NUCLEAR CHEMISTRY

By Mr M

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

SchematicsSchematics

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

Who uses it?Who uses it?

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…

ChernobylChernobyl

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

Other ApplicationsOther Applications

Sterilizing medical equipmentSterilizing medical equipment Dating fossilsDating fossils Teflon pots and pansTeflon pots and pans Smoke detectorsSmoke detectors Exit signsExit signs Radium paint for watchesRadium paint for watches