Transcript Chapter 16/17 RAD Guide

Chapter 16/17 RAD Guide
April 12, 2016
NUCLEAR ENERGY
Atomic Model
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Atomic Model (cont)
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Atomic consists of:
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Protons ( + charge)
Nuetrons (neutral charge)
Electrons (- charge)
Protons and neutrons makes the nucleus
Majority of atomic mass is in the nucleus
Electrons orbit the nucleus
Atomic Number & Mass Number
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Atomic number: the number of protons in an
atom.
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Example: if oxygen has 8 protons, what is
oxygen’s atomic number?
Mass number: the number of protons plus the
number of neutrons in an atom.
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We neglect electrons for mass number because
mass of electrons is negligible.
Isotopes
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Isotopes (cont)
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Atoms of the same element that have different
numbers of neutrons are called isotopes.
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This means that isotopes of the same element
will have different mass numbers.
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Note: the number of protons in isotopes are
always the same.
Radioactivity
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Unstable atoms decay, emitting particles and
energy from the nucleus.
After a series of decay changes, a radioactive
element becomes stable.
Types of Particles Emitted from
Unstable Nuclei (Radiation)
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Alpha particles (α): decay that gives off 2
protons and 2 neutrons
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Beta particles (β): decay that gives off an
electron, converting a neutron into a proton
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Gamma (γ) radiation: form of electromagnetic
radiation. A large burst of energy.
Question
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Do these emissions alter an element’s …
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Atomic number?
Mass number?
Half-Life
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The amount of time it takes for half of the
atoms in a sample of radioactive material to
decay.
Reactions and Reactors
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Nuclear Fission
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Energy holds the protons and neutrons in
an atom’s nucleus together.
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Question: what would happen if we were
to split the nucleus of an atom apart?
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Nuclear Fission: Reaction in which the
nucleus of a large atom is split into smaller
nuclei.
Uranium -235 Chain Reaction
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most commonly used in nuclear reactors.
Structure & function of nuclear power
plant.
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Fission of U-235 in reactor vessel 
heats H2O  steam  turns turbines 
energy stored in generator  used as
electricity
Water circulates between fuel rods,
acting as a coolant and slowing neutrons.
control rods control how fast or slow
reaction occurs
Nuclear Power Plant
Breeder Reactors
Radioactive Waste
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Harmful to living organisms
 Immediate effect: skin burns, anemia,
death
 Long term effect: changes in DNA,
leading to cancer & genetic mutations
Radioactive Waste
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High-level wastes
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Emit large amounts of radiation.
Uranium fuel rods, control rods, coolant water.
Medium/Low-level wastes
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large volume of this type of waste is generated.
Most common
Effects may not be immediately noticeable.
Nuclear Waste Disposal
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High level wastes
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Stored in tanks outside power plants
Tanks often leak, leading to contaminated site.
Low/medium level wastes
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Often buried
Enclosed and dropped into oceans.
Nuclear Waste Disposal
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Issues in finding permanent disposal method:
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Long half-lives
hazardous/poisonous.
Wastes must be sealed in containers that will
never corrode
Containers often leak into environment
Waste sites must be geologically stable.
Deep underground storage is highly expensive.
Nuclear Meltdown
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If the cooling and control systems in a reactor
core fail, the chain reaction becomes
uncontrollable and melts reactor core.
Nuclear Meltdown
Chernobyl Disaster
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Solar Energy
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The Sun
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Source of almost all the energy on Earth’s
surface
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Ecosystems
Water Cycle
Causes the winds to blow
Ecosystems
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Water Cycle
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Wind
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Thermonuclear Fusion
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Solar Energy
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Harnessing the sun’s energy to generate heat
and electricity.
Advantages
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renewable, nonpolluting.
Disadvantages
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Energy source is not constant
Equipment is not size and cost efficient.
Passive Solar Energy
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Passive: sun’s energy is
collected, stored, &
distributed naturally in
enclosed dwelling
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Not used to produce electricity,
but reduces the need for it.
Achieved through building
design and positioning.
