Nuclear Fission Hillary Call Outline Benefits of Nuclear

Nuclear Fission Hillary Call

Outline � Benefits of Nuclear Energy � How Fission Works � Nuclear Power Plant Basics � Overview of Uranium Fuel Cycle � Energy Lifecycle of Nuclear Power � Generation IV Reactors � Technical Challenges � Conclusions

Benefits of Nuclear Energy � Continuous, reliable supply of energy � Well-developed technology › 12, 700 reactor-years of commercial experience › Accounts for ~16% of world electricity generation � Extensive fuel supply › Breeder reactors › Fissile materials other than Uranium

How Fission Works � � � Water or other moderator slows neutrons, thermalizing them Thermal neutron collides with U 235 Unstable nucleus splits in two Energy and neutrons are released Reaction repeats

Pressurized Water Reactor (PWR) A common type of Light Water Reactor (LWR) http: //www. eas. asu. edu/~holbert/eee 460/pwrdiag. gif

Uranium Fuel Cycle http: //www. arevaresources. com/nuclear_energy/datagb/cyclerep. gif

Energy Lifecycle of Nuclear Power Energy Source Contribution by Mass Conversion to Energy Contribution Coal 0. 467 grams 0. 00676 KWHr/gram 0. 0031 KW-Hr Crude Oil 0. 32 grams 0. 011 KWHr/gram 0. 0035 KW-Hr Lignite 0. 234 grams 0. 0038 KWHr/gram 0. 00089 KW-Hr Natural Gas 0. 115 grams 0. 015 KWHr/gram 0. 00173 KW-Hr Hydro-Electricity 0. 00146 KW-Hr 1 0. 00146 KW-Hr Wood 0. 041 grams 0. 0042 KWHr/gram 0. 00017 Total 0. 0107 KW-Hr Based on 3090 MW Forsmark plant operating for 40 years. http: //nuclearinfo. net/Nuclearpower/The. Science. Of. Nuclear. Power

Challenges � Radioactive waste storage/disposal › Yucca Mountain › Reprocess spent fuel � Safety › Only fatalities from commercial nuclear power plant occurred at Chernobyl › Must overcome public fear

Generation IV Reactors neutron spectrum (fast/ thermal) coolant temperature (°C) pressure* fuel cycle size(s) (MWe) uses Gas-cooled fast reactors fast helium 850 high U-238 + closed, on site 288 electricity & hydrogen 50 -150** 300 -400 1200 electricity & hydrogen Lead-cooled fast reactors fast Pb-Bi 550 -800 low U-238 + closed, regional Molten salt reactors epithermal fluoride salts 700 -800 low UF in salt closed 1000 electricity & hydrogen Sodiumcooled fast reactors fast sodium 550 low U-238 & MOX closed 150 -500 500 -1500 electricity 250 hydrogen & electricity Supercritical thermal or water-cooled fast reactors water 510 -550 very high UO 2 open (thermal) closed (fast) Very high temperature gas reactors helium 1000 high UO 2 prism or pebbles open thermal http: //www. world-nuclear. org/info/inf 77. html * high = 7 -15 Mpa + = with some U-235 or Pu-239 ** 'battery' model with long cassette core life (15 -20 yr) or replaceable reactor module

Fast Breeder Reactors U-238 captures a neutron and transmutes to Pu-239 � Pu-239 is fissile like U-235 � Increases efficiency of uranium use >50 x � Could use up depleted uranium stockpiles & plutonium from dismantled weapons � http: //www. atomeromu. hu/mukodes/tipusok/gyorsreak-e. htm

Fast Breeder Reactors � 290 reactor-years of commercial experience � Monju (Japan) and Superphenix (France) � Not economically practical � More costly to construct � More difficult to operate � Proliferation dangers associated with plutonium

Conclusions � Nuclear fission is a viable energy source � It cuts down on CO 2 emissions, improving air quality � New designs have made nuclear power safer and more economically feasible � Issue of radioactive waste will need to be addressed