Open-Book paper Essay

Alpha and beta decay are two types of naturally occurring radioactive decay. In alpha decay, an unstable nucleus emits an alpha particle (? ), a particle made up of two protons and two neutrons. For example1 2 In beta decay, a neutron in the nucleus is converted into a proton and a beta particle (i ), an electron. Specifically, as protons and neutrons are both made of quarks, i -decay converts an up quark into a down quark releasing a i -particle and an antineutrino (an antineutrino has no charge or galvanic pile, so does not affect the chemistry of i -decay). This occurs by the weak tingeic force.3 For example4 This table shows some of the differences between ? -decay and i -decay emissions5 ?-decay i -decay Particle emitted helium nucleus electron Relative charge +2 -1 Relative caboodle 4 0. 00055 Range in air 10cm 10m Stopped by Paper Aluminium foil excursion by electrical field Low High The fundamental difference between radioactive decay and atomic fission is that, whe reas radioactive decay is spontaneous, nuclear fission must be induced. In nuclear fission, when an unstable nucleus absorbs a neutron, it splits, emitting more neutrons and setting off a continuous chain reaction.This leads to products with nuclear masses around half those of the initial nuclei, whereas in radioactive decay, the initial and final nuclear masses are relatively close together. The other major(ip) difference is that fission releases considerably more energy than decay. This energy beds from mass lost in fission, according to the equation E = mc2, where E is energy, m is mass and c is the speed of light. Synthesis of Elements in Stars Stars make water their energy from nuclear fusion, in which nuclei join together to make larger nuclei. Hydrogen is used in normal-sized stars(e+ represents a positively charged electron, and ? e is a neutrino).This process requires temperatures of around 13 million K and pressures of around 300 billion atmospheres. 6 When closely all of the hydrogen has fused, the helium nuclei can collide to make nuclei such as beryllium7 This leads to the creation of further nuclei containing four nucleons carbon, oxygen, neon and magnesium. at once all the helium has fused, further collisions take place between the created nuclei. This leads to the production of small amounts of hydrogen and helium, producing most of the first 18 elements, such as atomic number 38.Lithium can also be produced by the collision of a Beryllium-7 nucleus and an electron. The nuclear process that takes place here is electron capture, in which an atom captures an electron, turning a proton into a neutron and releasing a neutrino. This happens by the weak interaction, like i -decay9 Smaller amounts of lithium can also be produced in the fission of some nuclei by cosmic rays and in supernovae, when heavy stars become unstable and explode. 10 Producing Energy through nuclear nuclear fission and Fusion.In nuclear fission, an unstable nucleus absorbs a neutron, exciting the nucleus, ca utilize it to oscillate and split into two smaller nuclei. This process releases more neutrons, causing more nuclei to split, and so on. This is shown in Fig. 211 with Uranium-235. The energy produced by nuclear fission, by E = mc2, is 3. 210-11 J per fission. 12 Uranium-235 is used to produce energy by fission confab Fig. 313. Controlling this reaction Uranium-238 is mixed with uranium-235. Uranium-238 nuclei absorb neutrons but do not react by fission, breaking the chain in the reaction.Graphite moderators placed in between the uranium rods reduce the kinetic energy of the neutrons produced so they can induce fission. Boron-coated steel control rods absorb neutrons, and can be moved in and out of the reactor. If they are fully in, the reaction stops. Nuclear fusion takes place when, under certain conditions, two nuclei fuse together. For example, with deuterium and tritium14 The energy produced comes from the mass lost 3. 1710-29 kg 15 16. By E = mc2, this gives out 2. 8610-12 J per fusion. On earth, for this to happen the nuclei must be in ionise plasma at temperatures of 15108 iC. The puzzle with this is that it must be kept away from the walls of the container to minimise heat loss. To do this, a tokamak is used. This uses magnetic currents to hang in the plasma from touching the walls ( fancy Fig. 417). The walls are made of graphite, which is not harmed by the temperature. Both fission and fusion have several advantages and disadvantages for use in producing electricity Advantages Disadvantages Fission Uranium-235 produces 3. 