Lim Jus494 Nuclear


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Lim Jus494 Nuclear

  1. 1. Nuclear Technology & Us & Us JUS 394 Arizona State University Science, Technology & InEquality Professor: Merlyna Lim
  2. 2. What IS Nuclear Technology <ul><li>Images of our world </li></ul><ul><ul><li>Weapons </li></ul></ul><ul><ul><li>Reactors </li></ul></ul><ul><ul><li>Nuclear waste </li></ul></ul><ul><ul><li>Hiroshima </li></ul></ul><ul><ul><li>Anti Nuclear Protests </li></ul></ul><ul><li>Media bring nuclear technology to our attention </li></ul><ul><li>How to sort out the issues from the noise? </li></ul>
  3. 3. Nuclear POWER
  4. 4. Scientific Views <ul><li>for easy introduction: </li></ul><ul><li>ENERGY -- the driving force of change </li></ul><ul><li>ENERGY -- heart of nuclear technology; radioactivity, nuclear fission, and nuclear fusion (reactions) are also driven by energy </li></ul>
  5. 5. Energy plays an important part And it’s used in all this work; Energy, yest energy with power so great, A kind that cannot shirk. If the farmer had not this energy, He would be at a loss, But it’s sad to think, this energy Belongs to a little brown horse. A school verse by Richard Feynman a Nobel laureate for physics
  6. 6. Nuclear ENERGY <ul><li>Energy forms -- transfer and conversion (recalling your high-school physics class!!) </li></ul><ul><li>Part of nuclear technology -- for the conversion of nuclear energy into heat and electric energy; its development is related to the development of other technologies </li></ul><ul><li>The Sun is a nuclear fusion reactor -- nuclear technology imitates the energy producing process of the Sun </li></ul>
  7. 7. Nuclear Fission <ul><li>A process by which a heavy nuclide splits into two of more pieces -- became the top secret in Germany, England, the former USSR and the United States </li></ul><ul><li>Transuranium: Fermi (1901-1954) in Rome, F. Joliot (1990-1958) and I. Curie in Paris, and Otto Hahn.... </li></ul>
  8. 8. Nuclear Fission <ul><li>Uranium isotopes -- 235 U </li></ul><ul><li>How much energy is released per fission reaction? How can the amount be estimated or calculated? What are the applications of fission energy in war and peace? </li></ul><ul><li>235 U to give two nuclides --> 117 Sn 50 , and 118 Sn 50 , their masses being 116.902956 and 117.901609 amu respectively. The mass of 235 U 92 is 235.043924 amu. The difference in mass: 235.043924 - (116.902956 + 117.901609) = 0.2394 amu ( 931.5 MeV / 1 amu ) = 223 MeV. </li></ul><ul><li>E = m c 2 </li></ul>
  9. 9. Common Perceptions <ul><li> </li></ul><ul><li>Are these images represent “the truth” behind nuclear technology? </li></ul><ul><li>We should understand our own biases </li></ul>
  10. 13. <ul><li>Nuclear weapons: Can any rational person make a case for their continued existence? </li></ul><ul><li>Nuclear reactors: if they are very dangerous, can we afford to use them? </li></ul>
  11. 14. Nuclear Technology & MEDIA Representation MEDIA Representation MEDIA Representation
  12. 17. Radiation As constructed in the Media in the Media in the Media
  13. 20. Media Stories <ul><li>Do I have to worry about radiation on airplanes? </li></ul><ul><li>Is flying like working in a nuclear power plant? </li></ul><ul><li>Does that mean nuclear plants are safe or flying is hazardous? </li></ul>
  14. 21. Other Nuclear News
  15. 24. Radon
  16. 27. Radon Media Stories <ul><li>What is it </li></ul><ul><li>Should I get my house tested? </li></ul><ul><li>Is it related to nuclear power? </li></ul><ul><li>Why didn’t someone tell me about it earlier? </li></ul>
