Nuclear power standard

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  • 1. Standard Nuclear Power Unit 7
  • 2. Know and describe the following terms:
    • Element – a substance that cannot be divided into simpler substances
  • 3. Uranium – 92 protons Uranium 235 = atomic mass (protons and neutrons)
  • 4.  
  • 5. Know and describe the following terms:
    • Periodic table – a chart that organizes elements based upon electron arrangements and their properties
    • Nucleus – small, positively charged core of an atom. Contains protons (positive particles) and neutrons (neutral particles).
    • Electrons – are tiny in comparison with protons and neutrons, have a negative charge.
    • Atomic number – the number of protons in an atom’s nucleus (the number found above the element symbol in the periodic table).
  • 6.
    • Mass number – the number of nucleons (protons and neutrons) in the nucleus of the atom
    • Isotopes – atoms of the same element that differ in the number of neutrons they contain – they are named by their mass numbers.
      • U-235 – Mass number = _____________________
      • U-238 – Mass number = _____________________
  • 7. Memorize the elements for these symbols:
    • H = ___________________
    • He = __________________
    • C = ___________________
    • N = ___________________
    • O = ___________________
    • Na = __________________
    • S = ___________________
    • Cl= ________________
    • K = _______________
    • Ca = _______________
    • Ni =_______________
    • I = ________________
    • Pb = _______________
    • U = ________________
  • 8. What is radioactivity?
    • When nuclei are unstable, they will emit radiation to try to get stable. Thus, they are radioactive.
  • 9. How do atoms try to fix their instability?
    • Through decaying.
  • 10. What are the three most common ways nuclei decay?
    • - (alpha particles) – are the nuclei of fast-moving helium atoms. They only move a few inches in the air and cannot penetrate through paper or dead skin.
    • - particle emissions (beta particles) – are fast-moving electrons. They can move several feet within the air and cannot penetrate through plastic, glass or aluminum.
  • 11.
    • - ray emissions (gamma rays) – are electromagnetic radiation of very high frequencies. Have an unknown range and can penetrate long distances through air or several centimeters through lead. Cannot penetrate through concrete, water or thick lead.
  • 12. What is a half-life and what does it mean?
    • A half-life refers to the time it takes half the atoms of a particular radioactive substance to disintegrate to another form that is more stable.
      • After 1 year, 50% of a sample is not longer radioactive, therefore, the half-life of the material is 1 year.
      • After 2 years, one half of the remaining radioactive half will no longer be radioactive thus in total, you will have 75% of the original material that is no longer radioactive.
      • After 3 years 87.5% of the material is no longer radioactive.
    • The half-life serves as a “fingerprint” for identifying materials. (Scientists use this concept when determining the age of rocks on earth – this is called radiometric dating).
  • 13.  
  • 14. Is the nuclear fuel cycle really a cycle? Why?
    • No, the nuclear fuel cycle is not really a cycle because nothing is fed back to the beginning of the chain.
  • 15. What is nuclear fission vs. nuclear fusion?
    • Nuclear fission is when the nucleus of an atom is separated to form two atoms.
    • Nuclear fusion is when two atoms are combined to form one.
  • 16.  
  • 17.  
  • 18. Describe each step of the cycle:
    • 1. Exploration and Mining – Uranium must be obtained through open pit or underground mining.
    • 2. Milling – Uranium ore is removed from the rock by being crushed, sampled and concentrated. This material is now called yellowcake.
  • 19.  
  • 20. Describe each step of the cycle:
    • 3. Conversion and Enrichment – Typical nuclear reactors use enriched U-235 for fuel. Naturally, only 0.7% of uranium is U-235. For nuclear fuel rods, this must be increased to 3-4% (for bomb-grade material it must be at least 85%).
      • Gaseous diffusion – is a common enrichment technique. Yellowcake is converted to a gas and passed through hundreds of porous barriers. The type of material allows U-235 to diffuse faster than U-238.
    • 4. Fuel Fabrication – The gas is converted to a uranium powder and made into pellets that are then installed in fuel rods.
