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I. Mining Law of 1872 – encouraged mineral exploration and mining. 1. First declare your belief that minerals on the land. Then spend $500 in improvements, pay $100 per year and the land is yours 2. Domestic and foreign companies take out $2-$3 billion/ year 3. Allows corporations and individuals to claim ownership of U.S. public lands. 4. Leads to exploitation of land and mineral resources. http://seattlepi.nwsource.com/specials/mining/26875_mine11.shtml
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Energy APES I. Mining Law of 1872 encouraged mineral exploration
and mining.
1.First declare your belief that minerals on the land. Then spend
$500 in improvements, pay $100 per year and the land is yours
2.Domestic and foreign companies take out $2-$3 billion/ year
3.Allows corporations and individuals to claim ownership of U.S.
public lands. 4.Leads to exploitation of land and mineral
resources. "This archaic, 132-year-old law permits mining companies
to gouge billions of dollars worth of minerals from public lands,
without paying one red cent to the real owners, the American
people.And, these same companies often leave the unsuspecting
taxpayers with the bill for the billions of dollars required to
clean up the environmental mess left behind." -- Senator Dale
Bumpers (D-AR, retired) Nature and Formation of Mineral
Resources
A.Nonrenewable Resources a concentration of naturally occurring
material in or on the earths crust that can be extracted and
processed at an affordable cost. Non-renewable resources are
mineral and energy resources such as coal, oil, gold, and copper
that take a long period of time to produce. Nature and Formation of
Mineral Resources
1. Metallic Mineral Resources iron, copper, aluminum 2. Nonmetallic
Mineral Resources salt, gypsum, clay, sand, phosphates, water and
soil. 3. Energy resource: coal, oil, natural gas and uranium Nature
and Formation of Mineral Resources
B.Identified Resources deposits of a nonrenewable mineral resource
that have a known location, quantity and quality based on direct
geological evidence and measurements C.Undiscovered Resources
potential supplies of nonrenewable mineral resources that are
assumed to exist on the basis of geologic knowledge and theory
(specific locations, quantity and quality are not known) D.Reserves
identified resources of minerals that can be extracted profitably
at current prices. Other Resources resources that are not
classified as reserves. Ore Formation 1.Magma (molten rock) magma
cools and crystallizes into various layers of mineral containing
igneous rock. Ore Formation Hydrothermal Processes: most common way
of mineral formation A.Gaps in sea floor are formed by retreating
tectonic plates B.Water enters gaps and comes in contact with magma
C.Superheated water dissolves minerals from rock or magma D.Metal
bearing solutions cool to form hydrothermal ore deposits. E.Black
Smokers upwelling magma solidifies.Miniature volcanoes shoot hot,
black, mineral rich water through vents of solidified magma on the
seafloor.Support chemosynthetic organisms. Ore Formation Manganese
Nodules (pacific ocean) ore nodules crystallized from hot solutions
arising from volcanic activity.Contain manganese, iron copper and
nickel. Ore Formation 3. Sedimentary Processes sediments settle and
form ore deposits. A.Placer Deposits site of sediment deposition
near bedrock or course gravel in streams B.Precipitation: Water
evaporates in the desert to form evaporite mineral deposits. (salt,
borax, sodium carbonate) C.Weathering water dissolves soluble metal
ions from soil and rock near earths surface. Ions of insoluble
compounds are left in the soil to form residual deposits of metal
ores such as iron and aluminum (bauxite ore). Methods For Finding
Mineral Deposits
A.Photos and Satellite Images B.Airplanes fly with radiation
equipment and magnetometers C.Gravimeter (density) D.Drilling
E.Electric Resistance Measurement F.Seismic Surveys G.Chemical
analysis of water and plants Mineral Extraction Surface Mining:
overburden (soil and rock on top of ore) is removed and becomes
spoil. 1.open pit mining digging holes 2.Dredging scraping up
underwater mineral deposits 3.Area Strip Mining on a flat area an
earthmover strips overburden 4.Contour Strip Mining scraping ore
from hilly areas Subsurface Mining: 1.dig a deep vertical shaft,
blast underground tunnels to get mineral deposit, remove ore or
coal and transport to surface 2.disturbs less land and produces
less waste 3.less resource recovered, more dangerous and expensive
4.Dangers: collapse, explosions (natural gas), and lung disease
Environmental Impacts of Mineral Resources
A.Scarring and disruption of land, B.Collapse or subsidence C.Wind
and water erosion of toxic laced mine waste D.Air pollution toxic
chemicals E.Exposure of animals to toxic waste F.Acid mine
drainage: seeping rainwater carries sulfuric acid ( acid comes from
bacteria breaking down iron sulfides)from the mine to local
waterway Google earth Environmental Effects
Steps Environmental Effects Disturbed land; mining accidents;
health hazards; mine waste dumping; oil spills and blowouts; noise;
ugliness; heat Mining exploration, extraction Processing Solid
wastes; radioactive material; air, water, and soil pollution;
noise; safety and health hazards; ugliness; heat transportation,
purification, manufacturing Use Noise; ugliness thermal water
pollution; pollution of air, water, and soil; solid and radioactive
wastes; safety and health hazards; heat transportation or
transmission to individual user, eventual use, and discarding Fig.
