APES 1/26 Please get a laptop to take notes on our final two presentations! Hydroelectric Power A river is dammed so water flows downhill and spins a turbine The kinetic energy from the turbine is converted to electricity by a generator Hydroelectric Power Pros: Non-depletable resource Low cost to run Flood control Cons: High construction costs Damage to river ecosystems Siltation- sediments build up on bottom of reservoir (to part) and have to be dredged out Nuclear Energy Our energy solution, or our greatest danger? Source of Nuclear Energy Isotopes (atoms with more/less neutrons than normal) can be radioactive Nuclei spontaneously break down, release energy Nuclear isotopes are non-renewable Source of Nuclear Radiation Most common fuel is Uranium-235 Mined from earth, enriched to 3%, purified, placed in fuel rod Source of Nuclear Energy The disintegration of an isotopes nucleus releases radiation Alpha radiation consists of neutrons and protons, and can damage cells in high conc. Beta radiation consists of electrons, and causes minor cell damage Gamma radiation is used in X rays, light, and radio waves, and causes minor biological damage Source of Nuclear Energy When neutrons exit the disintegrating atom, they strike the nuclei of other atoms, creating nuclear fission The struck nuclei also split, giving off more neutrons and causing a nuclear chain reaction Isotopes of uranium and plutonium are most commonly used Uranium 235 is an unstable isotope of Uranium 238; Plutonium is an unstable isotope of Plutonium 244 Nuclear Reactors Nuclear reactors allow for controlled fission chain reactions Contain fuel rods of uranium or plutonium Contain control rods of stable atoms to absorb neutrons Fuel rods are surrounded by a reactor containing water to absorb energy Nuclear Reactors Nuclear fission heats the water in the reactor, creating steam Steam operates a turbine that generates electricity Who Uses Nuclear Power? As of today, there are 440 operational nuclear power plants around the world and 65 under construction The U.S. has over 100 reactors that make up 30% of world nuclear energy production 6 more being built Who Uses Nuclear Power? Pros and Efficiency Nuclear is cheaper and by far more efficiency than fossil fuels Ample supply Does not create CO2, NOx, SOx Drawbacks of Nuclear Energy 1.Thermal Pollution: release of hot water used to cool control rods into nearby waterways can lower oxygen levels Drawbacks of Nuclear Energy 2. Radioactive waste: when fuel rods can no longer produce enough heat to be useful they become waste Placed in multi-walled metal containers at the plant High level radioactive waste has nowhere to go! Yucca Mtn, Nevada plans are on hold Drawbacks of Nuclear Energy 3. Ground Water Pollution: inadequate storage can allow leakage of nuclear waste into soil and nearby bodies of water Hanford, WA- built in 1943 as part of Manhattan Project. 1 st Plutonium plant; made material for bomb dropped on Nagasaki, Japan. Nuclear waste has been leaking into the Columbia River since the 1940s; a 60 billion dollar clean up effort is underway! Dangers of Nuclear Energy 4. Accidents at Nuclear Power Plants can release radioactive particles into the air Radioactive particles damage living tissue Can cause cancer (uncontrolled cell division) in existing cells Can cause birth defects by mutating the DNA in sperm and egg cells Can cause instant death in high enough doses Dangers of Nuclear Energy 5. Uranium and Plutonium isotopes can be used to make atomic bombs and smaller dirty bombs i.e. bombs dropped on Hiroshima and Nagasaki by U.S. in World War II New Reactor Designs- less likely to meltdown Advanced light-water reactors Pebble-bed modular reactors Nuclear Accident Jigsaw In groups of 3, split up the three online articles about nuclear accidents Summarize for your article in your lab book: What happened? Who was responsible? What were the effects on the environment? People nearby? When/where did it happen? Current status of the Power Plant?