Chem 1100 Lecture 16Outline of Last Lecture I. Nuclear HistoryII. Writing Nuclear ReactionsIII. Chemical vs Nuclear ReactionsIV. Enriching UraniumOutline of Current Lecture I. RadioactivityII. Carbon DatingIII. HistoryIV. Nuclear Weapons ProfilerationCurrent LectureI. Radioactivitya. Spontaneous emission of radiation by certain elements/isotopes. Not just electromagnetic radiation but also particulate radiation.b. Unstable isotopes tend to spit out this radioactivity and also particles.c.d. Alpha emission: 222/86Rn  4/2He^+2 + 218/84PoThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. You can stop an alpha particle with only a piece of paper. It is the least penetrating.e. Beta emission: 14/6C  0/-1B + 14/7Ni. The carbon has 6 protons and 8 neutrons. One of the neutrons is breakingdown into a proton and an electron.ii. The beta will go right through paper, but can be stopped by aluminum.f. Gamma emission: most damaging radiationi. U238 breaks down into 4/2Helium+2 and 234Thoriumii. Goes through paper and aluminum. And the only thing that can block it is lead but even then a few particles will get through.g. Time, distance, & shieldingi. The three ways to avoid radiation damage.h. Staying Radioactivei. Different isotopes decay at different ratesii. Half Life: How long it takes for radiation to drop by half.iii. U-238  4.5 billion yearsiv. Rn-222  3.82 daysv. Po-214  16 microsecondsII. Carbon Datinga. Cosmic rays hit the upper atmosphere and this results in neutrons and atomic nitrogen to form and also create carbon 14. b. In the atmosphere the carbon 14 will go into the carbon cycle and plants will absorb it and make co2. Animals eat plants, people eat animals, and we all have alittle carbon 14 in us. c. C-14 half-life is about 6000 years. There’s not much in our bodies. About 1 trillionth of the carbon particles in our bodies are C-14.d. Carbon intake stops at death so that’s how they use carbon dating to tell how oldthings are after they’ve died.e. Limitationsi. Max age: we can only carbon date about 60,000 years with the equipment we have. If something died over 60,000 years ago it probably doesn’t have any carbon in it. Not enough to detect anyway.ii. Solar storms: if the sun spits out a whole bunch of radiation this will increase the carbon-14 levels in the atmosphere because more atoms are being blown apart.iii. Climate Change can effect carbon 14 levelsiv. Nuclear bomb testing  increases carbon 14 levels because atoms are being blown apart.v. Burning fossil fuels will decrease the percentage of carbon 14 in the atmosphere because the fossil fuels are more than 60,000 years old so they don’t have any carbon 14 in them when they are burned.vi. Volcanoesvii. Shroud of Turin – the burial cloth of Jesusf. Nuclear Wastei. Daughter products: Cs137, Sr90, half lives are about 30 years, and storageis an issue. g. Waste disposali. Low-level waste can be buried in canisters 10 meters deep but we are running out of places to bury it.ii. High-level waste is stuff that will take way too long for radiation to dissipate. Right now the only place we store it is at the site where it is produced in pools. iii. Yucca Mountain: planned to make a centralize location for high level waste but the governor of Nevada said he’d tear up the railroad to prevent them taking waste there. III. Historya. Chernobyl – on April 26, 1986 while performing a safety test on reactor 4, technicians allowed a power surge that reached 120 times the rated capacity of the reactor. The surge, or “slow nuclear explosion,” ripped open the core, including cooling water pipes, and caused a huge steam explosion. The 4,000 ton concrete covering over the reactor was blown away. Fires broke out in many places all over the site. Fifty different radioactive isotopes were released, with half-lives spanning from two years to 24,000 years. These isotopes were shot 1.5 miles into the sky. The control rods in Chernobyl were made of graphite. Graphiteis made of carbon which is flammable. b. Social and Environmental Consequences: Over 1,000 injuries and thiry-one deaths of firefighters and other who reported to the scene of the accident. 150,000 people evacuated form their Ukraine homes. Radioactive cloud released over a large part of Europe. Health threatening levels of radioactive materials were found in at least twenty nations, and as far away as 2,000 km from Chernobyl. Estimated 250 million people were exposed to unhealthy amounts of radiation. Estimates of future cancers from the accident range anywhere from 7,500 to 1 million. Radioactive particles in the environment and in the food chain. Large amount of uncertainty and fear in the population.c. Political Consequences: Distrust of government happened because they tried to cover it up. Sweden and Poland were the first nations to bring attention to the accident. Other nations attempted to downplay the health effects of the accidentin their own nations. Public opposition to building additional nuclear power plants increased significantly worldwide.d.e.IV. Nuclear Weapons Proliferationa. Irani. Looking to enrich uraniumii. For fuel (4%)iii. Will they try to go to 90%? Will they follow North Korea and try and makenuclear weapons? If they try to develop nuclear weapons they will probably try and do it like North Korea did by extracting the U238 from the spent fuel rods by removing the plutonium and making a plutonium bomb.b. Spent Fuel Rodsi. About 1% of the fuel rodii. Pu undergoes a chain reactioniii. Had about 8000 rods and extracted Pu from themiv. Enough to make 5-6 bombsc. Plutoniumi. Critical mass 33Kg about the size of a softballii. Uncontrolled reaction – mushroom cloudiii. Hiroshima U bombiv. Nagasaki & North Korea – Plutonium bombv. Mix 10% Pu with 90% depleted Uvi. Breeder