4 chapter 4 nuclear power station 4-1

Chapter 8
Nuclear Power station
• The Motivation for Nuclear Energy
• Neutron Reactions, Nuclear Fission and Fusion
• Nuclear Reactors
• Nuclear Fuel Cycle
• Nuclear Energy Systems: Generation IV
• Storage and Disposal of Nuclear Wastes
• Nuclear Reactor Safety
By: Prof. Ghada Amer

NUCLEAR POWER
STATION
Lecture 1

Chapter 8
• Chain Reactions and Nuclear Reactors

The Motivation for Nuclear Energy
• The generation of electricity from fossil fuels, particularly natural
gas and coal, is a major and growing contributor to the emission of
carbon dioxide – a greenhouse
• At least for the next few decades, there are only a few realistic
options for reducing carbon dioxide emissions from electricity
generation:
 increase efficiency in electricity generation
 expand use of renewable energy sources such as wind, solar,
biomass, and geothermal;
 capture carbon dioxide emissions at fossil-fueled (especially coal)
electric generating plants and permanently sequester the carbon;
and
 increase use of nuclear power.
Nuclear Energy - Prof. Ghada Amer4/10/2018 4

• In certain report from the MIT, in USA in 2015 they wrote “In
our view, it is likely that we shall need all of the above
options and accordingly it would be a mistake at this time to
exclude any of these four options from an overall carbon
emissions management strategy.
Nuclear Energy - Prof. Ghada Amer
Rather we seek to explore and
evaluate actions that could be taken to
maintain nuclear power as one of the
significant options for meeting future
world energy needs at low cost and in
an environmentally acceptable
manner.
4/10/2018 5

A Brief History of Nuclear Power
• The first nuclear reactors were all designed to produce plutonium for
nuclear weapons programmes.
• ‘‘In the post war era, as Britain still had to import relatively expensive oil,
policy makers thought that nuclear energy could be a cheap alternative.
• The shift from military to peaceful uses of nuclear power gained power in
1953 when President Eisenhower proposed his ‘‘Atoms for Peace’’
programme, suggested nuclear materials be used to provide ‘‘ample electrical
energy in the power-starved areas of the world’’.
• This was beneficial to governments who were keen to develop their nuclear
weapons programme away from the glare of public examination.
• The optimism and almost euphoria about the possible manifold peaceful uses
of the atom captured the imagination of writers and scientists, with claims
we would see:
‘‘nuclear powered planes, ships, trains . . . nuclear energy would naturally
modify crops and preserve grains and fish’’. (Scurlock 2007)
• The cold war enabled nuclear power to be constructed as vital for national
security.

• The initial reactors were of elementary
design, graphite blocks into which
uranium fuel was placed and plutonium
chemically extracted from the spent fuel
to be used in atomic bombs.
• The world’s first nuclear reactor, built as
part of the Manhattan project, it
achieved criticality in December 1942.
• As a result of the research conducted
during the Manhattan project,
researchers in the West and the USSR
realised that the heat generated from
nuclear fission could be attached to
generate electricity for power hungry
nations, as well as to provide force for
submarines and aircraft carriers.

• The remarkable proposition was that the
UN commission would in effect own and
control the nuclear fuel cycle, from
uranium mining through to reprocessing,
and in effect release uranium to nations
who wanted to build nuclear power plants
for electricity production only.
• As part of this international control of
nuclear technology, the US release a report
suggested, should license its control on
nuclear weapons sharing knowledge with
nations but not proceeding with weapons
development.
• It seemed to be a win-win situation.
Countries could take advantage of the
promise of cheap base load electricity from
nuclear power plants and the international
community could nip proliferation risks in
the bud.

• BUT!! This small window of opportunity that existed for
international cooperation on nuclear matters was firmly shut,
leading to the nuclear arms race and the cold war, the
outcomes of which ring down to the present day.
• The US Congress in 1946 passed the report, which firmly denied
foreigners’ (even wartime allies) access to US nuclear data.
Individual countries had to
pursue their own nuclear
weapons and nuclear energy
programmes with all the
attendant costs and risks of
‘‘going it alone’’.

Expansion of Nuclear Power
• The large scale use of nuclear power during the 1950s and 1960s was
concentrated in the USA, UK, Russia and Canada.
• Then expanded later 1960s and 1970s (Sweden, Japan, West
Germany).
• It was also touted as a solution to the urban pollution caused
primarily by coal-fired power stations.
• As a result, the federal government financed and built a number of
demonstration reactors to prove to the Energy companies that
nuclear was feasible.
• A pamphlet published by the nuclear company Westinghouse in the
1960’s captures the prevailing optimism about the promise of
nuclear power:
‘‘It will give us all the power we need and more. That’s what it’s all
about. Power seemingly without end. Power to do everything that man
is intended to do. We have found what may be called lasting youth’’.

