Upload
lucas-matthews
View
226
Download
3
Embed Size (px)
Citation preview
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.
However, in these nuclear reactions, a bit of mass IS destroyed, and converted into….
LOTS OF ENERGY!
How much energy?
Einstein says…..
Einstein’s equation
Energy = mass x (speed of light)
2
Very small X very very bigVery big =
• 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
n + U Ba + Kr + 3 n + energy1
023592
14256
9136 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
1
This can be the start of a chain reaction
Nuclear power plants use fission to create energy to make electricity
Three Mile Island
Nuclear Reactors
FUEL
• Must be FISSIONABLE• Controlled chain
reactions• U-233• U-235• Pu-239• Radioactive Waste can
be solid, liquid or gas
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
Nuclear Reactor
Nuclear accidents can happen when the chain reaction goes out of control
Thanks to FUSION, we have sunlight!
Hydrogen fuses withHydrogen to makeHelium + energyin 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