14.6, p. 326 Percolation to groundwater Leaching of toxic
metals
Subsurface Mine Opening Surface Mine Runoff of sediment Acid
drainage from reaction of mineral or ore with water Spoil banks
Percolation to groundwater Leaching of toxic metals and other
compounds from mine spoil Leaching may carry acids into soil and
ground water supplies Fig. 14.7, p. 326 Scattered in
environment
Smelting Separation of ore from gangue Melting metal Conversion to
product Metal ore Recycling Surface mining Discarding of product
Fig. 14.8, p. 327 Scattered in environment A. Life Cycle of Metal
Resources (fig. 14-8)
Mining Ore A.Ore has two components: gangue(waste) and desired
metal B.Separation of ore and gangue which leaves tailings
C.Smelting (air and water pollution and hazardous waste which
contaminates the soil around the smelter for decades) D.Melting
Metal E.Conversion to product and discarding product Economic
Impact on Mineral Supplies
A.Mineral prices are lowbecause of subsidies: depletion allowances
and deduct cost of finding more B.Mineral scarcity does not raise
the market prices C.Mining Low Grade Ore: Some analysts say all we
need to do is mine more low grade ores to meet our need 1.We are
able to mine low grade ore dueto improved technology 2.The problem
is cost of mining and processing, availability of fresh
water,environmental impact Recycle; increase reserves by improved
mining
Mine, use, throw away; no new discoveries; rising prices Recycle;
increase reserves by improved mining technology, higher prices, and
new discoveries B Production Recycle, reuse, reduce consumption;
increase reserves by improved mining technology, higher prices, and
new discoveries C Present Depletion time A Depletion time B
Depletion time C Fig. 14.9, p. 329 Time Fig , p. 329 A. Mining
Oceans 1.Minerals are found in seawater, but occur in too low of a
concentration 2.Continental shelf can be mined 3.Deep Ocean are
extremely expensive to extract(not currently viable) A. Substitutes
for metals
1. Materials Revolution 2.Ceramics and Plastics 3.Some substitutes
are inferior (aluminum for copper in wire) 4.Will be difficult to
find substitutes for helium, manganese, phosphorus and copper
Evaluating Energy Sources
What types of energy do we use? 1. 99% of our heat energy comes
directly from the sun (renewable fusion of hydrogen atoms) 2.
Indirect forms of solar energy (renewable) wind hydro biomass Oil
and Natural Gas Coal Geothermal Energy Contour strip mining
Hot water storage Floating oil drilling platform Oil storage
Geothermal power plant Oil drilling platform on legs Pipeline Area
strip mining Oil well Pipeline Mined coal Drilling tower Gas well
Valves Pump Water penetrates down through the rock Underground coal
mine Water is heated and brought up as dry steam or wet steam
Impervious rock Natural gas Coal seam Oil Hot rock Water Water
Magma Fig , p. 332 Kilocalories per Person per Day
Society Kilocalories per Person per Day Modern industrial (United
States) 260,000 Modern industrial (other developed nations) 130,000
Early industrial 60,000 Advanced agricultural 20,000 Early
agricultural 12,000 Hunter gatherer 5,000 Primitive 2,000 Fig , p.
