The Atom and Radiation
Nuclear Radiation
Goals: To answer the following
questions

What is radiation?
Are there different types?
 Are all forms (equally) dangerous?


Where is radiation found?


What is radiation used for?


Is all radiation man-made?
Are there benefits to some types?
How long is something radioactive for?
The Discovery of Radioactivity



The German physicist W.K. Roentgen
“accidentally” discovers a mysterious source of
radiant energy that can pass through low density
shields (like card board). He calls this
mysterious energy X-rays.
Further research showed that X-rays cannot
pass through everything, particularly high
density materials like lead and bone.
Roentgen takes the first X-rays of his wife’s
hand to present to his colleagues.
Hand X-ray, December 22, 1895
The Discovery of Radioactivity



The French physicist Henri Becquerel takes interest in
Roentgen's X-rays in 1896. He investigated whether
certain minerals could emit X-rays. He experiments with
Uranium and a photographic plate (develops upon
exposure to light).
Another accident happens…Becquerel becomes
frustrated with his research, wraps the photographic
plate in black paper (to prevent light exposure), throws it
in his desk drawer with a piece of Uranium on top and
closes it up.
What do you know??? A few days later, Becquerel
discovers that the photographic plate has been exposed
while sitting in his dark drawer.
The Discovery of Radioactivity
What Becquerel inadvertently discovered
was radioactivity, the spontaneous
emission of nuclear radiation.
 Soon after (in 1898,) Becquerel's
colleagues, Marie Curie and her husband
Pierre discover two other radioactive
elements: polonium and radium.

What is Radioactivity?


Radioactivity: the spontaneous emission of
nuclear radiation.
We now know that there are two categories of
radiation:

Non-ionizing radiation – low-energy radiation that
transfers energy to matter


usually only harmful in large amounts
Ionizing radiation – high-energy radiation that can
eject electrons from atoms/molecules to form highly
reactive ions and can cause serious cell damage

exposure should be limited.
Concerns…..

But radiation is all around us…the
question is, should we be concerned about
our safety?? Are we in danger of serious
exposure to radiation? Can we use
radiation?
Forms of Radiation

Radiation comes in several forms as shown in
the electromagnetic spectrum below; but not all
forms are represented here
Types of Radiation
 Three
main types (from the 2 categories) :
1. Non-ionizing electromagnetic radiation
 Radio
 Micro
 Infrared
 Visible
 low energy UV
2. Ionizing electromagnetic radiation
High UV
 X-rays
 Gamma rays

3. Ionizing atomic particle radiation

radioactive elements
Why are some elements radioactive? To
answer this question, you must
understand a little about atomic structure.
 All matter can be broken down into atoms:


1.
2.
3.
An atom is
composed of three
parts:
Protons
Neutrons
Electrons
Isotopes (cont.)






Some isotopes are stable and others are
unstable. This is where radioactivity comes in.
A stable isotope is not radioactive, but an
unstable isotope is!
Ex. 12C is stable
13C is stable
14C is radioactive
Radioactive elements will emit radiation until
they become a stable isotope.


Every Element has Isotopes – the amount of
each isotope is fixed
Ex. Uranium
Mass
238
235
234

Abundance
99.28%
0.71%
0.0054%
Which isotope of Uranium is used to make an
atomic bomb?
Emitted radiation
This emitted radiation can be one of three
types:
 Alpha ( 24 α or 42 He )

heavy particle radiation
 easily blocked because its so big, but
 the most dangerous particle


Beta ( -10 β or -10 e)

particle radiation smaller than alpha
Emitted radiation
This emitted radiation can be one of three
types:
0 β or 0 e )
 Positron ( +1
+1



positive beta radiation
Gamma ( 00 γ )

high energy radiation
Emitted radiation


Alpha and Beta emission cause radioactive
elements to change to a new element.
Gamma causes no change in the radioactive
element.
Radiation Exposure
Naturally occurring radioisotopes provide a
constant small dose of radiation
 Radioactive isotopes constantly decay,
releasing alpha, beta and/or gamma
radiation.
 This constant, inescapable radiation is
called background radiation.

Natural background radiation:
- Outer space

All forms of electromagnetic radiation
- Ground water, rocks, soil

contain Uranium and Thorium
- Atmosphere

contains radon
- Food and Environment

like C-14 and potassium
Radon
Produced as Uranium in the soil decays.
Uranium decays to produce radon gas:
 When this gas is inhaled, it further decays
in your lungs into Polonium, Bismuth and
Lead (these heavy metals cannot be
exhaled).
 The resulting alpha radiation is being
released into your body, causing cell
damage.

