Nuclear Power Station 2020

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
Nuclear Power Station - Prof. Ghada Amer

Chapter 8
Nuclear Power Station
• 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:

The Motivation for
Nuclear Energy
➢ 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 Power Station - Prof. Ghada Amer

• 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.
✓ 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.

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’’.

A Brief History of Nuclear Power
• 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. Nuclear Power Station - Prof. Ghada Amer

• 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 reverberate 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 destined to do. We have found what may be called perpetual
youth’’.

• In 2019, nuclear power
supplied 20% of United
States and accounting for
more than 30% of
worldwide nuclear
generation of electricity.
• 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.

• 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 Power station

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 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.

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

It then splits into 2 fission fragments and releases
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.

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 Power Station - Prof. Ghada Amer

Chapter 8

What is a nuclear reactor?
• A nuclear reactor is a system that contains, and controls sustained
nuclear chain reactions.
• Reactors are used for generating electricity,
moving aircraft carriers and submarines,
producing medical isotopes for imaging
and cancer treatment, and for conducting
research.
• Fuel, made up of heavy atoms that split
when they absorb neutrons, is placed into
the reactor vessel (basically a large tank)
along with a small neutron source.
• The neutrons start a chain reaction where each
atom that splits releases more neutrons that
cause other atoms to split.

• The heat is carried out of the reactor by coolant, which is most
commonly just plain water. The coolant heats up and goes off to a
turbine to spin a generator or drive shaft. Nuclear reactors are
just exotic heat sources.

Nuclear Reactor Main components
• The core of the reactor contains all of the nuclear fuel and generates all
of the heat. It contains low-enriched uranium (<5% U-235), control
systems, and structural materials. The core can contain hundreds of
thousands of individual fuel pins.

• The coolant is the material that passes through the core,
transferring the heat from the fuel to a turbine.
It could be:
✓ water,
✓ heavy-water,
✓ liquid sodium,
✓ helium, or something else.
In the US fleet of power reactors, water is the standard.

• The turbine transfers the heat from the coolant to
electricity, just like in a fossil-fuel plant.
• The containment is the structure that separates the reactor
from the environment. These are usually dome-shaped,
made of high-density, steel-reinforced concrete. Chernobyl
did not have a containment to speak of.

• Cooling towers are needed by some plants to dump the excess
heat that cannot be converted to energy due to the laws of
thermodynamics. These are the hyperbolic icons of nuclear
energy. They emit only clean water vapor.

• The image above shows a nuclear reactor heating up water and
spinning a generator to produce electricity.
• It captures the essence of the system well. The water coming into the
condenser and then going right back out would be water from a river,
lake, or ocean.
• It goes out the cooling towers. As you can see, this water does not go
near the radioactivity, which is in the reactor vessel.Nuclear Power Station - Prof. Ghada Amer

Fuel pins
• The smallest unit of the reactor is the fuel pin.
• These are typically uranium-oxide (UO2), but can take on other
forms, including thorium-bearing material.
• They are often surrounded by a metal tube (called the cladding) to
keep fission products from escaping into the coolant.

Fuel Assembly
• Fuel assemblies are bundles of fuel pins.
• Fuel is put in and taken out of the reactor in assemblies.
• The assemblies have some structural material to keep the
pins close but not touching, so that there’s room for
coolant.

Full core
• This is a full core, made up of several hundred assemblies. Some
assemblies are control assemblies.
• Various fuel assemblies around the core have different fuel in them.
• They vary in enrichment and age, among other parameters.
• The assemblies may also vary with height, with different
enrichments at the top of the core from those at the bottom.

Types of Reactors
• There are many different
kinds of nuclear fuel forms
and cooling materials can be
used in a nuclear reactor. As
a result, there are thousands
of different possible nuclear
reactor designs.
• Here, we discuss a few of the
designs that have been built
before, but don’t limit your
imagination; many other
reactor designs are possible.
Dream up your own!

Pressurized Water Reactor (PWR)
• The most common type of reactor.
• The PWR uses regular old water as a coolant.
• The primary cooling water is kept at very high pressure so it does not
boil.
• It goes through a heat exchanger, transferring heat to a secondary coolant
loop, which then spins the turbine.
• These use oxide fuel
pellets stacked in
zirconium tubes.
• They could possibly
burn thorium or
plutonium fuel as
well.

