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Nuclear Energy. Nuclear Energy. ESCI 420 Spring 07. ESCI 420 Galen University Spring 2007. Nuclear Fission. Nuclear Fission: breaking apart atom’s nucleus to produce huge amounts of energy Strong Force responsible for holding together protons and neutrons in a nucleus
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Nuclear Energy Nuclear Energy ESCI 420 Spring 07 ESCI 420 Galen University Spring 2007
Nuclear Fission • Nuclear Fission: breaking apart atom’s nucleus to produce huge amounts of energy • Strong Force responsible for holding together protons and neutrons in a nucleus • Fission breaks apart this binding energy • Energy released is HUGE– 10 million times more than the energy released from the combustion of a carbon atom in coal
How it Works • Fissile atomic nucleus (U-235 or Pu-239) is bombarded by neutrons to break it apart and produce smaller nuclei as fission products • These neutrons then trigger further fusion, causing a controlled chain reaction • Energy released from broken bonds can be used to heat water, producing steam, and then drive a turbine that generates electricity • Water is usually used to moderate/cool reactors
Uranium Usage • In naturally-occurring Uranium, about 0.7% is U-235 and around 99.3% is U-238 • U-235 can be enriched to around 3%/97% • U-235 is fissile, U-238 is not • Current Light Water Reactors use up the U-235 and throw the rest away • Huge amount of nuclear waste being produced from leftover U-238 material
Nuclear Reprocessing • Nuclear Reprocessing Plants can recycle this nuclear waste to generate more energy • U-238 is irradiated with neutrons, undergoes the reaction U-238 + n Pu-239 • Pu-239 is a fissile material, so it can be re-used to create energy
Nuclear Reprocessing cont’d • Nuclear Reprocessing can recycle up to 95% of the nuclear waste from the original fuel rods • Reprocessing on a large scale is done in Britain, France, Russia, and Japan • Dramatically reduces the amount of nuclear solid waste in nuclear plants
Concerns about Nuclear Reprocessing • Reprocessing turns U-238 into useful Pu-239, which can be used to make nuclear weapons • U.S. currently forbids reprocessing on the grounds of anti-proliferation
Nuclear Accidents • Three Mile Island 1979 • Partial core meltdown • Worst accident in US commercial nuclear power generating history • Reactor was brought under control and radiation contained • Led to no deaths or injuries • Chernobyl 1986 • Steam explosions caused nuclear meltdown, core of reactor is destroyed • Huge cloud of radioactive fallout drifted over parts of Western Soviet Union, Eastern and Western Europe, the UK, Ireland, and Eastern North America • Estimates range from 30-6,000 deaths and illnesses as a result of the accident • Many attribute accident to bad design of power plant
Other Nuclear Concerns • Storage: Nuclear waste is currently contained and stored in plants, but running out of room • Yucca Mountain in Nevada – huge proposed nuclear waste storing repository about 90 miles from Las Vegas • Scheduled to be built in the next decade • Costs: Significantly more expensive to build and maintain • Requires huge amount of initial capital • Expensive waste management issue • Uranium mining: takes large amounts of energy to get usable uranium for reactors • Fossil-fuel intensive • Environmental justice issues
Proponents of Nuclear Power • Emits fewer greenhouse gases • Only by-product from plants is steam • Produces large amounts of electricity with less pollution than coal-powered plants • Reprocessing would potentially lower this pollution amount significantly • Abundant Supply • Uranium is relatively common • Supplies are estimated to last for hundreds to thousands of years
Is Nuclear Feasible? • Political ramifications • Public opinion • Research & Development • Initial investment