Nuclear Changes Nuclear Energy

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Nuclear ChangesNuclear Energy An introduction

• Chapter 9

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Radioactivity

• Radioactive materials have an unstable nucleus
  that release one or more particles or energy
• Nuclear radiation refers to the released energy
  and matter.

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• Where does radiation come from?
• Radiation is generally produced when particles
  interact or decay
• A large contribution of the radiation on the
  earth is from the sun (solar) or from radioactive
  isotopes of the elements (terrestrial)
• Radiation is going through you at this very
  moment!

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Isotopes (a review)

• Whats an isotope?
• Two or more varieties of an element having the
  same number of protons but different number of
  neutrons. Certain isotopes are unstable and
  decay to lighter isotopes or elements.Deuterium
  and tritium are isotopes of hydrogen. In
  addition to the 1 proton, they have 1 and 2
  additional neutrons in the nucleus respectively.

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Nuclear Radiation

• As the radioactive nucleus decays, nuclear
  radiation leaves the nucleus and interacts with
  other matter.
• Types of nuclear radiation (4)
• 1. Alpha Particles (a)
• 2. Beta particles (b)
• 3. Gamma rays (g)
• 4. Neutron emission

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• 1. Alpha Particles a positively charged particle
  and has a large mass. (consists of 2 protons and
  2 neutrons).
• Do not travel far because of its size.
• Can barely travel through a piece of paper.

Radium R226
Radon Rn222

a (4He)
86 protons 136 neutrons
2 protons 2 neutrons
88 protons 138 neutrons
The alpha-particle (a) is a Helium nucleus.
Its the same as the element Helium, with the
electrons stripped off !
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• 2. Beta Particles negatively charged particle
  that has little mass
• Travels much faster than alpha particles
• Travel through 3mm of aluminum or 10 mm of
  woodbut are stopped because they lose energy
  fairly quickly.

Carbon C14
Nitrogen N14

e-
electron (beta-particle)
6 protons 8 neutrons
7 protons 7 neutrons
We see that one of the neutrons from the C14
nucleus converted into a proton, and an
electron was ejected. The remaining nucleus
contains 7p and 7n, which is a nitrogen nucleus.

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• Gamma Rays are not made of matter and do not
  have an electric charge
• Gamma Rays consist of electromagnetic energy
  called PHOTONS
• Have very high energycan travel through 60 cm of
  aluminum or 7 cm of lead
• Gamma Rays are more dangerous to living things
  than alpha or beta particles.

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Gamma particles (g)
In much the same way that electrons in atoms can
be in an excited state, so can a nucleus.
Neon Ne20
Neon Ne20

10 protons 10 neutrons(in excited state)
10 protons 10 neutrons(lowest energy state)
gamma
A gamma is a high energy light particle. It is
NOT visible by your naked eye because it is not
in the visible part of the EM spectrum.
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Gamma Rays
Neon Ne20
Neon Ne20

The gamma from nuclear decayis in the X-ray/
Gamma ray part of the EM spectrum(very
energetic!)
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Nuclear Radiation

• Neutron Emission The release of a neutron from a
  nucleusdoes not have any charge.
• Can travel much farther because they do not lose
  energy very quickly.
• Can travel through a 15 cm block of lead.

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Half-Life

• The half-life (h) is the time it takes for
  half the atoms of a radioactive substance to
  decay.
• For example, suppose we had 20,000 atoms of a
  radioactive substance. If the half-life is 1
  hour, how many atoms of that substance would be
  left after

10,000 (50)
1 hour (one lifetime) ?
5,000 (25)
2 hours (two lifetimes) ?
2,500 (12.5)
3 hours (three lifetimes) ?
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Predicting Age

• Scientists use the Half-Life of an object to
  determine its age.
• For example Potassium-40 decays to Argon-40, so
  the ratio of Potassium-40 to argon-40 is smaller
  for older rocks than it is for younger rocks.
• Scientists use Carbon-14 to date more recent
  materials like remains of an animal or parts of
  ancient clothing.

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Practicing Half-Life

• Radium 226 has a half-life of 1599 years. How
  long would it take seven-eighths of a radium-226
  sample to decay?
• Given half-life 1599 years
• Given fraction of sample decayed 7/8
• Unknown fraction of sample remaining
• Unknown total time of decay

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• 1. Calculate the fraction of radioactive sample
  remaining.
• Fraction of sample remaining 1 7/8 1/8
• 2. Calculate the number of half-lives
• Amount of sample remaining after one half-life
  ½
• Amount of sample remaining after 2 half-lives ¼
• Amount of sample remaining after 3 half-lives
  1/8
• 3 Half-lives are needed for one-eighth of the
  sample to remain undecayed.
• 3. Calculate the total time required for the
  radioactive decay.
• Total time of decay 3 half-lives x 1599 years
  4797 years

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Radioactive Dating Game

• Sign out a laptop
• Log in and open the Internet
• Go to phet.colorado.edu
• New Sims - PhET Simulations

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Nuclear Energy

• Basics of Nuclear Power Video Clip

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Brief History

• Nuclear energy was first discovered in 1934 by
  Enrico Fermi
• The first nuclear bombs were built in 1945 as a
  result of the Manhattan Project
• The first plutonium bomb (Trinity) was detonated
  on July 16, 1945
• The first uranium bomb was detonated over
  Hiroshima on August 6th 1945
• The second plutonium bomb was dropped on Nagasaki
  on August 9th 1945
• Electricity was produced with nuclear energy in
  1951.

