Phy107Spr06Lect33

Phy107Spr06Lect33 - E x a m 3 : W e d . A p r. 1 9 C o v e...

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1 Fri, Apr. 14, 2006 Phy107 Lecture 33 1 Exam 3: Wed. Apr. 19 Covers Quantum Physics, Solids, Nuclear Physics From last time… • Fission of heavy elements produces energy • Only works with 235 U, 239 Pu • Fission initiated by neutron absorption. • Fission products are two lighter nuclei, plus individual neutrons. • These neutrons cause other fission events: chain reaction Today: controlled fission and fusion reactions Fri, Apr. 14, 2006 Phy107 Lecture 33 2 Oil 37.5% Gas 21.1% Coal 21.8% Nuclear 6.0% Hydro 6.6% Traditional 6.4% Geothermal 0.12% Wind 0.04% Biomass 0.4% Solar 0.009% New renewables 0.57% Global energy production 2000 Fri, Apr. 14, 2006 Phy107 Lecture 33 3 Unpressurized steam reactor Fri, Apr. 14, 2006 Phy107 Lecture 33 4 Controlled Fission Reactors • The reactor in a nuclear power plant does the same thing that a boiler does in a fossil fuel plant – it produces heat. • Basic parts of a reactor: – Core ( contains fissionable material ) – Moderator ( slows neutrons down to enhance capture ) – Control rods ( controllably absorb neutrons ) – Coolant ( carries heat away from core to produce power ) – Shielding ( shields environment from radiation ) • 1,000 megawatt light-water reactor has a core with ~ 75 tons of uranium ~ 200 fuel assemblies. Fri, Apr. 14, 2006 Phy107 Lecture 33 5 The Moderator Slow neutrons are more likely to cause fission events Most neutrons released in the fission process have energies of about 2 MeV In order to sustain the chain reaction, the neutrons must be slowed down A moderator surrounds the fuel Collisions with the atoms of the moderator slow the neutrons down as some kinetic energy is transferred Most modern reactors use heavy water as the moderator
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Phy107Spr06Lect33 - E x a m 3 : W e d . A p r. 1 9 C o v e...

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