Ecology Chapter 16 Notes-Nuclear Energy
Atoms:
 Matter is made up of atoms
 All atoms are made up of three types of particles: Protons (+), Electrons (-), Neutrons
(no charge).
 Protons and Neutrons are found in the nucleus (located in the center)
 Electrons spin around the nucleus of an atom
 Each atom has a certain number of protons, electrons, and neutrons
o Atomic number is equal to the number of protons
o Proton number is equal to the number of electrons
o Atomic mass number are both the protons and neutrons
Radioactivity:
 Atoms of the same element having a different number of neutrons than normal are
called isotopes.
o Some isotopes are unstable
o Unstable atoms that decay are called radioactive atoms
 Marie Curie won a Nobel Prize in chemistry and physics for her work but
died of Cancer because of the discovery of radiation.
 Decay changes cause radiation to occur due to the emissions of
alpha, beta, and/or gamma rays
 A series of decay changes eventually stables the element and
stops the decaying process. When that occurs the element
becomes a different element
 Each time an element goes through a decaying process one halflife occurs. A half-life is the amount of time it takes for half of the
atoms in the radioactive element to decay
Energy
 Energy is required to keep protons and neutrons together in the nucleus of an atom.
 Scientists developed ways to release energy from atoms so we can use that energy for
electricity
1. Nuclear fission –splits the nucleus of an atom apart
o Uranium-235 is commonly used in fission reactions
o When Uranium -235 is split it produces 2 daughter nuclei, energy is formed,
and several more neutrons are released. This continues and a chain reaction
occurs
2. Nuclear fusion-(In Chapter17) occurs when two atomic nuclei fuse to become
one larger nucleus
o Can produce enormous energy (Same as the SUN), but scientists have not
learned how to control it, make it, nor use it efficiently.
 Nuclear reactors use nuclear fuel made up of 97% U-238 (not fissionable) and 3 % U-235
(fissionable)
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o Long rods are filled with pellets containing U-235 and the fuel rods are kept cool
with water.- The U-235 will only split when in captures a slow-moving neutron
o The speed is controlled by control rods made of Cadmium, Boron, or other
materials that absorb neutrons.
 Breeder Reactors use U-238 to absorb neutrons to make Pu-239 fissionable. (Not used
in USA because it is much more dangerous)
Radioactive Waste
 Radioactive exposure is measured in rems.
 Most American receive between 0.2-0.5 rems per year from background radiation-like
the Sun.
 Too much exposure can lead to diseases such as Cancer
 Types of Radioactive waste:
1. Large amount –high level waste
2. Medium amounts—Medium level waste
3. Low amount-Low-level waste
 Waste Disposal-very dangerous and very hard to dispose of because the half-lives can
last for 1000’s or millions of years.
o Pu-239 half-life 24,000 years
o U-235 half-life 7.4 x 108 years
Dangers of Nuclear Accidents
When the rods are too hot meltdown occurs-The process that involves the chain reaction going
out of control and melts the reactor core
 In April 1986 Chernobyl nuclear plant in Ukraine did meltdown-Killing lots of people and
making the area unfit for life even now
 The Earthquake and tsunami that hit Japan in Mar. 2011 caused the meltdown process
to begin there and at least 30 miles around that area is still unfit for life
o Workers risk their lives to go back into the affected area and to use Sea water to
stop the meltdown
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