Nuclear Energy
Notes
18.2 & 18.3
1. Nuclear Reactions: Change
the composition of an
atom’s nucleus.
2. The strong nuclear force holds
the nucleus together.
3. Most atoms are stable
(equal number of p & n).
These are the smaller atoms
which are NOT radioactive.
4. Unstable nuclei have more neutrons than
protons. These isotopes are radioactive.
5. As the elements become larger they become
more unstable.
6. All elements have at least 1 radioactive
isotope. All the isotopes of those elements
with atomic numbers greater than 83 are
radioactive.
7. The larger nuclei are radioactive because
they have more neutrons than protons.
Unstable Nucleus
8. Characteristics of Subatomic
Particles and Rays:
Particle
Mass (amu)
Charge
Proton
1.00727647
+1
Neutron
1.00866490
0
Beta
Particle
(electron)
0.00054858
-1
Alpha
Particle
4.00150617
(He nucleus)
+2
Gamma
Ray
0
0
Symbol
p+ or
1
1
Stopped by
H
n0 or 01 n
0
1
4
2
e or -10 β
Heavy
clothing/Al foil
He or 42 α
paper
γ or E
Several
centimeters of
lead/concrete
0
0
Nuclear Radiation Penetrating Power
Nuclear Radiation Penetrating Power
9. Spontaneous Emission of Radiation:
A. Unstable nuclei will spontaneously emit 3
types of natural radiation, this is also called
radioactive decay.
B. When an atom emits 1 kind of radiation the
original nucleus decomposes or decays to
form a new nucleus and releases radiation.
This is written in a nuclear equation.
Alpha & Beta Decay
10. 3 Types of Spontaneous Radiation:
A. Alpha Decay – spontaneous emission of an alpha particle
from the nucleus.
226
88
Ra 
222
86
Rn  α
4
2
185
79
Au  _________  42 α
181
77 Ir
B. Beta Decay – spontaneous emission of beta particle from the
nucleus
131
131
0
14
Xe
14
0
I

____
+
N  β
54
53
1 e
C  ________
6
7
1
C. Gamma Decay – spontaneous emission of gamma rays from
the nucleus
238
92
238
0
U  ________
92 U  0 γ
Uranium Radioactive Decay Series
How Radon Gas Enters your House
Ways to Remove Radon Gas from Your Home
• External view of a Radon
mitigation system from a
home basement.
• Below is a view of the fan
inside which runs 24 hours
a day pulling air from
under the basement floor.
Testing Methods for Radon
U.S. Radon Zones
11. Transmutation: Changing into a new element by
either decay or bombardment.
Nuclear Bombardment Reactions
A. Process in which a new element is formed by
bombarding a nucleus with small energetic particles.
B. The energetic particle, a projectile, hits the target
nucleus and forms an unstable compound nucleus,
which is short-lived.
C. This nucleus can emit an ejected particle to stabilize
itself.
D. This is the process used in particle accelerators where
artificial isotopes and transuranium (those above U)
elements have been produced.
Particle Accelerator in Switzerland
with a 16.7 mile circumference
Nuclear Bombardment Reaction
target nucleus
14
7
ejected particle
N  He  [ F]  O  H
4
2
projectile
18
9
17
8
new isotope
(element)
1
1
12. Nuclear Fission
A. Process by which a heavy nucleus splits into two
smaller nuclei.
B. Most fission reactions are induced.
C. The energy yield for fission reactions are very
high.
D. Fission reactions are the source of energy used to
generate electricity in nuclear power plants.
E. U-235 & Pu-239 are the radioisotopes used in
reactors.
Fission Is Similar To Pool
Nuclear Fission Reaction
temporary
unstable nuclei
Nuclear fuel
235
92
U  n [
1
0
projectile – starts
the chain
reaction
236
92
start additional
fission reactions
U]  Kr 
93
36
Splits in 2
140
56
Ba  3 n
1
0
F. In fission reactions, the product nuclei have far too
many neutrons, and are intensely radioactive. This
is considered radioactive waste.
G. The released neutrons can cause another reaction as
long as sufficient U-235 remains.
H. This is called a chain reaction.
I. The smallest amount (minimum volume) of
fissionable material needed to sustain a chain
reaction is called the critical mass.