☺Pros:
• Strong negative void coefficient — reactor cools down if water
starts bubbling because the coolant is the moderator, which is
required to sustain the chain reaction
• Secondary loop keeps radioactive stuff away from turbines,
making maintenance easy.
• Very much operating experience has been accumulated and
the designs and procedures have been largely optimized.
Cons:
• Pressurized coolant escapes rapidly if a pipe breaks,
necessitating lots of back-up cooling systems.
• Can’t breed new fuel — susceptible to "uranium shortage"

Boiling Water Reactor
• Second most common, the BWR is similar to the PWR in many ways.
However, they only have one coolant loop.
• The hot nuclear fuel boils water as it goes out the top of the reactor,
where the steam heads over to the turbine to spin it.

☺Pros:
• Simpler plumbing reduces costs
• Power levels can be increased simply by speeding up the jet pumps,
giving less boiled water and more moderation. Thus, load-following is
simple and easy.
• Very much operating experience has been accumulated and the designs
and procedures have been largely optimized.
Cons:
• With liquid and gaseous water in the system, many weird transients are
possible, making safety analysis difficult
• Primary coolant is in direct contact with turbines, so if a fuel rod had a
leak, radioactive material could be placed on the turbine. This
complicates maintenance as the staff must be dressed for radioactive
environments.
• Can’t breed new fuel — susceptible to "uranium shortage"
• Does not typically perform well in station blackout events, as in
Fukushima.

Canada Deuterium-Uranium Reactors (CANDU)
• CANDUs are a Canadian design found in Canada and around the world.
• They contain heavy water, where the Hydrogen in H2O has an extra
neutron (making it Deuterium instead of Hydrogen).
• Deuterium absorbs many fewer neutrons than Hydrogen, and CANDUs
can operate using only natural uranium instead of enriched.

☺Pros:
• Require very little uranium enrichment.
• Can be refueled while operating, keeping capacity factors high
(as long as the fuel handling machines don’t break).
• Are very flexible, and can use any type of fuel.
Cons:
• Some variants have positive coolant temperature coefficients,
leading to safety concerns.
• Neutron absorption in deuterium leads to tritium production,
which is radioactive and often leaks in small quantities.
• Can theoretically be modified to produce weapons-grade
plutonium slightly faster than conventional reactors could be.

Sodium Cooled Fast Reactor
• These reactors are cooled by liquid sodium metal.
• Sodium is heavier than hydrogen, a fact that leads to the neutrons moving
around at higher speeds (hence fast). These can use metal or oxide fuel,
and burn a wide variety of fuels.

☺Pros:
• Can breed its own fuel, effectively eliminating any concerns about uranium
shortages
• Can burn its own waste
• Metallic fuel and excellent thermal properties of sodium allow for passively
safe operation — the reactor will shut itself down safely without any backup-
systems working (or people around), only relying on physics.
Cons:
• Sodium coolant is reactive with air and water. Thus, leaks in the pipes results in
sodium fires. These can be engineered around but are a major setback for
these reactors.
• To fully burn waste, these require reprocessing facilities which can also be used
for nuclear proliferation.
• The excess neutrons used to give the reactor its resource-utilization capabilities
could covertly be used to make plutonium for weapons.
• Positive void coefficients are inherent to most fast reactors, especially large
ones. This is a safety concern.
• Not as much operating experience has been accumulated. We have only about
300 reactor-years of experience with sodium cooled reactors

High Temperature Gas Cooled Reactor (HTGRs)
• HTGRs use little pellets of fuel backed into either hexagonal compacts or
into larger pebbles (in the prismatic and pebble-bed designs).
• Gas such as helium or carbon dioxide is passed through the reactor
rapidly to cool it. Due to their low power density, these reactors are seen
as promising for using nuclear energy outside of electricity: in
transportation, in industry, and in residential regimes. They are not
particularly good at just producing electricity.

