1 / 28

Nuclear Power

Nuclear Power. Robert Mingey Catherine Perego. Nuclear Power. Nuclear power accounts for 16% of the world’s energy Although it is not a renewable resource, it is an important source of energy because it has no carbon dioxide emissions

gay
Download Presentation

Nuclear Power

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Nuclear Power Robert Mingey Catherine Perego

  2. Nuclear Power • Nuclear power accounts for 16% of the world’s energy • Although it is not a renewable resource, it is an important source of energy because it has no carbon dioxide emissions • Because of this, it is an important bridge between the coal and gas energy we use today and the completely clean, renewable energy we are working towards

  3. Timeline of Nuclear History • 1898 —Marie Curie (France), a two-time Nobel Prize winner in Chemistry and Physics, discovered the radioactive elements radium and polonium.   • 1899 —Ernest Rutherford (Canada) discovered two kinds of rays emitting from radium. He called the first rays, alpha rays; and the more penetrating rays, beta rays.  • 1900 —Frederick Soddy (England) observed spontaneous disintegration of radioactive elements into variants. • 1919 —Rutherford (United Kingdom) bombarded nitrogen gas with alpha.  The transmutation of nitrogen into oxygen was the first artificially induced nuclear reaction.

  4. Timeline (cont’d) • 1934—Enrico Fermi (U.S. immigrant from Italy) irradiated uranium with neutrons. He had split the atom, thus achieving the world's first nuclear fission. • 1940—A new element (atomic number 94), was found and named plutonium. American physicists confirmed that plutonium was fissionable, thus usable for a bomb. • 1942—The first self-sustaining, controlled nuclear chain reaction led by Enrico Fermi (U.S. immigrant from Italy) and other scientists at the University of Chicago. • 1951—An experimental breeder reactor (EBR Reactor I, or EBR-I) in Idaho produced the first usable electric power from the atom, lighting four light bulbs. • 1953 —The first Boiling Reactor Experiment reactor was built in Idaho.

  5. Timeline (cont’d) • 1974—Nuclear Regulatory Commission (NRC) was created to regulate the nuclear industry. • 1979—The accident at the Three Mile Island Unit 2 (TMI-2) nuclear power plant near Middletown, Pennsylvania, on March 28, 1979, was the most serious in the U.S. nuclear power plant industry's operating history. • 1980s—For the first time, nuclear energy generated more electricity than oil in the United States. It surpassed hydropower as the second-largest source of electricity in the US, after coal. • 1986—The world's worst nuclear power accident happened at the Chernobyl plant in the former USSR (now Ukraine). • 1987—Congress selected Yucca Mountain in Nevada for study as the first high-level nuclear waste repository site. • 2006—A survey, in the United States, found a high level of support for nuclear energy among the public; with 68% favoring nuclear energy as one way to generate electricity and 49% stating a need to build more nuclear plants. • 2010—President Obama discusses the importance of nuclear power at the State of the Union address.

  6. What is a radioactive element? • A radioactive element is any isotope of an element that is not stable. This is due to an imbalance of charges in the nucleus (either too many or too few protons or neutrons). • A radioactive element emits energy from the nucleus to get back down to a more stable energy. This is called radioactive decay. • There are 5 types of radioactive decay (α-particles, β-particles, γ-rays, positron emission, and electron capture) • The radioactive elements decay until they reach a more stable nucleus. The time it takes for half of the sample of the radioactive isotope to decay is called a half-life. If an isotope has a shorter half-life, it is more reactive, thus emitting particles into the atmosphere more frequently. This poses a greater threat to the people around it.