Manmade background radiation
Fallout (nuclear weapons testing)
 Airplane flights
 Released from

burning fossil fuels
 nuclear power plants
 mining
 making

 cement
 concrete
 sheet
rock
Medical Applications

Medical uses of radioisotopes fall into two
categories.

Diagnostic

Therapeutic
Diagnostic
A standard x-ray cannot produce an image
of an organ like the heart, liver, pancreas,
blood vessels, etc.
 To illuminate the targeted region, a
radioisotope is injected into the body.
 Radioisotopes used are low dosages with
a short half-life.


localized 0.1 to 50 rem doses are common
Commonly Used Radioisotopes
Americium-241= Diagnose thyroid
disorders, smoke detectors.
 Cesium-137= Cancer treatment.
 Iodine-125,131= Diagnosis & treatment
liver, kidney, heart, lung and brain.
 Technetium-99=Bone and brain imaging;
thyroid and liver studies; localization of
brain tumors.

CAT & PET scans
A computerized tomography scan is an
enhanced x-ray machine using multiple
beams capable of producing a 3D image.
 A positron emission tomography scan
uses a positron emitter to generate a 3D
image.

CAT & PET scans
MRI
In magnetic resonance imaging, a
powerful magnetic field is used along with
low energy radio frequency to generate an
image.
 Based on the premise that hydrogen
atoms have “spin.”
 In a powerful magnetic field, these
hydrogen atoms can be made to flip
between the two spin states.
 THIS IS NOT NUCLEAR RADIATION

MRI
Therapeutic
In radiation therapy, radiation is used to
target cancer cells.
 Radiation levels are in very high dosages.



localized 4000 – 6000rem doses are common
Cyberknife treatment uses computer
technology to aim 100’s of x-ray beams
precisely at a tumor.
Measuring Radiation
Mainly, two units are used to measure
radiation:
 RAD = radiation absorbed dosage



RBE = a multiplier for each type of
radiation.


1 RAD = 1.0 x 10-2 J / kg of body tissue
alpha = 20; protons, neutrons = 10; betas,
positrons, and gammas = 1.
REM = radiation equivalent in humans

REM = RAD x RBE

There are several other units out there; we are not going to worry about those.
Biological Effects
Alpha particles cannot penetrate our skin,
yet internally they can cause massive
damage on soft tissues like the lungs and
intestinal linings.
 Beta particles can cause a burn on the
outer portion of the skin.
 Gamma particles penetrate completely
and if exposed to large quantities is
deadly.

Biological Effects

Radiation affects those cells in our body
that undergo rapid cell division like bone
marrow, intestinal lining, and the skin.

Radiation tends not to affect cells that
remain unchanged like our brain, liver,
muscles, etc.

Doesn’t mean it CAN’T, it just is less likely
How It Works…

When radiation hits a molecule like water,
it ionizes.
H 2O  radiation  H 2O 1  1e-

This water molecule reacts with another
water molecule.
H 2 O 1  H 2 O  H 3O 1   OH
How It Works…
The “dot” on the OH is an odd electron.
 Molecules with an odd electron are called
free radicals.
 Free radicals are electron scavengers and
interfere with electron transfer reactions –
many of which are vital in the function of
the body.

How much is safe?
 Ionizing radiation breaks bonds in
molecules within the body. At low
exposure levels, your body can fix the
minimal damage. Higher exposure
levels that your body cannot fix will
lead to damaged DNA, causing
mutations (tumors and birth defects)

Average U.S. individual receives 0.360
rem per year.
 About 0.300 rem of this is from natural
sources
 U.S. limit for background radiation in a
given area is 0.500 rem.
 U.S. safe exposure in the work
environment is 5.000 rem.

Dose Response Relationships
0-15 rem—No or minimal symptoms
 15-40 rem—Moderate to severe illness
 40-80 rem—Severe illness deaths start
above 50 rem
 Above 80 rem—Fatal

***Acute whole body doses
Your Annual Exposure
Activity
Smoking
Typical Dose
280 millirem/year
Radioactive materials use
in a UM lab
<10 millirem/year
Dental x-ray
Chest x-ray
Drinking water
Cross country round trip by
air
Coal Burning power plant
10 millirem per xray
8 millirem per xray
5 millirem/year
5 millirem per trip
0.165
millirem/year
Radiation Protection

Decrease Time

Increase Distance

Increase Shielding
Measurement and Detection
A Geiger tube is often used to detect
radiation.
 Consists of a metal tube filled with a gas
like Argon.
 When radiation enters the tube, it ionizes
the gas.
 The ions are attracted to a negative
charged wire and the electrons are then
counted.