  18. 29. Radiation Fictions <ul><li>Fear: </li></ul><ul><ul><li>“ It’s gonna blow!!!” </li></ul></ul><ul><li>Controversy: </li></ul><ul><ul><li>“ We’re all gonna die!” </li></ul></ul><ul><li>Misunderstanding: </li></ul><ul><ul><li>“ It’s not natural!” </li></ul></ul><ul><li>Mistrust </li></ul><ul><ul><li>“ They’re all liars. We know mutant bugs will take over the earth and enslave us.” </li></ul></ul>
  19. 30. Nuclear Technology <ul><li>Too little we know on ‘what it is’ </li></ul><ul><li>Dominant perception (mainstream political stories, media representation) reflect only partial truth </li></ul><ul><li>Preconceived notions can hinder clear thinking and fruitful discussions </li></ul><ul><li>Don’t we need to understand the basis of the technology to be able to come to ‘better’ decision? </li></ul><ul><li>Doesn’t public deserve more information? </li></ul><ul><li>Doesn’t public (us) need to be better informed? </li></ul>
  20. 31. Radiation Facts <ul><li>It’s been around forever </li></ul><ul><li>First was noticed ~ 1895 </li></ul><ul><li>A lot was learned since then: </li></ul><ul><ul><li>doctors & radiation could cure cancer </li></ul></ul><ul><ul><li>quacks & radiation could kill people </li></ul></ul><ul><ul><li>the Military & radiation could kill a LOT of people </li></ul></ul><ul><li>Basic limits set in the 1950s still hold </li></ul>
  21. 32. Environmental Radiation <ul><li>Radiation & radionuclides older than the Earth </li></ul><ul><li>Natural part of our environment </li></ul><ul><li>Radiation field varies by geology, elevation, season, living conditions </li></ul>
  22. 33. “ Artificial” Radiation <ul><li>Medical </li></ul><ul><li>Occupational </li></ul><ul><li>Nuclear Fuel Cycle </li></ul><ul><li>Fallout </li></ul><ul><li>Petroleum Industries </li></ul><ul><li>Power generation </li></ul><ul><li>Other </li></ul>
  23. 34. Quanties & Units <ul><li>Amount (activity): </li></ul><ul><ul><li>Becquerel (Bq) dis/s </li></ul></ul><ul><ul><li>Curie (Ci) 3.7 x 10 10 dis/s </li></ul></ul><ul><li>Dose: </li></ul><ul><ul><li>gray (Gy) 1 J/kg </li></ul></ul><ul><ul><li>rad, 0.01 Gy </li></ul></ul><ul><li>Dose equivalent </li></ul><ul><ul><li>sievert (Sv) </li></ul></ul><ul><ul><li>rem, 0.01 Sv </li></ul></ul><ul><li>Exposure (roentgen, R) </li></ul>
  24. 35. Range of Doses <ul><li>General public - 360 mrem/y natural </li></ul><ul><ul><li>Radon: 200 mrem </li></ul></ul><ul><ul><li>Other natural: 97 mrem </li></ul></ul><ul><ul><li>Remainder ~ 15 % medical, 3% products, 1% other </li></ul></ul><ul><li>Medical procedures (per procedure) </li></ul><ul><ul><li>CT head and body: 110 mrem </li></ul></ul><ul><ul><li>Chest X-ray: 8 mrem </li></ul></ul><ul><ul><li>Abdominal X-ray: 56 mrem </li></ul></ul>
  25. 36. %Contribution to Dose <ul><li>Contribution of various radiation sources to total average dose equivalent to persons in the United States (NCRP, 1987). </li></ul>
  26. 37. Basic Facts <ul><li>Two main types: </li></ul><ul><ul><li>electromagnetic (X-rays and gamma rays) </li></ul></ul><ul><ul><li>particulate (electrons, protons, alpha particles..) </li></ul></ul><ul><li>Produced in the nucleus or through atomic orbital transitions </li></ul><ul><li>Capable of ionizing (removing electrons) from atoms </li></ul>
  27. 38. Electromagnetic Radiation Gamma Rays γ X Rays Ultraviolet Light Visible Light Infrared (heat) radiation Radio Waves Frequency Photon Energy Wavelength