  7. Nuclear Fission • Nuclear fission is the process of splitting atoms. Let's discuss those reactions. • In each of the previous reactions, 1 neutron splits the atom. When the atom is split, 1 additional neutron is released. This is how a chain reaction works. If more U-235 is present, those 2 neutrons can cause 2 more atoms to split. Each of those atoms releases 1 more neutron bringing the total neutrons to 4. Those 4 neutrons can strike 4 more U-235 atoms, releasing even more neutrons. The chain reaction will continue until all the U-235 fuel is spent. This is roughly what happens in an atomic bomb. It is called a runaway nuclear reaction. • In a nuclear power plant, this reaction is controlled using control rods filled with boron and cadmium, two elements that absorb neutrons. They are lowered into the reaction as necessary to maintain a high enough level of neutrons to continue the chain reaction without having them get out of control, causing a runaway nuclear reaction.

  8. Nuclear Fuel Cycle • Uranium is collected from mines and mills • It is then converted into uranium hexafluoride—UF₆, which is highly toxic • This compound makes it simpler to separate the uranium isotopes to extract U-235, which is easily fissionable. The concentration of U-235 goes from .4% to 3-5% • This is then transformed into uranium oxide (UO₂), which is used in the fuel rods in the power reactors

  9. How does Nuclear Power Work? • The splitting of the atoms, nuclear fission, is a high energy exothermic process (gives off a lot of heat). This heat is then used to boil water to create steam, which then spins the turbines, which then powers the generator to produce electricity.

  10. Nuclear Reactor Designs • There are two main types of nuclear reactors, boiling water reactors (BWR) and pressurized water reactors.

  11. PWR • PWRs keep water under pressure so that it heats but does not boil. Water from the reactor and the water that is turned into steam are in separate pipes and never mix.

  12. BWR In BWRs, the water heated by fission actually boils and turns into steam to turn the generator. The rest of the generation process is the same in both types of plants.

  13. Spent Fuel • Once the fuel does not contain a high enough concentration of U-235 to sustain a fission reaction, the fuel rods are replaced. These are called spent fuel. • The spent fuel is still very radioactive, which causes an issue with how to dispose of it. • For the first few years after a fuel rod is spent, it is submerged in a deep pool because the water acts as a barrier to the radiation. Afterwards, it is transferred into special casks made of concrete.

  14. Environmental Issues

  15. Air Quality • Direct nuclear power generation does not emit C02, Sulfur Dioxide, or Nitrogen Oxides. • Wells-to-Wheels approach reveals some greenhouse gas emission.

  16. Water Pollution • Nuclear power plants use large quantities of water for steam production and for cooling. • Heavy metal and salts can be found in plant water. • Some pollution results from mining.

  17. Waste Disposal • 2000 Metric tons of waste created per year in US. • 25-30 Tonnes per plant per year • Waste stored on site • Can leak-cause environmental damage

  18. Yucca Mountain • Located in Nevada, 80 miles NE of Las Vegas • Set to be national store of radioactive waste • Set to open in 1997 but legal challenges have delayed it to 2020 or beyond

  19. Sustainablity • Proven Reserves: 3-4 million tonnes Uranium • Equivalent of 50 years of fuel • Fast breeder reactors might increase efficiency. • Uranium is non-renewable

  20. Social Consequences

  21. Social Problems • 1950’s: Public Expected new Nuclear Age • 80’s/90’s: Two accidents change public opinion • Three Mile Island • Chernobyl • 2010: President Obama promises to increase public utilization of nuclear power.

  22. Three Mile Island • Occurred March 28, 1979 • TMI-2 reactor melted down • No deaths directly associated with incident. • Estimates are that the average dose to about 2 million people in the area was only about 1 millirem.

  23. Chernobyl • Occurred April 26, 1986 • Reactor meltdown leaks massive amounts of radiation • Over 300,000 people evacuated from surrounding area • 30 died directly while 4000 more died due to cancer

  24. Other Issues • Fear of terrorist attack • Nuclear proliferation

  25. Economics • Nuclear plants have high capital costs compared to other types of plants • Nuclear: $0.067 per kWh • Coal: $0.042 per kWh • Carbon taxes and rising fuel prices might shift this balance

More Related