7 million times the energy per unit mass as coal18 Uranium-235 will not run out on the same timescale as dodo fuels19.It produces no gases that directly cause global warming Fission produces waste radioactive actinides, which are dangerous for thousands of years Fission has led to disasters such as Chernobyl in 1986, which caused over 4000 deaths20 Fusion The fuel hydrogen is abundant The radioactive waste products have half-lives hundreds of years less than those of fission Fusion is safer than fission, as scarce small amounts of products are used It produces no gases that directly cause global warming The conditions required for fission are hard to produce.The process used to produce energy by fusion is not yet perfect put one over below Challenges Facing the Development of Fusion Power Stations The major problem with fusion is generating and containing the conditions required for the reaction. As detailed above, a tokamak is used, this has some problems. The plasma still touches the bottom of the chamber, and where it does this hydrogen reacts with the walls forming hydrocarbon radicals. These can form a film, which flakes away into the plasma, modify performance21. Possible solutions include removing the film with lasers22 or using tungsten walls, which would not erode23.A probable source of a solution is the International Tokamak Experimental Researcher, c urrently being built in France. It will be used as a prototype to test the reaction on the necessary levels required. Fusion should be available to produce commercial power by 2040.References Used throughout the report Chemistry Review Lise Meitner Radiochemist, physicist and co-discoverer of nuclear fission, Gordon Woods, Volume 16 Number 1, family line 2006 (Article 1) Fusion, Powering the future? , Chris Warrick, Volume 16 Number 1, September 2006 and Lithium, Chris Ennis, Volume 15 Number 31, February 2006 (Article 2).Salters advance Chemistry chemical Ideas, George Burton et al, Heinemann Educational Publishers, Halley Court, Jordan Hill, Oxford, OX2 8EJ, ISBN 0-435-63129-9, first edition 1994, bite edition 2000 1 Equation copied from page 3, Lise MeitnerRadiochemist, physicist and co-discoverer of nuclear fission see above 2 Fig. 1 copied manually from summon 487, The exchange nature of forces, Advanced Physics, Tom Duncan, John Murray (Publishers) Ltd, 50 Albemarle Stree t, London, W1S 4BD, first edition 1972, ISBN 0-7195-7669-5, fifth edition 2000, reprinted 2002 3http//www. chemie. de/lexikon/e/Beta_decay, Beta Decay, (c) 1997-2008 Chemie.de Information Service 4 Equation copied from page 3, Lise Meitner.Radiochemist, physicist and co-discoverer of nuclear fission see above 5 Table adapted from scallywag 20, Nuclear Reactions, Salters Advanced Chemistry Chemical Ideas see above 6Where did the chemical elements come from? , Page 131, The Universe A Biography, John Gribbin published by Penguin Books Ltd, 80 Strand, London, WC2R ORL, ISBN 978-0-1410-2147-8, 2006 7Equation copied from Box 1 Nucleogenesis.Page 21, Lithium, Chris Ennis see above 8Equation copied from Box 1 Nucleogenesis, Page 21, Lithium, Chris Ennis see above.9 http//www. britannica. com/nobelprize/article-48278, electron capture with a Beryllium-7 nucleus, from the Encyclopaedia Britannicas Guide to the Nobel Prizes, (c) 2008 Encyclopaedia Britannica, Inc. 10.Where do the chemical el ements come from? , Page 10, Salters Advanced Chemistry Chemical Storylines, George Burton et al, Heinemann Educational Publishers, Halley Court, Jordan Hill, Oxford, OX2 8EJ, ISBN 0-435-63119-5 first edition 1994, second edition 2000 11 Fig. 2 taken from http//www. astro. bas. bg/petrov/herter00. html, lecture notes for astronomy.Bulgarian Institute of Astronomy http//www.astro. bas. bg/ 12 http//www. lancs. ac. uk/ug/bloomer/nuclearpower/theory. htm, Nuclear Fission and Nuclear Fusion, from the University of Lancaster, www. lancs. ac. uk 13 Fig. 3 copied manually from Box 2, Article 1 (see above) adapted from Chemistry Today, (c) E. Henderson, Macmillan Publishers Ltd, 1977. 14 Equation copied from Box 2, Fusion, powering the future? , Chris Warrick see above 15 Mass of reactants and products given in proton masses in Box 2, Fusion, powering the future?Chris Warrick see above 16 Proton masses converted to kilograms using the mass of one proton as 1.6710-27 kg, from Data Sheet, Pag e 3, AQA GCE AS Physics A Unit 1, January 2007 17 Fig. 4 taken from http//www. jet. efda. org/pages/fusion- fundamental principle/fusion3. html, Fusion Basics, (c) EFDA-JET 18 http//www. virtualnucleartourist. com/basics/reasons1. htm, a website intended to provide you basic information about the different types of plants and their principle of operation, (c) 2006.The Virtual Nuclear Tourist 19 http//www. abc. net. au/rn/scienceshow/stories/2007/2080110. htm, an interview with Professor Martin Sevior from the University of Melbourne by the Australian Broadcasting.Corporation20 http//www. who. nt/ionizing_radiation/chernobyl/who_chernobyl_report_2006. pdf, the World Health Organisations report on Chernobyl 21 Chemistry Review Fusion, powering the future? , Chris Warrick see above 22 http//www. lasers. org. uk/paperstore/Cleaning14. pdf, Dust Removal from Next Generation Tokamaks by Laser and Flashlamp Cleaning, K. G. Watkins et al, Lasers and Laser Engineering, University of Liverpoo l, 2001 23 http//www. jet. efda. org/documents/articles/samm. pdf, Controlled thermonuclear fusion enters with ITER into a new era, Page 12 Ulrich Samm, EFDA-JET, 2003.