Bio36_15_Nuclear - 1 2 1 2 3 4 5 1 2 6 1 2 7 1 Overview Ch....

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1 Overview • Ch. 15: Nuclear Power – History of Nuclear Power – How Nuclear Power Works – Nuclear Wastes – More Advanced Reactors – Future of Nuclear Power History of Nuclear Power • The Nuclear Age – Development of nuclear power plants after WWII • Curtailed after 1975 – Orders cancelled – 28 units have been shut down in U.S. • Current situation – 104 in operation in U.S. – 19% of U.S. electricity • Global picture – 439 in operation – 14% of world’s electricity Nuclear Share of Electrical Power How Nuclear Power Works • Control nuclear reactions – Energy released gradually as heat – Heat boils water to drive turbogenerators • Mass b energy – Fission: large atom split into 2 smaller atoms – Fusion: 2 small atoms combine into a larger atom Nuclear Fuel • Fission of uranium-235 – Isotope 235 U: mass # = 235 (protons + neutrons) – Only 0.7%; 99.3% 238 U – Enrichment separates 235 U from 238 U – Fission chain reaction • Nuclear bomb – Spontaneous fission of highly enriched 235 U – Self-amplifying Nuclear Reactors • Sustain a continuous chain reaction – Some 238 U converts to 239 Pu, also undergoes fission – Geometric pattern • Moderator – Slows neutrons to correct speed for fission – Light-water reactors in U.S. • Fuel rods – UO 2 loaded into long metal tubes – Radioactive spent-fuel elements replaced • Control rods – Neutron-absorbing material – Help moderate chain reaction Nuclear Power Plants • Boiling-water reactor – Circulate water through the reactor • Pressurized-water reactor – Superheated reactor water is circulated to boil other water – Two-thirds in U.S. 1 2 1 2 3 4 5 1 2 6 1 2 7 1
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2 • Loss-of-coolant accident (LOCA) – Crack in reactor vessel – Core overheats •Meltdown: core materials melt •Steam explosion •Backup cooling systems; housed in thick concrete containment building Nuclear Power vs. Coal Power • Fuel needed – Mining uranium vs. coal •Energy from 1 lb. uranium fuel = 50 tons coal energy environmental damage accidental deaths • CO 2 emissions – None from nuclear plants •Fossil fuels used: mining, enriching, construction, decommissioning of plants • SO 2 – No acid-forming pollutants from nuclear • Radioactivity – 100x more from coal • Solid wastes – 600,000 tons of ash from coal •Much reused for cement – 250 tons from nuclear •Highly radioactive wastes Nuclear Power vs. Coal Power
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This note was uploaded on 01/12/2012 for the course BIOLOGY 36 taught by Professor Teresafinnern during the Fall '11 term at Riverside Community College.

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Bio36_15_Nuclear - 1 2 1 2 3 4 5 1 2 6 1 2 7 1 Overview Ch....

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