☺Pros:
• Can operate at very high temperatures, leading to great thermal
efficiency (near 50%!) and the ability to create process heat for things like
oil refineries, water desalination plants, hydrogen fuel cell production,
and much more.
• Each little pebble of fuel has its own containment structure, adding yet
another barrier between radioactive material and the environment.
Cons:
• High temperature has a bad side too. Materials that can stay structurally
sound in high temperatures and with many neutrons flying through them
are hard to come by.
• If the gas stops flowing, the reactor heats up very quickly. Backup cooling
systems are necessary.
• Gas is a poor coolant, necessitating large amounts of coolant for
relatively small amounts of power. Therefore, these reactors must be
very large to produce power at the rate of other reactors.
• Not as much operating experience

Molten Salt Reactor
• Molten Salt Reactors (MSRs) are nuclear reactors that use a fluid fuel in the form of very
hot fluoride or chloride salt instead of the solid fuel used in most reactors.
• Since the fuel salt is liquid, it can be both the fuel (producing the heat) and the coolant
(transporting the heat to the power plant).
• There are many different types of MSRs, but the most talked about one is definitely the
Liquid Fluoride Thorium Reactor (LFTR).
• This MSR has Thorium and Uranium dissolved in a fluoride salt and can get planet-scale
amounts of energy out of our natural resources of Thorium minerals, much like a fast
breeder can get large amounts of energy out of our Uranium minerals.
• There are also fast breeder fluoride MSRs
that don’t use Th at all.
• And there are chloride salt based fast
MSRs that are usually studied as nuclear
waste-burners due to their extraordinary
amount of very fast neutrons.

☺Pros:
• Can constantly breed new fuel, eliminating concerns over energy
resources
• Can make excellent use of thorium, an alternative nuclear fuel to
uranium
• Can be maintained online with chemical fission product removal,
eliminating the need to shut down during refueling.
• No cladding means less neutron-absorbing material in the core,
which leads to better neutron efficiency and thus higher fuel
utilization
• Liquid fuel also means that structural dose does not limit the life
of the fuel, allowing the reactor to extract very much energy out of
the loaded fuel.

Cons:
• Radioactive gaseous fission products are not contained in small pins, as
they are in typical reactors. So if there is a containment breach, all the
fission gases can release instead of just the gases from one tiny pin. This
necessitates things like triple-redundant containments, etc. and can be
handled.
• The presence of an online reprocessing facility with incoming pre-
melted fuel is a proliferation concern. The operator could divert Pa-233
to provide a small stream of nearly pure weapons-grade U-233. Also,
the entire uranium inventory can be separated without much effort. In
his autobiography, Alvin Weinberg explains how this was done at Oak
Ridge National Lab: "It was a remarkable feat! In only 4 days all of the
218 kg of uranium in the reactor were separated from the intensely
radioactive fission products and its radioactivity reduced five billion-
fold."
• Very little operating experience, though a successful test reactor was
operated in the 1960s

• A nuclear reactor is a system that contains, and controls sustained
nuclear chain reactions.
Reactors are used for:
✓ generating electricity,
✓ moving aircraft carriers and submarines,
✓ producing medical isotopes for imaging and
cancer treatment, and
✓ for conducting research.

• The heat is carried out of the reactor by coolant, which is most
commonly just plain water.
• The coolant heats up and goes off to a turbine to spin a generator
or drive shaft. Nuclear reactors are just exotic heat sources.

Nuclear Reactor Main components
• The core of the reactor contains all of the nuclear fuel and generates all
of the heat.
• It contains low-enriched uranium (<5% U-235), control systems, and
structural materials. The core can contain hundreds of thousands of
individual fuel pins.

The coolant is the material that passes through the core,
transferring the heat from the fuel to a turbine.
It could be:
✓ water,
✓ heavy-water,
✓ liquid sodium,
✓ helium, or something else.
In the US fleet of power reactors, water is the standard.

• Cooling towers are needed by some plants to dump the excess
heat that cannot be converted to energy due to the laws of
thermodynamics. These are the hyperbolic icons of nuclear energy.
They emit only clean water vapor.

Types of Reactors
• As a result, there are
thousands of different
possible nuclear reactor
designs.
• Here, we discuss a few of the
designs that have been built
before, but don’t limit your
imagination; many other
reactor designs are possible.
Dream up your own!
• There are many different kinds of nuclear fuel forms and
cooling materials can be used in a nuclear reactor.

