L43S07_NuclearApplications 05-04-07

L43S07_NuclearApplications 05-04-07 - CHEM 1A L43:...

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Unformatted text preview: CHEM 1A L43: "Nuclear Applications" Summary 2004 M.Kubinec, H.Nitsche L43-1 160 Actinides 202 The Nuclides Zone of Stability (neutron : proton) 140 120 neutrons 100 decay region - (1.5:1) 80 Hg ratio 80 110 48 60 (1.3:1) Cd (1:1) 56 40 26 20 6 decay region Fe (1.2:1) + stable light nuclei (1:1) (1.5:1) stable heavy nuclei Li (1:1) 3 0 20 40 2004 M.Kubinec, H.Nitsche protons 60 80 100 nuclear `magic numbers' 2, 8, 20, 28, 50, 82, 126 L43-2 90 38 100 Decay Rate Sr Half-life 0 90 -1 N (number of atoms) e + 39 Y 1 Curie (Ci) = 3.7 x 1010 disintegrations s-1 (Ci) exponential decay: Nt=Noe-t 29 y N half-life = t1/2 = 29 y: t1/2 = ln2/ ln2/ half10 half-lives ~ 99.9% decay half- 20 40 60 80 100 years 120 L43-3 2004 M.Kubinec, H.Nitsche 2004 M.Kubinec, H.Nitsche 1 CHEM 1A L43: "Nuclear Applications" Radiation & Health (r) ce tan dis 1 I ~ r2 Maximize shielding exp osu re tim e Summary Detection Methods 40 Minimize 2004 M.Kubinec, H.Nitsche L42-8 Natural RadioactivityRadioactivityK 19 0 -1 40K e+ 40 20 Ca + 40 Geiger-Mller Counter Geigerflorophore - half-life = 1.28 billion years half- 1 in 10,000 K atoms is radioactive 1 banana = 370 pCi = 0.01 mrem K detector He H 2 Liquid 2004 H.Nitsche 2004 M.Kubinec, M.Kubinec, H.Nitsche 1 3 3 Scintillation Recommended Daily Allowance (RDA): 3.5 g K = 2.863 nCi L42-7 2004 M.Kubinec, H.Nitsche L43-4 L42-9 Detection Methods Geiger-Mller Counter Geigerflorophore 3 1 detector H 3 2 He Liquid Scintillation 2004 M.Kubinec, H.Nitsche L43-5 Radiation & Health 1 I ~ r2 (r) ce tan dis Maximize shielding e xp osu re tim e Minimize 2004 M.Kubinec, H.Nitsche L43-6 2004 M.Kubinec, H.Nitsche 2 CHEM 1A L43: "Nuclear Applications" Natural Radioactivity- 40K 40 19 K 0 -1 e+ 40 20 Ca 40 1 in 10,000 K atoms is radioactive K half-life = 1.28 billion years half1 banana = 370 pCi = 0.01 mrem Recommended Daily Allowance (RDA): 3.5 g K = 2.863 nCi 2004 M.Kubinec, H.Nitsche L43-7 ChemQuiz 43.1 How many bananas would you have to eat to receive the yearly average exposure from the nuclear power industry? (0.2 mrem/y) industry? mrem/y) 1) ~20 2004 M.Kubinec, H.Nitsche 40 K 2) ~200 3) ~2000 L43-8 Nuclear Medicine 11C Positron emitters 15O 18F 0 -1 Positron Emission Tomography (PET Scan) t1/2 = 20.39 min t1/2 = 2.037 min t1/2 = 1.803 min 0 e + +1 e 180 180 2 detector Summary 2004 M.Kubinec, H.Nitsche t1 t1 L42-12 2004 M.Kubinec, H.Nitsche L42-13 Isotopic Dating is created in upper atmosphere by 14N Nuclear Power 14C + 1n 14C + 1H 14C/12C is constant When organism dies, 14C no longer enters the body's cells body' t1/2 of 14C = 5730 y 2004 M.Kubinec, H.Nitsche 1 0 n + 235 92 U 92 36 Kr + 141 56 Ba + 3 0n 1 2004 M.Kubinec, H.Nitsche L42-14 ~200 MeV / fission 2004 M.Kubinec, H.Nitsche L43-10 L42-15 2004 M.Kubinec, H.Nitsche 3 CHEM 1A L43: "Nuclear Applications" Nuclear Medicine 2004 M.Kubinec, H.Nitsche L43-11 Positron emitters 11C Positron Emission Tomography (PET Scan) t1/2 = 20.39 min