nuclear power plants
Post on 30-Dec-2015
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Nuclear Fission
• The process of splitting a larger atomic nucleus into two smaller nuclei by bombarding it with neutrons. This process releases energy that is stored in the nucleus.
• Our current nuclear power plants run on fission They use theU-235 isotope of Uranium as fuel. Most uranium in natural ores exists in as U-238 Only U-235 is fissionable. Processed uranium must be “enriched” in centrifuges to concentrate the U-235. Uranium used in reactors is 4-5% U-235. Uranium used in nuclear weapons must be 90% U-235.
• The fission process can continue until all of the available “big atoms” are gone. This is a chain reaction. Reactions must be slowed down with neutron-absorbing control rods.
Controlling the Chain Reaction
Control rods
Fuel Assemblies
Withdraw control rods,reaction increases
Insert control rods,reaction decreases
Safety Is Engineered Into Reactor Designs
Containment Vessel1.5-inch thick steel
Shield Building Wall3 foot thick reinforced concrete
Dry Well Wall5 foot thick reinforced concrete
Bio Shield4 foot thick leaded concrete with1.5-inch thick steel lining inside and out
Reactor Vessel4 to 8 inches thick steel
Reactor Fuel
Weir Wall1.5 foot thick concrete
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