Chernobyl Essays (1237 words) - Nuclear Technology,

Chernobyl April 26th 1986 marked the date of the worst nuclear accident to ever occur. Chernobyl, a nuclear power plant in Russia was undergoing routine safety tests that envolved running the reactor on less then full power, followed by a standard shut down. At Chernobyls reactor number 4 a specific test was designed to show that a coasting turbine could produce enough power to pump coolant through the reactor core while waiting for electricity from diesel generators. During the test turbine feed valves were closed to initiate turbine coasting, and automatic control rods were withdrawn from the core. When the steam valves to the turbine close, the pressure in the reactor should go up causing the boiling point of the water to increase. This creates more water in the reactor, increasing cooling. During this test there was a problem with the feed water supply, so the increase in cooling water did not happen. What did happen was an uncontrolled increase in the steam pressure. The operator saw this and started to shut down the reaction by reinserting the control rods. The initial insertion of the control rods caused the reaction to concentrate in the bottom of the reactor. The reactor power rose well above its maximum capacity. Fuel pellets shattered, reacting with the cooling water, creating high pressure in the fuel containers. This surge in pressure caused the fuel containers to rupture. This led to two severe explosions, one a steam explosion, the other a rapid expansion of fuel vapor. The force of these explosions lifted the pile cap, allowing air to enter the reactor. The graphite used in the reactor construction caught on fire, ending a horrible and tragic sequence of events, but beginning another. Local firemen, unaware of the dangerous amounts of radiation, were called in to put out the fire. All of the firemen died, either a result of the fire, or from breathing radioactive debris. Unfortunately, their heroic attempts were useless, because the core of the reactor was exposed making the fire much to hot for water to cool. The first thing the Russians did was try to cover up the accident. This turned out to be impossible, considering the amounts of radioactive debris released into the air. Shortly after the accident a nuclear power plant in Sweden measured high amounts of radioactivity in their area, called the Russians to inquire if there had been an accident. The Russians shortly thereafter alerted the press, and evacuated towns surrounding Chernobyl. This of course wasnt their biggest problem. They needed to find the fuel that had escaped from the reactor in order to avoid another massive chain reaction. This was a huge problem due to the extreme amounts of radioactivity inside the sarcophagus. They didnt have the money for robots, so they sent in the Soviet Army. 3400 men were used on roof runs in which theyd go and collect samples from the roof of the reactor. During these missions soldiers could be subjected to 20 Rankins of radiation. Many people who have worked at Chernobyl have died from sudden heart failure. The Russian government denies that this has anything to do with their work at Chernobyl, but their have been too many deaths related to heart failure for it not to be. The next move was to find the fuel. Unlike American nuclear power plants that have their reactors over steel reinforced concrete the crazy Russians built their reactor on top of offices. Inside these offices radiation levels reach around 100 to 250 Rankins of radiation per hour. This means it would be impossible to ever work safely inside Chernobyl, unless of course you had a few hundred thousand years on your hands for the radioactivity to fall to safe levels. Unfortunately they didnt, they had to find the fuel before another chain reaction occurred, releasing more nuclear fallout into the environment. Throughout their early investigation they could find no clues to the whereabouts of the fuel. Finally, one cold December day in 1986, scientists came across a large highly radioactive mass approximately 2 meters across in size. Because of its unique shape they titled it the Elephants Foot. Their only dilemma was, what the heck is it? This problem