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Fission History and Overview

• Discovered 1938 by Otto Hahn and Frittz
  Strassmann
• Presented in 1939 by Lise Meitner and Otto Frisch
• Research of Nuclear Fission began U.S. weapons
  program
• 1942 first controlled self sustaining fission
  reaction by Enrico Fermi
• Nuclear fission creates Electricity

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Fission Overview

• Fission is the process of splitting heavier
  nuclei into lighter nuclei
• Fission releases Energy
• The mass equivalent of 1kg of matter is more than
  the chemical energy of 22 million tons of TNT
• Neutrons released by fission can start a chain
  reactiona continuous series of nuclear fission
  reactions.

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Fission Today

• 435 Nuclear Power plants worldwide
• 1/6 of the worlds power is nuclear
• World Energy Consumption doubled by 2050
• World will turn to fission energy

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World Nuclear Power Plants How Stuff Works -
Nuclear Energy
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United States Nuclear Power Plants
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Nuclear Power in Northeast U.S.
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Japans Nuclear Power Problems
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Japans Power Plant Meltdown

• Japans Nuclear Emergency
• Efforts to cool down the nuclear reactor
• Concerns about Proximity to the Power plant

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Fusion Overview and History

• British Physicists in the 1940s and 50s housed
  ina hangar at Harwell a device called ZETA-Zero
  Energy Toroidal Assembly which was the first
  fusion based operating system
• Masked in the secrecy of the Cold War
• Fusion is the production of a thermonuclear
  reaction in a gas discharge
• Called fusion because it is based on fusing light
  nuclei such as hydrogen isotopes to release
  energy, similar to that which powers the sun and
  other stars.

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Fast Facts

• A vast, new source of energy
• Fuels are plentiful
• Inherently safe since any malfunction results in
  a rapid shutdown
• No atmospheric pollution leading to acid rain or
  the greenhouse effect
• Sunlight is energy released from fusion reactions
  in the sun.

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The Future is Fusion

• The sun is our greatest source of energythe sun
  uses fusion.
• The source of fusion is vastly abundant in our
  oceans (an isotope of hydrogen in water)
• The waste of fusion is helium, and there is no
  pollution of long term extent
• The price of fusion is estimated to be equivalent
  to that of fossil fuels
• Fusion can give us energy for millions of years

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Nuclear Waste
33
Most used Nuclear Waste Sites
34
Nuclear Waste

• Nuclear Waste has been accumulating since the
  mid-1940s and is currently in temporary storage
  at 131 sites in 39 states
• Nuclear waste remains highly radioactive for
  thousands of years.
• It will still be potentially harmful to humans
  long after the manmade containers holding the
  waste have disintegrated.

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Yucca Mountain

• Will become the nation's first long-term geologic
  repository for spent nuclear fuel and high-level
  radioactive waste that is currently stored at 126
  sites around the nation.
• Yucca Mountain is located in a remote desert on
  federally protected land within the secure
  boundaries of the Nevada Test Site in Nye County,
  Nevada. It is approximately 100 miles northwest
  of Las Vegas, Nevada.

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Nuclear Radiation Today
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Radiation

• You are exposed to radiation everyday
• Background Radiation nuclear radiation that
  arises naturally from cosmic rays and from
  radioactive isotopes in the soil and air
• We are adapted to survive low levels of this
  natural source of radiation
• Radiation is measured in rems or millirems

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What are the Possible Effects of Radiation?

