Unit 5: Nuclear Energy

1. Unit 5: Nuclear Energy Radioactivity in Your Home

2. Nuclear Reactions: Change the composition of an atom’s nucleus. 2. The strong nuclear forceholds the nucleus together. 3. Most atoms are stable (equal number of p &n). These are the smaller atoms which are NOT radioactive.

3. 4. Unstable nuclei have more neutrons than protons. These isotopes areradioactive. 5. As the elements become larger they become more unstable. 6. All elements have at least 1 radioactive isotope. All the isotopes of those elements with atomic numbers greater than 83 are radioactive. 7. The larger nuclei are radioactive because they have more neutrons than protons.

4. Unstable Nucleus

5. 8. Characteristics of Subatomic Particles and Rays: +1 p+or 0 n0 or Heavy clothing/Al foil -1 +2 paper Several centimeters of lead/concrete 0

6. Nuclear Radiation Penetrating Power

7. Nuclear Radiation Penetrating Power

10. 9. Spontaneous Emission of Radiation: A. Unstable nuclei will spontaneouslyemit 3 types of natural radiation, this is also called radioactive decay. B. When an atom emits 1 kind of radiation the original nucleus decomposesor decays to form a new nucleus and releases radiation. This is written in a nuclearequation.

11. Alpha & Beta Decay

12. 10. 3 Types of Spontaneous Radiation: A. Alpha Decay – spontaneous emission of an alpha particle from the nucleus. B. Beta Decay – spontaneous emission of beta particle from the nucleus C. Gamma Decay – spontaneous emission of gamma rays from the nucleus

13. Uranium Radioactive Decay Series

14. How Radon Gas Enters your House

15. Ways to Remove Radon Gas from Your Home

16. External view of a Radon mitigation system from a home basement. • Below is a view of the fan inside which runs 24 hours a day pulling air from under the basement floor.

17. Testing Methods for Radon

18. U.S. Radon Zones

19. 11. Transmutation: Changing into a new element by either decay or bombardment. Nuclear Bombardment Reactions A. Process in which a new element is formed by bombarding a nucleus with small energetic particles. B. The energetic particle, a projectile, hits the target nucleus and forms an unstable compound nucleus, which is short-lived. C. This nucleus can emit an ejected particleto stabilize itself. D. This is the process used in particleacceleratorswhere artificial isotopes and transuranium (those above U) elements have been produced.

20. Particle Accelerator in Switzerland with a 16.7 mile circumference 60 Minutes Special

21. Nuclear Bombardment Reaction target nucleus ejected particle new isotope (element) projectile

22. 12. Nuclear Fission • Process by which a heavy nucleus splits into two smaller nuclei. • Most fission reactions are induced. • The energy yield for fission reactions are very high. • Fission reactions are the source of energy used to generate electricity innuclearpowerplants. E.U-235 & Pu-239 are the radioisotopes used in reactors.

23. Fission Is Similar To Pool

24. Nuclear Fission Reaction temporary unstable nuclei start additional fission reactions Nuclear fuel projectile – starts the chain reaction Splits in 2

25. F. In fission reactions, the product nuclei have far too many neutrons, and are intensely radioactive. This is considered radioactivewaste. G. The releasedneutronscan cause another reaction as long as sufficient U-235 remains. H. This is called a chainreaction. I. The smallest amount (minimum volume) of fissionable material needed to sustain a chain reaction is called the criticalmass.

26. Nuclear Chain Reaction Fuel: U-235 or Pu-239 Critical mass for U is 110 lbs

27. 16. Nuclear Fusion: A. This is a thermonuclear reaction - requires hightemperatures. B. Occurs when two small nuclei fuse, or join, to form larger, more stable nuclei. C. Releases a large amount of energy. D. Process that occurs on the sun and in a hydrogen bomb. E. If fusion reactions are going to be practical, they need to produce more energy than they require to get started. F. In a fusion reaction, the starting materials are in a form of plasma. G. The biggest problem is obtaining the high temperatures necessary for a fusion reaction to occur. H. A“magnetic bottle” could be used to hold plasma at these high temperatures.

28. Krypton-92 Fission 3 neutrons Nuclear Power Plants/A-bomb neutron U-235 Energy Barium-141 Fusion The Sun/ H-bomb

29. The first Atomic Bomb is detonated at Trinity Site near Alamogordo, New Mexico on July 16, 1945. shows the result of the blast. A wooden house built 1km away from the test site… A Monument stands at the test site today.

30. “Little Boy”Uranium fission bombdropped on Hiroshima, Japan by the “Enola Gay” flown by Colonel Paul Tibbets

31. Hiroshima - August 6, 1945

32. Hiroshima 1945 & Today

33. Nagasaki - August 9, 1945 “Fat Man” – Plutonium Fuel

35. U.S. Nuclear Testing • Large craters pockmark Frenchman Flats, Nevada, a former test site for U.S. nuclear weapons. The US conducted more than 1050 tests here and in Alaska, Colorado, Mississippi, New Mexico between 1945 and 1992. • The Soviet Union, UK, France, China, India and Pakistan had a similar total number of tests over the same time period.

37. Fusion Bombs • The first thermonuclear weapon (hydrogen bomb), code-named Mike, was detonated at Enewetak atoll in the Marshall Islands, Nov. 1, 1952. The photograph was taken at an altitude of 12,000 feet over 50 miles from the detonation site.

38. Video of all the Nuclear Explosions on the Planet from 1945-1998

39. Only 6 countries have detonated a hydrogen bomb – US, UK, Soviet Union, France, China and India. • To obtain temperatures in the millions of degrees Celsius a fission reaction is set off first to start the fusion reaction.

40. Nuclear Reactors • There are currently 111 commercial nuclear power plants in the U.S. They provide 20% of our country’s electricity, but 80%of the electricity used in southeastern PA.

41. B. There are 530 nuclear reactors in 30 nations around the world that provide 1/6 of the world’s electricity. To produce electricity you need to turn a turbine. This can be accomplished by wind or water, must most commonly by steam. The only difference between a nuclear power plant and a conventional fossil fuel plant is the method used to produce boiling water.

42. 14. Parts of a Nuclear Reactor • Fuel Rods: Composed of 97% U-238 and 3% U-235 (the fissionable isotope). Chalk- sized pellets are arranged in long steel cylinders in the reactor core. When the fuel has given up most of its energy it is called spent. It will be reloaded every 1 to 3 years. There can be 10,000,000 pellets in 1 plant. B. Control Rods control the rate of a nuclear reaction. Without them the reaction would occur too fastfor it to be effective. C. Moderator is usually heavy water (D2O). Without sufficient cooling of the core a meltdown could occur. This water also shields workers.

43. Nuclear Power Plant Control Room

44. View of fuel rods and control rods immersed in “heavy water.”

45. Fuel Rods Filled With Pellets Are Grouped Into Fuel Assemblies

47. 14. Parts of a Nuclear Reactor con’t. D. Generator produces electricity by turning a steam turbine from the boiling water. E. Cooling System: Water from outside is used to cool the steam (it does not come into contact with the cooling water in the core). Excess steam rises up in the cooling tower, condenses and falls back. Cooling Towers Limerick, PA

48. Nuclear Power Plant Turbine and Generator Steam Spinning turbine blades and generator Boiling water

49. Nuclear Power Plant Diagram

50. Pressurized-Water Reactor