10 Interesting Fluorine Facts

10 Interesting Fluorine Facts Fluorine (F) is an element you encounter daily, most often as fluoride in water and toothpaste. Here are 10 interesting facts about this important element. You can get more detailed information about chemical and physical properties on the fluorine facts page. Fast Facts: Fluorine Element Name: FluorineElement Symbol: FAtomic Number: 9Atomic Weight: 18.9984Group: Group 17 (Halogens)Category: NonmetalElectron Configuration: [He]2s2sp5 Fluorine is the most reactive and most electronegative of all the chemical elements. The only elements it doesnt vigorously react with are oxygen, helium, neon, and argon. It is one of the few elements that will form compounds with noble gases xenon, krypton, and radon.Fluorine is the lightest halogen, with atomic number 9. Its standard atomic weight is 18.9984 and is based on its single natural isotope, fluorine-19.George Gore managed to isolate fluorine using an  electrolytic process in 1869, but the experiment ended in disaster when fluorine reacted explosively with hydrogen gas.  Henri Moisson was awarded the 1906 Nobel Memorial Prize in Chemistry for isolating fluorine in 1886. He also used electrolysis to obtain the element but kept the fluorine gas separate from the hydrogen gas.  Although he was the first to successfully obtain pure fluorine, Moissons work was interrupted multiple times when he was poisoned by the reactive element. Moisson was also the first person to m ake artificial diamonds, by compressing charcoal. The 13th most abundant element in the Earths crust is fluorine. It is so reactive that it is not found naturally in pure form but only in compounds. The element is found in minerals, including fluorite, topaz, and feldspar.Fluorine has many uses. It is found as fluoride in toothpaste and drinking water, in Teflon (polytetrafluoroethylene), drugs including the chemotherapeutic drug  5-fluorouracil, and etchant hydrofluoric acid. It is used in refrigerants (chlorofluorocarbons or CFCs), propellants, and for the enrichment of uranium by UF6 gas. Fluorine is not an essential element in human or animal nutrition. Topical fluoride application, as from toothpaste or mouthwash, was once believed to be effective for a conversion of tooth enamel hydroxyapatite into stronger fluorapatite, but more recent studies indicate fluoride aids enamel regrowth. Trace dietary fluorine levels may impact bone strength. While fluorine compounds are not found in animals, there are natural organofluorines in plants, which typically act as defenses against herbivores. Because it is so reactive, fluorine is difficult to store. Hydrofluoric acid (HF), for example, is so corrosive it will dissolve glass. Even so, HF is safer and easier to transport and handle than pure fluorine. Hydrogen fluoride is considered to be a weak acid at low concentrations, but it acts as a strong acid at high concentrations.Although fluorine is relatively common on Earth, it is rare in the universe, believed to be found at concentrations of about 400 parts per billion. While fluorine forms in stars,  nuclear fusion with hydrogen produces helium and oxygen, or fusion with helium makes neon and hydrogen.Fluorine is one of the few elements that can attack diamond.The pure non-metallic element is a gas at room temperature and pressure. Fluorine changes from an extremely pale yellow diatomic gas (F2) into a bright yellow liquid at -188 C (-307 F). Fluorine resembles another halogen, chlorine. The solid has two allotropes. The alpha form is soft and transparent, while the beta form is hard and opaque. Fluorine has a characteristic pungent odor that can be smelled at a concentration as low as 20 parts per billion. There is only one stable isotope of fluorine, F-19. Fluorine-19 is highly sensitive to magnetic fields, so it is used in magnetic resonance imaging. Another 17 radioisotopes of fluorine have been synthesized, ranging in mass number from 14 to 31. The most stable is fluorine-17, which has a half-life just of under 110 minutes. Two metastable isomers are also known.  The isomer 18mF has a half-life of about 1600 nanoseconds, while 26mF has a half-life of 2.2 milliseconds. Sources Banks, R. E. (1986). Isolation of Fluorine by Moissan: Setting the Scene.  Journal of Fluorine Chemistry.  33  (1–4): 3–26.Bà ©guà ©, Jean-Pierre; Bonnet-Delpon, Danià ¨le (2008). Bioorganic and Medicinal Chemistry of Fluorine. Hoboken: John Wiley Sons. ISBN 978-0-470-27830-7.Lide, David R. (2004). Handbook of Chemistry and Physics (84th ed.). Boca Raton: CRC Press. ISBN 0-8493-0566-7.