Nuclear Fission
http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/fission.html
Fission products
http://www.euronuclear.org/info/encyclopedia/f/fissionproducts.htm
http://en.wikipedia.org/wiki/Fission_products
Nuclear Reactors (LWR’s)
http://reactor.engr.wisc.edu/power.html
Boiling water reactor (BWR) Pressurized water reactor (PWR)66% of US reactors are this type
American Nuclear Plants
http://www.nrc.gov/info-finder/reactor/
Radioactive wastes
http://www.uic.com.au/nip09.htm
Nuclear Waste depots
http://en.wikipedia.org/wiki/Radioactive_waste
Yucca Mountain
http://www.ocrwm.doe.gov/ymp/about/why.shtml
Nuclear Plants world wide
http://en.wikipedia.org/wiki/Radioactive_waste
Nuclear Fusionhttp://www.nuc.berkeley.edu/fusion/fusion.html
The reaction shown is the easiest to use, but D-D is also possible and is whatwe discussed in class, simply because it is easier to get the fuel and the mathis a bit easier. 2*MD= 4.027106 amu vs. 3He + p = (3.0160293+1.007825) amu + ~2MeV or 3H + n = (3.0160492+1.008665) amu + ~3MeV
NOTE: 3He and p are stable 3H has a half-life of 12 years, n of 15 minutes.This process produces no long-lived radioactivity directly, unlike fission.
ITER
http://www.iter.org/index.htm
Proposed 500MWFusion testFacility. First plasma expected2016.
“InternationalThermonuclearExperimental Reactor”
Inertial confinement
http://www.nuc.berkeley.edu/thyd/icf/target.html
Review for Final Exam
• Exam will have roughly 28 questions (i.e. slightly longer than previous exams, but you have much more time).
• Roughly half of the questions will cover material discussed since exam II, the rest will be roughly equally split between material covered on exam I and exam II
• Cover page will be on ONCOURSE some time next week.
Exam Review: Electricity
• Action of a battery, the concept of EMF
• Ohm’s law and power: V=IR P= IV
• Parallel and series circuits
• Faraday’s law and the generation of electricity
• Transformers
• The electric power grid: Generation, transmission, distribution
Summary of wind power
• Power available is roughly:– P=2.8x10-4 D2 v3 kW (D in m, V in m/s)
• i.e. you get much more power at higher wind speeds with larger turbines
• 3-blade turbines are more efficient than multi-blade, but the latter work at lower wind speeds.
• At higher wind speeds you need to “feather” the blades to avoid overloading the generator and gears.
• Typical power turbines can produce 1 -3.5 MW• You still find people question having even this
form of generator near where they live!
• Provide a source of DC electric power where the EMF is provided by absorbed light
• Need to absorb the light– Anti-reflective coating + multiple layers
• Need to get the electrons out into the circuit (low resistance and recombination)– Low disorder helps with both (hence crystal is more efficient than
amorphous)
• Record efficiency of 42.8% was announced in July 2007 (U. Delaware/Dupont).
• Crystalline Si: highest efficiency (typically 15-25%), poorer coverage, bulk material but only the surface contributes, expensive (e.g. NASA).
• Amorphous Si: lower efficiency (5-13%), less stable (can degrade when exposed to sunlight).
Synopsis of Solar Cells
• Chemical energy is converted directly to (DC) electrical energy.
• Similar to battery, but there is an input fuel, you’re not limited to an “on-board” chemical supply.
• Need electrodes, electrolyte, probably catalysts at the electrodes, and perhaps a reformer.
• Different types have different chemistry, electrolyte, operating temperatures, efficiencies, size, and robustness (etc.)
Synopsis of Fuel Cells
• Alkaline Acid– High efficiency (up to 60%), small, pure H2 fuel, very sensitive– Used by NASA (very expensive, so only they can afford it)
• Molten Carbonate– High efficiency (up to 60%), high temp operation (600C), bulky,
robust– Used in back-up generation/ Combined Heat/Power (CHP) modes
(Fuel Cell Energy)• Polymer Electrolyte Membrane (PEM)
– Lower temp operation (<100C), sensitive catalysts/ reformers needed, compact, lower efficiency (35%??)
– Leading candidate for transportation (Ballard)• Solid Oxide Fuel Cells
– Highest efficiency (70%), very high-T operation (1000C)– Still in development, not yet commercially viable
Synopsis of Fuel Cells
Nuclear Energy
• Binding energy of nuclei are MUCH LARGER than that of moelcules– E=mc2
• Radioactivity– Comes from both the primary reactions (especially in fission)
and activation by the neutrons released in the reactions (both).– Half life, decay modes, health hazards
• Fission:– Split a large nucleus into smaller nuclei PLUS 2 or 3 neutrons
after absorption of a SLOW neutron. – Energy release on the order of 0.74MeV/amu of fuel– Lots of such plants exist throughout the world, but there are
problems• Expensive to build (especially in the US)• Safety issues
Nuclear Energy (cont.)
• Waste from nuclear power:– Spent fuel and decommissioned parts are both
radioactive– Short-term issue (proliferation concerns) as well as
long-term• Fusion:
– Combine two light nuclei (typically isotopes of hydrogen) into one (typically He) with release of energy ~0.84MeV/amu (and neutron(s)).
– Fuel “waste” is much easier to deal with (less active, shorter half-lives)
– Decommissioning may be even a bigger problem than with fission