Measurement and Detection
Animation: http://www.dlt.ncssm.edu/tiger/Flash/nuclear/GeigerTube.html
Alpha
Radioactive isotopes decay until a stable
nucleus can be formed. What happens
when radioactive isotopes decay?
 Many elements release alpha radiation:

226
Ra
88
(radium)

4
2 He +
(alpha particle)
222
86
Rn
(Radon)
As these radioactive isotopes decay, an
alpha particle is released and a new
element is formed.
Alpha Particles
•Alpha Particles: 2
neutrons and 2
protons
•They travel short
distances, have
large mass
•Only a hazard when
inhaled or formed in
the lungs
•because they
can’t pass
through skin)
Beta
Many elements release beta radiation:
222
86
Rn
(radon)
 As
0
-1
e +
(neg. beta particle)
222
87
Fr
(Francium)
these radioactive isotopes decay, a
beta particle is released and a new
element is formed.
Beta
Many elements release beta radiation:
222
86
Rn
(radon)
 As
0
1
e +
(pos. beta particle)
222
85
At
(Astatine)
these radioactive isotopes decay, a
beta particle is released and a new
element is formed.
Beta Particles
Beta Particles: Electrons or positrons having small mass and
variable energy. Electrons form when a neutron transforms into a
proton and an electron or
1
0
n

0
-1
e +
1
1
H
Gamma

In addition to releasing a radiation particle
(alpha or beta), most radioactive decay is
accompanied by the release of gamma
radiation too. Remember, gamma
radiation is just energy; it is not a particle,
so it does not cause the element to
change its identity.
Gamma Rays
Gamma Rays (or photons): Result when the nucleus releases
Energy, usually after an alpha, beta or positron transition
X-Rays
X-Rays: Occur whenever an inner shell orbital electron is
removed and rearrangement of the atomic electrons results
with the release of the elements characteristic X-Ray
energy
Neutrons
Neutrons: Have the same mass as protons but are
uncharged; they behave like bowling balls- they wreck
things when they hit them
- Identify the starting element and write the
symbol.
- Identify the type of radiation released.
- Subtract the two upper left numbers to find
the mass of the new element formed.
- Subtract the two lower left numbers to find
the atomic number of the new element
formed.
- Look up the new atomic number on the
periodic table to find the new element
made.
In a completed nuclear equation, the
 sum of the mass numbers of the unstable
isotope and the products are equal
 sum of the atomic numbers of the unstable
isotope and the products are equal
Sum of Mass Numbers
251
251Cf
=
247Cm
98
98
+
251
4He
96
=
2
98
Sum of Atomic Numbers
57
58
Write an equation for the alpha decay of
STEP 1 Write the incomplete equation:
222
86
Rn
 ? +
4
2
222Rn.
He
STEP 2 Determine the mass number: 222 – 4 = 218
STEP 3 Determine the atomic number: 86 – 2 = 84
STEP 4 Determine the symbol of element: 84 = Po
STEP 5 Complete the equation:
222
86
Rn

218
84
Po +
4
2
He
84
Po
85
At
86
Rn
4
2
He
59
STEP 1 Write an equation for the decay of
K42 (potassium-42), a beta emitter.
42
19
K  ? + e
0
-1
STEP 2 Mass number: (same) = 42
STEP 3 Atomic number: 19 + 1 = 20
STEP 4 Symbol of element: 20 = Ca
42
19
K 
42
20
Ca +
0
-1
e
STEP 5 Complete the equation:
0
-1
e
19
K
20
Ca
60
Write the nuclear equation for the beta
decay of
Co-60.
61
60
27
Co

60
28
Ni +
0
-1
e
beta particle
62
In positron emission,
 a proton is converted to a neutron and a
positron
1
1
H  n 
1
0
0
+1
e
 the mass number of the new nucleus is the
same, but the atomic number decreases by 1
49
25
Mn

49
24
Cr +
0
+1
e
63
In gamma radiation,
 energy is emitted from an unstable
nucleus, indicated by m following the
mass number
 the mass number and the atomic number
of the new nucleus are for the same
element
99m
43
Tc

