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Nuclear energy by_arman


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this powerpoint presentation gives you all the details on Nuclear Energy

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Nuclear energy by_arman

  1. 1. • Nuclear Fission = • Nuclear Fusion =
  2. 2. Nuclear Fission
  3. 3. Nuclear Fusion
  4. 4. Nuclear Change Nuclear Fission • Bombs & power plants • Big, unstable isotopes are struck by neutrons, which splits the isotope’s nuclei Nuclear Fusion • Sun and stars, some weapons • 2 small (light) isotopes are forced together – H + H = He • More neutrons ―shoot out‖ to strike nearby isotopes, causing a chain reaction. • Need temps > 100,000,000ºC • Releases more E than fission
  5. 5. When people think about nuclear power they think about… 1. Effects of radiation 2. Nuclear disasters 3. Nuclear waste disposal
  6. 6. What is Radiation? • Radiation = particles given off by unstable atoms. • 3 Types: – Alpha (α) • Travels few inches • Blocked by paper (skin) – Beta (β) • Travels few feet • Blocked by aluminum, glass – Gamma (γ) • Travels far • Blocked by lead (steel & concrete).
  7. 7. EVR3019/Nuclear_Waste.ppt
  8. 8. Background Radiation • The amount of radiation we are exposed to daily from the environment • Average = 360 millirem/year
  9. 9. Effects of Radiation • Genetic damages: from mutations that alter genes • defects can become apparent in the next generation • Somatic damages: to tissue, such as burns, miscarriages & cancers t
  10. 10. History - Continued People began to see the potential for using nuclear energy for peaceful purposes. The world’s first electricity generating reactor was constructed in the US in 1951. In December 1953, President Dwight D. Eisenhower, in his ―Atoms for Peace‖ speech said, ―Nuclear reactors will produce electricity so cheaply that it will not be necessary to meter it. The user will pay an annual fee and use as much electricity as they want. Atoms will provide a safe, clean, and dependable source of electricity.‖ The Russians built their first plant in 1954.
  11. 11. Half-Life = time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a stable isotope Uranium 235 Plutonium 239 Half-time 710 million yrs 24.000 yrs emitted alpha, gamma alpha, gamma t
  12. 12. Renewable or NonRenewable?
  13. 13. Power plants use heat to produce electricity. Nuclear energy produces electricity from heat through a process called fission. Nuclear power plants use the heat produced by fission of certain atoms. Nuclear fission nucleus of atom is split into parts, produces free neutrons and energy
  14. 14. 92 U Uranium 2. Uranium-235 Fission of U-235 splits nucleus in two pieces The fuel used in nuclear power plants is an isotope of the radioactive element uranium releases neutrons for chain reaction Nuclear fission chain reaction  releases energy in the form of heat.
  15. 15. A slow moving neutron induces fission in Uranium 235
  16. 16. Uranium Mining • Uranium is usually mined similarly to other heavy metals—under ground or in open pits—but other methods can also be used. After the uranium is mined it is milled near the excavation site using leaching processes. The mining process explained here is a combination of two of major mines in Australia.
  17. 17. Mining risk • “…uranium mining, a polluting activity that devastates large areas. Uranium ore sometimes contains as little as 500 grams recoverable uranium per 1000 kilograms of earth. So, enormous amounts of rock have to be dug up, crushed and chemically processed to extract the uranium. The remaining wastes, which still contain large amounts of radioactivity, remain at the mines. These "tailings" are often stored in a very poor condition, resulting in the contamination of surface- and groundwater.‖
  18. 18. Mining • Uranium ore is usually located aerially; core samples are then drilled and analyzed by geologists. The uranium ore is extracted by means of drilling and blasting. Mines can be in either open pits or underground. Uranium concentrations are a small percentage of the rock that is mined, so tons of tailings waste are generated by the mining process.
  19. 19. Milling & Leaching •The ore is first crushed into smaller bits, then it is sent through a ball mill where it is crushed into a fine powder. The fine ore is mixed with water, thickened, and then put into leaching tanks where 90% of the uranium ore is leached out with sulfuric acid. Next the uranium ore is separated from the depleted ore in a multistage washing system. The depleted ore is then neutralized with lime and put into a tailings repository.
  20. 20. Yellowcake •Meanwhile, the uranium solution is filtered, and then goes through a solvent extraction process that includes kerosene and ammonia to purify the uranium solution. After purification the uranium is put into precipitation tanks—the result is a product commonly called yellowcake.
  21. 21. Transportation •In the final processes the yellow cake is heated to 800˚Celcius which makes a dark green powder which is 98% U3O8. The dark green powder is put into 200 liter drums and loaded into shipping containers and are shipped overseas to fuel nuclear power plants.
  22. 22. Mining Leaders • Australia and Canada are currently the biggest Uranium miners. The processes mentioned before that takes place in Australia is exported because Australia does not have a nuclear energy program. • The mining in Australian is primarily open pit, while the mining in Canada is mostly underground. • One is the major uranium producing countries, the other is of the major corporations that actually do the mining.
