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Fission and Fusion. Fission is the splitting of a heavy atom into Two or more lighter nuclei Fusion is combining two small nuclei to make a heavier nucleus. Fission and Fusion break the Law of Conservation of Mass!!!. The law says mass (matter) can not be created or destroyed.
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Fission is the splitting of a heavy atom into Two or more lighter nuclei Fusion is combining two small nuclei to make a heavier nucleus
Fission and Fusion break the Law of Conservation of Mass!!! The law says mass (matter) can not be created or destroyed. However, in these nuclear reactions, a bit of mass IS destroyed, and converted into….
How much energy? Einstein says…..
2 Energy = mass x (speed of light) X very very big Very big = Very small
In fusion and fission, small amounts of mass are converted into huge amounts of energy • Compared to a gram of natural gas (methane), a gram of material converted to energy in a nuclear reaction gives off one BILLION times more energy
Fission Reactions Neutron + U-235 A neutron is fired at U-235 and is captured, forming unstable U-236, which then splits up
Fission Reactions 1 142 235 91 1 n + U Ba + Kr + 3 n + energy 92 56 36 0 0 A neutron bombards a U-235 and it splits into Ba-142, Kr-91 three neutrons and ENERGY The three neutrons can then go on to start other fission reactions
Nuclear power plants use fission to create energy to make electricity Three Mile Island
Nuclear Reactors FUEL CONTROL Control Rods (MODERATORS) absorb neutrons Control rods made of Cadmium (Cd), Graphite (C), Boron (B) COOLANT = Liquid Sodium Na (l) or Heavy Water Steel and High Density concrete shield personnel • Must be FISSIONABLE • Controlled chain reactions • U-233 • U-235 • Pu-239 • Radioactive Waste can be solid, liquid or gas
Nuclear accidents can happen when the chain reaction goes out of control
Thanks to FUSION, we have sunlight! Hydrogen fuses with Hydrogen to make Helium + energy in stars, like our own sun
Fusion Fusion is not as dangerous as fission Unfortunately …… it can not yet be used in power plants because too much energy is needed to overcome the repulsion of the two positively charged nuclei to be cost effective