1. Nuclear Energy Chapter 15

2. RADIOACTIVITY 15.1

3. Remember: Atoms are made of protons, neutrons, and electrons

4. Most atoms are stable They have a correct balance of protons and neutrons.

5. Other atoms are unstable They have an “off-balance” number of protons and neutrons.

6. radioactive Atoms whose nuclei are unstable are said to be

7. Eventually, these atoms breakdown.

8. The process is called “radioactivity”.

9. Radioactivity is not new. Radioactivity is not caused by man.

11. Radioactive decay in Earth’s interior heats the water for geysers

12. Radioactive decay in Earth’s interior heats the water for hot springs

13. Most of the radiation we encounter

14. Nuclear Technology - Pros Medical X-rays & Anti Cancer Treatments

15. Nuclear Technology - Pros Smoke detectors

16. Nuclear Technology - Pros Nuclear Energy

17. Nuclear Technology - Cons Nuclear Disaster

18. Nuclear Technology - Cons Nuclear Weapons

19. Nuclear Technology - Cons Nuclear Weapons

20. Nuclear Technology Demands Responsibility Safeguard nuclear material Safe, clean disposal Protect the environment for future generations

21. It’s up to you to make the decisions for the future!

22. Alpha, Beta, and Gamma Rays Chapter 15.2

23. Radioactive elements emit 3 different types of particles alpha beta gamma α β γ

24. α particles are positively charged β particles are negatively charged γ particles are neutral

25. http://www.youtube.com /watch?v=o-9yt7OAYmE http://www.youtube.com /watch?v=o-9yt7OAYmE

27. α particles are He nuclei

28. α particles are Helium nuclei

29. α particles Relatively low speed Eventually become HE Easy to shield against Can’t go through paper or clothing

30. β particles are electrons Neutrons “decay” Produce a proton and electron

31. β particles Faster than α particles Can penetrate paper and clothes Can penetrate and damage skin Can not penetrate denser material like aluminum

32. γ (gamma) rays are pure energy Gamma rays have more energy than visible light, UV light or X-rays

33. γ (gamma) rays Can easily penetrate and damage living tissue Can penetrate most materials – except lead

34. Let’s Compare Penetrating Power

35. γ (gamma) rays can help preserve food

36. Question Pretend you are given three radioactive rocks. One is an alpha emitter, one is a beta emitter and one is a gamma emitter and you know which is which.

37. Question You can throw one away. Of the other two, you must hold one in your hand and place one in your shirt pocket.

38. Question What can you do to minimize your exposure?

39. Answer Hold the alpha emitter in your hand. The skin on your hand will shield you.

40. Answer Put the beta emitter in your pocket. The combined thickness of you skin and clothing should shield you from the beta emissions.

41. Answer THROW AWAY THE GAMMA EMITTER! Because it would penetrate your body from any of these locations.

42. Answer In a perfect world…… Distance yourself from all the rocks!.

43. Environmental Radiation Chapter 15.3

44. Most radiation we encounter originates in nature Common rocks and minerals

45. Which family is exposed to more radiation? The one living in a Brick house? Or the one living in a wooden house?

46. More radiation exposure Naturally Occurring

47. Radon A Common Source of Radiation Radon

48. Heavy, inert gas Arises from uranium deposits

50. Is Radon Dangerous? According to the EPA, radon is the second leading cause of lung cancer. It is the leading cause of lung cancer in non-smokers.

51. How radon produces cancer

52. Levels vary with geology

53. You can check radon levels with a test kit

54. High levels require action

55. Here’s another interesting question….

56. Which is a greater source of radiation? Coal CombustionNuclear power

57. The Coal Industry! Global combustion of coal releases about 13,000 tons of radioactive thorium and uranium into the atmosphere. In addition to other polluting molecules released into the air.

58. Worldwide they generate about 10,000 tons of radioactive waste each year Almost all the waste is contained and not released into the atmosphere. Nuclear plants

59. RADIATION DAMAGE TO THE BODY

60. Remember Most of the radiation we receive is from natural sources and medical procedures

61. The human body itself is a source of radiation!

62. The radiation comes from the potassium we eat.

63. Our bodies contain about 200 mg K ≈ 180 mg other K isotopes ≈ 20 mg K 40 *radioactive * β emitter

64. Between every heartbeat… ≈ 5000 K 40 undergo spontaneous radioactive decay!

65. Radiation is everywhere!

66. Radiation can cause damage to cells

67. Radiation can cause serious burns and hair loss

68. Cells can repair radiation damage if it is not too severe

69. Radiation can damage DNA

70. Radiation can damage DNA resulting in cancer

71. High doses of radiation can damage DNA resulting hereditary birth defects

72. Common sense Avoid radiation when possible All radiation can not be avoided Most is simply part of nature

73. HALF- LIFE Chapter 15.5

74. Radioactive isotopes decay at different rates Measured in terms of a characteristic time “Half-life”

75. Half-life The time needed for half the radioactive atoms of a radioactive material to decay

76. Radium (Ra 226 ) Half life = 1620 years

77. Half lives are constant Not affected by external conditions Some are less than 1/1,000,000 sec Some are much longer

79. Uranium - 238 Half life = 4.5 billion years In 4.5 billion years, half the uranium on earth will be lead!

80. ISOTOPIC DATING

81. Cosmic rays constantly bombard the atmosphere Radioactive C 14 is ultimately produced.

82. 14 C 14 CO 2 O2O2 O2O2 Carbon dioxide takes C 14 into the food cycle

83. Animals eat the plants so all animals have some C 14 in them

85. …..so all living things on Earth contain some C 14

86. After death C 12 remains constant The amount of C 14 decreases

87. Scientists can use this information to determine the age of carbon containing artifacts Carbon-14 Dating

88. C-14 dating can only be used on something that was previously alive

89. Scientists use the elements lead (Pb) and Uranium (U) to date rocks samples.

91. Meteor crater, Arizona Meteor Crater Video -- Killer Asteroid -- National Geographic