333 Hydropower, geothermal,
Nuclear power 6% Hydropower, geothermal, Solar, wind 7% Natural Gas
23% Biomass 12% Coal 22% Oil 30% Fig a, p. 333 World Nuclear power
7% Hydropower geothermal, solar, wind 5% Natural Gas 22%
Coal 22% Biomass 4% Oil 40% Fig b, p. 333 United States 20th
Century Trends 1. Coal use decreases from 55% to 22% 2. Oil
increased from 2% to 30% 3. Natural Gas increased from 0% to 25% 4.
Nuclear increased from 0% to 6% 100 Wood Coal 80 60 Natural gas Oil
40 Hydrogen Solar 20 Nuclear 1800
Contribution to total energy consumption (percent) Oil 40 Hydrogen
Solar 20 Nuclear 1800 1875 1950 2025 2100 Year Fig , p. 334
Evaluating Energy Sources
Evaluating Energy Resources; Take into consideration the following:
Availability net energy yield Cost environmental impact Electric
resistance heating (coal-fired plant) 0.4
Space Heating Passive solar 5.8 Natural gas 4.9 Oil 4.5 Active
solar 1.9 Coal gasification 1.5 Electric resistance heating
(coal-fired plant) 0.4 Electric resistance heating
(natural-gas-fired plant) 0.4 Electric resistance heating (nuclear
plant) 0.3 Fig a, p. 335 High-Temperature Industrial Heat
28.2 Surface-mined coal Underground-mined coal 25.8 Natural gas 4.9
Oil 4.7 Coal gasification 1.5 Direct solar (highly concentrated by
mirrors, heliostats, or other devices) 0.9 Fig b, p. 335 Gasoline
(refined crude oil) 4.1
Transportation Natural gas 4.9 Gasoline (refined crude oil) 4.1
Biofuel (ethyl alcohol) 1.9 Coal liquefaction 1.4 Oil shale 1.2 Fig
c, p. 335 Net Energy Net Energy total amount of energy available
from a given source minus theamount of energy used to get the
energy to consumers (locate, remove, process and transport) G. Net
Energy Ratio - ratio of useful energy produced to the useful energy
usedto produce it. Oil A.Petroleum/Crude Oil thick liquid
consisting ofhundreds of combustible hydrocarbons and small
concentrations of nitrogen, sulfur, and oxygen impurities.
B.Produced by the decomposition of dead plankton that were buried
under ancient lakes and oceans. It is found dispersed in rocks. Oil
Life Cycle 1:14 1. Primary Oil Recovery a. drill well
b.pump out light crude oil 1:14 Secondary Oil Recovery
a.pump water under pressure into a well to force heavy crude oil
toward the well b.pump oil and water mixture to the surface
c.separate oil and water d.reuse water to get more oil Tertiary Oil
Recovery a.inject detergent to dissolve the remaining heavy oil
b.pump mixture to the surface c.separate out the oil d.reuse
detergent Transport oil to the refinery (pipeline, truck, boat) Oil
refining heating and distilling based on boiling points of the
variouspetrochemicals found in the crude oil. (fractional
distillation in a cracking tower) Gases Gasoline Aviation fuel
Heating oil Heated crude oil Diesel oil
Naphtha Grease and wax Furnace Fig , p. 337 Asphalt Conversion to
product a.Industrial organic chemicals b.Pesticides c.Plastics
d.Synthetic fibers e.Paints f.Medicines g.Fuel . Location of World
Oil Supplies
1. 64% Middle East (67% OPEC 11 countries) a. Saudi Arabia (26%) b.
