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Nuclear Power: 

Nuclear Power BC cartoon

Nuclear Energy: 

Nuclear 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 Waste

History: 

History Henry Becquerel 1896 Discovered radioactivity: notably that uranium undergoes spontaneous disintegration Name coined by Marie Curie

Slide4: 

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 Society 1313 Dolley Madison Blvd., Suite 402 Mclean, Virginia 22101

Nuclear Energy: 

Nuclear 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 Waste

What is it and how does it work? : 

What 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, 87Rb

What is it and how does it work? : 

What 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? : 

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 energy

What is it and how does it work? : 

What is it and how does it work? http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html#c2

What is it and how does it work? How do we accelerate fission?: 

What 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 reaction: 

What is it and how does it work? Chain reaction http://www.atomicarchive.com/Fission/Fission2.shtml

What is it and how does it work? : 

What is it and how does it work? 106 ev = 1.6 x 10-13 joules

What is it and how does it work? : 

What is it and how does it work? Energy from fissioning 1 gram of 235U A 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 oil

What is it and how does it work? : 

What is it and how does it work?

Half Life: 

Half Life http://www.colorado.edu/physics/2000/isotopes/radioactive_decay3.html

Where do we get the U? : 

Where 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 diffusion

Where do we get the U? : 

Where 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: 

Nuclear 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 Waste

Nuclear Reactors: 

Nuclear Reactors Magnox Reactor (un-enriched natural U) Advanced Gas Reactor (AGR) Water moderated and cooled reactors (BWR) (PWR) Oak Ridge Fast Breeder Reactor

What components do all reactors need?: 

What components do all reactors need? Fuel (either enriched or natural) Moderators –slow neutrons down so that they can be captured: graphite or deuterium commonly used Control rods (to speed up or slow down reactions) Heat exchange system Turbine generator

Magnox Reactor: 

Magnox Reactor

AGR : 

AGR

PWR: 

PWR http://www.nucleartourist.com/type/pwr.htm

Boiling Water Reactor : 

Boiling Water Reactor http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/reactor.html

From Oak Ridge: 

From Oak Ridge

Fast Breeder Reactor: 

Fast Breeder Reactor

LMFBR: 

LMFBR

Nuclear Energy: 

Nuclear 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 Waste

Uranium Deposits: 

Uranium Deposits How do you fine them 1. Surface using either a Geiger or scintillation counter 2. Gamma ray spectroscopy 3. Radon Gas

U—2 ppm: 

U—2 ppm Has to be concentrated either by sedimentary, igneous processes or hydrogenic processes See your text book 205-209

http://www.euronuclear.org/info/encyclopedia/u/uranium-reserves.htm: 

http://www.euronuclear.org/info/encyclopedia/u/uranium-reserves.htm Uranium reserves The global uranium reserves with mining costs up to US $ 80 per kilogram amount to about 2 million tonnes. The uranium reserves correspond to an energy equivalent of 28 billion tonnes hard coal when used in light water reactors. The deposits with large uranium reserves which can be mined in a cost-effective way are distributed to many countries. Country Uranium Australia 460,000 t Canada 426,000 t Kazakhstan 254,000 t South Africa 186,000 t Brazil 112,000 t Namibia 110,000 t Uzbekistan 109,000 t USA 102,000 t Niger 94,000 t Russia 75,000 t These ten countries possess about 96% of the global uranium reserves. With their 2 million tonnes, all 439 world-wide operated nuclear power plants can be supplied for several decades. If mining costs of up to 130 $/kg are taken into consideration the global uranium reserves are increased by further 3 million tonnes. The uranium resources are estimated to be 15 to 20 million tonnes. Estimates for coal reserves in 2002 were 1081 billion tons

Will we run out?: 

Will we run out? http://www.uic.com.au/nip75.htm

Nuclear Energy: 

Nuclear 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 Waste

http://www.world-nuclear.org/info/reactors.html: 

http://www.world-nuclear.org/info/reactors.html From this site we can get briefings of countries that have nuclear power plants We can also see that there are 435 operating reactors in the world http://www.uic.com.au/nip07.htm

http://www.nrc.gov/info-finder/reactor: 

http://www.nrc.gov/info-finder/reactor

In Minnesota: 

In Minnesota Nuclear Power in Minnesota Electricity Production Number of nuclear units: 3 Monticello, Monticello, Mn Prairie Island 1-2, Red Wing, Mn Nuclear energy supplies 24.4 percent of the electricity generated in Minnesota. Clean Air Benefits Nuclear energy in Minnesota emits no harmful gases into the environment, avoiding emissions that would have been produced by other energy sources used for baseload electricity generation. During 2004, Minnesota's nuclear power plants avoided approximately 50,900 tons of sulfur dioxide emissions, 32,400 tons of nitrogen oxide emissions, and 14.2 million metric tons of carbon dioxide emissions. Avoiding these additional emissions is particularly important to areas that are experiencing air quality problems due to traffic and industry. http://www.nei.org/doc.asp?docid=1073

