Nuclear Power ES 302 Nuclear Trivia Utilities develop in 1950’s Atomic Energy Commission – promised utilities cheap electricity Gov’t pay ¼ building

Nuclear Power

ES 302

Nuclear Trivia

Utilities develop in 1950’s

•Atomic Energy Commission – promised utilities cheap electricity•Gov’t pay ¼ building cost

•Price Anderson ActPrice Anderson Act•Liability protection

By ’96 : gov’t subsidized $2T

437 commercial reactors in 32 countries, producing 17% electricity

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

http://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/hsw/11945-nuclear-energy-introduction-to-nuclear-energy-video.htm

Nuclear Fission

Nuclear Fusion

Nulear ChangeNuclear Fission

• Bombs & power plants

• Big, unstable isotopes are struck by neutrons, which splits the isotope’s nuclei

• More neutrons “shoot out” to strike nearby isotopes, causing a chain reaction.

Nuclear Fusion

• Sun and stars, some weapons

• 2 small (light) isotopes are forced together– H + H = He

• Need temps > 100,000,000ºC

• Releases more E than fission

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

• 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


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

cstl-cst.semo.edu/bornstein/BS105/ Energy%20Use%20-%203.ppt


•http://www.animatedsoftware.com/environm/nukequiz/nukequiz_one/nuke_parts/reactor_parts.swf

Nuclear Reactor: Summary• CoreCore

– 35-40,000 fuel rods

– Uranium oxide pellets

• 97% U238 (nonfissionable), 3% U235

• Control rodsControl rods– Absorb neutrons

• ModeratorModerator

– Slows down neutrons, maintains chain rxn.

– Water [75%], solid graphite [20%], heavy water (D2O) [5%]

• CoolantCoolant

– Transfers heat to steam lines– Prevents meltdown

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– some remain dangerous for tens of thousands

of years

• How should we store this waste?

= 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




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?

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

Renewable or Non-Renewable?

What do you think?

• What are the pros and cons for nuclear energy?

• What should we do with radioactive waste?

Nuclear Reactor

• Domed building

• 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

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.

• http://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=BE0FB49C-7C70-4C56-95F2-B3904BC9077F

• 10 min video on nuclear energy– Fission, fusion, overview

http://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=BE0FB49C-7C70-4C56-95F2-B3904BC9077F




Uranium92U

238.02891

6

CCarbon12.011

How many protons?

How many electrons?

How many neutrons?

92 protons92 electrons146 neutrons

NUCLEAR CHANGE

• Isotopes vary by number of neutrons

• Spontaneously undergo change (vary neutrons)

• 3 types: radioactive decay

nuclear fission

nuclear fusion

• Radioactivity: Nuclear changes in which unstable (radioactive) isotopes emit particles & energy

• Radioactive decay continues until

• original isotope (radioisotope) stable isotope

RadioactivityRadioactivity




Radioactive Decay• Emits high energy radiation &/or particles

– Gamma radiation– Alpha particles– Beta particles

• The isotopes “shoot out” these particles, forming different isotopes

• The rate this change occurs at = half-life

Documents

Nuclear Power ES 302 Nuclear Trivia Utilities develop in 1950’s Atomic Energy Commission – promised utilities cheap electricity Gov’t pay ¼ building