Iraq, Kuwait, Iran,(9-10% each) 2.Latin America (14%) (Venezuela
and Mexico) 3.Africa (7%) 4.Former Soviet Union (6%) 5.Asia (4%)
(China 3%) 6.United States (2.3%) we import 52% of the oil we use
7.Europe (2%) ALASKA CANADA UNITED STATES MEXICO
Arctic Ocean Prudhoe Bay Coal Beaufort Sea ALASKA Gas Trans Alaska
oil pipeline Arctic National Wildlife Refuge Oil Prince William
Sound High potential areas Gulf of Alaska Valdez CANADA Grand Banks
Pacific Ocean UNITED STATES Atlantic Ocean Fig , p. 338 MEXICO Oil
price per barrel ($)
70 60 50 40 Oil price per barrel ($) 30 20 (1997 dollars) 10 1950
1960 1970 1980 1990 2000 2010 Year Fig , p. 339 40 2,000 x 109
barrels total 30 (x 109 barrels per year)
Annual production 20 10 1900 1925 1950 1975 2000 2025 2050 2075
2100 Year World Fig a, p. 339 4 200 x 109 barrels total 1975 3
Undiscovered: 32 x 109 barrels
(x 109 barrels per year) Annual production Proven reserves: 34 x
109 barrels 2 1 1900 1920 1940 1960 2080 2000 2020 2040 Year United
States Fig b, p. 339 286% Coal-fired electricity Synthetic oil and
150% gas produced
from coal 150% 100% Coal 86% Oil 58% Natural gas 17% Nuclear power
Fig , p. 339 Advantages Disadvantages
Ample supply for 4293 years Need to find substitute within 50 years
Low cost (with huge subsidies) Artificially low price encourages
waste and discourages search for alternatives High net energy yield
Easily transported within and between countries Air pollution when
burned Low land use Releases CO2 when burned Moderate water
pollution Fig , p. 340 How long will the oil last
1. Identified Reserve will last 53 years at current usage rates
2.Known and projected supplies are likely to be 80% depleted within
42 to 93 years depending on usage rate US oil supplies are expected
to be depleted within 15 to 48 years depending on the annual usage
rate Heavy Oils Oil Shale fine grained sedimentary rock containing
solid organic combustible material called kerogenShale Oil kerogen
distilled from oil shale. a. could meet U.S. crude oil demand for
40 years at current usage rates (Colorado, Utah and Wyoming public
lands) Tar Sand mixture of clay sand and water containing bitumen
(high sulfur heavy oil) Fig , p. 340 Shale oil pumped to
surface
Mined oil shale Retort Conveyor Spent shale Above Ground Conveyor
Pipeline Shale oil storage Impurities removed Hydrogen added Crude
oil Refinery Air compressors Sulfur and nitrogen compounds Air
injection Shale layer Shale oil pumped to surface Underground Shale
heated to vaporized kerogen, which is condensed to provide shale
oil Fig , p. 341 Tar sand is mined. Tar sand is heated until
bitumen floats to the top.
Bitumen vapor Is cooled and condensed. Pipeline Impurities removed
Hydrogen added Synthetic crude oil Refinery Fig , p. 341 Advantages
Disadvantages
Moderate existing supplies High costs Low net energy yield Large
potential supplies Large amount of water needed to process Severe
land disruption from surface mining Water pollution from mining
residues Air pollution when burned CO2 emissions when burned Fig ,
p. 342 XI. Natural Gas Natural Gas is a mixture of 50-90% methane
(CH4) by volume; contains smaller amounts ofethane, propane, butane
and toxic hydrogen sulfide. B. Conventional natural gas - lies
above most reservoirs of crude oil C. Unconventional deposits -
include coal beds, shale rock, deep deposits of tight sands and
deep zones that contain natural gas dissolved in hot hot water Oil
and Natural Gas Coal Geothermal Energy Contour strip mining
Hot water storage Floating oil drilling platform Oil storage
Geothermal power plant Oil drilling platform on legs Pipeline Area
strip mining Oil well Pipeline Mined coal Drilling tower Gas well
Valves Pump Water penetrates down through the rock Underground coal
mine Water is heated and brought up as dry steam or wet steam
Impervious rock Natural gas Coal seam Oil Hot rock Water Water
Magma Fig , p. 332 XI. Natural Gas Gas Hydrates - an ice-like
material that occurs in underground deposits (globally) Liquefied
Petroleum Gas (LPG) - propane and butane are liquefied and removed
from natural gas fields. Stored in pressurized tanks. Liquefied
Natural Gas (LNG) - natural gas is converted at a very low
temperature (-184oC) Where is the worlds natural gas?