  28. 39. Radiation Particles - α β α , Helium-4 nucleus (radon is a source) β , nuclear electron ( 40 K is a source) orbital electron
  29. 40. Types and properties of ionizing radiation Types of radiation Gamma Ray X-ray Beta Particle (electron) Neutron Proton Alpha Relative mass & charge 0 0 0 0 0.0005 -/+ 1 1 0 1 +1 4 +2 Range in Soft Tissue centimeters centimeters millimeters centimeters microns microns
  30. 41. Radiation Effects in Living Tissues Nuclide decays Emitted radiation ionizes atom Free radicals created Cell/DNA attacked Cell killed or damaged dead cell ⇒ dead organ damaged cell ⇒ cancer(?) OH
  31. 42. Routes of Radiation Exposure Internal: α , β , γ , n External: α , β , γ , n
  32. 43. Range of Radiation Effects <ul><li>Hormesis (a little is good for you) </li></ul><ul><li>Nothing </li></ul><ul><li>Impaired organ function </li></ul><ul><li>Cancer </li></ul><ul><li>Genetic (mutation in offspring) </li></ul><ul><li>Teratogen (impairment in offspring) </li></ul><ul><li>Death </li></ul>
  33. 44. Factors Determining Impact <ul><li>Radiation type ( α , β , γ , n ) </li></ul><ul><li>Duration of delivery (s -> y) </li></ul><ul><li>Location (external or internal) </li></ul><ul><li>Distribution in / around body </li></ul><ul><li>Magnitude of dose </li></ul><ul><li>Sensitive individual </li></ul>
  34. 45. ‘predicting’ Radiation Effects Radiation Effects <ul><li>Why the “uncertainty”? </li></ul><ul><ul><li>Not all effects are apparent </li></ul></ul><ul><ul><li>Knowledge limitations (likely impact) </li></ul></ul><ul><ul><li>Natural variations (radiation field changes) </li></ul></ul><ul><ul><li>Measurement ability (you can only go so low) </li></ul></ul><ul><li>Dose is predicted </li></ul><ul><li>Risk (death, cancer) projected </li></ul><ul><li>Where do we get “risk” numbers? </li></ul>
  35. 46. Radiation Effects Model Potential Damage to Health Linear Hypothesis 370 mrem 100,000 mrem Doses Causing Observed Adverse Health Effects Area of controversy Real data
  36. 47. Radiation Effects Data Base <ul><li>Mainly for people or lab rats </li></ul><ul><li>Good data in high dose/high dose-rate region </li></ul><ul><li>Limited/contradictory data in low dose/low-dose rate region </li></ul><ul><li>Some data suggest threshold (~10 rem) </li></ul>
  37. 48. What about other biota? <ul><li>Insects are tough to kill </li></ul><ul><li>Big trees are as sensitive as we are </li></ul><ul><li>So are most mammals </li></ul><ul><li>Fish and plants are about 10x more resistant </li></ul><ul><li>But….. </li></ul><ul><ul><li>radionuclides are “more concentrated” lower in food chain </li></ul></ul><ul><ul><li>lower form biota “naturally” get higher dose </li></ul></ul>
  38. 49. Radiosensitivity of Species Least Sensitive Acute radiation dose, rads Micro- organisms Inverte- brates Plants Fish Amphibians Birds Mammals Humans 10 100 1,000 10,000 100,000 1,000,000 Most Sensitive
  39. 50. So...... <ul><li>Radiation in high doses can kill you </li></ul><ul><li>Radiation in moderate doses increases your cancer risk </li></ul><ul><li>Radiation at doses near or below background may : </li></ul><ul><ul><li>do nothing ??? </li></ul></ul><ul><ul><li>help you ??? </li></ul></ul><ul><ul><li>hinder you </li></ul></ul>
  40. 51. <ul><li>Should we sink ourselves in ‘the fear’ of technology? Just based on too little knowledge... of we have seen and heard? </li></ul><ul><li>Nuclear..... “clean technology”, how clean is clean enough? </li></ul><ul><li>“a little bit of knowledge is a dangerous thing.....” </li></ul>