Nuclear Energy

Why nuclear? Power shortages Rising prices Emissions of gases Running out of oil Good option??

Brief History of Nuclear Power In The USA US Utility Companies Begin Development in late 1950s Support From Government: Atomic Energy Commission Subsidies Government Assumes Liability Slow/No Growth in US in Last 30 Years – fear based 103 Plants in US Generate About 21% of Electricity This May Change…. (decreasing use) Worldwide, 441 plants, 32 under construction. 17% of world’s energy

Nuclear Power Plants in the United States

Some Definitions…. *Fission: a large atom of one element is split to produce two different smaller elements (uranium -> by products, neutrons and energy) Fusion: two small atoms combine to form a larger atom of a different element (Hydrogens -> Helium + energy and neutron) Isotope: different (mass number) forms of the same element (uranium 235, 238 – differ in neutrons, same proton and electron #)

How Fission Works

Nuclear Fuel Of the two Uranium isotopes, U-235 readily undergoes fission Fuel for reactor Enriched Uranium (separating isotopes to choose for U-235 4% enrichment (4% U-235, 96% U-238 to prevent amplification of explosion) Highly enriched = spontaneous fission

The Light Water Nuclear Reactor Fuel rods: rods full of 235U pellets Moderator: fluid (water) coolant that slows down neutrons so neutrons are traveling at the right speed to trigger another fission rxn. Get hot during reactions. Control rods: (boron or cadmium) moderate rate of the chain reaction by absorbing neutrons

In the Core

Comparing Nuclear vs. Coal Power Plants Ample Supply Ample Uranium Supply Low Net Energy Yield High Net Energy Yield Very High Air Pollution Low Air Pollution High CO2 Emissions Low CO2 Emissions High Land Disruption Low Land Disruption High Land Use Moderate/Low Land Use Low Cost High Cost Base Load Power – best comparison is nuclear vs. coal

Comparing Coal and Nuclear Power

Concerns With Nuclear Power Radioactive emissions Radioactive wastes Disposal of radioactive wastes Nuclear power accidents Safety and nuclear power Economic problems with nuclear power

Some Definitions: Radioisotopes: unstable isotopes of the elements resulting from the fission process Radioactive emissions: subatomic particles (neutrons) and high-energy radiation (alpha, beta, and gamma rays) Radioactive wastes: materials that become radioactive by absorbing neutrons from the fission process

Radiation is Everywhere – Nuclear Power is Not the Only Source (or even a Major Source) Television Household Radon Airplane Flights Emissions From Coal Power Plants Medical X-Rays Radon

Radioactive Decay

What to do with the waste? It Depends…. Waste could be spent fuel rods Waste could be dismantled reactor parts Two Stages: Short-term containment (short-lived isotopes decay to a point where they are easier to deal with) Long-term containment (10000 year minimum!)

What to do with the waste? Siting (NIMBY) Transport Cost ($60 billion to 1.5 trillion) Yucca Mountain in southwestern Nevada = the nation’s nuclear waste repository (operational in 2010? Or 2015 Or NEVER)

Nuclear Accidents –Three Mile Island United States: Three-mile Island 1979 Harrisburg, PA Loss of coolant in reactor vessel Damage so bad, reactor shut down permanently Unknown amount of radiation released into atmosphere

Nuclear Accidents – Chernobyl Loss of water coolant perhaps triggered the accident. When the water-circulation system failed, the temperature in the reactor core increased to over 5,000 oF, causing the uranium fuel to begin melting and producing steam that reacted with the zirconium alloy cladding of the fuel rods to produce hydrogen gas. A second reaction between steam and graphite produced free hydrogen and carbon oxides. When this gas combined with oxygen, a blast blew off the top of the building, igniting the graphite. The burning graphite threw a dense cloud of radioactive fission products into the air.

Kidd of Speed

http://www.youtube.com/watch?v=7lkxKlFbmio&feature=related