• Inside Chernobyl - National Geographic Magazine
• Kasakhstan Fallout Video Clip
• Safety Videos
• Duck and Cover
• Living Under the Shadow of the Nuclear Umbrella
  Video Clip

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Radiation Exposure

• There are many occupations where people are
  exposed to higher levels of radiation.
• Nuclear radiation, health physics, radiology,
  radiochemistry, X-ray technology, MRI
• It has been decided that these occupations can be
  exposed to 5000 millirems annually plus regular
  background radiation.
• Exposure amounts will also depend on where a
  person lives.
• Exposure may increase based on some day-to-day
  activities as well

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Radiation Exposure

• Average annual radiation dose is 360 millirems
  per person. 300 from natural sources.
• Sleeping next to someone for 8 hours 2 mrems
• Exposure comes from the naturally radioactive
  potassium in the other person's body
• Coal plant, living within 50 miles .03 mrem
  There is much thorium and uranium in coal.
• Living within 50 miles of a nuclear power plant
  adds .009 mrem of exposure. Both figures are
  considered extremely low levels.
• Living in a masonry home 7 mrems Stone, brick
  and adobe have natural radioisotopes in them.
• Living on the Earth 200 mrems We are living in a
  sea of radon. It is made from the natural decay
  of uranium and thorium in the soil, left over
  from the creation of the solar system. Radon is a
  rare gas that diffuses out of soil and into the
  air. It contributes more than half of our
  background

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• Smoking up to 16,000 mrems The tobacco leaf acts
  like the absorbing surface of charcoal in a radon
  test kit. It collects long-lived isotopes of
  airborne radon, like lead-210 and polonium. Small
  portions of the lungs can get relatively whopping
  doses, compared to background levels.
• Porcelain teeth or crowns tenths of a rem
  Uranium is often added to these dental products
  to increase whiteness and florescence.
• Air Travel 1 mrem per 1000 miles 30,000 feet
  above the ground you're closer to the ionizing
  radiation (high-energy gammas well as particles)
  from the sun.
• Grand Central Station, NYC 120 mrem for
  employees Its granite walls have a high uranium
  content.
• Brazil Nuts This is the world's most radioactive
  food due to high radium concentrations 1000-times
  that of average foods.The US Capitol Building in
• Washington DC This building is so radioactive,
  due to the high uranium content in its granite
  walls, it could never be licensed as a nuclear
  power reactor site.

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Radiation Exposure

• 1500 increase in incidence of testicular and
  ovarian cancer in children on Navaho reservation
  in uranium mining area
• 500 increase in bone cancer in children affected
  by uranium
• 250 increase in leukemia (all ages) in the
  Navaho population
• 200 increase in each of the following non-cancer
  effects miscarriage, infant death, congenital
  defects, genetic abnormalities, learning
  disorders.

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• 400 increase in leukemia incidence in the
  population living downwind of the Pilgrim nuclear
  power reactor in Massachusetts in the first 5
  years after fuel was know to have leaked excess
  radioactivity.Baseline Disease in population
  before and after Pilgrim radioactive releases and
  comparison to upwind population.
• 300400 increase in lung cancer in the general
  population within the plume of the Three Mile
  Island accident releases
• 600700 increase in leukemia in the general
  population within the plume of Three Mile Island
  accident releases Baseline Disease in population
  upwind (out of the radiation plume path) is
  compared to disease in population downwind (in
  the pollution plume.)
• 50 increase in childhood cancer incidence in the
  Three Mile Island area for each 10 millirem
  increase in radiation exposure per year.

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• 500 increase in leukemia among Utah nuclear bomb
  test Downwinders
• 121 increase in thyroid cancer incidence in the
  same group
• 200 increase in breast cancer
• 700 increase in bone cancer
• a greater then 120 increase in thyroid cancer in
  those who drank milk laced with Iodine-131 from
  atmospheric nuclear weapons tests
• 200 increase in lung cancer in women who
  received radiation treatments for breast cancer
• 6696 increase in early cancer deaths due to
  background radiation

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Radiation Exposure in the U.S.
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Benefits of Nuclear Radiation

• Nuclear radiation is used in a controlled way
• Smoke Detectors use nuclear radiation in small
  amounts
• Alpha particles are charged and produce an
  electric current
• Detecting disease
• Ultrasound, CT scanning, Radioactive tracers

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Benefits in Medicine

• Radioactive tracers are short-lived isotopes that
  tend to accumulate in specfic cellshelp to find
  tumors.

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Benefits in Medicine

• Radiotherapy is used to treat cancers.
• Controlled doses of nuclear radiation are used to
  kill fast growing cells (also damages healthy
  cells)

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Uses in Agriculture

• Radioactive tracers are used to identify the flow
  of water and how it moves through the crops.
• Help to identify biochemical processes

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• NUCLEAR RADIATION A REVIEW

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Risks of Nuclear Radiation

• Nuclear radiation reacts with living tissue
  (alpha, beta, and gamma particles)
• They change the number of electrons in atoms of
  living materials
• Alpha particles stopped by layer of clothing
• Beta particles travel through a fraction of an
  inch in solids and liquids
• Gamma particles depends on energy can travel
  through several feet.

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Nuclear Radiation
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Risk and Amount of Radiation

• Small amount of nuclear radiation --- changes
  cannot be detected.
• Relationship with high levels of nuclear
  radiation and cancer
• Cancers related to radiation levels include
  leukemia, breast cancer, lung cancer, and stomach
  cancer