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

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.

Nuclear Fission

Nuclear Fusion

Nulear Change Nuclear 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 > 100,000,000 º C 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).

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 Radiation t

Nuclear Power Plant 1.a controlled nuclear fission chain reaction 2.heats water 3.produce high-pressure steam 4.that turns turbines 5.which turns generator and creates electricity.

Controlled Nuclear Fission Reaction cstl-cst.semo.edu/bornstein/BS105/ Energy%20Use%20- %203.ppt

t m/environm/nukequiz/nukequiz_ one/nuke_parts/reactor_parts.s wfhttp:// m/environm/nukequiz/nukequiz_ one/nuke_parts/reactor_parts.s wf

Nuclear Reactor: Summary CoreCore –35-40,000 fuel rods –Uranium oxide pellets 97% U 238 (nonfissionable), 3% U 235 Control rodsControl rods –Absorb neutrons ModeratorModerator –Slows down neutrons, maintains chain rxn. –Water [75%], solid graphite [20%], heavy water (D 2 O) [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 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-timeemitted Uranium million yrsalpha, gamma Plutonium yrsalpha, gamma Half-Life t

Decommissioning Life span of a power plant = 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 years 1940  1970: 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.

earch/assetDetail.cfm?guidAssetID=BE0F B49C-7C70-4C56-95F2-B3904BC9077Fhttp://streaming.discoveryeducation.com/s earch/assetDetail.cfm?guidAssetID=BE0F B49C-7C70-4C56-95F2-B3904BC9077F 10 min video on nuclear energy –Fission, fusion, overview

Uranium 92 U C Carbon How many protons? How many electrons? How many neutrons? 92 protons 92 electrons 146 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 Radioactivity t

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