Russia and Kazakhstan - 40% Iran - 15% Qatar - 5% Saudi Arabia - 4%
Algeria - 4% United States - 3% Nigeria - 3% Venezuela - 3%
Advantages: 1. Cheaper than Oil 2. World reserves - >125
years
3. Easily transported over land (pipeline) 4. High net energy yield
5. Produces less air pollution than other fossil fuels 6. Produces
less CO2 than coal or oil 7. Extracting natural gas damages the
environment much less that either coal or uranium ore 8. Easier to
process than oil 9. Can be used to transport vehicles 10. Can be
used in highly efficient fuel cells Advantages Disadvantages
Ample supplies (125 years) Releases CO2 when burned High net energy
yield Methane (a greenhouse gas) can leak from pipelines Low cost
(with huge subsidies) Shipped across ocean as highly explosive LNG
Less air pollution than other fossil fuels Sometimes burned off and
wasted at wells because of low price Lower CO2 emissions than other
fossil fuels Moderate environ- mental impact Easily transported by
pipeline Low land use Good fuel for fuel cells and gas turbines Fig
, p. 342 Disadvantages: 1. When processed, H2S and SO2 are released
into the atmosphere 2. Must be converted to LNG before it can be
shipped (expensive and dangerous) 3. Conversion to LNG reduces net
energy yield by one-fourth 4. Can leak into the atmosphere; methane
is a greenhouse gas that is more potent than CO2. XII. Coal Coal is
a solid, rocklike fossil fuel; formed in several stages as the
buried remains of ancient swamp plants that died during the
Carboniferous period (ended 286 million years ago); subjected to
intense pressure and heat over millions of years. Coal is mostly
carbon (40-98%); small amount of water, sulfur and other materials
Three types of coal lignite (brown coal) bituminous coal (soft
coal) anthracite (hard coal) Carbon content increases as coal ages;
heat content increases with carbon content Increasing heat and
carbon content Increasing moisture content
Peat (not a coal) Lignite (brown coal) Bituminous Coal (soft coal)
Anthracite (hard coal) Heat Heat Heat Pressure Pressure Pressure
Partially decayed plant matter in swamps and bogs; low heat content
Low heat content; low sulfur content; limited supplies in most
areas Extensively used as a fuel because of its high heat content
and large supplies; normally has a high sulfur content Highly
desirable fuel because of its high heat content and low sulfur
content; supplies are limited in most areas Fig , p. 344 Coal
Extraction Subsurface Mining - labor intensive; worlds most
dangerous occupation (accidents and black lung disease Surface
Mining - three types 1. Area strip mining 2. contour strip mining
3. open-pit mining Oil and Natural Gas Coal Geothermal Energy
Contour strip mining
Hot water storage Floating oil drilling platform Oil storage
Geothermal power plant Oil drilling platform on legs Pipeline Area
strip mining Oil well Pipeline Mined coal Drilling tower Gas well
Valves Pump Water penetrates down through the rock Underground coal
mine Water is heated and brought up as dry steam or wet steam
Impervious rock Natural gas Coal seam Oil Hot rock Water Water
Magma Fig , p. 332 Why we need coal Coal provides 25% of worlds
commercial energy (22% in US). Used to make 75% of worlds steel
Generates 64% of worlds electricity Coal-Fired Electric Power
Plant
Coal is pulverized to a fine dust and burned at a high temperature
in a huge boiler. Purified water in the heat exchanger is converted
to high-pressure steam that spins the shaft of the turbine. The
shaft turns the rotor of the generator (a large electromagnet) to
produce electricity. . Coal-Fired Electric Power Plant
Air pollutants are removed using electrostatic precipitators
(particulate matter) and scrubbers (gases). Ash is disposed of in
landfills. Sulfur dioxide emissions can be reduced by using
low-sulfur coal. I. Worlds Coal Supplies
US - 66% of worlds proven reserves Identified reserves should last
220 years at current usage rates. Unidentified reserves could last
about 900 years . Pros and Cons of Solid Coal
Advantages Worlds most abundant and dirtiest fossil fuel, High net
energy yield Advantages Disadvantages
Ample supplies (225900 years) Very high environmental impact High
net energy yield Severe land disturbance, air pollution, and water
pollution Low cost (with huge subsidies) High land use (including
mining) Severe threat to human health High CO2 emissions when
burned Releases radioactive particles and mercury into air Fig , p.
