7.23

  17. Box. 7.18

  18. What is the problem with Nuclear Power and Harmful Effects to People? Talk about this during the next lecture……

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