99
43
Tc +

0
0
64
65
What radioactive isotope is produced
when a neutron bombards 59Co?
59
27
Co + n  ? + He
1
0
4
2
66
Sum of mass numbers
60
59
27
=
Co + n 
1
0
27
=
56
25
60
4
2
Mn + He
27
Sum of atomic numbers
67
Energy and Atomic Structure
 There
is energy associated with holding
the parts of an atom together
 Remember
that the protons repel each
other
 There is no electrostatic attraction that
holds the neutrons together, nor holding
them to the protons
 But…. The nucleus still stays together
despite the repulsion and lack of attraction
 It
is held together by what we call “strong force” or
nuclear force.
Stability of Nuclei and Energy
 Remember
that all things like to be at the
lowest energy level possible.
 Forming
a nucleus releases energy, putting
the particles in a lower energy state than
when alone as p+, n0, and e- alone
 Some nuclei are inherently more stable than
others so building a bigger nucleus isn’t the
final answer in getting lower in energy
Decay stabilizes the nucleus, getting to an
arrangement of protons and neutrons that
is favorable for that element
So, what makes some nuclei radionuclides?

If the correct proton to neutron ratio is not present for
that atom, it will spontaneously give off radiation
(decay) in order to achieve a more stable nucleus that
has a more favorable proton to neutron ratio for that
element

The proper ratio ISN’T NECESSARILY 1:1



For most elements over 18, there are more neutrons than protons in
the stable isotope(s)
All nuclides that with a mass number (A) ≥ 83 are inherently unstable,
but lighter elements can be unstable, too
Radioactive atoms give off radiation (decay)
spontaneously, but at a constant, predictable rate
for that radionuclide
 This
is the half-life of the radionuclide
The Odd-Even Rule
In the odd-even rule, when the numbers of neutrons
and protons in the nucleus are both even numbers,
the isotopes tends to be far more stable than when
they are both odd. Out of all the 264 stable isotopes,
only 5 have both odd numbers of both, whereas 157
have even numbers of both, and the rest have a
mixed number.
This has to do with the spins of nucleons. Both
protons and neutrons spin. When two protons or
neutrons have paired spins (opposite spins), their
combined energy is less than when they are
unpaired.
http://library.thinkquest.org/3659/nucreact/stability.html
The Magic Numbers
Another rule of nuclear stability is that isotopes
with certain numbers of protons or neutrons tend
to be more stable then the rest. These certain
numbers are called the magic numbers, and they
are, for reasons to detailed to explain here, 2, 8,
20, 28, 50, 82, and 126. When a nucleus has a
number of protons and neutrons that are the same
magic number, it is very stable. For
example: 42He, 168O, and 4020Ca. One stable
isotope of lead, 20882Pb, has 82 protons and 126
neutrons.
http://library.thinkquest.org/3659/nucreact/s
tability.html
•Band of Stability: The area of
stable nuclei (here, the middle of
the dots)
•Based upon location near the
band, the type of radiation emitted
is predictable
Radionuclides
emit radiation
until a stable
nuclei is
reached
Half-Life



Radioactive isotopes change
what they are as they decay and
release radiation.
Scientists call the amount of
time it takes for half of a
radioactive sample to decay a
half life.
14C has a half life of 5,730
years.

This means that if we started
with 100 grams of 14C, only 50
grams of 14C would remain after
5,730 years have passed. The
other 50 grams will have turned
into 14N as a beta particle is
released.
Half-Life
How long does it take for a
radioactive sample to decay?


Although it is not possible to predict
when any individual isotope will
decay, this question can be
answered for an entire radioactive
sample by the half-life of each
radioisotope.
The half-life of radioisotopes varies
greatly, but is constant for a
particular radioisotope. So constant
and reliable, it could be used to keep
time.
How long does it take for a
radioactive sample to decay?


Why would anyone want to know
this?
It’ very useful to know how long a
radioisotope used in medicine will
remain radioactive within the body,
to plan how long hazardous nuclear
wastes must be stored and to
estimate the age of ancient
organisms, cavitations or rocks
(fossils).
Learning Check

The isotope Cr-51 has a half-life of 28
days. How much of a 160.mg sample
would remain after 112 days?

A patient is injected with N-13, which has a
half-life of 10 minutes. If the original
activity of the sample is 40 mCi, what
activity would be remain after 40 minutes?