Nuclear Chain Reaction
Fuel: U-235 or Pu-239
Critical mass for U is 110 lbs
16. Nuclear Fusion:
A. This is a thermonuclear reaction - requires high temperatures.
B. Occurs when two small nuclei fuse, or join, to form larger,
more stable nuclei.
C. Releases a large amount of energy.
D. Process that occurs on the sun and in a hydrogen bomb.
E. If fusion reactions are going to be practical, they need to
produce more energy than they require to get started.
F. In a fusion reaction, the starting materials are in a form of
plasma.
G. The biggest problem is obtaining the high temperatures
necessary for a fusion reaction to occur.
2 H  2 H  He  2 H  ENERGY
2
1
4
1
1
1
2
1
H. A “magnetic bottle” could be used to hold plasma at these high
temperatures.
Krypton-92
Fission
3 neutrons
Nuclear Power
Plants/A-bomb
neutron
U-235
Fusion
2
1
1
1
H
Energy
Barium-141
1
1
H
H
The Sun/
H-bomb
4
2
2
1
H
1
1
H
He
1
1
H
Energy
The first Atomic Bomb is detonated
at Trinity Site near Alamogordo,
New Mexico on July 16, 1945.
A wooden house
built 1km away
from the test site…
A Monument
stands at the
test site today.
shows the
result of the
blast.
“Little Boy”
Uranium fission bomb dropped
on Hiroshima, Japan by the
“Enola Gay” flown by
Colonel Paul Tibbets
Hiroshima - August 6, 1945
Distance from
Ground Zero
(km)
Killed
Injured
0 -1.0
86%
10%
31,020
1.0 - 2.5
27%
37%
144,800
2.5 - 5.0
2%
25%
80,300
Total
27%
30%
256,300
Population
Hiroshima 1945 & Today
Nagasaki - August 9, 1945
Distance from
Ground Zero
(km)
Killed
Injured
0 -1.0
88%
6%
30,900
1.0 - 2.5
34%
29%
144,800
2.5 - 5.0
11%
10%
15,200
Total
22%
12%
173,800
Population
“Fat Man” –
Plutonium Fuel
U.S. Nuclear Testing
• Large craters pockmark Frenchman Flats, Nevada, a
former test site for U.S. nuclear weapons. The US
conducted more than 1050 tests here and in Alaska,
Colorado, Mississippi, New Mexico between 1945
and 1992.
• The Soviet Union,
UK, France, China,
India and Pakistan
had a similar total
number of tests
over the same
time period.
Fusion Bombs
• The first thermonuclear weapon (hydrogen
bomb), code-named Mike, was detonated at
Enewetak atoll in the Marshall Islands, Nov.
1, 1952. The photograph was taken at an
altitude of 12,000 feet over 50 miles from the
detonation site.
Video of all the
Nuclear
Explosions on
the Planet from
1945-1998
• Only 6 countries have detonated a hydrogen bomb
– US, UK, Soviet Union, France, China and India.
• To obtain temperatures in the millions of degrees
Celsius a fission reaction is set off first to start the
fusion reaction.
Nuclear Reactors
A. There are currently 111 commercial nuclear
power plants in the U.S. They provide 20%
of our country’s electricity, but 80% of the electricity
used in southeastern PA.
B. There are 530 nuclear reactors in 30 nations
around the world that provide 1/6 of the
world’s electricity. To produce electricity you
need to turn a turbine. This can be accomplished
by wind or water, must most commonly by steam.
The only difference between a nuclear power
plant and a conventional fossil fuel plant is the
method used to produce boiling water.
14. Parts of a Nuclear Reactor
A.Fuel Rods: Composed of 97% U-238 and 3%
U-235 (the fissionable isotope). Chalk- sized pellets
are arranged in long steel cylinders in the reactor core.
When the fuel has given up most of its energy it is
called spent. It will be reloaded every 1 to 3 years.
There can be 10,000,000 pellets in 1 plant.
B. Control Rods control the rate of a nuclear reaction.
Without them the reaction would occur too fast for it
to be effective.
C. Moderator is usually heavy water (D2O). Without
sufficient cooling of the core a meltdown could occur.
This water also shields workers.
