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RadiationRadiation
All elements after bismuth are All elements after bismuth are radioactiveradioactive• Some others are, but only in certain forms Some others are, but only in certain forms
like carbon 14like carbon 14• Being radioactive means that the element Being radioactive means that the element
is naturally unstable and wants to fall is naturally unstable and wants to fall apart into smaller elements and radiationapart into smaller elements and radiation
There are three main types of nuclear There are three main types of nuclear radiation…radiation…
Alpha RadiationAlpha Radiation
αα or or Helium nucleiHelium nuclei Can be stopped by a piece of paper Can be stopped by a piece of paper
or a layer of skinor a layer of skin Not very dangerous for external Not very dangerous for external
contact, must be consumed to do contact, must be consumed to do harmharm
BetaBeta
ββ or or ElectronElectron Can be stopped by a piece of metal Can be stopped by a piece of metal
or wood beamor wood beam Can cause damage from external Can cause damage from external
exposure exposure
GammaGamma
γγ or or Piece of the electromagnetic Piece of the electromagnetic
spectrumspectrum Takes a few feet of concrete to stop Takes a few feet of concrete to stop
itit Will rip through the human body Will rip through the human body
Fission/FusionFission/Fusion
Fission = the splitting of an atomFission = the splitting of an atom• Ex. Uranium splits into barium and Ex. Uranium splits into barium and
kryptonkrypton Fusion = the combining of atomsFusion = the combining of atoms
• ex. Hydrogen fuse into heliumex. Hydrogen fuse into helium
Nuclear PowerNuclear Power
Nuclear power plants use fissionNuclear power plants use fission 3% U-235 is needed for a nuclear 3% U-235 is needed for a nuclear
power plantpower plant 11
00n + n + 235235U -> U -> 142142Ba + Ba + 9191Kr + 3 Kr + 3 1100nn
Control rods Control rods absorb neutronsabsorb neutrons The heat of the reactions turns water The heat of the reactions turns water
to steamto steam• The steam turns a turbine which makes The steam turns a turbine which makes
the power that goes to your housethe power that goes to your house
Is it safe?Is it safe?
Used fuel rods must be stored after Used fuel rods must be stored after useuse• Pu-239 is a radioactive waste productPu-239 is a radioactive waste product• It has a half life of 24,000 yearsIt has a half life of 24,000 years
Shielding = radiation absorbing Shielding = radiation absorbing materialmaterial
Moderator = slow down fast neutronsModerator = slow down fast neutrons Nuclear waste is stored deep under Nuclear waste is stored deep under
groundground
What if something does go wrong?What if something does go wrong?
ChernobylChernobyl• 1985, Chernobyl Ukraine1985, Chernobyl Ukraine• Engineers lost control of the plant during Engineers lost control of the plant during
a routine test by overriding the plant’s a routine test by overriding the plant’s safety mechanisms and withdrew most safety mechanisms and withdrew most of the control rods from the reactor coreof the control rods from the reactor core
• The reactor overheated and broke out The reactor overheated and broke out into a fire, this resulted in an into a fire, this resulted in an explosion…explosion…
Thyroid CancerThyroid Cancer
The explosion released radioactive The explosion released radioactive iodineiodine
KI pills are given out to dilute the KI pills are given out to dilute the amount of radioactive iodine in the amount of radioactive iodine in the bodybody
The beta radiation from the The beta radiation from the radioactive I initiates thyroid cancerradioactive I initiates thyroid cancer
Three Mile IslandThree Mile Island
1979, Harrisburg Pennsylvania1979, Harrisburg Pennsylvania Failures in the water based cooling Failures in the water based cooling
systemsystem The core heated to over 2200°CThe core heated to over 2200°C
• Half of it meltedHalf of it melted• The plant was thirty minutes from The plant was thirty minutes from
complete meltdowncomplete meltdown
WasteWaste
The waste from a nuclear power The waste from a nuclear power plant is still radioactive and will be plant is still radioactive and will be for hundreds of years.for hundreds of years.
It can be reused in the newest power It can be reused in the newest power plantsplants
It can be stored in salt minesIt can be stored in salt mines
Fusion PlantsFusion Plants
22H + 2H + 233He -> He -> 44He +2protonsHe +2protons Produces almost a million times as Produces almost a million times as
much energy as regular exothermic much energy as regular exothermic chemical reactionschemical reactions
Requires higher temperatures and Requires higher temperatures and confinementconfinement
Best source of Best source of 33He is the moonHe is the moon
Harnessing Nuclear Energy: The Harnessing Nuclear Energy: The BombBomb
Atomic bombs use 97% U-235Atomic bombs use 97% U-235 This high of a concentration can be This high of a concentration can be
detected by flying over a weapon detected by flying over a weapon plantplant
Missiles are stored underground or Missiles are stored underground or under waterunder water
Critical MassCritical Mass
The minimum amount of nuclide that The minimum amount of nuclide that provides the number of neutrons provides the number of neutrons needed to sustain a chain reactionneeded to sustain a chain reaction• 52 kg for U-23552 kg for U-235
PET ScansPET Scans
Positron emission tomography Positron emission tomography Nuclear MedicineNuclear Medicine
Medical ScansMedical Scans
MRI = magnetic Resonance ImagingMRI = magnetic Resonance Imaging CAT Scan = Computer Aided CAT Scan = Computer Aided
TomographyTomography
RadonRadon
Radon is an elemental gasRadon is an elemental gas It is in the air we breath, but does not It is in the air we breath, but does not
react or dissolve well so posses little react or dissolve well so posses little threatthreat
Radon loses alpha particles which do Radon loses alpha particles which do not go much more than 10 cmnot go much more than 10 cm
Daughter ElementsDaughter Elements
Radon decomposes in lead, Radon decomposes in lead, polonium, and bismuthpolonium, and bismuth
They attach to dust particles and can They attach to dust particles and can cause radiation damage to bronchial cause radiation damage to bronchial cellscells• This leads to lung cancerThis leads to lung cancer• It is the second leading cause of lung It is the second leading cause of lung
cancercancer