Nuclear Power. The True meaning Of Nuclear Power On Earth

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Cuthbert Cannon
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1 Nuclear Power The True meaning Of Nuclear Power On Earth

2 Basics of Fission Nuclear Fission is the division of generally large and unstable elements (like uranium and plutonium) into smaller elements Nuclear Fission and Fusion produce not by breaking chemical bonds but instead by converting some of their mass into energy. This makes nuclear reactions millions of times more powerful than any known chemical ones. Because of this they require far less "fuel" and since they don't involve combustion, produce no CO2

3 Fission chain reactions A fission reaction will often produce free neutrons when it splits These neutrons can cause new atoms to undergo fission, leading to a chain reaction Sometimes, this is what is wanted: But NOT in a fission power plant. To prevent chain reactions several measures,such as control rods, and low enrichment levels are used to control the rate of fission, making a fission explosion impossible.

4 Mass-Energy Conversion Energy is a property of mass, and Mass is a property of energy. The mass of an atom is more than the mass of it's individual particles because of binding energy (the strong force) In fission, some of this matter is lost from the atom, and therefore, because E=Mc2 energy is released. MASS IS NOT TURNED INTO ENERGY! The mass leaves with the energy. It's very confusing I know, so let's move on.

5 Energy Transformation in Fission plant and roll of heat exchanger The energy from fission reactions is released through photons as well as an increase in the kinetic energy of the products, this produces heat. The heat is used to create steam from water through a heat exchanger, which allows thermal energy to transfer from the rods to water. by expanding its volume, the water vapor increases in pressure, and pushes itself through turbines, which then produce electricity The electricity is then converted to high voltage, transferred to a local power station, brought down to a usable voltage, and delivered to homes and buisnesses.

6 Fuel Enrichment Most commonly used with uranium, fuel enrichment is the process of increasing the percentage of uranium235 in the given amount of uranium nuclear fuel. Natural uranium contains approximately 0.7% of uranium-235, the majority is uranium-238. U-235 is the more useful isotope for nuclear power. Some reactors, using graphite or heavy water, can use natural uranium, but light water reactors need to have the uranium-235 proportion increased to around 4%. Increasing the uranium-235 proportion is called uranium enrichment, or fuel enrichment.

nuclear heat exchange diagram from http://www.nrc.

7 nuclear heat exchange diagram from

8 Flow diagram of energy degradation

9 Purpose of control rods and moderators Control rods are made of silver, cadmium or indium. Their purpose is to control the rate of fission by absorbing neutrons without fissioning. The amount of control rods, size, composition, and so forth affect how fast fission occurs, and therefore how much energy is produced. The most common moderator in a nuclear reactor is water moderators are used to slow down the neutrons released in a nuclear reaction These neutrons are traveling at about.07 C (20,000 KM/S) and are unlikely to hit more atoms, a moderator goes through collisions with the neutrons to slow them down to increase their chance of causing more uranium reactions.

10 Creation of Plutonium-239 from Uranium-238 Uranium-238 is non fissionable, which is why uranium is enriched to increase the amount of U-235, however, under certain circumstances Uranium-238 can become Plutonium-239 Pu-235 is even more potent than U-235, and is more useful in nuclear bombs as it has a lower critical mass (less to start a chain reaction) U-238 can absorb a neutron and become an unstable U-239 This will quickly cause a beta decay, where one neutron is turned into a proton and an electron, and the electron (along with an antineutrino) are emitted to form Np-239, this happens again to form the slightly more stable, but still fissionable and radioactive Plutonium-239, fun fact, Iran is doing that!

11 Plutonium-239 as a Nuclear Fuel Primary fission material in fission bombs Important because of it's use for bombs, and it can also be added to uranium in a reactor to increase reactions and reduce the need for uranium enrichment With the end of the cold war, the U.S. and Soviet Union began dismantling lots of nuclear weapons, resulting in a surplus of highly enriched plutonium It is now a big part in nuclear weapons (fission bombs, etc.), partly because it is so abundant. A byproduct of Plutonium 239 production is plutonium 238, which is used in spacecraft that use radioactive material as their power source, and is now becoming scarce w/o new Pu

12 Safety Issues and Risks Some issues in producing nuclear power are: Nuclear Meltdown - Occurs when a nuclear power plant component fails so the reactor core overheats and melts. Can occur because of a lack of coolant, which is supposed to decrease the temperature of the reactor. A meltdown releases the core's highly radioactive materials into the environment, and can harm many people Radioactive waste - Nuclear wastes are radioactive materials that are produced as a result of the nuclear reaction. This waste must be isolated for a long time (depending on the element/isotope) in order to prevent sickness from radiation

13 Safety issues continued Another issue with Nuclear power plants is that mining uranium, a popular element for the production of nuclear power, is that it naturally decays and produces Radon222, which is a cancer causing agent. Human contact to Radon-222 and the contamination it provides to the air, water, and soil around it, are very harmful to the body Terrorist attacks on nuclear power plants/on nuclear waste that is transported, communities all around are put in risk from potential radioactive contamination as trains/trucks travel around countries

14 Solutions to issues and risks Preventing nuclear meltdowns all comes down to controlling the heat in the reactor, and having enough coolant so the reactor doesn't overheat. Properly "disposing" or taking care of radioactive waste can also eliminate many problems with nuclear reactors, keeping them away from humans and transporting them without labeling the trucks or trains with what they're transporting can eliminate terrorist attacks

16 Nuclear Fusion Nuclear Fusion is the combining of elements to create larger atoms. Nuclear Fusion is what powers the sun, at it's core, the sun fuses 700 million tons of hydrogen into helium a second, which releases the mass energy equivalent of 4 million tons a second (E=Mc2), or 4*1026 Joules a second Although Fusion may occur with any atoms, it is most common fusion of Hydrogen into Helium, as it requires the least amount of heat and pressure to do so. Beyond a certain point, however, fusion becomes endothermic, Iron is the last element that can be fused exothermically, and therefore it is when too much iron builds up in a core of a massive star that it will collapse and explode in a supernova.

17 Advantages of Fusion Fusion creates no radioactive waste, the product is Helium, an inert noble gas. Fusion uses hydrogen, which can be formed by steam reformation of hydrocarbons or water electrolysis, instead of having to be mined. If fusion could be successfully implemented, the amount of energy produced would far outweigh the energy required Per unit mass, Fusion is more efficient than nuclear fission as the reactants are much less massive, only direct Matter-Antimatter annihilation is more energetic per mass.

18 Problems with fusion There are two main problems with nuclear fusion power production: having more energy be produced than used, and containment of the reaction. While the sun can fuse hydrogen at a chilly 15 million K (27 million of), it is aided by the pressure of 330 thousand earths. On earth without this pressure a temperature of about 150 million K (270 million of) is required. To be power efficient, a fusion reaction should fuel itself. This fusioning plasma will try and expand violently at such temperatures, therefore very powerful magnets and specialized heat resistant materials must be used to try and contain this material, in addition, the wall material must be able to withstand a bombardment of neutrons which are not contained by the fields.

19 Small fusion power plant prototype under construction

20 Fusion conclusion Fusion reactor prototypes are being tested, but it will be decades or perhaps even centuries before they can be mass used.

Basics of Nuclear Physics and Fission

Basics of Nuclear Physics and Fission A basic background in nuclear physics for those who want to start at the beginning. Some of the terms used in this factsheet can be found in IEER s on-line glossary.