The Atom and RadiationThe Atom and Radiation

Nuclear Radiation and an Nuclear Radiation and an Introduction to Electromagnetic Introduction to Electromagnetic

RadiationRadiation

Goals: To answer the following Goals: To answer the following questionsquestions

What is radiation?What is radiation? Where is radiation found?Where is radiation found? What is radiation used for?What is radiation used for?

Complete the survey on page 410. You Complete the survey on page 410. You should copy each statement in your should copy each statement in your notebook and indicate whether you feel notebook and indicate whether you feel the statement is true or false. We will the statement is true or false. We will revisit these at the end of the unit.revisit these at the end of the unit.

The Discovery of RadioactivityThe Discovery of Radioactivity

The German physicist W.K. Roentgen The German physicist W.K. Roentgen “accidentally” discovers a mysterious source of “accidentally” discovers a mysterious source of radiant energy that can pass through low density radiant energy that can pass through low density shields (like card board). He calls this shields (like card board). He calls this mysterious energy X-rays.mysterious energy X-rays.

Further research showed that X-rays cannot Further research showed that X-rays cannot pass through everything, particularly high pass through everything, particularly high density materials like lead and bone.density materials like lead and bone.

Roentgen takes the first X-rays of his wife’s Roentgen takes the first X-rays of his wife’s hand to present to his colleagues.hand to present to his colleagues.

The Discovery of RadioactivityThe Discovery of Radioactivity

The French physicist Henri Becquerel takes interest in The French physicist Henri Becquerel takes interest in Roentgen's X-rays. He investigated whether certain Roentgen's X-rays. He investigated whether certain minerals could emit X-rays. He experiments with minerals could emit X-rays. He experiments with Uranium and a photographic plate (develops upon Uranium and a photographic plate (develops upon exposure to light).exposure to light).

Another accident happens…Becquerel becomes Another accident happens…Becquerel becomes frustrated with his research, wraps the photographic frustrated with his research, wraps the photographic plate in black paper (to prevent light exposure), throws it plate in black paper (to prevent light exposure), throws it in his desk drawer with a piece of Uranium on top and in his desk drawer with a piece of Uranium on top and closes it up.closes it up.

What do you know??? A few days later, Becquerel What do you know??? A few days later, Becquerel discovers that the photographic plate has been exposed discovers that the photographic plate has been exposed while sitting in his dark drawer.while sitting in his dark drawer.

The Discovery of RadioactivityThe Discovery of Radioactivity

What Becquerel inadvertently discovered What Becquerel inadvertently discovered was was radioactivityradioactivity, the spontaneous , the spontaneous emission of nuclear radiation.emission of nuclear radiation.

Soon after, Becquerel's colleagues, Marie Soon after, Becquerel's colleagues, Marie Curie and her husband Pierre discover two Curie and her husband Pierre discover two other radioactive elements: polonium and other radioactive elements: polonium and radium.radium.

What is Radioactivity?What is Radioactivity?

RadioactivityRadioactivity: the spontaneous emission of : the spontaneous emission of nuclear radiation.nuclear radiation.

We now know that there are two categories of We now know that there are two categories of radiation:radiation: Non-ionizing radiationNon-ionizing radiation – low-energy radiation that – low-energy radiation that

transfers energy to matter transfers energy to matter usually only harmful in large amountsusually only harmful in large amounts

Ionizing radiationIonizing radiation – high-energy radiation that can – high-energy radiation that can eject electrons from atoms/molecules to form highly eject electrons from atoms/molecules to form highly reactive ions and can cause serious cell damage reactive ions and can cause serious cell damage

exposure should be limited.exposure should be limited.

Concerns…..Concerns…..

But radiation is all around us…the But radiation is all around us…the question is, should we be concerned about question is, should we be concerned about our safety?? Are we in danger of serious our safety?? Are we in danger of serious exposure to radiation?exposure to radiation?

