Nuclear FissionHillary 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)

http://www.eas.asu.edu/~holbert/eee460/pwrdiag.gif

A common type of Light Water Reactor (LWR)

Uranium Fuel Cycle

http://www.arevaresources.com/nuclear_energy/datagb/cycle/cyclerep.gif

Energy Lifecycle of Nuclear Power

Energy Source Contribution by Mass

Conversion to Energy

Energy Contribution

Coal 0.467 grams 0.00676 KW-Hr/gram 0.0031 KW-Hr

Crude Oil 0.32 grams 0.011 KW-Hr/gram 0.0035 KW-Hr

Lignite 0.234 grams 0.0038 KW-Hr/gram 0.00089 KW-Hr

Natural Gas 0.115 grams 0.015 KW-Hr/gram 0.00173 KW-Hr

Hydro-Electricity 0.00146 KW-Hr 1 0.00146 KW-Hr

Wood 0.041 grams 0.0042 KW-Hr/gram 0.00017

Total     0.0107 KW-Hr

Based on 3090 MW Forsmark plant operating for 40 years.

http://nuclearinfo.net/Nuclearpower/TheScienceOfNuclearPower

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)

coolanttemperature

(°C)pressure* fuel fuel cycle

size(s)(MWe)

uses

Gas-cooled fast reactors

fast helium 850 high U-238 +closed, on

site288

electricity& hydrogen

Lead-cooled fast reactors

fast Pb-Bi 550-800 low U-238 +closed, regional

50-150**300-400

1200

electricity& hydrogen

Molten salt reactors

epithermalfluoride

salts700-800 low UF in salt closed 1000

electricity& hydrogen

Sodium-cooled fast

reactorsfast sodium 550 low

U-238 & MOX

closed150-500

500-1500electricity

Supercritical water-cooled

reactors

thermal or fast

water 510-550 very high UO2

open (thermal)

closed (fast)

1500 electricity

Very high temperature gas reactors

thermal helium 1000 highUO2

prism or pebbles

open 250hydrogen

& electricity

* 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

http://www.world-nuclear.org/info/inf77.html

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 >50x 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 CO2 emissions, improving air quality

New designs have made nuclear power safer and more economically feasible

Issue of radioactive waste will need to be addressed