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Presentation on theme: "Nuclear Reactions: AN INTRODUCTION TO FISSION, FUSION, AND NUCLEAR POWER."— Presentation transcript:



3 ã Nuclear reactions deal with interactions between the nuclei of atoms ã The focus of this presentation are the processes of nuclear fission and nuclear fusion ã Both fission and fusion processes deal with matter and energy Introduction

4 Matter and Energy ã Previous studies have taught us that matter and energy cannot be created nor destroyed ã We now need to understand that Matter and Energy are two forms of the same thing

5 ã Matter can be changed into Energy ã Einsteins formula above tells us how the change occurs ã In the equation above: E = Energy m = Mass c = Speed of Light (Universal Constant) E = mc 2

6 ã The equation may be read as follows: Energy (E) is equal to Mass (m) multiplied by the Speed of Light (c) squared ã This tells us that a small amount of mass can be converted into a very large amount of energy because the speed of light (c) is an extremely large number

7 Fission notes ã Fission may be defined as the process of splitting an atomic nucleus into fission fragments ã The fission fragments are generally in the form of smaller atomic nuclei and neutrons ã Large amounts of energy are produced by the fission process

8 Fission notes ã Fissile nuclei are generally heavy atoms with large numbers of nucleons ã The nuclei of such heavy atoms are struck by neutrons initiating the fission process ã Fission occurs due to electrostatic repulsion created by large numbers of protons within the nuclei of heavy atoms

9 ã A classic example of a fission reaction is that of U-235: U-235 + 1 Neutron 2 Neutrons + Kr-92 + Ba-142 + Energy ã In this example, a stray neutron strikes an atom of U-235. It absorbs the neutron and becomes an unstable atom of U-236. It then undergoes fission. Notice that more neutrons are released in the reaction. These neutrons can strike other U-235 atoms to initiate their fission. Fission notes

10 ã The fission process is a natural one. A French researcher found a natural uranium reactor in Gabon, West Africa; it has been estimated to be over 2 billion years old ã Fission produces large amounts of heat energy and it is this heat that is captured by nuclear power plants to produce electricity

11 ã Fusion is a nuclear reaction whereby two light atomic nuclei fuse or combine to form a single larger, heavier nucleus ã The fusion process generates tremendous amounts of energy; refer back to Einsteins equation ã For fusion to occur, a large amount of energy is needed to overcome the electrical charges of the nuclei and fuse them together Fusion notes

12 ã Fusion reactions do not occur naturally on our planet but are the principal type of reaction found in stars ã The large masses, densities, and high temperatures of stars provide the initial energies needed to fuel fusion reactions ã The sun fuses hydrogen atoms to produce helium, subatomic particles, and vast amounts of energy

13 ã Mass and Energy are two forms of the same thing; neither can be created nor destroyed but mass can be converted into energy (E = mc 2 ) ã Fission is a nuclear reaction in which a heavy atomic nucleus is split into lighter atomic nuclei ã Fusion is a nuclear reaction in which 2 light atomic nuclei are combined into a single, heavier atomic nucleus Review notes

14 Nuclear reaction notes ã Chain reaction occurs when a Uranium atom splits ã Different reactions –Atomic Bomb in a split second –Nuclear Power Reactor more controlled, cannot explode like a bomb

15 History of nuclear power 1938– Scientists study Uranium nucleus 1941 – Manhattan Project begins 1942 – Controlled nuclear chain reaction 1945 – U.S. uses two atomic bombs on Japan 1949 – Soviets develop atomic bomb 1952 – U.S. tests hydrogen bomb 1955 – First U.S. nuclear submarine

16 Atoms for Peace Program to justify nuclear technology Proposals for power, canal-building, exports First commercial power plant, England 19561956

17 ã The energy in one pound of highly enriched Uranium is comparable to that of one million gallons of gasoline. ã One million times as much energy in one pound of Uranium as in one pound of coal. Economic advantages notes

18 Emissions Free notes ã Nuclear energy annually prevents –5.1 million tons of sulfur –2.4 million tons of nitrogen oxide –164 metric tons of carbon ã Nuclear often pitted against fossil fuels –Some coal contains radioactivity –Nuclear plants have released low-level radiation

19 Nuclear Power Plants

20 Nuclear power around the globe ã 17% of worlds electricity from nuclear power –U.S. about 20% (2nd largest source) ã 431 nuclear plants in 31 countries –103 of them in the U.S. –Built none since 1970s (Wisconsin as leader). –U.S. firms have exported nukes. –Push from Bush/Cheney for new nukes.

21 Countries Generating Nuclear Power CountryTotal MW USA99,784 France58,493 Japan38,875 Germany22,657 Russia19,843 Canada15,755 Ukraine12,679 United Kingdom11,720 Sweden10,002 South Korea8,170

22 Technology depends on operators


24 Nuclear Reactor Process ã 3% enriched Uranium pellets formed into rods, which are formed into bundles ã Bundles submerged in water coolant inside pressure vessel, with control rods. ã Bundles must be SUPERCRITICAL; will overheat and melt if no control rods. Reaction converts water to steam, which powers steam turbine


26 Nuclear Reactor Structure ã Reactors pressure vessel typically housed in 8 of steel ã 36 concrete shielding ã 45 steel reinforced concrete



29 Back end: Radioactive waste ã Low-level wastes in commercial facilities ã Spent fuel in pools or dry casks by plants ã Nuclear lab wastes –Hanford wastes leaked radiation into Columbia River ã High-level underground repository –Yucca Mountain in Nevada to 2037 –Wolf River Batholith in Wisconsin after 2037? –Risks of cracks in bedrock, water seepage


31 Yucca Mountain


33 Radioactive Waste Recycling ã Disposal of radioactive waste from nuclear power plants and weapons facilities by recycling it into household products. ã In 1996, 15,000 tons of metal were received by the Association of Radioactive Metal Recyclers. Much was recycled into products without consumer knowledge. ã Depleted Uranium munitions for military.

34 ã Nuclear energy has no typical pollutants or greenhouse gasses ã Nuclear waste contains high levels of radioactive waste, which are active for hundreds of thousands of years. ã The controversy around nuclear energy stems from all parts of the nuclear chain. Summary notes


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