The amount of F-18 decreases from 40.mg
to 10.mg in 220 minutes. What is the halflife of this radioisotope?
Learning Check

The isotope Cr-51 has a half-life of 28
days. How much of a 160.mg sample
would remain after 112 days? 10mg

A patient is injected with N-13, which has a
half-life of 10 minutes. If the original
activity of the sample is 40 mCi, what
activity would be remain after 40 minutes?
2.5 mCi

The amount of F-18 decreases from 40.mg
to 10.mg in 220 minutes. What is the halflife of this radioisotope? 110 minutes
Fusion
Fusion involves taking two or more smaller
nuclei and fusing them together.
 Once again, mass is converted to energy.
 This is the process by which all stars work.


All elements lighter than Fe have formed in
stars via fusion reactions
1
1
H  11H  11H  11H  42 He  201 β
Fusion

On our planet, fusion has been achieved.
2
1
H  31H  42 He  01n
The temperatures required are extremely
high.
 Currently, more energy is required to
achieve fusion than we get back from the
reaction.
 Research continues as this represents the
“holy grail” of energy.

Learning Check

In one possible fission reaction for U-235,
the U-235 is bombarded with a neutron
producing Kr-91, three neutrons, and
another nuclei. What is the unidentified
nuclei?
Fission
Nuclear fission is the process by which a
larger nuclei is split into two smaller ones.
 During this process, a small percentage of
the mass is converted to energy as
predicted by Einstein.
 E = mc2 ; where c = speed of light.
 1 x 10-3 g “lost” can generate 9.0 x 1010 kJ
of energy.
 Only two fissionable isotopes are known.


U-235 and Pu-239
Nuclear Fission
 How
much energy ??? The fission of
uranium-235 produces 26 million times
more energy than the combustion of
methane.
 It
releases the nuclear binding energy
How does nuclear fission work???
+ 235U —> 93Kr + 140Ba + 3 1n + ENERGY
Bombarding a uranium atom with one neutron
produces two smaller atoms and two more
neutrons, free to collide with other uranium
atoms. This causes a chain reaction to occur.
 1n

Animation U-235 Fission
Animation 2- moderation v
unmoderatied
Fission
Begins when a neutron strikes a U-235
atom.
 The products are numerous – below is just
one example.

235
92
U  01n 
139
56
Ba 
94
36
Kr  3 01n  energy
On average, three new neutrons are
produced.
 Each new neutron can split another U-235.



Since not all of the neutrons produced will hit
and split a uranium nucleus, a minimum amount
of uranium is necessary. The more uranium
present, the more likely the produced neutrons
will hit and split another uranium nucleus.
This minimum amount of uranium is called its
critical mass. It is the minimum amount of
fissionable material required to sustain a chain
reaction.
Fission

In a nuclear
weapon, a
____________
of U-235 is
imploded
producing an
uncontrolled
chain reaction.
Fission
In a nuclear power plant, the quantity of U235 cannot sustain a chain reaction.
 Control rods absorb excess neutrons.
 Waste products, with long half-life’s, from
spent fuel rods are stored in large pools at
the power plant.

Reactor Animation
Cooling System
Uranium
Mined from the ground as Uranium Oxide
U3O8
 Two isotopes

1. Uranium-235
- natural abundance = 0.720%
- used for fission in nuclear reactions and
weapons
2. Uranium-238
- most abundant = 99.275%
Enrichment
Must have between 1 to 3% U-235 for
fission
 2 ways to enrich U-235

1. Change U3O8 into UF6 gas
- needs to be done about 1200 times
- get 4% u-235
2. Use lasers
- excite electrons of lighter isotope (U-235)
- collected using magnetic fields
- works in 1 try
Decay Series of Uranium
Mass Defect

Difference between the mass of an
atom and the mass of its individual
particles.
4.00260 amu
4.03298 amu
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Nuclear Binding Energy
Energy released when a nucleus is
formed from nucleons.
 High binding energy = stable nucleus.