Forms of RadiationForms of Radiation

RadiationRadiation comes in several forms as shown in comes in several forms as shown in the electromagnetic spectrum below; but not all the electromagnetic spectrum below; but not all forms are represented hereforms are represented here

Types of RadiationTypes of Radiation

Three main types Three main types (from the 2 categories)(from the 2 categories) : :1. Non-ionizing electromagnetic radiation 1. Non-ionizing electromagnetic radiation

RadioRadioMicroMicroInfraredInfraredVisibleVisiblelow energy UVlow energy UV

2. Ionizing electromagnetic radiation 2. Ionizing electromagnetic radiation High UVHigh UVX-rays X-rays Gamma raysGamma rays

3. Ionizing atomic particle radiation 3. Ionizing atomic particle radiation radioactive elementsradioactive elements

Why are some elements radioactive? To Why are some elements radioactive? To answer this question, you must answer this question, you must understand a little about atomic structure.understand a little about atomic structure.

All matter can be broken down into atoms:All matter can be broken down into atoms:

An atom is An atom is composed of three composed of three parts:parts:

1.1. ProtonsProtons

2.2. Neutrons Neutrons

3.3. ElectronsElectrons

Parts of the AtomParts of the Atom

A A protonproton is a positively charged particle is a positively charged particle that is located in the center of an atom. All that is located in the center of an atom. All atoms of an element have the SAME atoms of an element have the SAME number of protonsnumber of protons

A A neutronneutron is a particle with no charge and is a particle with no charge and is also located in the center of an atom.is also located in the center of an atom.

An An electronelectron is a negatively charged is a negatively charged particle that orbits around the protons and particle that orbits around the protons and neutrons.neutrons.

Parts of the AtomParts of the Atom

The center of the atom where the protons and The center of the atom where the protons and neutrons are located is called the neutrons are located is called the nucleusnucleus..

NameName LocationLocation ChargeCharge

ProtonProton NucleusNucleus +1+1

ElectronElectron Outside Outside NucleusNucleus

-1-1

NeutronNeutron NucleusNucleus 00

• The Number of Protons is the Atomic Number (found on the periodic table)

• Mass of an atom is the number of Neutrons plus number of Protons

• Mass Atom = Protons + Neutrons• Notation

C12

6

Mass #Symbol of element

Atomic #

E.g.

EAZ

Symbol of element

number p + number n

number p

Element Protons Neutrons Mass # Symbol

KK 3939 K K

NitrogenNitrogen 1414 N N

AlAl 2727 Al Al

HeHe 44 He He

LithiumLithium 77 Li Li

SodiumSodium 2323 Na Na

CaCa 4040 Ca Ca

NeNe 2020 Ne Ne

ZincZinc 6565 Zn Zn

SS 3232 S S

19

7

13

2

3

11

20

10

30

16

19 20 39

7 7 14

13 14 27

2 2 4

3 4 7

11 12 23

20 20 40

10 10 20

30 35 65

16 16 32

IsotopesIsotopes

While all atoms of the same element must have While all atoms of the same element must have the same number of protons, they do not all the same number of protons, they do not all have to have the same number of neutrons. have to have the same number of neutrons. This makes some atoms of the same element This makes some atoms of the same element heavier than others. These are referred to as heavier than others. These are referred to as isotopes:isotopes:

Isotope Isotope – Atom of the same element (same # – Atom of the same element (same # protons) but with different Mass Number due to protons) but with different Mass Number due to varying numbers of neutronsvarying numbers of neutrons

Element Protons Neutrons Mass # Symbol

LiLi 33 44 77 Li Li

LiLi 88 Li Li

66 1212 C C

66 1313 1313 C C

66 1414 1414 C C

44 99 99 B B

66 1111 1111 B B

11 11 11 H H

11 22 22 H H

11 33 33 H H

3

3

6

6

6

5

5

1

1

1

3 5

C

C

C

7

12

7

5

5

B

B

H

HH

6

8

8

0

1

2

Isotopes Isotopes (cont.)(cont.)

Some isotopes are stable and others are Some isotopes are stable and others are unstable. This is where radioactivity comes in.unstable. This is where radioactivity comes in.

A stable isotope is not radioactive, but an A stable isotope is not radioactive, but an unstable isotope is!unstable isotope is!

Ex. Ex. 12C is stable12C is stable 13C is stable13C is stable 14C is radioactive14C is radioactive Radioactive elements will emit radiation until Radioactive elements will emit radiation until

they become a stable isotope.they become a stable isotope.