Nuclear Power Plant Control Room
View of fuel
rods and
control rods
immersed in
“heavy water.”
Fuel Rods Filled With Pellets
Are Grouped Into Fuel Assemblies
14. Parts of a Nuclear Reactor con’t.
D. Generator produces
electricity by turning a
steam turbine from the
boiling water.
E. Cooling System: Water
from outside is used to
cool the steam (it does
not come into contact
with the cooling water in
the core). Excess steam
rises up in the cooling
tower, condenses and
falls back.
Cooling Towers
Limerick, PA
Nuclear Power Plant Turbine and Generator
Steam
Boiling water
Spinning
turbine
blades and
generator
Nuclear Power Plant Diagram
Pressurized-Water Reactor
Boiling-Water
Reactor
Boiling
Water Reactor
Nuclear power (% of total
primary energy supply)
IEA (International Energy Agency) 2007
France
42.6
Sweden
36.2
Lithuania
31.9
Armenia
27.7
Slovakia
24.8
Bulgaria
24.3
Switzerland
22.5
Belgium
21.9
Slovenia
21
Korea (Republic of)
17.9
Finland
17.3
Ukraine
16.1
Japan
Czech Republic
15
14.3
Hungary
13
Germany
12.3
Spain
10.3
United Kingdom
9.1
United States
9
Canada
8.8
Russian Federation
6.1
Romania
3.8
Argentina
2.8
South Africa
2.3
Electricity
Generation Sources in U.S.
0.2% GEOTHERMAL & OTHERS
3.7% OIL
9.6% GAS
21% NUCLEAR
9.5% HYDRO
56% COAL
Wind And Solar
Are Great, But…
Availability
Nuclear
89.6%
Coal
Natural Gas
Wind
Hydro
70.6%
39.9%
33.0%
30.2%
One fuel pellet
•
=
One fuel pellet produces as much energy
as:
• 3 barrels of oil
• 1 ton of coal
• 2.5 tons of wood
• 17,000 cubic feet of natural gas
15. Radioactive Waste:
A. Spent fuel rods have been accumulating for about
40 years. Spent fuel rods are highly radioactive,
with some isotopes remaining active for thousands
of years. By federal law reactor waste must be
stored on site. The U.S. Government has not yet
opened any permanent storage sites, but one called
Yucca Mountain in Nevada is currently being
negotiated. On-site storage is only a temporary
measure, as tanks require too much maintenance
to be safe for long term storage.
Radioactive Waste
• Radioactive
waste is stored
under water until
it decays to lower
levels.
Radioactive Warning Symbol
Temporary Radioactive Waste Storage
• Waste is transferred to storage casks and stored on-site at
each power plant.
Permanent Radioactive Waste Storage
• If permanent storage
is opened, it would be
transported to a
location where it
would be placed ½
mile underground in
mine shafts drilled in
rock that is above the
water table and free
from seismic activity.
Current Waste Storage Locations
Nuclear Accidents
• Three Mile Island
March 28, 1979 on
the Susquehanna
River near
Harrisburg, PA. The
worst nuclear accident
in U.S. history was
caused by technical
failures and human
error. About 2
million people were
exposed to 1mrem of
radiation which led to
no deaths or injuries.
Nuclear Accidents
• Chernobyl April 26, 1986 in the
northern Ukraine. The core
melt meltdown caused
radioactive materials to spread
over a wide area of Europe.
Officials at a Sweden Nuclear
Power Plant 1st noticed that
radioactive particles were on
their clothes and thought their
own plant was malfunctioning.
The worst nuclear accident in
the world was caused by a
flawed reactor design and
inadequately trained operators.
• 57 immediate deaths with
4000 additional cancer
deaths long term. Over
360,000 people were
evacuated permanently
from the area which
remains closed. The
initial cover-up of the
incident made clean up
worse.
Over 360,000 people
were evacuated
permanently from the
area which remains
closed. The initial
cover-up of the
incident made clean
up worse.
Fukushima-Japan- March 11, 2011
Fukushima
• Comprised of 6 boiling water
reactors
• An earthquake and resulting
tsunami caused the loss of
electrical power.
• Units 4, 5 and 6 were not
operational at the time of the
tsunami
• Worst nuclear accident since
Chernobyl.
