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http://www.youtube.com/watch?v=vZAJbJc1ayc start 2:27
When people think about nuclear power they think about…
1. Effects of radiation
2. Nuclear disasters
3. Nuclear waste disposal
What is Radiation?• Radiation = particles given off by
unstable atoms.
• 3 Types:– Alpha (α)
• Travels few inches• Blocked by paper (skin)
– Beta (β)• Travels few feet• Blocked by aluminum, glass
– Gamma (γ)• Travels far• Blocked by lead (steel & concrete).
www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt
Background Radiation
• The amount of radiation we are exposed to daily from the environment
• Average =
360 millirem/year or
3 millisieverts
• Genetic damages: from mutations that alter genes
• defects can become apparent in the next generation
• Somatic damages: to tissue, such as burns, miscarriages & cancers
Effects of RadiationEffects of Radiation
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
437 commercial reactors in 32 countries, producing 17% electricity
Nuclear Energy
• The energy that exists within the nucleus of an atom.
• Nuclear Fission = the release of energy from the splitting of atoms!
• Nuclear Fusion = the combining of two smaller atoms into one larger atom.
• http://videos.howstuffworks.com/discovery/29389-assignment-discovery-nuclear-basics-video.htm
Nuclear Fission
http://www.youtube.com/watch?v=Pmy5fivI_4U
Nuclear Fusion
Nuclear Power PlantNuclear Power Plant1. a controlled nuclear fission chain
reaction 2. heats water3. produce high-pressure steam 4. that turns turbines 5. which turns generator and creates
electricity.
http://www.howstuffworks.com/nuclear-power2.htm
Controlled Nuclear Fission Controlled Nuclear Fission ReactionReaction
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
•http://www.animatedsoftware.com/environm/nukequiz/nukequiz_one/nuke_parts/reactor_parts.swf
http://www.ida.liu.se/~her/npp/demo.html
Nuclear Reactor
• Where nuclear fission occurs.
• Surrounded by thick concrete, steel & lead.
• Blocks all radiation!
Inside the Reactor
• Fuel Rods– 35,000 – 70,000 fuel rods– 3% Uranium-235 pellets– In water (moderator)
• Control Rods– absorb extra neutrons– Control the chain reaction
http://online.wsj.com/article/SB10001424052748704396504576205000098975380.html#project%3DFUELASSEMBLY0317%26articleTabs%3Dinteractive
Cooling Tower
• Water is the coolant in the system.
• Tower is used to condense hot steam to liquid water.
• Usually taken from river, lake, ocean.
• Water can be reused.
Renewable or Non-Renewable?
Nuclear waste
• Power plants produce radioactive wastes– mostly spent fuel rods (3-4 years)– each reactor produces about 20-30 tons yearly
• Currently stored in pools on site and then above ground casks– some remain dangerous for tens of thousands
of years
• How should we store this waste?
Yucca Mountain
Options for Waste
– Keep onsight– Bury– Shoot into space– Bury in ocean floor– Bury in Antarctica– Change it into harmless or reprocess to make new
fuel
Low-Level & High Level Radioactive Waste
• Emit small amounts of ionizing radiation
• Stored 100-500 years
• 19401970: put in steel drums, dumped in ocean (still UK & Pakistan)
• 1970+: gov’t run landfills
• Stored for thousands of years
• Mostly spent fuel rods (240,000 yrs)
• Safety debate• Options:
– Keep onsight– Bury– Shoot into space– Bury in ocean floor– Bury in Antarctica– Change it into harmless
Decommissioning• Life span of a power plant = 15-40
years– Parts wear out, Fuel is spent– Plant is shut down
• Highly radioactive for 240,000 years
• Must store for 10 times the half-life– What can we do with them?
= time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a stable isotope
Half-time emitted Uranium 235 710 million yrs alpha, gammaPlutonium 239 24,000 yrs alpha, gamma
Half-LifeHalf-Life
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
• http://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=BE0FB49C-7C70-4C56-95F2-B3904BC9077F
• 10 min video on nuclear energy– Fission, fusion, overview
Uranium92U
238.02891
6
CCarbon12.011
How many protons?
How many electrons?
How many neutrons?
92 protons92 electrons146 neutrons
What is Radiation?
Pressurized Water Reactor
Boiling Water Reactor
Three Mile Island - 1979
• .008 sieverts over 7 days
• Remember 1,000 sieverts is radiation sickness
• 5,000 is death
http://maps.google.com/maps?um=1&hl=en&q=three%20mile%20island%20plant%20map&ndsp=20&safe=on&ie=UTF-8&sa=N&tab=il
Chernobyl - 1986
• 300 sieverts per hour
• 240 acute radiation sickness; 31 died within 3 months
• 100,000 people evacuated
• Some claim up to 985,000 deaths due to Chernobyl
Chernobyl Fallout
Japan
• 0.4 sieverts per hour• 70,000 people
evacuated• 140,000 told to stay
inside
CHERNOBYL
Then
And
Now