Emitted radiationEmitted radiation

This emitted radiation can be one of three This emitted radiation can be one of three types:types:

Alpha ( Alpha ( 44 α or α or 44 He He )– heavy particle )– heavy particle radiation (easily blocked because its so radiation (easily blocked because its so big). big).

Beta ( Beta ( 00 β or β or 0 0 ee )– particle radiation smaller )– particle radiation smaller than alphathan alpha

Gamma ( Gamma ( 0 0 γ )– high energy radiation γ )– high energy radiation

22

-1 -1

0

Alpha and Beta cause radioactive elements to Alpha and Beta cause radioactive elements to change to a new element.change to a new element.

Gamma causes no change in the radioactive Gamma causes no change in the radioactive element.element.

Emitted radiationEmitted radiation

Every Element has Isotopes – the amount of each isotope is fixedEvery Element has Isotopes – the amount of each isotope is fixed Ex. UraniumEx. Uranium

Which isotope of Uranium is used to make an atomic bomb?Which isotope of Uranium is used to make an atomic bomb? Complete the Assignment in your notebook:Complete the Assignment in your notebook:

Pg. 426-427 #2, 4, 17, 18, 21 and 24Pg. 426-427 #2, 4, 17, 18, 21 and 24MassMass AbundanceAbundance

238238 99.28%99.28%

235235 0.71%0.71%

234234 0.0054%0.0054%

Radiation ExposureRadiation Exposure

Naturally occurring radioisotopes provide a Naturally occurring radioisotopes provide a constant small dose of radiationconstant small dose of radiation

Radioactive isotopes constantly decay, Radioactive isotopes constantly decay, releasing alpha, beta and/or gamma releasing alpha, beta and/or gamma radiation. radiation.

This constant, inescapable radiation is This constant, inescapable radiation is called called background radiationbackground radiation..

Natural backgroundNatural background radiation: radiation:

- Outer space- Outer space All forms of electromagnetic radiationAll forms of electromagnetic radiation

- Ground water, rocks, soil - Ground water, rocks, soil contain Uranium and Thoriumcontain Uranium and Thorium

- Atmosphere - Atmosphere contains radoncontains radon

- Food and Environment- Food and Environment like C-14 and potassium like C-14 and potassium

Manmade backgroundManmade background radiation: radiation: Fallout (nuclear weapons testing)Fallout (nuclear weapons testing) Airplane flightsAirplane flights Released from Released from

burning fossil fuels burning fossil fuels nuclear power plantsnuclear power plants miningmining making making

cement cement concrete concrete sheet rocksheet rock

Two units are used to measure radiation:Two units are used to measure radiation:RadRad measures the absorbed dose of measures the absorbed dose of

radiationradiationRemRem measures the ionizing effect of the measures the ionizing effect of the

radiationradiation

Average U.S. individual receives 0.360 Average U.S. individual receives 0.360 rem per year.rem per year.

About 0.300 rem of this is from natural About 0.300 rem of this is from natural sourcessources

U.S. limit for background radiation in a U.S. limit for background radiation in a given area is 0.500 rem.given area is 0.500 rem.

U.S. safe exposure in the work U.S. safe exposure in the work environment is 5.000 rem.environment is 5.000 rem.

How much is safe?How much is safe? Ionizing radiation breaks bonds in molecules Ionizing radiation breaks bonds in molecules

within the body. At low exposure levels, within the body. At low exposure levels, your body can fix the minimal damage. your body can fix the minimal damage. Higher exposure levels that your body Higher exposure levels that your body cannot fix will lead to damaged DNA, causing cannot fix will lead to damaged DNA, causing mutations (tumors and birth defects)mutations (tumors and birth defects)

Copy the dosage chart on page 433 into your notebook

AlphaAlphaRadioactive isotopes decay until a stable Radioactive isotopes decay until a stable

nucleus can be formed. What happens nucleus can be formed. What happens when radioactive isotopes decay?when radioactive isotopes decay?

Many elements release alpha radiation:Many elements release alpha radiation:

226226 Ra Ra 44 He + He + 222222 Rn Rn

(radium)(radium) (alpha particle) (Radon)(alpha particle) (Radon)

As these radioactive isotopes decay, an As these radioactive isotopes decay, an alpha particle is released and a new alpha particle is released and a new element is formed.element is formed.