Ex: Greenhouse
Passive Solar Energy (cont)
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Passive Solar Energy (summary)
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South facing windows
Building materials that absorb solar energy
Glass-enclosed areas
Dark colored walls and floors
Good insulation
Thick, heavy curtains or shutters.
Active Solar Energy
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Active: devices are used to
collect, store, and circulate
heat produced from solar
energy.
Types
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Flat-plate solar collectors
Photovoltaic cells
Flat-Plate Solar collectors
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Flat-Plate Solar Collectors
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Solar One in Mojave Desert, CA.
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Photovoltaic (PV) Cells
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Only solar energy device that produces
electricity directly.
Uses thin wafers of semiconductor material.
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Silicon or selenium
Structure:
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Two thin slices of semiconductor material joined.
Sunlight striking the cell causes electrons to move
from one slice to the other, resulting in an electric
current.
PV Cells (cont)
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PV Cell (cont)
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Uses
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Solar powered Calculators
Solar powered watch
Electricity for homes, industry, automobiles
Advantages
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Light weight
No wastes or pollutants
No moving parts
Do not consume any materials
Hydroelectric Energy
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Dams
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Flowing Water
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Water behind dam is directed at the turbine blades
Water pushes against the turbine blades, causing
them to turn. (kinetic energy to mechanical energy)
Mechanical energy of the turbine is transferred to
coils within a generator
The coils spin through a magnetic field, producing
sent electricity
Function of Dams
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Advantages of Dams
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Renewable
Controls flow of water
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Flood control
Navigation of Boats
Reservoirs
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Recreation areas (fish, boat, swim)
Store water (irrigation and home use)
Disadvantages of Dams
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Changed water depth and flow alters natural
plant & animal life
Shoreline can flood, leading to erosion &
change ecosystems
Fish caught in turbine blades
Prevent salmon from completing reproductive
cycle
Stored water released into downstream water
causes changes a rapid change in temp
Tidal Energy (still hydroelectricity)
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High and low tides cause turbines to turn in
both directions generating electricity.
Tidal Energy Disadvantages
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In most regions, the difference between high
and low tide is insufficient to power a
generator
Equipment damages surrounding wetlands
Affects local ecosystems.
Wind Energy
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Aerogenerator
Windmills that are
used to generate
electricity (wind
turbine generators)
Aerogenerators
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Winds causes blades to turn
energy is stored in generator
sent out as electricity
Types
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Blades on horizontal (like airplane)
Blades on vertical (like eggbeater)
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Used for calmer conditions
Wind Farms
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Advantages of Wind Power
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Renewable
Free
Unlimited
nonpolluting
Disadvantages of Wind Power
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DISADVANTAGES
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Not always windy enough
Wins farms Require a lot of land
Interferes with radio & TV signals
Impact wildlife
Ugly (?)
Geothermal Energy
Heat Source
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Radioactive decay of elements deep beneath
the ground.
This decay gives off heat
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lava, geysers steam vents, hot springs, &
bubbling mud.
Hot Rock Zones
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1.Hot water is pumped from deep underground
through a well under high pressure.
2.When the water reaches the surface, the pressure is
dropped, which causes the water to turn into steam.
3.The steam spins a turbine, which is connected to a
generator that produces electricity.
4.The steam cools off in a cooling tower and
condenses back to water.
5.The cooled water is pumped back into the Earth to
begin the process again.
Hot Rock Zones
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What are some advantages &
disadvantages to using geothermal?
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ADVANTAGES
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DISADVANTAGES
Not easy to find
Most areas have very little
geothermal heat at surface,
and it’s not worth extracting.
Hydrogen Sulfide gas
pollutes the air.
Minerals and salts corrode
pipes.
Lack local H2O supply for
steam production.
Recall: Thermonuclear Fusion
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Nuclear Fusion using Deuterium
Nuclear Fusion
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Recall: Occurs when 2 atomic nuclei fuse to
become one larger nucleus
The fuel for nuclear fusion reactions is
deuterium (H-2 isotope of hydrogen).
Fuel is readily available in seawater
Fusion produces much less waste than fission,
and produces enormous amounts of energy
However, scientists are still learning how to
harness this energy source efficiently.