344 Disadvantages: harmful environmental effects -mining is
dangerous (accidents and -black lung disease) -harms the land and
causes water pollution -Causes land subsidence -Surface mining
causes severe land disturbance and soil erosion -Surface mined land
can be restored - involves burying toxic materials, returning land
to its original contour, and planting vegetation (Expensive and not
often done) -Acids and toxic metals drain from piles of water
materials -Coal is expensive to transport -Cannot be used in sold
form in cars (must be converted to liquid or gaseous form)
-Dirtiest fossil fuel to burn releases CO, CO2, SO2, NO, NO2,
particulate matter (flyash), toxic metals and some radioactive
elements. -Burning Coal releases thousands of times more
radioactive particles into the atmosphere per unit of energy than
does a nuclear power plant -Produces more CO2 per unit of energy
than other fossil fuels and accelerates global warming. -A severe
threat to human health (respiratory disease) Clean Coal Technology
. Fluidized-bed combustion - developed to burn coal more cleanly
and efficiently. Use of low sulfur coal - reduces SO2 emission Coal
gasification uses coal to producesynthetic natural gas (SNG) . Coal
liquefaction - produce a liquid fuel - methanol or synthetic
gasoline Flue gases Coal Limestone Steam Fluidized bed Water Air
nozzles Air
Calcium sulfate and ash Fig , p. 345 Raw coal Remove dust, tar,
water, sulfur Recover sulfur Air or oxygen
Steam Raw gases Clean Methane gas 2C Coal + O2 2CO Pulverizer
Recycle unreacted carbon (char) CO + 3H2 CH4 + H2O Methane (natural
gas) Slag removal Pulverized coal Fig , p. 345 Advantages
Disadvantages
Large potential supply Low to moderate net energy yield Higher cost
than coal Vehicle fuel High environmental impact Increased surface
mining of coal High water use Higher CO2 emissions than coal Fig ,
p. 346 Clean Coal Technology Synfuels - can be transported by
pipeline inexpensively; burned to produce electricity; burned to
heat houses and water; used to propel vehicles. XIII. Nuclear
Energy A. Three reasons why nuclear power plants were developed in
the late 1950s: 1. Atomic Energy Commission promised electricity at
a much lower cost than coal 2. US Govt paid ~1/4 the cost of
building the first reactors 3. Price Anderson Act protected nuclear
industry from liability in case of accidents Gigawatts of
electricity
375 300 225 Gigawatts of electricity 150 75 1960 1970 1980 1990
2000 2010 2020 Year Fig a, p. 348 Gigawatts of electricity
35 30 25 20 Gigawatts of electricity 15 10 5 1960 1970 1980 1990
2000 2010 Year Fig b, p. 348 Why is nuclear power on the
decline?
B. Globally, nuclear energy produces only 17% of worlds electricity
(6% of commercial energy) -huge construction overruns -high
operating costs -frequent malfunctions -false assurances -cover-ups
by government and industry -inflated estimates of electricity use
-poor management -Chernobyl -Three Mile Island -public concerns
about safety, cost and disposal of radioactive wastes C. How a
Nuclear Reactor Works
Nuclear fission of Uranium-235 and Plutonium-239 releases energy
that is converted into high-temperature heat. This rate of
conversion is controlled. The heat generated can produce
high-pressure steam that spins turbines that generate electricity.