  23. 23. Production in 2000 Canada 10,682 Australia 7,578 Niger 2,895 Cameco 7218 Namibia 2,714 Cogema 6643 Uzbekistan 2,350 WMC 3693 Russia (est) 2,000 ERA 3564 Kazakhstan 1,752 Navoi 2400 USA 1,456 Rossing 2239 KazAtomProm 2018 Priargunsky 2000 South Africa 878 China (est) 500 Ukraine (est) 500 India (est) 200 France 319 others 422 tonnes U 500 Czech Republic company Total world 34,746 One is the major uranium producing countries, the other is of the major corporations that actually do the mining.
  24. 24. World Nuclear Power Plants
  25. 25. Uranium miners today • “Uranium threatens the health of mine workers and the communities surrounding the mines. According to the International Physicians for the Prevention of Nuclear War, uranium mining has been responsible for the largest collective exposure of workers to radiation. One estimate puts the number of workers who have died of lungs cancer and silicosis due to mining and milling alone at 20,000. Mine workers are principally exposed to ionizing radiation from radioactive uranium and the accompanying radium and radon gases emitted from the ore. Ionizing radiation is the part of the electromagnetic spectrum that extends from ultraviolet radiation to cosmic rays. This type of radiation releases high energy particles that damage cells and DNA structure, producing mutations, impairing the immune system and causing cancers.‖
  26. 26. 3. Nuclear Reactor  device built to sustain a controlled nuclear fission chain reaction Main Components of Nuclear Reactor: - reactor vessel - tubes of uranium - control rods - containment structure control rods control radioactivity, absorbs neutrons Containment structure contains the reaction in at least 3 feet of concrete!
  27. 27. How a Nuclear Reactor works • • • • • • • 235U fissions by absorbing a neutron and producing 2 to 3 neutrons, which initiate on average one more fission to make a controlled chain reaction Normal water is used as a moderator to slow the neutrons since slow neutrons take longer to pass by a U nucleus and have more time to be absorbed The protons in the hydrogen in the water have the same mass as the neutron and stop them by a billiard ball effect The extra neutrons are taken up by protons to form deuterons 235U is enriched from its 0.7% in nature to about 3% to produce the reaction, and is contained in rods in the water Boron control rods are inserted to absorb neutrons when it is time to shut down the reactor The hot water is boiled or sent through a heat exchanger to produce steam. The steam then powers turbines.
  28. 28. Inside a Nuclear Reactor • Steam outlet  • Fuel Rods  • Control Rods 
  29. 29. Nuclear Reactors • There are usually several hundred fuel assemblies in a reactor core. There are several types of reactors, but they all use a controlled fission process with a moderator like water or graphite. • •Pictured above is the Diablo Canyon reactor in California.
  30. 30. 235 92 U 1 0 n 92 36 Kr 141 56 Ba 301 n +201Mev Chain reaction In the case of 235U, however, fission is induced when the nucleus absorbs a neutron. Not only does the nucleus then split into two lighter nuclei, but two or three neutrons are also released. These newly produced neutrons can then collide with other 235U nuclei, inducing them to fission. There can be a nuclear chain reaction, in which the number of fission events rapidly increase.
  31. 31. Chain reaction showing
  32. 32. chain reaction
  33. 33. Fission occurs in the reactor vessel. Heat is produced. The steam is cooled in the condenser to return to the liquid phase. Nuclear power plant consists of all the parts needed to create electricity by using The heat is used nuclear energy to heat water to create steam The steam is used to turn the turbine in the generator to produce electricity
  34. 34. 反应堆 Cadmium rods concrete Water pipe cooling Heat exchanging Fuel rods graphite moderator fast neutron → slow neutron
  35. 35. Three Mile Island • Three Mile Island is a pair of PRW’s. The second one was built in a hurry for tax purposes (started operation on December 30, 1978 to meet deadline). On March 28, 1979, the Pilot Operated Relief Valve was stuck open and caused pressure to be released from the primary cooling system. The fuel rods came apart and radioactive material discharged into the sky. Two days later 3,500 pregnant women and children were evacuated. Although there were no official instructions to do so, many others left as well. Numerous residents in the aftermath developed various cancers and thyroid diseases.
  36. 36. • Chernobyl Chernobyl had the RBMK design. In an experiment, technicians let the power of reactor 4 fall, and on April 26, 1986 the result was rapid power levels rising inside the core— melting fuel and causing a reactor containment breach—in addition to an internal hydrogen explosion. The top of the reactor blew off and spewed radioactive material into the atmosphere for 10 days.
