Nuclear Fission and Fusion
TEKS Par 112.35 #12c
Discovery of Fission
James Chadwick discovered the neutral particle in the nucleus of the atom in 1932.
He called it a “neutron.” Many scientists then started experimenting with
neutrons. Enrico Fermi and his team bombarded every
known element with neutrons, and found among the products some new, radioactive elements.
Neutrons had caused fission, or breakup, of nuclei
Fission of Uranium
Uranium produced lighter but radioactive products when bombarded with neutrons.
Fermi discovered that neutrons could be slowed down by first funneling them through light elements like carbon.
Ida Noddack, Otto Hahn and Lise Meitner showed that uranium was fissioning into barium and other lighter, radioactive elements.
Later, U-235 and Pu-239 were shown to be the best candidates for fission with slow neutrons.
Fission Reaction
U-235 fissions like this:
Visionlearning.com
Nuclearenergyissafe.com
The products of fission are unpredictable and radioactive
Nuclear Energy
Because matter is converted into energy in nuclear reactions, fission produces a great deal of heat
When controlled, this can be used to drive turbines that produce electricity, as in the South Texas Nuclear Project.
Window.state.tx.us
Nuclear Energy
Because matter is converted into energy in nuclear reactions, fission produces a great deal of heat
When released from a carefully engineered nuclear weapon, this energy can do an incredible amount of damage, as when the U.S. dropped bombs on Japan to end WW2.
Nuclear-news.net
Nuclear Fission
Nuclear fission occurs when two light elements are forced together to make a heavier one.
The two nuclei FUSE into a new one. This releases a great deal of energy. Here is a typical reaction equation:
H-3 + H-2 → He-4 + n + energy
Uses of Fusion
Nuclear fusion occurs in the sun and other stars, and so it gives us all the energy used on earth in photosynthesis.
Gosunstove.com
So if your house has solar cells, fusion is the ultimate source of the electricity.
Uses of Fusion
Nuclear fusion is the driving force behind thermonuclear weapons.
They are no longer tested in the atmosphere. They had released much harmful radioactive isotopes in the 1950s.
en.wikipedia.org
Electricity from fusion?
Nuclear fusion would use a cheap fuel—hydrogen from water.
It would generate less nuclear waste. Research into fusion reactors has been going on
since the 1940s. There is no working fusion reactor yet.
Summary
Nuclear Reactions
Type WhatHappens
By-products
EnergyUses
WasteProblems?
Fission U-235 or Pu-239 splits
Radio-active
isotopes
ElectricPower/
weapons
Where to store the
radioactive waste?
Terrorism.
Fusion H nuclei forced
together
NeutronsSmall
elements
Sun & stars/
weapons
If weapons are used,
uncontrolled radiowaste
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