Saturday, 4 May 2013

chain reaction uranium fission






Uranium-235 Fission

Detailed exampleChain reaction. Fission fragments.Average energy release.
Index

Fission concepts

Reference
Mulligan
 
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Uranium-235 Fission Example

Initiation of this processChain reaction. Fission fragments.Average energy release.
Detailed energy release calculation
Index

Fission concepts

Reference
Mulligan
 
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Energy From Uranium Fission

Form of Energy Released Amount of Energy Released (MeV)
Kinetic energy of two fission fragments
168
Immediate gamma rays
7
Delayed gamma rays
3-12
Fission neutrons
5
Energy of decay products of fission fragments
...
Gamma rays
7
Beta particles
8
Neutrons
12
Average total energy released
215 MeV
Index

Fission concepts

Reference
Mulligan
Table 12.3.
 
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If at least one neutron from each fission strikes another U-235 nucleus and initiates fission, then the chain reaction is sustained.
More detail on chain reaction.Initiation of chain reaction.
Index

Fission concepts
 
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Uranium-235 Chain Reaction

If an least one neutron from U-235 fission strikes another nucleus and causes it to fission, then the chain reaction will continue. If the reaction will sustain itself, it is said to be "critical", and the mass of U-235 required to produced the critical condition is said to be a "critical mass". A critical chain reaction can be achieved at low concentrations of U-235 if the neutrons from fission are moderated to lower their speed, since the probability for fission with slow neutrons is greater.

A fission chain reaction produces intermediate mass fragments which are highly radioactive and produce further energy by their radioactive decay. Some of them produce neutrons, called delayed neutrons, which contribute to the fission chain reaction.
Index

Fission concepts
 
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