Nuclear Energy: 

Nuclear Energy History What is it and how does it work? Uranium Resources and Reserves Initial Nuclear Reactors Who is using nuclear power? Problems with Nuclear Reactors Radioactive Waste

Problems with Nuclear Reactors: 

Problems with Nuclear Reactors Fear of Nuclear Accidents Three Mile Island Chernobyl Nuclear Waste

Safety: 

Safety All reactors are equipped with A. Control rods that react to power fluctuations—i.e. they are automatically raised and lowered to keep constant power (Boron or Cd) absorb neutrons B. Ancillary control rods respond to any failure in A

Safety: 

Safety Explosion is not a problem, but rather an increase in heat which might melt (or vaporize) the reactor. This would produce 131I, (8 day half-life) Xn, Kr gas as well as isotopes of Sr and Cs

Safety with different reactors: 

Safety with different reactors Candu program (Canada) Uses heavy water as moderator. Can dump tank and thus no moderator so the u-235 can’t capture neutrons PWR water is coolant too, therefore a problem. If you lose it, it can overheat Three Mile Island: March 28, 1979

Chernobyl--1986: 

Chernobyl--1986 We will have a talk about this

Radioactivity: 

Radioactivity Basic unit of absorbed dose of ionizing radiation is the Rad = 10-5 joules/gm of absorbing material Biological effects of different kins of radiation are not the same, thus we use a unit of dose that is adjusted for different radiation sources Rem (roentgen equivalent for man) Also seivert (sv) which is 100 rem Dose of ½ seivert to a human being in the course of one day results in rations sickness in hours. 10 seiverts is certain death

Natural Background Radiation: 

Natural Background Radiation Annually each of us receive 0.00185 Sv or 1860 x 10-6 μSv, and add 30% for medical xrays in a year

http://www.es.lancs.ac.uk/casestud/case3.htm: 

http://www.es.lancs.ac.uk/casestud/case3.htm In the first year after the accident, the average radiation dose to an adult in the U.K. from Chernobyl radionuclides was 37 microSieverts (µSv) (range 20-190 µSv). Of this, 80% came from foodstuffs (60% from milk), while the remainder came from breathing in radionuclides, and gamma radiation from contaminated ground. For comparison, the average radiation dose received each year by the U.K. population is 2600 µSv, of which 87% comes from natural sources.

Nuclear Energy: 

Nuclear 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 Waste

Radioactive Waste: 

Radioactive Waste After ten cycles of a half-life, most of the material has been used up. So if the half life is 5700 years (such as Carbon 14), then after 57000 years, there isn’t enough for us to measure for dating— Remember this when we look at the radionuclides left in the radioactive waste

Radioactive Waste: 

Radioactive Waste Page 109 of your text has a table that lists all the principal radioactive isotopes in nuclear waste. The half-life varies from 30 seconds for Rhodium-106 to 17,000,000 years for Iodine-129. Most are less than 40 years. U.S. DOE estimates that high level waste must be retained for more than 10000 years before it will have low enough radiation not to be a hazard!

Radioactive Waste: 

Radioactive Waste Low Level: up to 1000x background Medium Level: 1000x to 106 times bgd High: > 106 x bgd

Low Level Radioactive Waste: 

Low Level Radioactive Waste A. Uranium mines—tailings Tailings contain Thorium 230 which has a half life of 77,000 years. Tailings should be contained. Radon also monitored B. Nuclear power station/labs/hospitals E.g. clothing is placed in drums and buried

Intermediate Level Radioactive Waste: 

Intermediate Level Radioactive Waste Solid components from nuclear power plants Liquids Flasks used to transport fuel Now stored in tanks at nuclear plants (US)

High Level Radioactive Waste: 

High Level Radioactive Waste 95% of the radioactivity but only 0.1% of the volume of the waste generated Liquid wastes and spent fuel rods

http://www.heartland.org/Article.cfm?artId=16809: 

http://www.heartland.org/Article.cfm?artId=16809 In 1998 a Swiss study looked at 13,914 severe accidents, including 4,290 in the energy industry, between 1969 and 1996. This included both Three Mile Island and Chernobyl. Even including those two highly publicized incidents, the study determined that among conventional energy sources--coal, oil, natural gas, and nuclear--nuclear power was by far the safest. The second safest power source, natural gas, has a fatality rate 10 times higher than nuclear power. The Swiss report, "Comprehensive Assessment of Energy Systems Severe Accidents," published by the Paul Scherrer Institute in 2003, concluded that in the production of a full year of a trillion watts (terawatt-year) of energy--which might require many years to produce, as all of Canada takes 15 years to generate a terawatt-year--fatalities expected from the various potential energy sources are: Nuclear 8 fatalities Natural Gas 85 fatalities Coal 342 fatalities Oil 418 fatalities

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