Nuclear fission is a reliable source of energy that provides 16% of the world's electricity through the fission of uranium-235 atoms. It works by thermal neutrons splitting unstable uranium nuclei, releasing energy and more neutrons to sustain a chain reaction. Modern nuclear power plants, such as pressurized water reactors, use the energy from fission to heat water and produce steam that drives electricity-generating turbines. While nuclear power produces little greenhouse gas emissions, it faces challenges from radioactive waste storage and public safety concerns that new reactor designs hope to address.

1. Nuclear Fission
ANIMOL .A

2. 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

3. 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

4. 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

5. Pressurized Water Reactor (PWR)
http://www.eas.asu.edu/~holbert/eee460/pwrdiag.gif
A common type of Light Water Reactor (LWR)

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

7. Energy Lifecycle of Nuclear Power
Energy Source
Contribution by
Mass
Conversion to EnergyEnergy 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

8. 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

9. Generation IV Reactors
neutron
spectrum
(fast/
thermal)
coolant
temperature
(°C)
pressure* fuel fuel cycle
size(s)
(MWe)
uses
Gas-cooled
fast reactors
fast helium 850 high U-238 +
closed, on
site
288
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
epithermal
fluoride
salts
700-800 low UF in salt closed 1000
electricity
& hydrogen
Sodium-
cooled fast
reactors
fast sodium 550 low
U-238 &
MOX
closed
150-500
500-1500
electricity
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 high
UO2
prism or
pebbles
open 250
hydrogen
& 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

10. 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

11. 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

12. 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