8686228888

BetaBeta

Many elements release beta radiation:Many elements release beta radiation:

222222 Rn Rn 00 e + e + 222222 Fr Fr

(radon)(radon) (beta particle) (Francium)(beta particle) (Francium)

As these radioactive isotopes decay, a As these radioactive isotopes decay, a beta particle is released and a new beta particle is released and a new element is formed.element is formed.

8686 -1-1 8787

GammaGamma

In addition to releasing a radiation particle In addition to releasing a radiation particle (alpha or beta), most radioactive decay is (alpha or beta), most radioactive decay is accompanied by the release of gamma accompanied by the release of gamma radiation too. Remember, gamma radiation too. Remember, gamma radiation is just energy; it is not a particle, radiation is just energy; it is not a particle, so it does not cause the element to so it does not cause the element to change its identity.change its identity.

How do you determine the new How do you determine the new element made after radioactive decay?element made after radioactive decay?

1.1. Identify the starting element and write the Identify the starting element and write the symbol.symbol.

2.2. Identify the type of radiation released.Identify the type of radiation released.

3.3. Subtract the two upper left numbers to find the Subtract the two upper left numbers to find the mass of the new element formed.mass of the new element formed.

4.4. Subtract the two lower left numbers to find the Subtract the two lower left numbers to find the atomic number of the new element formed.atomic number of the new element formed.

5.5. Look up the new atomic number on the Look up the new atomic number on the periodic table to find the new element made.periodic table to find the new element made.

RadonRadon Produced as Uranium in the soil decays. Produced as Uranium in the soil decays.

Uranium decays to produce radon gas:Uranium decays to produce radon gas: When this gas is inhaled, it further decays in When this gas is inhaled, it further decays in

your lungs into Polonium, Bismuth and Lead your lungs into Polonium, Bismuth and Lead (these heavy metals cannot be exhaled).(these heavy metals cannot be exhaled).

The alpha radiation is being released into your The alpha radiation is being released into your body, causing cell damage.body, causing cell damage.

Complete the Assignment in your notebook:Complete the Assignment in your notebook: Pg. 446-447 # 1, 2, 4, 5, 8, 13, 23 and 24Pg. 446-447 # 1, 2, 4, 5, 8, 13, 23 and 24

Half-LifeHalf-Life

Radioactive isotopes change Radioactive isotopes change what they are as they decay and what they are as they decay and release radiation.release radiation.

Scientists call the amount of Scientists call the amount of time it takes for half of a time it takes for half of a radioactive sample to decay a radioactive sample to decay a half lifehalf life..

1414C has a half life of 5,730 years.C has a half life of 5,730 years. 66

This means that if we started This means that if we started with 100 grams of with 100 grams of 1414C, only 50 C, only 50 grams of grams of 1414C would remain after C would remain after 5,730 years have passed. The 5,730 years have passed. The other 50 grams will have turned other 50 grams will have turned into into 1414N as a beta particle is N as a beta particle is released.released.

66

66

77

How long does it take for a How long does it take for a radioactive sample to decay?radioactive sample to decay?

Although it is not possible to predict Although it is not possible to predict when any individual isotope will when any individual isotope will decay, this question can be decay, this question can be answered for an entire radioactive answered for an entire radioactive sample by the half-life of each sample by the half-life of each radioisotope.radioisotope.

The half-life of radioisotopes varies The half-life of radioisotopes varies greatly, but is constant for a greatly, but is constant for a particular radioisotope. So constant particular radioisotope. So constant and reliable, it could be used to keep and reliable, it could be used to keep time.time.

How long does it take for a How long does it take for a radioactive sample to decay?radioactive sample to decay?

Why would anyone want to know Why would anyone want to know this? this?

It’ very useful to know how long a It’ very useful to know how long a radioisotope used in medicine will radioisotope used in medicine will remain radioactive within the body, to remain radioactive within the body, to plan how long hazardous nuclear plan how long hazardous nuclear wastes must be stored and to wastes must be stored and to estimate the age of ancient estimate the age of ancient organisms, cavitations or rocks organisms, cavitations or rocks (fossils).(fossils).