• In 2016, nuclear power supplied 20% of United States and
17% of world electricity consumption.
• Experts project worldwide electricity consumption will
increase substantially in the coming decades, especially in
the developing world, accompanying economic growth and
social progress.
• However, official forecasts call for a mere 10% increase in
nuclear electricity generating capacity worldwide by 2020.
• These projections entail little new nuclear plant
construction and reflect both economic considerations and
growing anti-nuclear sentiment in key countries.
• The limited prospects for nuclear power today are
attributable, ultimately, to four unresolved problems:

1. Costs: nuclear power has higher overall lifetime costs compared to
natural gas with combined cycle turbine technology (CCGT) and coal, at
least in the absence of a carbon tax or an equivalent “cap and trade”
mechanism for reducing carbon emissions;
2. Safety: nuclear power has perceived adverse safety, environmental, and
health effects, heightened by the 1979 Three Mile Island and 1986
Chernobyl reactor accidents, but also by accidents at fuel cycle facilities
in the United States, Russia, and Japan. There is also growing concern
about the safe and secure transportation of nuclear materials and the
security of nuclear facilities from terrorist attack;
3. Proliferation: nuclear power entails potential security risks, notably the
possible misuse of commercial or associated nuclear facilities and
operations to acquire technology or materials as a precursor to the
acquisition of a nuclear weapons capability. Fuel cycles that involve the
chemical reprocessing of spent fuel to separate weapons-usable
plutonium and uranium enrichment technologies are of special concern,
especially as nuclear power spreads around the world

4. Waste: nuclear power has unresolved challenges in long-term
management of radioactive wastes. The United States and other
countries have yet to implement final disposition of spent fuel or high
level radioactive waste streams created at various stages of the
nuclear fuel cycle. Since these radioactive wastes present some danger
to present and future generations, the public and its elected
representatives, as well as prospective investors in nuclear power
plants, properly expect continuing and substantial progress towards
solution to the waste disposal problem. Successful operation of the
planned disposal facility at Yucca Mountain would ease, but not solve,
the waste issue for the U.S. and other countries if nuclear power
expands substantially.

Chapter 8

Nuclear Reactions
• Nuclear reactions deal with interactions between the nuclei
of atoms including of nuclear fission and nuclear fusion
• Both fission and fusion processes deal with matter and energy
• Fission is the process of splitting of a nucleus into two
"daughter" nuclei leading to energy being released
• Fusion is the process of two "parent" nuclei fuse into one
daughter nucleus leading to energy being released

• Nuclear reactions are different from chemical reactions
Chemical
Reactions
Mass is
conserved
(doesn’t
change)
Small
energy
changes
No changes in the
nuclei; involve
ONLY valance
electrons
Nuclear
Reactions
Small
changes in
mass
Huge
energy
changes
protons, neutrons,
electrons and
gamma rays can be
lost or gained

Mass Defect
• Some of the mass can be converted into
energy
• Shown by a very famous equation!
E=mc2
Energy
Mass
Speed of light Nuclear Energy - Prof. Ghada Amer4/10/2018 17

Nuclear Reactions
• Two types:
–Fission = the splitting of nuclei
–Fusion = the joining of nuclei (they fuse
together)
• Both reactions involve extremely large
amounts of energy
Albert Einstein’s
equation E = mc2
illustrates the energy
found in even small
amounts of matter

Nuclear Fission:
• Is the splitting of one heavy nucleus into two or more smaller nuclei, as
well as some sub-atomic particles and energy.
• A heavy nucleus is usually unstable, due to many positive protons
pushing apart.
• When fission occurs:
1.Energy is produced.
2.More neutrons are given off.
• Neutrons are used to make nuclei unstable
– It is much easier to crash a neutral neutron than a positive
proton into a nucleus to release energy.
There are 2 types of fission that exist:
1. Spontaneous Fission
2. Induced Fission

FYI: The penetrating power of radiation.

Spontaneous Fission
• Some radioisotopes contain nuclei which are highly unstable and
decay spontaneously by splitting into 2 smaller nuclei.
• Such spontaneous decays are accompanied by the release of
neutrons.
Induced Fission
• Nuclear fission can be induced by bombarding atoms with
neutrons.
• The nuclei of the atoms then split into 2 equal parts.
• Induced fission decays are also accompanied by the release of
neutrons.

U
235
92n
1
0
The Fission Process
A neutron travels at high speed towards a uranium-235 nucleus.

U
235
92n
1
0
The Fission Process
A neutron travels at high speed towards a uranium-235
nucleus.

U
235
92n
1
0
The neutron strikes the nucleus which then captures
the neutron.
The Fission Process

U
236
92
The nucleus changes from being uranium-235 to
uranium-236 as it has captured a neutron.
The Fission Process

The uranium-236 nucleus formed is very unstable.
The Fission Process
It transforms into an elongated shape for a short time.