• The seawall of 19 feet could not handle the over 40
foot tall tsunami.
• The backup generators were flooded causing the
pumps that circulate cooling water to not function.
• Rising heat causes a rise in pressure and
radioactive gases were released from the reactor
core to relieve the increase in pressure.
• Sea water was sent into the
reactors as a last result since
it renders reactors useless.
• Explosions occur on March
12th, 13th and 15th
• Three reactors undergo full
meltdown with the highest
radiation ever leaked into
the ocean.
• A 12.5 mile “no go” zone is
established around nuclear
facility.
•Radioactive particles are also released into the air and reach
the jet stream.
•Reports of radiation leakage and resulting health impacts are
not consistent.
•People living in the vicinity have radioactive urine.
Fukushima March 11, 2011
17. Uses for Nuclear Chemistry:
A. Half life
1. The time required for ½ of the atoms of a
radioactive isotope to decay.
2. Using radioactive isotopes to determine
the age of an object is called radio carbon
dating. (also called carbon-14 dating)
B. Radioactive Isotopes and Dating
1. All animals and plants contain carbon-14.
2. Even though carbon-14 undergoes
radioactive decay, it is constantly replenished
during a lifespan.
3. The half-life of carbon-14 is 5730 years.
4. The ratio of C-12 to C-14 is compared to
another object of a similar age.
5. Cannot use carbon-14 dating with objects
that never lived.
6. After 4 half lives, the amount of carbon-14
remaining is too small to give reliable data.
7. Carbon-14 is not useful for specimens over
25,000 years old, so Potassium-40
is used instead. It has a half-life of 1.28
billion years.
Radioactive Decay of Strontium-90
What is the ½ Life of Strontium-90???
How long until no more Strontium-90 remains?
28 years
What is the ½ Life of this
Radioactive Sample?
2 days
131
53
Ex. If I have 1.00 mg of I, which has a ½
life of 8.04 days, how much will be left
after 1 half-life? After 2? After 3?
C. Smoke Detectors:
1. Smoke detectors emit a small amount of alpha
particles.
2. When smoke particles mix with the gas, they slow
the current flow setting off the alarm.
D. Medical Uses
1. CAT SCAN – the body is analyzed
using X-rays.
2. MRI and NMR – detects body’s absorption
of radio waves.
3. PET – Measures gamma rays from certain
part of the brain.
4. Radioisotopes prepared in a nuclear
reactor can be used to both treat and
detect various medical conditions.
Tracers can be used to follow a particular
isotope through its normal path in the
body to show any abnormalities.
Ex) Upper and Lower GI uses radioactive
Barium to detect stomach and intestinal
problems. An IVP measures the bodies
absorption of radioactive iodine to
detect kidney stones.
5. Irradiation can be used
as an energy source to
treat cancer. The
diseased area is exposed
to ionizing radiation to
kill cancerous cells.
Ex) Ingest large amounts
of I-131 kills thyroid
cancer, External beam
of Co-60 can be
directed at a cancerous
spot. Irradiation can
also be used to sterilize
medical instruments
and preserve food.
Food Irradiation Symbol
• Radioisotopes
found in various
parts of the body
18. Exposure to Radioactivity:
A. Continued exposure to
radiation is dangerous;
therefore, people working
in these conditions must
monitor their exposure to
radiation.
B. People working with
radiation wear film
badges to monitor their
exposure.
C. A dosimeter measures
radiation in people, a
Geiger Counter measures
radiation of objects.
D. Radiation is usually
measured in units of
mrems. Higher doses for
a longer period of time
over a large area cause
the most damage,
especially for rapidly
dividing cells like sex
cells and blood cells.
Sources of Our Radiation Exposure
Radiation Exposure
From Different Activities (in millirem)
Natural Background Radiation (1 year)
300
Working at a Nuclear Power Plant (1 year)
115
One Diagnostic X-ray
20
Living in a Stone, Brick or Concrete Building (1 year)
7
One Cross-Country Flight
5
Watching TV (average person, 1 year)
Living Within 50 miles of a Coal-Fired Plant (1 year)
Living Within 50 miles of a Nuclear Plant (1 year)
91
1.5
0.03
0.009