Radioisotopes and MedicineRadioisotopes and Medicine

1. 1. Diagnostic Diagnostic: help to understand what is : help to understand what is happening inside the bodyhappening inside the body

Tracer StudiesTracer Studies Study a specific part of the bodyStudy a specific part of the body Radioactive isotopes behave the same way Radioactive isotopes behave the same way

as non-radioactive onesas non-radioactive ones Can be “seen” moving through the bodyCan be “seen” moving through the body Can “see” where they accumulateCan “see” where they accumulate Show how body processes that chemicalShow how body processes that chemical(copy top chart on p 455)(copy top chart on p 455)

Used as TracersUsed as Tracers

RadioisotopesRadioisotopes Half-LifeHalf-Life UseUse

Technetium-99Technetium-99 6.01 h6.01 h Measure Cardiac output; locate Measure Cardiac output; locate strokes, brain and bone tumors.strokes, brain and bone tumors.

Gallium-67Gallium-67 78.3 h78.3 h Diagnosis of Hodgkin’s diseaseDiagnosis of Hodgkin’s disease

Iron-59Iron-59 44.5 d44.5 d Determine the rate of red blood cell Determine the rate of red blood cell formation (these contain iron); anemia formation (these contain iron); anemia assessmentassessment

Chromium-51Chromium-51 27.7 d27.7 d Determine blood volume and lifespan Determine blood volume and lifespan of red blood cellsof red blood cells

Hydrogen-3Hydrogen-3 12.3 y12.3 y Determine volume of body’s water; Determine volume of body’s water; assess vitamin D usage in bodyassess vitamin D usage in body

Thallium-201Thallium-201 72.9 h72.9 h Cardiac arrestCardiac arrest

Iodine-123Iodine-123 13.3 h13.3 h Thyroid function diagnosisThyroid function diagnosis

2. 2. TherapeuticTherapeutic: Treats the disease: Treats the disease

Used for Irradiation TherapyUsed for Irradiation Therapy

RadioisotopesRadioisotopes Half-LifeHalf-Life UseUse

Cesium-137Cesium-137 30.1 y30.1 y Treat shallow tumors (external source)Treat shallow tumors (external source)

Phosphorus-32Phosphorus-32 14.3 d14.3 d Treat leukemia a bone cancer affecting Treat leukemia a bone cancer affecting white blood cells (internal source)white blood cells (internal source)

Iodine-131Iodine-131 8.0 d8.0 d Treat thyroid cancer (external source)Treat thyroid cancer (external source)

Cobalt-60Cobalt-60 5.3 y5.3 y Treat shallow tumors (external source)Treat shallow tumors (external source)

Yttrium-90Yttrium-90 64.1 h64.1 h Treat pituitary gland cancer internally Treat pituitary gland cancer internally with ceramic beadswith ceramic beads

Suitable or UnsuitableSuitable or UnsuitableMust have a short half lifeMust have a short half lifeCannot emit alpha radiationCannot emit alpha radiationCannot be poisonous to the patientCannot be poisonous to the patient

Diagnostic ScansDiagnostic Scans1. X-ray: 1. X-ray:

Wave that’s part of EMS Wave that’s part of EMS Not an atom/elementNot an atom/elementHigh energyHigh energy

2. MRI: 2. MRI: uses hydrogen protons and radio waves uses hydrogen protons and radio waves *NOT RADIOACTIVE!**NOT RADIOACTIVE!*

Scans Scans (cont.)(cont.)

3. CAT scan: 3. CAT scan: X-ray that produces cross section images of your X-ray that produces cross section images of your

body that rather than the overlapping images body that rather than the overlapping images the X-ray unit rotates around your body then a the X-ray unit rotates around your body then a

powerful computer creates cross-sectional images, powerful computer creates cross-sectional images, like slices, of the inside of your body. like slices, of the inside of your body.