Small amounts of Radioactive gases Uranium fuel input (reactor
core)
Containment shell Waste heat Electrical power Emergency core
Cooling system Steam Control rods Useful energy 25 to 30% Turbine
Generator Heat exchanger Hot coolant Hot water output Condenser
Pump Pump Coolant Coolant passage Moderator Cool water input Black
Pump Waste heat Pressure vessel Water Shielding Waste heat Water
source (river, lake, ocean) Periodic removal and storage of
radioactive wastes and spent fuel assemblies Periodic removal and
storage of radioactive liquid wastes Fig , p. 346 Front end Back
end Fuel assemblies Spent fuel assemblies Reactor
(conversion of enriched UF6 to UO2 and fabrication of fuel
assemblies) Open fuel cycle today Prospective closed end fuel cycle
Fuel fabrication Interim storage Under water Enriched UF6
Plutonium-239 as PuO2 Spent fuel assemblies Enrichment UF6 Spent
fuel reprocessing Decommissioning of reactor Uranium-235 as UF6
High-level radioactive waste or spent fuel assemblies Conversion of
U3O8 to UF6 Uranium tailings (low level but long half-life)
Processed uranium ore Geologic disposal of moderate- and high-level
radioactive wastes Uranium mines and mills Ore and ore concentrate
(U3O8) Fig , p. 347 Front end Back end D. Light-water reactors
(LWR)
1. Core containing 35,000-40,000 fuel rods containing pellets of
uranium oxide fuel. Pellet is 97% uranium-238 (nonfissionable
isotope) and 3% uranium-235 (fissionable). 2.Control rods - move in
and out of the reactor to regulate the rate of fission 3. Moderator
- slows down the neutrons so the chain reaction can be kept going [
liquid water in pressurized water reactors; solid graphite or heavy
water (D2O) ]. 4. Coolant - water to remove heat from the reactor
core and produce steam Decommissioning Power Plants
1/3 of fuel rod assemblies must be replaced every 3-4 years. They
are placed in concrete lined pools of water (radiation shield and
coolant). A. Nuclear wastes must be stored for 10,000 years B.
After years of operation, the plant must be decommissioned by 1.
dismantling it 2. putting up a physical barrier, or 3. enclosing
the entire plant in a tomb (to last several thousand years)
Advantages Disadvantages
Large fuel supply High cost (even with large subsidies) Low
environmental impact (without accidents) Low net energy yield High
environmental impact (with major accidents) Emits 1/6 as much CO2
as coal Moderate land disruption and water pollution (without
accidents) Catastrophic accidents can happen (Chernobyl) Moderate
land use No acceptable solution for long-term storage of
radioactive wastes and decommissioning worn-out plants Low risk of
accidents because of multiple safety systems (except in 35 poorly
designed and run reactors in former Soviet Union and Eastern
Europe) Spreads knowledge and technology for building nuclear
weapons Fig , p. 349 Coal Nuclear Ample supply Ample supply of
uranium High net energy
yield Low net energy yield Low air pollution (mostly from fuel
reprocessing) Very high air pollution High CO2 emissions Low CO2
emissions (mostly from fuel reprocessing) 65,000 to 200,000 deaths
per year in U.S. About 6,000 deaths per year in U.S. High land
disruption from surface mining Much lower land disruption from
surface mining High land use Moderate land use Low cost (with huge
subsidies) High cost (with huge subsidies) Fig , p. 349 F.
Advantages of Nuclear Power:
1. Dont emit air pollutants 2. Water pollution and land disruption
are low G. Nuclear Power Plant Safety
1. Very low risk of exposure to radioactivity 2. Three Mile Island
- March 29, 1979; No. 2 reactor lost coolant water due to a series
of mechanical failures and human error. Core was partially
uncovered 3. Nuclear Regulatory Commission estimates there is a
15-45% chance of a complete core meltdown at a US reactor during
the next 20 years. 4. US National Academy of Sciences estimates
that US nuclear power plants cause 6000 premature deaths and 3700
serious genetic defects each year. Chernobyl Crane for moving fuel
rods Steam generator Cooling pond
Almost all control rods were removed from the core during
experiment. Automatic safety devices that shut down the reactor
when water and steam levels fall below normal and turbine stops
were shut off because engineers didnt want systems to spoil
experiment. Crane for moving fuel rods Emergency cooling system was
turned off to conduct an experiment. Steam generator Cooling pond
Turbines Radiation shields Reactor Water pumps Reactor power output
was lowered too much, making it too difficult to control.