  37. 37. Health Impacts • Thirty people died in direct relation to the accident. They were the workers in the plant and the people who assisted in the cleanup. Approximately 2,500 additional deaths were related to the accident. Since the accident rates of Thyroid cancer has risen significantly. The rate of thyroid cancer in children 15 years and younger increase from 4 to 6 per million to 45 per million in the Ukraine region between 1986 to 1997 (compared to 1981 to 1985). 64% of these cases were in the most contaminated regions.
  38. 38. Environmental Impacts • Radioactive fall out spread throughout the Ukraine and Europe, and eventually the whole northern hemisphere. In the local ecosystem (10 km radius) coniferous trees and small mammals died. The natural environment is recovering but there may be long-term genetic effects.
  39. 39. Weapons •Nuclear weapons fall under two categories—fission weapons and fusion weapons. Fission is splitting the nucleus of an atom into two or more elements, which causes a huge amount of energy to be released. In addition if there is left over neutrons they will cause fission in other elements—sustaining a chain reaction. Fusion is almost the reverse because it requires the putting together of two nuclei. The Hydrogen bomb is a fusion weapon, while weapons that use U235 and Pu239 are fission weapons. A thermonuclear weapon detonates in three steps: fission chain reaction, fusion reaction, and then fission again. When a thermonuclear weapon explodes, there is an explosion of neutrons and gamma rays that causes a silent flash of heat and light, followed by the extreme pressure of a mushroom cloud that raises millions of tons of earth resulting in nuclear fallout. Atomic bomb
  40. 40. Hiroshima & Nagasaki • The Hiroshima bomb was nicknamed ―little boy‖ (on the left) and was detonated on August 6, 1945 killing approximately 140,000 by the end of that year—and an estimated total of 200,000 altogether. ―Fat Man‖ (on the right) was dropped three days later on Nagasaki killing approximately 70,000 people. Entire families were wiped out. The effects of the radiation caused birth defects in some of the survivors’ children, while others could no longer have babies. The physical, psychological, and environmental impacts of these atrocities can hardly be put into words.
  41. 41. Hiroshima—before
  42. 42. Hiroshima—after
  43. 43. Hiroshima—after • This picture was taken by a US army medic named Henry Dittner in October 1945.
  44. 44. Weapons Testing • Since 1945 there has been 2,050 nuclear weapons tests world wide.* This picture is of ―Dog Shot‖ in the Nevada desert in 1951. The second series of tests, the first series with large scale troops present (with 6500 soliders). **
  45. 45. Nuclear Waste • There four different kinds of waste: Highlevel (spent fuel and plutonium waste), transuranic (contaminated tools and clothes), low and mixed low-level (hazardous waste from hospitals), and uranium mill tailings. In the US there is approximately 91 million gallons of high-level waste, 11.3 million cubic feet of transuranic waste, 472 million cubic feet of low and mixed low level waste, and 265 million tons of uranium tailings.
  46. 46. Moab, Utah • This is a picture of a ten-million ton pile of uranium tailings. The pile is right next to the Colorado River, and leaks ammonia into it threatening the fish. The owners of the pile when bankrupt, so no the citizens of Moab are waiting for the Department of Energy to clean it up. The clean up will cost an estimated 64 million dollars.
  47. 47. Yucca Mountain •Yucca Mountain located in southern Nevada. Although this location has not been built yet, the plan is to have the waste buried deep in the mountain. Waste would be transported from all over the country in specially design railroad cars and truck trailers. The waste would then be repackaged for final burial. This plan is highly controversial.
  48. 48. Coal-fired electric plants Nuclear plants (one 1000 MW plant) (one 1000 MW plant) • releases 4.5 million tons of • produces 70 ft3 of CO2 HLW/year • produces 3.5 million ft3 of waste ash/year • no CO2 released • releases 300 tons of SO2 and ~100 tons NOx/day • no acidic oxides of sulfur and nitrogen released • releases Uranium and Thorium from coal
  49. 49. Reactor Hazards • Reactor pose a serious threat radiation threat— especially to the employees and surrounding communities. Recently the New York times featured an article ―Extraordinary Reactor Leak Get’s the Industries Attention.‖ The implication is that if this reactor can leak, so can others. Typically, the reactors develop boric acid under their lids— which eats away at the steel encasement (fixable), but this leak is in at the bottom of a reactor.* In an article featured on CorpWatch, ―Bechtel’s Nuclear Nightmares‖ talks about a reactor that the Bechtel corporation built in San Onofre— that’s been shut down since 1992 for lack of safety upgrades. The problem is that there is no place to permanently send the reactor to and is a risk because it was built on a fault line.** Three Mile Island and Chernobyl are two of the worst incidences of reactor breaches.
  50. 50. Conclusion • • Overall, nuclear energy disproportionately effects rural communities and the communities near nuclear facilities. Uranium mining and bombing are particularly detrimental to the environment. Further, the effects of radiation (cancer, illness, and death) are significant. If you find yourself in a situation where you are being exposed to radiation, shield yourself from the blast, and then move as far away from the detonation area as possible (otherwise remain indoors).