4. PET scan: 4. PET scan: uses positions (positively charged antimatter) uses positions (positively charged antimatter)

attached to sugarsattached to sugarsCollect/gather where cells grow quicklyCollect/gather where cells grow quickly

Cancer and RadiationCancer and Radiation

Cancer cellsCancer cells Contain mutated DNAContain mutated DNA Multiply at abnormally fast rates (tumor formation)Multiply at abnormally fast rates (tumor formation)

Radiation in cancer treatmentRadiation in cancer treatment Ionizing radiation kills all kinds of cellsIonizing radiation kills all kinds of cells Use to target cancer cellsUse to target cancer cells

Answer the following questions on pg. 462-463Answer the following questions on pg. 462-463

# 8-11, #13# 8-11, #13

Nuclear ForcesNuclear Forces

Nuclear fissionNuclear fission: The splitting of the atom : The splitting of the atom into smaller atoms, often resulting in the into smaller atoms, often resulting in the release of tremendous amounts of energyrelease of tremendous amounts of energy

How much??? The fission of Uranium-235 How much??? The fission of Uranium-235 produces 26 million times more energy produces 26 million times more energy than the combustion of methane.than the combustion of methane.

How does nuclear fission work??? How does nuclear fission work???

11n + n + 235235U —> U —> 9393Kr + Kr + 140140Ba + 3 Ba + 3 11n + ENERGYn + ENERGY

Bombarding a uranium atom with one neutron produces Bombarding a uranium atom with one neutron produces two smaller atoms and two more neutrons, free to collide two smaller atoms and two more neutrons, free to collide with other uranium atoms. This causes a with other uranium atoms. This causes a chain chain reactionreaction to occur. to occur.

Animation

Animation 2

5656 00 9292 3636 00

Since not all of the neutrons produced will hit Since not all of the neutrons produced will hit and split a uranium nucleus, a minimum amount and split a uranium nucleus, a minimum amount of uranium is necessary. The more uranium of uranium is necessary. The more uranium present, the more likely the produced neutrons present, the more likely the produced neutrons will hit and split another uranium nucleus.will hit and split another uranium nucleus.

This minimum amount of uranium is called its This minimum amount of uranium is called its critical masscritical mass. It is the minimum amount of . It is the minimum amount of fissionable material required to sustain a chain fissionable material required to sustain a chain reaction.reaction.

UraniumUranium

Mined from the ground as Uranium Oxide Mined from the ground as Uranium Oxide UU33OO88

Two isotopesTwo isotopes1. Uranium-2351. Uranium-235

- natural abundance = 0.720%- natural abundance = 0.720%

- used for fission in nuclear reactions and- used for fission in nuclear reactions and

weaponsweapons

2. Uranium-2382. Uranium-238

- most abundant = 99.275%- most abundant = 99.275%

EnrichmentEnrichment

Must have between 1 to 3% U-235 for fissionMust have between 1 to 3% U-235 for fission 2 ways to enrich U-2352 ways to enrich U-235

1. Change U1. Change U33OO88 into UF into UF6 6 gasgas

- needs to be done about 1200 times- needs to be done about 1200 times- get 4% u-235- get 4% u-235

2. Use lasers2. Use lasers- excite electrons of lighter isotope (U-235)- excite electrons of lighter isotope (U-235)- collected using magnetic fields- collected using magnetic fields- works in 1 try- works in 1 try

Nuclear WeaponsNuclear Weapons

Fission Bomb (a.k.a. Atom Bomb)Fission Bomb (a.k.a. Atom Bomb)1. 2 non-critical masses1. 2 non-critical masses

2 portions of U-235 are propelled into each other – 2 portions of U-235 are propelled into each other – make 1 critical massmake 1 critical mass

1 neutron then starts fission, then…BOOM!1 neutron then starts fission, then…BOOM!

2. 1 critical mass2. 1 critical massUsually PlutoniumUsually PlutoniumCompressed to get explosionCompressed to get explosion

Nuclear WeaponsNuclear Weapons

Fusion Bomb (a.k.a. H-Bomb)Fusion Bomb (a.k.a. H-Bomb)Uses Lithium HydrideUses Lithium Hydride

High temperatures create fusionHigh temperatures create fusionFusion: 2 different isotopes fuse togetherFusion: 2 different isotopes fuse togetherReleases more energy (100x)Releases more energy (100x)

Nuclear Power Nuclear Power There are many benefits in using nuclear There are many benefits in using nuclear

technology to create electricity, but this must be technology to create electricity, but this must be carefully regulated. If the reactor reaches carefully regulated. If the reactor reaches temperatures that are too high, the danger of a temperatures that are too high, the danger of a meltdown occurs.meltdown occurs.