The Fission Process

It then splits into 2 fission fragments and releases
neutrons.
141
56Ba
92
36Kr
n
1
0
n
1
0
n
1
0
The Fission Process

neutrons.
141
56Ba
92
36Kr
n
1
0
n
1
0
n
1
0
The Fission Process

neutrons.
141
56Ba
92
36Kr
1
n
1
0
n
1
0
The Fission Process

Energy from Fission
Both the fission fragments and neutrons travel at high
speed.
The kinetic energy of the products of fission are far
greater than that of the bombarding neutron and
target atom.
EK before fission << EK after fission
Energy is being released as a result of the fission reaction.

Energy from Fission
U
235
92
+Cs
138
55
+ n
1
0
2n
1
0
+Rb
96
37
Element Atomic Mass (kg)
235
92U 3.9014 x 10-25
138
55Cs 2.2895 x 10-25
96
37Rb 1.5925 x 10-25
1
0n 1.6750 x 10-27

Energy from Fission
Calculate the total mass before and after fission takes place.
The total mass before fission (LHS of the equation):
The total mass after fission (RHS of the equation):
3.9014 x 10-25 + 1.6750 x 10-27 = 3.91815 x 10-25 kg
2.2895 x 10-25 + 1.5925 x 10-25 + (2 x 1.6750 x 10-27) = 3.9155 x 10-25 kg

The total mass before fission =
The total mass after fission =
3.91815 x 10-25 kg
3.91550 x 10-25 kg
total mass before fission > total mass after fission
mass difference,
m = total mass before fission – total mass after fission
m = 3.91815 x 10-25 – 3.91550 x 10-25
m = 2.65 x 10-28 kg
This reduction in mass results in the release of
energy.

The energy released can be calculated using the equation:
E = mc2
Where:
E = energy released (J)
m = mass difference (kg)
c = speed of light in a vacuum (3 x 108 ms-1)
E
m c2

Energy from Fission
E = mc2
U
235
92 +Cs
138
55+ n
1
02n
1
0 +Rb
96
37
Calculate the energy released from the following fission
reaction:
m = 2.65 x 10-28 kg
c = 3 x 108 ms-1
E = E
E = 2.65 x 10-28 x (3 x 108)2
E = 2.385 x 10-11 J
• The energy released from this fission reaction does not seem a
lot. This is because it is produced from the fission of a single
nucleus.
• Large amounts of energy are released when a large number of
nuclei undergo fission reactions.Nuclear Energy - Prof. Ghada Amer4/10/2018 39

Fission
produces
a chain
reaction

 Each uranium-235 atom has a mass of 3.9014 x 10-25 kg.
 The total number of atoms in 1 kg of uranium-235 can be found
as follows:
 No. of atoms in 1 kg of uranium-235 = 1/3.9014 x 10-25
 No. of atoms in 1 kg of uranium-235 = 2.56 x 1024 atoms
If one uranium-235 atom undergoes a fission reaction
and releases 2.385 x 10-11 J of energy, then the amount
of energy released by 1 kg of uranium-235 can be
calculated as follows:
total energy = energy per fission x number of atoms
total energy = 2.385 x 10-11 x 2.56 x 1024
total energy = 6.1056 x 1013 J

Nuclear Fusion
In nuclear fusion, two nuclei with low mass numbers combine to
produce a single nucleus with a higher mass number.
H
2
1
+He
4
2
+ n
1
0
H
3
1
+ Energy
H
2
1
H
3
1

H
2
1
H
3
1
Nuclear Fusion

Nuclear Fusion

He
4
2
n
1
0
Nuclear Fusion

Energy from Fusion
Element Atomic Mass (kg)
2
1H 3.345 x 10-27
3
1H 5.008 x 10-27
4
2He 6.647 x 10-27
1
0n 1.6750 x 10-27
H
2
1
+He
4
2
+ n
1
0
H
3
1 +Energy

Calculate the following:
• The mass difference.
• The energy released per fusion.
The total mass before fusion (LHS of the equation):
The total mass after fission (RHS of the equation):
3.345 x 10-27 + 5.008 x 10-27 = 8.353 x 10-27 kg
6.647 x 10-27 + 1.675 x 10-27 = 8.322 x 10-27 kg
H
2
1
+He
4
2
+ n
1
0
H
3
1 +Energy

m = total mass before fission – total mass after fission
m = 8.353 x 10-27 – 8.322 x 10-27
m = 3.1 x 10-29 kg
E = mc2m = 3.1 x 10-29 kg
c = 3 x 108 ms-1
E = E
E = 3.1 x 10-29 x (3 x 108)2
E = 2.79 x 10-12 J
H
2
1
+He
4
2
+ n
1
0
H
3
1 +Energy
The energy released per fusion is 2.79 x 10-12 J.Nuclear Energy - Prof. Ghada Amer4/10/2018 56

4/10/2018 Nuclear Energy - Prof. Ghada Amer 57

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