E=
2
mc
E: energy (J)
m: mass defect (kg)
c: speed of light
(3.00×108 m/s)
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
A nucleus will become more stable if a reaction
brings it closer to the iron peak
Nuclei heavier than iron do this by breaking up
into smaller nuclei via Fission
Nuclei lighter than iron do this by joining
together via Fusion reactions
Mass Defect and Nuclear Stability
2 protons:
(2 x 1.007276 amu) = 2.014552 amu
2 neutrons:
(2 x 1.008665 amu) = 2.017330 amu
2 electrons: (2 x 0.0005486 amu) = 0.001097 amu
Total combined mass:
4.032979 amu = 4.002602 amu
The atomic mass of He atom is 4.002602 amu.
This is 0.030366 amu less than the combined mass.
This difference between the mass of an atom and the sum of the masses
of its protons, neurons, and electrons is called the mass defect.
Nuclear Binding Energy
What causes the loss in mass?
According to Einstein’s equation E = mc2
Convert mass defect to energy units
0.030377 amu
1.6605 x 10-27 kg
1 amu
= 5.0441 x 10-29 kg
The energy equivalent can now be calculated
E = m c2
E = (5.0441 x 10-29 kg) (3.00 x 108 m/s)2
E = (4.54 x 10-12 kg m2/s2) = 4.54 x 10-12 J
This is the NUCLEAR BINDING ENERGY, the energy released
when a nucleus is formed from nucleons.
Mass Defect
If you add up a certain number of neutrons and protons and
put them together in a nucleus you end up with less
mass than you started with!
The ‘missing mass’ is known as the
Mass Defect and we can use
that mass change to determine the
energy released by using E=mc2
How do we detect that energy?
 That
energy is released as heat and/
or light
 That
light does not need to be visible
light, but can be any form of
electromagnetic radiation, or EMR
 The heat is what we harness in nuclear
power plants that use fission
The following
information is
F.Y.I
Nuclear Weapons

Fission Bomb (a.k.a. Atom Bomb)
1. 2 non-critical masses
portions of U-235 are propelled into each other –
make 1 critical mass
 1 neutron then starts fission, then…BOOM!
2
2. 1 critical mass
 Usually
Plutonium
 Compressed to get explosion
Nuclear Weapons

Fusion Bomb (a.k.a. H-Bomb)

Uses Lithium Hydride
 High
temperatures create fusion
 Fusion: 2 different isotopes fuse together
 Releases more energy (100x)
Nuclear Power


There are many benefits in using nuclear
technology to create electricity, but this must be
carefully regulated. If the reactor reaches
temperatures that are too high, the danger of a
meltdown occurs.
A nuclear meltdown can occur when
temperatures inside the reactor reach levels that
are too high. The materials used to construct
the reactor actually melt. If this happens, the
chain reaction is no longer contained and
dangerous radioactive material can be expelled
into the environment.
Animation
Animation 2
How does it work?
When the steam from
the generator is
cooled by water from
When
the steam
from
nearby
water sources
the generator is
cooled by water from
nearby water sources
Cooling Tower
Nuclear Power has reached
dangerous conditions three times.
Three Mile Island
Chernobyl
1979, Pennsylvania
1986, Russia
the reactor reached dangerous
temperatures, but no meltdown
occurred
the reactor reached temperatures
high enough to cause the core to
melt
caused by both equipment failure
and human error
caused by both poor plant design
and improper operation
while some radioactive material
was expelled into the atmosphere,
no damage sustained by people or
environment
radiation spewed into the
atmosphere and spread over the
entire Northern Hemisphere
caused government to create
stricter regulations over nuclear
power plants
an estimated 75 million people
exposed
Fukushima Daiichi
http://www.youtube.com/watch?v=BdbitRlbLDc

The Chernobyl
incident
happened April
26, 1986 in
Ukraine.

The Chernobyl
accident was a
result of a flawed
reactor design that
was operated with
inadequately
trained personnel
and without proper
regard for safety.

When the operator
went to shut down the
reactor from it’s
unstable condition
arising from previous
errors, a peculiarity of
design caused a
dramatic power surge.

3 mile island is
located in Harrisburg
PA

The 3 mile island is a
nuclear generating
station
What Happened?

Occurred on 4:00 a.m. March 28, 1979

Problem in secondary, non-nuclear section of the plant

The main water pump failed and prevented steam
generators from removing heat that the radioactive
material was producing

The pressure in the primary system (nuclear part of
plant) increased
What Happened?



The relief valve on top of
the pressurizer did not
close when the pressure
decreased
Workers reduced the flow
of coolant which made
the fuel overheat
Half of the long metal
tubes which held the
nuclear fuel pellets
ruptured and the pellets
started to melt
Future Technology…

Nuclear Fusion - the joining of two
smaller nuclei to create a large nucleus
and tremendous energy release.
Produces more energy per atom than fission
 Requires tremendous heat and pressure!
 Technology does not yet exist that allows
more energy to be produced than must be put
in.