t1/2 = 2.037 min 18F t 1/2 = 1.803 min 15O 0 -1 e + +1 e 180 180 0 2 detector t2 t1 2004 M.Kubinec, H.Nitsche L43-12 Isotopic Dating 14C is created in upper atmosphere by 14N + 1n 14C + 1H 14C/12C is constant When organism dies, 14C no longer enters the body's cells body' t1/2 of 14C = 5730 y 2004 M.Kubinec, H.Nitsche L43-13 2004 M.Kubinec, H.Nitsche 4 CHEM 1A L43: "Nuclear Applications" 56 9 26 Fe Binding Energy 84 36 binding energy / nucleon (MeV) 8 7 6 5 4 3 2 1 1 1 3 2 Kr 1 235 Fission 235 92 92 U 1 6 3 Fu sion Li 0 n+ U 92 36 Kr + 141 nuclear energy lighter 56 Ba + 3 0n He H 20 exothermic 1 1 `real' solar energy heavier real' 40 60 80 100 120 140 160 180 200 210 220 230 H + 1H 2 3 2 He 2004 M.Kubinec, H.Nitsche mass L43-14 Nuclear Fission Chain Reaction More stable nuclides 2004 M.Kubinec, H.Nitsche L43-15 Nuclear Power 1 0 n+ 235 92 U 92 36 Kr + 141 56 Ba + 3 0n 1 L43-16 ~200 MeV / fission 2004 M.Kubinec, H.Nitsche 1 MeV = 1.6 x 10-13J 2004 M.Kubinec, H.Nitsche 5 CHEM 1A L43: "Nuclear Applications" Greenhouse Effect and Global Warming The greenhouse effect occurs naturally, providing a habitable climate It describes the rise in temperature that the Earth experiences because certain gases in the atmosphere (for example water vapor, carbon dioxide, nitrous dioxide, oxide, and methane) trap energy from the sun. oxide, methane) Without these gases, heat would escape back into space and Earth's average temperature would be about Earth' 60F colder. Because of how they warm our world, 60 these gases are referred to as greenhouse gases Some of the gases that produce the greenhouse effect are increasing due to human activity and this is most the worlds scientists believe causes global warming 2004 M.Kubinec, H.Nitsche L43-17 Greenhouse Effect and Global Warming Carbon dioxide has now increased 31% since 1750 to a higher level than any time in the last 420,000 years, and probably 20 million years. It contributes 60% of the warming effect. About three quarters of the humanhumaninduced carbon dioxide emission is due to fossil fuel combustion. Worldwide emissions of CO2 from burning fossil fuels total about 25 billion tonnes per year. About 38% of this is from coal and about 43% from oil. Every 1000 MWe power station running on black coal means CO2 emissions of about 7 million tonnes per year. If brown coal is used, the amount is much greater. Nuclear power plants do not emit these gases and are the single most significant means of limiting the increased greenhouse gas concentrations while enabling access to abundant electricity. L43-18 2004 M.Kubinec, H.Nitsche ChemQuiz 43.2 What is the ratio of relative molar energy produced from the fission of 235U atoms compared methane combustion? combustion? 1 n + 235U 92 Kr + 141 Ba + 3 1n 0 56 92 36 0 ~200 MeV / fission Molar combustion of methane (-891 kJ/mol) (- 1) ~1 2004 M.Kubinec, H.Nitsche 2) ~103 3) ~109 L43-19 2004 M.Kubinec, H.Nitsche 6 CHEM 1A L43: "Nuclear Applications" Lecture Complete 2004 M.Kubinec, H.Nitsche L43-21 2004 M.Kubinec, H.Nitsche 7 ...
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