Do Now (silently, on a small paper)

1. Do Now (silently, on a small paper) What is the difference between biogenic and thermogenic natural gas?

2. Reminders: • Fossil Fuel homework is due on Monday (anyone want flashcards?) • Renewable energy homework is due on Wednesday (no really, flashcards?) • Flat Lorax project—any questions?

3. Nuclear Powergo to survey question

4. Radioactivity vs. Radiation Ionizing Radiation Radioactive Atom Alpha Particle Neutron Particle Beta Particle Gamma Ray

5. Average Annual Dose Cosmic 28 mrem Terrestrial 28 mrem Radon 200 mrem Internal 40 mrem Medical X-Rays 40 mrem Nuclear Medicine 14 mrem Consumer Products 10 mrem Natural Sources Man-Made Sources Other 3 mrem

6. Nuclear Power • Benefits: free of the air pollution caused by fossil fuel combustion • Costs: potential to be misused (weapons, etc), public safety, waste disposal • Developed in the 1950s, nuclear power is widely used worldwide

7. Nuclear Energy • Nuclear energy is the energy that holds together protons and neutrons within the nucleus of an atom • We can convert this energy into thermal energy, which can be used to generate electricity

8. Video!!!

9. Nuclear Fission • Nuclear fission is the process of splitting apart atomic nuclei • this is the process used in power plants • Uranium (U) or plutonium (Pu) are bombarded with neutrons, which break apart the nuclei

10. Nuclear Fission cont. • If not controlled, this reaction can become a chain reaction and release enormous amounts of energy • This is how a nuclear bomb is made • In a power plant, the reaction is carefully controlled

11. Uranium • Generally considered a nonrenewable resource because it is in finite supply • Used for nuclear power because it is radioactive • Radioactive isotopes emit subatomic particles and radiation as they decay into lighter radioisotopes, until they become stable isotopes • Uranium-235 decays into lead-207

12. Uranium cont. • Most uranium in nature occurs as uranium-238 • This isotope does not emit enough neutrons during fission to maintain a chain reaction • We use uranium-235 to generate nuclear power • The uranium is enriched to become more concentrated as uranium-235 • It is then incorporated into large metallic tubes called fuel rods to be used in nuclear reactors

13. Nuclear Reactors

14. Nuclear Reactors • The reactor corecontains the uranium fuel • It is inside a large steel container called the containment building • The fuel rods inside the reactor core are made of uranium in long metal tubes • Thousands of fuel rods make up the core • They are immersed in water, which slows the neutrons

15. Nuclear Reactors • Control rods are made of material that absorbs neutrons • They are placed in the reactor core with the fuels rods to regulate the reaction • Water inside of the primary loopis heated through the fission reaction • This water boils water in the secondary loop, creating steam

16. Nuclear Reactors • The steam drives turbines, which generate electricity • Cold water from a cooling tower circulates in a cooling loop, which condenses the steam from the secondary loop

18. Half-Life:The amount of time for the radiation to decrease by one-half. Half-Life of Licorice 1/1 Half-Life of m & m’s 1/4 1/2 1/8 etc. Half-Life of Paper

19. Nuclear Waste • As the fuel rods are used, the uranium slowly decays • About once a year, the old rods are removed • They are stored in water-filled pools

20. Nuclear Waste • The long term goal is to transport spent fuel rods to an underground facility for long-term storage, but no such facilities currently exist—YUCCA MOUNTAIN • The wastes need to be stored 10,000-240,000 years until their radioactivity falls to safe levels

22. Proposed Methods for Waste Disposal • Bury it deep underground—favored strategy • Shoot it into space or into the sun—costs are high and potential accidents during launch • Bury it under the Antarctic ice sheet—long term stability not known; prohibited by international law

23. Proposed Methods for Waste Disposal • Dump it into descending subduction zones of the ocean—might eventually be spread somewhere else • Bury in ocean floor—containers will eventually erode • Change it into harmless isotopes—currently we do not have the technology to do this

24. Why isn’t nuclear power more popular? • Nuclear power was developed in the 1950s for 3 reasons: energy was promised at lower cost, taxpayers were promised no cost overruns, and Congress limited liability for the companies • Researchers projected that there would be at least 1800 plants, supplying 21% of the world’s energy

25. Why isn’t nuclear power more popular? • In 2005, there are 443 commercial nuclear reactors in 30 countries, producing 6% of the world’s energy • No new nuclear power plants have been built in the US since 1978—they generate 20% of US electricity

26. Indian Point, NY

28. Three Mile Island • On March 28, 1979, a nuclear power plant in Pennsylvania experienced failures in the non-nuclear part of the plant • The nuclear fuel began to overheat and started to meltdown • The accident led to no major injuries but caused nuclear regulations to be tightened

29. The Chernobyl Accident • On April 26, 1986, a series of explosions in one of the reactors in a nuclear power plant in northern Ukraine blew the roof off a reactor building • The reactor partially melted down and caused graphite fires for 10 days

30. The Chernobyl Accident • The accident was caused by a combination of human error and poor reactor design • The reactors used in the United States have a much safer design • Several of the old type of reactors are still in use around Eastern Europe

31. The Chernobyl Accident • Huge radioactive clouds spread of Ukraine, Belarus, and part of Europe • By 2005, 56 people had died from radiation poisoning, and 4000 more people will eventually die from cancer • These estimate may be very low • 350,000 people had to abandon their homes because of radioactive fallout

32. The Chernobyl Accident • Many people in the area can still not drink the water or eat locally produced fruits, vegetables, fish, meat, or milk • Mothers cannot breastfeed

33. Japan • On March 11 2011, a 9.0 earthquake hit Japan, causing a subsequent tsunami • The Fukushima Nuclear Power Facility was severely damaged, disabling the reactor cooling systems and causing nuclear radiation leaks • The plant consists of 6 nuclear reactors, one of the largest stations in the world

35. Fukushima accident cont. • Radiation releases caused large evacuations, concern about food and water supplies, and treatment of nuclear workers • Trace amounts of radiation has been found around the world (New York State, Alaska, California, Canada, Austria) • Large amounts of radiation has been released into the Pacific Ocean

36. Fukushima accident cont. • Overall, the incidents in Japan were rated a 7 on the International Nuclear Event Scale (the highest rating possible) • As of August, the plant is still leaking low levels of radiation • Radiation has been found in the nation’s food supply up to 200 miles from the plant

39. http://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.htmlhttp://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html

40. Four Ways Radioactive Material Can Enter the Body Inhalation • Breathing • Smoking Wound or Cut Ingestion • Eating • Drinking • Chewing Absorbtion

41. Cells are undamaged. Cells are damaged, repair damage, & operate normally. Cells are damaged, repair damage, & operate abnormally Cells are damaged & die. Biological Effects of Radiation

42. Basic Protective Measures Time Distance Shielding

43. Nuclear Power and US security • After the terrorist attacks in the United States, people are very concerned about attacks on power plants or people stealing the radioactive material • Several studies have pointed to a lack of security at nuclear plants

44. Advantages of Nuclear Power • Large fuel supply • Low environmental impact (without accidents) • Emits 1/6 as much CO2 as coal • Moderate land and water disruption • Low risk of accidents

45. Disadvantages of Nuclear Power • Cannot compete economically without government subsidies • Low net energy yield • High environmental impacts if accidents occur • No long-term solution to waste storage • Subject to terrorist attacks or use for weapons