Nuclear PowerNuclear EnergyHistorySlide 4Slide 5What is it and how does it work?Slide 7Slide 8Slide 9What is it and how does it work? How do we accelerate fission?What is it and how does it work? Chain reactionSlide 12Slide 13Slide 14Half LifeWhere do we get the U?Slide 17Slide 18Nuclear ReactorsWhat components do all reactors need?Magnox ReactorAGRPWRBoiling Water ReactorFrom Oak RidgeFast Breeder ReactorLMFBRSlide 28Uranium DepositsU—2 ppmhttp://www.euronuclear.org/info/encyclopedia/u/uranium-reserves.htmWill we run out?Slide 33http://www.world-nuclear.org/info/reactors.htmlhttp://www.nrc.gov/info-finder/reactorIn MinnesotaSlide 37Problems with Nuclear ReactorsSafetySlide 40Safety with different reactorsChernobyl--1986RadioactivityNatural Background RadiationSlide 45http://www.es.lancs.ac.uk/casestud/case3.htmSlide 47Radioactive WasteSlide 49Slide 50Low Level Radioactive WasteIntermediate Level Radioactive WasteHigh Level Radioactive Wastehttp://www.heartland.org/Article.cfm?artId=16809Nuclear PowerBC cartoonNuclear Energy•History•What is it and how does it work?•Initial Nuclear Reactors •Uranium Resources and Reserves•Who is using nuclear power?•Problems with Nuclear Reactors•Radioactive WasteHistory•Henry Becquerel 1896•Discovered radioactivity: notably that uranium undergoes spontaneous disintegration•Name coined by Marie Curie•PIERRE & MARIE CURIE • By the time he met Marie Sklodowska, Pierre Curie had already established an impressive reputation. In 1880, he and his brother Jacques had discovered piezoelectricity whereby physical pressure applied to a crystal resulted in the creation of an electric potential. He had also made important investigations into the phenomenon of magnetism including the identification of a temperature, the curie point, above which a material's magnetic properties disappear. However, shortly after his marriage to Marie in 1895, Pierre subjugated his research to her interests. Together, they began investigating the phenomenon of radioactivity recently discovered in uranium ore. Although the phenomenon was discovered by Henri Becquerel, the term radioactivity was coined by Marie. After chemical extraction of uranium from the ore, Marie noted the residual material to be more "active" than the pure uranium. She concluded that the ore contained, in addition to uranium, new elements that were also radioactive. This led to the discoveries of the elements polonium and radium, but it took four more years of processing tons of ore under oppressive conditions to isolate enough of each element to determine its chemical properties. For their work on radioactivity, the Curies were awarded the 1903 Nobel Prize in physics. Tragically, Pierre was killed three years later in an accident while crossing a street in a rainstorm. Pierre's teaching position at the Sorbonne was given to Marie. Never before had a woman taught there in its 650 year history! Her first lecture began with the very sentence her husband had used to finish his last. In his honor, the 1910 Radiology Congress chose the curie as the basic unit of radioactivity; the quantity of radon in equilibrium with one gram of radium (current definition: 1Ci = 3.7 x 1010 dps). A year later, Marie was awarded the Nobel Prize in chemistry for her discoveries of radium and polonium, thus becoming the first person to receive two Nobel Prizes. For the remainder of her life she tirelessly investigated and promoted the use of radium as a treatment for cancer. Marie Curie died July 4, 1934, overtaken by pernicious anemia no doubt caused by years of overwork and radiation exposure. •The Health Physics Society1313 Dolley Madison Blvd., Suite 402Mclean, Virginia 22101Nuclear Energy•History•What is it and how does it work?•Initial Nuclear Reactors•Uranium Resources and Reserves•Who is using nuclear power?•Problems with Nuclear Reactors•Radioactive WasteWhat is it and how does it work?•Elements with an atomic number > 83 are radioactive: that is, their nuclei are so large that they are unstable•There are also lower atomic number elements that have naturally occurring radioactive isotopes–E.g. 14C, 40K, 87RbWhat is it and how does it work?•Isotope: What is this?•Species of the same chemical element having the same number of protons but a different number of neutrons (i.e. a different mass)What is it and how does it work?•Nuclear Fission: Breakdown of a large nucleus (such as that of U) into two smaller nuclei (such as Barium and Krypton) plus energy•Nuclear Fusion: joining of lighter elements such as H and Li to form larger, heavier elements. This also gives off energyWhat is it and how does it work?http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html#c2What is it and how does it work?How do we accelerate fission?•Uranium is the only naturally occurring element (with an isotope with mass 235) than is readily fissionable.•We bombard it with a neutron to cause a chain reaction (need a critical mass)What is it and how does it work?Chain reactionhttp://www.atomicarchive.com/Fission/Fission2.shtmlWhat is it and how does it work?106 ev = 1.6 x 10-13 joulesWhat is it and how does it work?•Energy from fissioning 1 gram of 235UA gm 235U would contain 2.56 x 1021 atoms thus 2.56 x10 21 *1.6x10-13 joules==4.096x108 joules• or in other words, it is equivalent to burning 2.7 metric tons of coal or 13.7 barrels of oilWhat is it and how does it work?Summary of Uranium Isotopes Isotope Percent in natural uraniumNo. of Protons No. of Neutrons Half-Life (in years)238U 99.285 92 146 4.46 billion 235U 0.711 92 143 704 million 234U 0.0055 92 142 245,000Half Life•http://www.colorado.edu/physics/2000/isotopes/radioactive_decay3.htmlWhere do we get the U?•Need to process U to enrich it in Uranium 235•Typical ore contains about 1% U3O8•Conventional beneficiation: milling and chemical leaching to make •Yellowcake: 70 to 80% U3O8•Separate out the isotopes using gaseous diffusionWhere do we get the U?•Gaseous Diffusion•Gas diffuses α 1/m2 where m is mass•Therefore the larger the mass, the slower it diffuses•Convert U3O8 to gaseous UF6•Lots of gaseous barriers to separate the 235UF6 from 238UF6•This process accounts for 30% of nuclear fuel cost•This is converted to ceramic powder and made into small pellets to form fuel rods (about 4% 235U)Nuclear Energy•History•What is it and how does it work?•Initial Nuclear Reactors •Uranium