A nuclear A nuclear meltdownmeltdown can occur when can occur when temperatures inside the reactor reach levels that temperatures inside the reactor reach levels that are too high. The materials used to construct are too high. The materials used to construct the reactor actually melt. If this happens, the the reactor actually melt. If this happens, the chain reaction is no longer contained and chain reaction is no longer contained and dangerous radioactive material can be expelled dangerous radioactive material can be expelled into the environment.into the environment.

Animation Animation 2

Cooling SystemCooling System

How does it work?How does it work?

When the steam from When the steam from the generator is the generator is cooled by water from cooled by water from nearby water sourcesnearby water sourcesWhen the steam from

the generator is cooled by water from nearby water sources

Cooling Tower

Nuclear Power Plants in USNuclear Power Plants in US

Nuclear Power has reached Nuclear Power has reached dangerous conditions twice.dangerous conditions twice.

Three Mile IslandThree Mile Island ChernobylChernobyl 1979, Pennsylvania 1979, Pennsylvania 1986, Russia 1986, Russia

the reactor reached dangerous the reactor reached dangerous temperatures, but no meltdown temperatures, but no meltdown

occurred occurred

the reactor reached temperatures the reactor reached temperatures high enough to cause the core to high enough to cause the core to

meltmelt

caused by both equipment failure caused by both equipment failure and human error and human error

caused by both poor plant design caused by both poor plant design and improper operationand improper operation

while some radioactive material while some radioactive material was expelled into the atmosphere, was expelled into the atmosphere, no damage sustained by people or no damage sustained by people or

environmentenvironment

radiation spewed into the radiation spewed into the atmosphere and spread over the atmosphere and spread over the

entire Northern Hemisphere entire Northern Hemisphere

caused government to create caused government to create stricter regulations over nuclear stricter regulations over nuclear

power plants power plants

an estimated 75 million people an estimated 75 million people exposed exposed

The Chernobyl The Chernobyl incident incident happened April happened April 26, 1986 in 26, 1986 in Ukraine. Ukraine.

The Chernobyl The Chernobyl accident was a accident was a result of a flawed result of a flawed reactor design that reactor design that was operated with was operated with inadequately inadequately trained personnel trained personnel and without proper and without proper regard for safety.regard for safety.

When the operator When the operator went to shut down the went to shut down the reactor from it’s reactor from it’s unstable condition unstable condition arising from previous arising from previous errors, a peculiarity of errors, a peculiarity of design caused a design caused a dramatic power surge.dramatic power surge.

3 mile island is 3 mile island is located in Harrisburg located in Harrisburg PAPA

The 3 mile island is a The 3 mile island is a nuclear generating nuclear generating stationstation

What Happened?What Happened?

Occurred on 4:00 a.m. March 28, 1979Occurred on 4:00 a.m. March 28, 1979

Problem in secondary, non-nuclear section of the plantProblem in secondary, non-nuclear section of the plant

The main water pump failed and prevented steam The main water pump failed and prevented steam generators from removing heat that the radioactive generators from removing heat that the radioactive material was producingmaterial was producing

The pressure in the primary system (nuclear part of The pressure in the primary system (nuclear part of plant) increasedplant) increased

What Happened?What Happened?

The relief valve on top of The relief valve on top of the pressurizer did not the pressurizer did not close when the pressure close when the pressure decreaseddecreased

Workers reduced the flow Workers reduced the flow of coolant which made of coolant which made the fuel overheatthe fuel overheat

Half of the long metal Half of the long metal tubes which held the tubes which held the nuclear fuel pellets nuclear fuel pellets ruptured and the pellets ruptured and the pellets started to meltstarted to melt

Future Technology…Future Technology…

Nuclear FusionNuclear Fusion - the joining of two smaller nuclei - the joining of two smaller nuclei to create a large nucleus and tremendous energy to create a large nucleus and tremendous energy release.release. Produces more energy per atom than fission Produces more energy per atom than fission Requires tremendous heat and pressure!Requires tremendous heat and pressure! Technology does not yet exist that allows more energy Technology does not yet exist that allows more energy

to be produced than must be put in.to be produced than must be put in.

Answer the following questions on pg. 481-482Answer the following questions on pg. 481-482

#1,2,8,9,16,18,19,20#1,2,8,9,16,18,19,20