  • 21. A typical pellet of uranium weighs about 7 grams (0.24 ounces). It can generate as much energy as 3.5 barrels of oil, 17,000 cubic feet of natural gas, or 1,780 pounds of coal.
  • 22. Describe each step of the cycle:
    • 5. Fuel Burning – These fuel rods are inserted into the reactor core. These must be replaced (once every 3 years) because they will build up radioactive wastes.
    • 6. Spent Fuel Reprocessing –Currently these fuel rods are stored under water for several months to allow the decay of short-lived radioactive wastes (but there are still long-lived radioactive wastes remaining!). So fuel rods are dissolved in acid and the radioactive wastes are separated out and prepared for long-term storage.
  • 23. Describe each step of the cycle:
    • 7. Waste Storage – Wastes will remain radioactive for thousands of years thus they must be continuously monitored. There are 5 categories of nuclear wastes.
  • 24.  
  • 25.  
  • 26. What is one main way in which to dispose of nuclear wastes? Why?
    • Burial, because it must be kept away from people and the environment for long periods of time.
  • 27. What is WIPP? What is its significance?
    • The Waste Isolation Pilot Plant found in New Mexico is the designated site for permanent disposal of radioactive waste.
  • 28. What occurs at Yucca Mountain in Nevada?
    • Yucca Mountain is the disposal site for spent fuel and high-level waste. It is necessary for this location to hold the wastes for the next 10,000 years.
  • 29.  
  • 30.  
  • 31. What is the difference in how nuclear power plants operate versus how other plants operate to produce electricity?
    • The only way power plants operate differently is in how energy is created to turn the turbine that connects to the generator. In nuclear power plants, a nuclear reaction produces heat which produces steam to drive the turbines.
  • 32.  
  • 33. Teacher Tube Video : How a Nuclear Power Plant Works
  • 34. How does a nuclear power plant actually work?
    • One neutron hits one nucleus; it causes that nucleus to fission (separate) into two parts.
    • Other neutrons are released, causing additional nuclei to fission so that we now have (at least) four parts.
    • This process continues until we have more and more nuclei fissioning.
      • In a bomb, this would continue uncontrolled. In a nuclear power plant, they use control rods that absorb neutrons and stop the reaction from continuing uncontrolled. (They simply drop them down into the reaction and it begins to cool down).
    • The continuous splitting of nuclei produces heat. This heat is made into steam to turn a turbine.
  • 35.  
  • 36.
    • Teachertube video on how nuclear power plants operate
  • 37. What is currently happening to US nuclear power?
    • It is currently at a standstill.
  • 38. Summarize figure 10.31 (the pros and cons of nuclear power) into your notes. Advantages Disadvantages Energy Source
    • Creates a lot of energy
    • Consumes uranium and thorium nuclear fuels; thus, if used a lot, we could deplete our nuclear reserves.
    Operation
    • We know how to build and operate fission reactors
    • Process creates long-lived nuclear wastes.
    • Difficult to store wastes safely
    Dependency
    • Using nuclear power will decrease our country’s dependence on petroleum
    • We may have to rely on foreign sources of uranium and thorium if we use it too much
    Pollution
    • No pollutants created, no greenhouse gases created
    • Thermal pollution requires expensive cooling towers and ponds.
    • Safely dispose of radioactive waste
  • 39.  
  • 40. What is radiation?
    • Radiation is any “thing” that is sent out from an object (sun, light bulb, heater) that is in the form of particles or waves. Radiation interacts with whatever it travels through.
  • 41. Radiation can be either an external or internal hazard. Describe these.
    • External hazard – when the radiation is able to penetrate deeply into wood, water or our bodies.
    • Internal hazard – when radiation enters into a substance (through ingestion or inhalation) and causes damage.
  • 42. Describe how cancer works.
    • Cancer results when a mutation occurs which causes cells to lose the ability to properly regulate their growth, thus, they typically grow out of control. Thus, increased exposure to radiation could potentially increase rates of cancer because they will cause mutations that affect our cells.
  • 43.