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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 =

From natural sources 310 millirem/year

From manmade sources

310 millirem/year

• 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 Radiation

www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

434 commercial reactors in 30 countries, producing 11% electricity

www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

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• https://www.youtube.com/watch?v=MGj_aJz7cTs – BBC ~4 mins

Nuclear Fission

http://www.youtube.com/watch?v=Pmy5fivI_4U

Nuclear Fusion

Nuclear 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 Reaction

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://safetyfirst.nei.org/safety-and-security/interactive-graphic

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 (~4.5 years)– each reactor produces about 20-30 tons yearly

• Currently stored in pools on site (~5 yrs) and then above ground dry 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-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