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POLY ENGINEERING3-3

DRILL

11 DEC 08

Copy tonight’s homework:

1. Impacts Journal #1 due Monday.2. Bring your protractor and compass to class

Monday (you should always bring them to class)3. Study for Friday Quiz on fossil fuels

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1. What are the fossil fuels?2. What makes them non-renewable?3. Explain the formation of Coal, Natural Gas, and Petroleum.4. What are the methods of extraction for fossil fuels?5. What are the three locations of natural gas?6. What are hydrocarbons? What is methane formula?7. What is mercaptan and why is it used?

Topic 1 Energy Sources – Fuels

QUIZ REVIEW

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8. Explain the operation of a seismic survey.9. Who are world top producers of natural gas?10. How are oil and natural gas transported?11. Why are fossil fuels processed prior to use?12. How is natural gas used in the home?13. What’s the difference between petroleum reservoirs and

reserves?14. What geographic region has largest oil reserves?

Topic 1 Energy Sources – Fuels

QUIZ REVIEW

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15. What 2 countries have the largest oil reserves?16. How many gallons are in a barrel of oil?17. How is a barrel of oil broken down in terms of end use?18. Is crude oil always same color/viscosity?19. What is distillation? Which fossil fuel is processed by it?20. Continent consuming greatest per capita oil?

Topic 1 Energy Sources – Fuels

QUIZ REVIEW

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Non-Renewable Fuels – Nuclear

1. Nucleus of a heavy element (e.g. Uranium) splits when bombarded by a free neutron

2. Two smaller atoms, 1-3 neutrons, plus energy3. Extra neutrons lead to chain reaction:

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Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle

Like coal, natural gas, and petroleum, Uranium (U) is an energy source that must be processed before use.

• Front End: preparing the fuel• Service Period: using fuel in reactor• Back End: safely manage, contain, reprocess/dispose

of spent fuel

Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Front End

1. Exploration:1) U is 500 times more abundant than gold2) Traces can be found everywhere – all rocks and

soils, rivers and oceans, food and human tissue2. Mining and Milling:

1) Mining – surface (strip) or underground mining2) Milling – grind up ore, use sulfuric acid to separate

U from waste rock – “yellow cake” U3O8

3. Conversion: U must be converted into a gas before it can be enriched (uranium hexafluoride – UF6 )

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Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle – Front End

Uranium Ore

Yellow Cake

UF6

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Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle – Front End

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Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle – Front End

Background Chemistry• The number of protons are the atomic number.

Uranium’s atomic number is 92• Atoms with different numbers of neutrons are called

isotopes – “same place”• Isotope U-235 is the only fissile isotope found in

nature

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Front End

4. Enrichment: increase concentration of U-235 and remove 85% of U-238Depleted Uranium: removed U-238, which includes .25% U-235, is used in metal to form yacht keels, radiation shielding, and (controversially) weapons as ammunition.

Keel

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Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle – Front End

5. Fuel Fabrication:1) UF6 converted to UO2 powder

2) Powder converted to pellets3) Pellets stacked in tubes4) These are nuclear fuel rods5) Groups of rods make up fuel assembly6) Hundreds of assemblies make up reactor core

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Non-Renewable Fuels – Nuclear

Radioactivity

1. Alpha particlesDo not penetrate skinHarmful is inhaled/ingested

2. Beta particlesDamage living cells, permanent nucleic changeOvaries/testes – damage passed to future generations

3. Gamma raysAs damaging as X-rayCauses mutation / cancer

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle

• Front End: preparing the fuel1. Exploration2. Mining and Milling3. Conversion4. Enrichment 5. Fabrication

• Service Period: using fuel in reactor • Back End: safely manage, contain, reprocess/dispose

of spent fuel

Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle – Service Period

27% Recycling

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Service Period

1. Electricity Generation1) Transport of radioactive materials2) In-core fuel management

Old fuel rods must be changed periodically (1/3 at a time)

2. Food and Agriculture1) FDA approved irradiation of food2) Kills bacteria, insects, and parasites

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Service Period

3. Nuclear medicine – Imaging1) Most medical imaging is anatomical – deals only

with structures2) Nuclear imaging shows physiological functioning

of organs3) Radiotracer injected into blood, inhaled, or

ingested4) “Gamma camera” detects energy given off

(PET scan – Positron Emission Tomography)

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Non-Renewable Fuels – Nuclear

3. Nuclear weapons1) Only two known uses of

nuclear weapons use – Hiroshima and Nagasaki during WW2

Nuclear Fuel Cycle – Service Period

“Fat Man” “Little Boy”

Nuclear Fuel Cycle – Service Period

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle

• Front End: preparing the fuel1. Exploration2. Mining and Milling3. Conversion4. Enrichment 5. Fabrication

• Service Period: using fuel in reactor Electricity, Medicine, Food and Agriculture, Military

• Back End: safely manage, contain, reprocess/dispose of spent fuel

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Back End

Two options for spent fuel: • Interim storage and final disposal• Reprocessing to recover usable portion

1. Interim Storage:1) Used fuel assemblies: hot and highly radioactive2) Stored in special ponds usually near reactor site3) Water is radiation barrier and cools fuel

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Back End

2. Reprocessing Reprocessing separates U and Pu from waste products – chop up fuel rods and dissolve them in acid to separate materials

1) U enrichmenta) Spent fuel contains ~96% of original Ub) U-235 reduced to 1%c) Therefore, send back to enrichment

2) Plutonium (Pu)a) Spent fuel contains ~1% radioactive Pub) Can be blended with enriched U for new fuelc) One of the most highly toxic elements known

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Back End

Waste1. Low-level waste – radioactive isotopes decay 10-50 years

1. Material used to handle highly radioactive parts of reactorCooling water pipes, radiation suits

2. Waste from medical uses3. Processing nuclear fuel generates depleted uranium (DU)

DU used as heavy metal2. High-level waste – radioactive isotopes decay >100,000 years

Material from core of reactor/decommissioned weapons

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Back End

Waste Disposal1. Low-level waste – radioactive isotopes decay 10-50 years

1. Temporary storage2. Standard disposal methods or reuse (heavy metal)

2. High-level waste – radioactive isotopes decay >100,000 years1. Currently only short-term storage exists2. Geologic disposal. Requires:

1. Absolutely stable geological formations2. Unprecedented stability of human institutions

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Non-Renewable Fuels – NuclearNuclear Fuel Cycle – Back End

Waste Disposal2. High-level waste – radioactive isotopes decay >100,000 years

Yucca Mountain• 80 miles northwest of Las Vegas• Only proposed site in U.S. for high-level waste storage• 77,000 tons capacity

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Non-Renewable Fuels – Nuclear

Nuclear Fuel Cycle – Back EndWaste Disposal

2. High-level waste – radioactive isotopes decay >100,000 yearsSpace Disposal

1. Limited capacity on rockets2. Rocket malfunction is possible

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Non-Renewable Fuels – Nuclear