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© Copyright Pearson Prentice Hall
Slide 1 of 20
Fission and Fusion of Atomic Nuclei
The sun is not actually burning. If the energy given off by the sun were the product of a combustion reaction, the sun would have burned out approximately 2000 years after it was formed, long before today. You will learn how energy is produced in the sun.
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© Copyright Pearson Prentice Hall
Fission and Fusion of Atomic Nuclei >
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Nuclear Fission
Nuclear Fission
splitting of a nucleus into smaller fragments
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Fission and Fusion of Atomic Nuclei > Nuclear Fission
When the nuclei of certain isotopes are bombarded with neutrons, they undergo fission,
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Slide 4 of 20
Fission and Fusion of Atomic Nuclei > Nuclear Fission
Chain Reactions
some of the neutrons produced react with other fissionable atoms, producing more neutrons which react with still more fissionable atoms.
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Slide 5 of 20
Fission and Fusion of Atomic Nuclei > Nuclear Fission
Nuclear Fission
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© Copyright Pearson Prentice Hall
Fission and Fusion of Atomic Nuclei > Nuclear Fission25.3
A Nuclear Power Plant
Slide 7 of 20
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Fission and Fusion of Atomic Nuclei > Nuclear Fission
Neutron Moderation
-is a process that slows down neutrons so the reactor fuel (uranium-235 or plutonium-239) captures them to continue the chain reaction.
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Slide 8 of 20
© Copyright Pearson Prentice Hall
Fission and Fusion of Atomic Nuclei > Nuclear Fission
Neutron Absorption
- is a process that decreases the number of slow-moving neutrons. Control rods, made of a material such a cadmium, are used to absorb neutrons.
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Fission and Fusion of Atomic Nuclei >
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Nuclear Waste
Nuclear Waste
spent fuel rods from a nuclear reaction stored in water
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Fission and Fusion of Atomic Nuclei > Nuclear Waste
-Water cools the spent rods
-also acts as a radiation shield to reduce the radiation levels.
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Fission and Fusion of Atomic Nuclei >
Slide 11 of 20
Nuclear Fusion
Nuclear Fusion
How do fission reactions and fusion reactions differ?
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Slide 12 of 20
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Fission and Fusion of Atomic Nuclei > Nuclear Fusion
Fusion- nuclei combine to produce a nucleus of greater mass.
In solar fusion, hydrogen nuclei (protons) fuse to make helium nuclei and two positrons.
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Slide 13 of 20
Fission and Fusion of Atomic Nuclei > Nuclear Fusion
Fusion reactions, release much more energy than fission reactions
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Fission and Fusion of Atomic Nuclei > Nuclear Fusion
The use of controlled fusion as an energy source on Earth is appealing.
• The potential fuels are inexpensive and readily available.
• The problems with fusion lie in achieving the high temperatures necessary to start the reaction and in containing the reaction once it has started.
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Slide 15 of 20
25.3 Section Quiz.
1. One of the control mechanisms for a sustainable nuclear chain reactor involves slowing down the released neutrons so they may be captured by other nuclei. This is done using
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25.3 Section Quiz.
2. Spent fuel rods are stored in
© Copyright Pearson Prentice Hall
Slide 17 of 20
25.3 Section Quiz.
3. Choose the correct words for the spaces. In solar fusion, _______ nuclei fuse to form _______ nuclei.