Additional water pump to cool reactor was turned on. But with low
power output and extra drain on system, water didnt actually reach
reactor. Chernobyl Fig , p. 350 H. Low-Level Radioactive
Waste
1. Low-level waste gives off small amounts of ionizing radiation;
must be stored for years before decaying to levels that dont pose
an unacceptable risk to public health and safety : low-level waste
was put into drums and dumped into the oceans. This is still done
by UK and Pakistan 3. Since 1970, waste is buried in commercial,
government-run landfills. 4. Above-ground storage is proposed by a
number of environmentalists. : the NRC proposed redefining
low-level radioactive waste as essentially nonradioactive. That
policy was never implemented (as of early 1999). I. High-Level
Radioactive Waste
1. Emit large amounts of ionizing radiation for a short time and
small amounts for a long time. Must be stored for about 240,000 2.
Spent fuel rods; wastes from plants that produce plutonium and
tritium for nuclear weapons. J. Possible Methods of Disposal and
their Drawbacks
1. Bury it deep in the ground 2. Shoot it into space or into the
sun 3. Bury it under the Antarctic ice sheet or the Greenland ice
cap 4. Dump it into descending subduction zones in the deep ocean
5. Bury it in thick deposits of muck on the deep ocean floor 6.
Change it into harmless (or less harmful) isotopes 7. Currently
high-level waste is stored in the DOE $2 billion Waste Isolation
Pilot Plant (WIPP) near Carlsbad, NM. (supposed to be put into
operation in 1999) Up to 60 deep trenches dug into clay. As many as
20 flatbed trucks
deliver waste containers daily. Barrels are stacked and surrounded
with sand. Covering is mounded to aid rain runoff. Clay bottom Fig
b, p. 351 What covers waste Grass Topsoil Gravel Soil Compacted
clay Sand Gravel
Fig c, p. 351 Waste container 2 meters wide 25 meters high Several
steel drums
holding waste Steel wall Steel wall Lead shielding Fig a, p. 351
Storage Containers Fuel rod Primary canister Overpack container
sealed
Fig c, p. 352 Underground Buried and capped Fig d, p. 352 Ground
Level Unloaded from train Lowered down shaft
Fig a, p. 352 2,500 ft. (760 m) deep Personnel elevator Air
shaft
Nuclear waste shaft Fig b, p. 352 K. Worn-Out Nuclear Plants
1. Walls of the reactors pressure vessel become brittle and thus
are more likely to crack. 2. Corrosion of pipes and valves 3.
Decommissioning a power plant (3 methods have been proposed)
A. immediate dismantling B. mothballing for years C. entombment
(several thousand years) 4. Each method involves shutting down the
plant, removing the spent fuel, draining all liquids, flushing all
pipes, sending all radioactive materials to an approved waste
storage site yet to be built. Connection between Nuclear Reactors
and the Spread of Nuclear Weapons
1. Components, materials and information to build and operate
reactors can be used to produce fissionable isotopes for use in
nuclear weapons. Los Alamos Muon Detector Could Thwart Nuclear
Smugglers M. Can We Afford Nuclear Power?
1. Main reason utilities, the government and investors are shying
away from nuclear power is the extremely high cost of making it a
safe technology. 2. All methods of producing electricity have
average costs well below the costs of nuclear power plants. N.
Breeder Reactors 1. Convert nonfissionable uranium-238 into
fissionable plutonium-239 2. Safety: liquid sodium coolant could
cause a runaway fission chain reaction and a nuclear explosion
powerful enough to blast open the containment building. 3. Breeders
produce plutonium fuel too slowly; it would take years to produce
enough plutonium to fuel a significant number of other breeder
reactors. O. Nuclear Fusion 1. D-T nuclear fusion reaction;
Deuterium and Tritium fuse at about 100 million degrees 2. Uses
more energy than it produces
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