Nuclear Fission Spring 2013
Lecture 16 1
UCSD Physics 12 UCSD Physics 12
Spring 2013 2
UCSD Physics 12
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UCSD Physics 12
Spring 2013 4 Q
Nuclear Fission Spring 2013
Lecture 16 2
UCSD Physics 12
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neutron
proton
anti-neutrino
electron Poof!
UCSD Physics 12
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UCSD Physics 12
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ZA XN
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612C6
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614C8
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92235U143
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92238U146
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94239Pu145
Q
Nuclear Fission Spring 2013
Lecture 16 3
UCSD Physics 12
Spring 2013 9
UCSD Physics 12
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Chart of the Nuclides
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3
2
1
0
β+
β-
α
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UCSD Physics 12
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source: http://www.epa.gov/radiation/understand/calculate.html 1 mrem carries 0.000055% chance of developing cancer: 350 mrem/yr expect cancer in 5000 years
Nuclear Fission Spring 2013
Lecture 16 4
UCSD Physics 12
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Barium and Krypton represent just one of many potential outcomes
UCSD Physics 12
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UCSD Physics 12
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Bottom line: at thermal energies (arrow), 235U is 1000 times more likely to undergo fission than 238U even when smacked hard
UCSD Physics 12
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Nuclear Fission Spring 2013
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UCSD Physics 12
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UCSD Physics 12
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• Iron (Fe) is at the peak • On the heavy side of iron, fission delivers energy • On the lighter side of iron, fusion delivers energy • This is why normal stars stop fusion after iron • Huge energy step to be gained in going from
hydrogen (H) to helium-4 via fusion
Nuclear Fission Spring 2013
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UCSD Physics 12
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UCSD Physics 12
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235U
daughter 1
daughter 2
stable nuclide radioactive (unstable) nuclide
daughter nuclei from fission are neutron-rich, and β- decay toward black (stable) nuclei some can fall outside of neutron “drip line” in white region (don’t have to be right on red line)
UCSD Physics 12
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UCSD Physics 12
Spring 2013 24 Q
Nuclear Fission Spring 2013
Lecture 16 7
UCSD Physics 12
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