Pressurized Water Reactor (PWR)
• The most common type of reactor.
• The PWR uses regular water as a coolant.
• The primary cooling water is kept at very high pressure, so it does not
boil.
• It goes through a heat exchanger, transferring heat to a secondary coolant
loop, which then spins the turbine.
• These use oxide fuel
pellets stacked in
zirconium tubes.
• They could possibly
burn thorium or
plutonium fuel as
well.

High Temperature Gas Cooled Reactor (HTGR)
• HTGR use little pellets of fuel
backed into either hexagonal
compacta or into larger pebbles
(in the prismatic and pebble-bed
designs).
• Gas such as helium or carbon
dioxide is passed through the
reactor rapidly to cool it. Due to
their low power density, these
reactors are seen as promising for
using nuclear energy outside of
electricity: in transportation, in
industry, and in residential
regimes. They are not particularly
good at just producing electricity.

Molten Salt Reactor
• Molten Salt Reactors (MSRs) are nuclear reactors that use a fluid fuel in the form
of very hot fluoride or chloride salt instead of the solid fuel used in most
reactors.

Molten Salt
Reactor
• Since the fuel salt is liquid, it can
be both the fuel (producing the
heat) and the coolant (transporting
the heat to the power plant).
• There are many different types of
MSRs, but the most talked about
one is definitely the Liquid
Fluoride Thorium Reactor (LFTR).
• This MSR has Thorium and
Uranium dissolved in a fluoride salt
and can get planet-scale amounts
of energy out of our natural
resources of Thorium minerals,
much like a fast breeder can get
large amounts of energy out of our
Uranium minerals. Nuclear Power Station - Prof. Ghada Amer

Molten Salt Reactor
• There are also fast breeder fluoride MSRs that don’t use Th at all.
• And there are chloride salt based fast MSRs that are usually studied
as nuclear waste-burners due to their extraordinary amount of very
fast neutrons.

Cons:
• Radioactive gaseous fission products are not contained in
small pins, as they are in typical reactors. So if there is a
containment breach, all the fission gases can release
instead of just the gases from one tiny pin. This
necessitates things like triple-redundant containments,
etc. and can be handled.
• The presence of an online reprocessing facility with
incoming pre-melted fuel is a proliferation concern. The
operator could divert Pa-233 to provide a small stream of
nearly pure weapons-grade U-233. Also, the entire
uranium inventory can be separated without much effort.
• Very little operating experience, though a successful test
reactor was operated in the 1960s

• They call it also VVER (from Russian water-water power reactor) is a series of
pressurized water reactor designs originally developed in the Soviet Union, and
now Russia.
• VVER were originally developed before the 1970s, and have been continually
updated. As a result, the name VVER is associated with a wide variety of reactor
designs spanning from generation I reactors to modern generation III+ reactor
designs.
• Power output ranges from 70 to 1300 MWe, with designs of up to 1700 MWe in
development.
The water-water energetic reactor (WWER)
• VVER power stations have been mostly
installed in Russia and the former
Soviet Union, but also in China, Finland,
Germany, Hungary, Slovakia, Bulgaria,
India, and Iran.
• Countries that are planning to
introduce VVER reactors include
Bangladesh, Egypt, Jordan, and Turkey.

Thanks for your attention

The Nuclear Fuel Cycle

Uranium
• URANIUM is a slightly radioactive metal that occurs throughout the
earth's crust.
• It is about 500 times more abundant than gold and about as common as
tin.
• It is present in most rocks and soils as well as in many rivers and in sea
water.
• Most of the radioactivity associated with uranium in nature is due to
other materials derived from it by radioactive decay processes, and
which are left behind in mining and milling.
• Economically feasible deposits of the ore, pitchblende, U3O8, range from
0.1% to 20% U3O8. Nuclear Power Station - Prof. Ghada Amer

Uranium
Mining
➢ Open pit mining is used where deposits are close to the
surface
➢ Underground mining is used for deep deposits, typically
greater than 120m deep.
➢ In situ leaching (ISL), where oxygenated groundwater
is circulated through a very porous ore body to
dissolve the uranium and bring it to the surface.
ISL may use slightly acidic or alkaline solutions to keep the
uranium in solution. The uranium is then recovered from
the solution. Nuclear Power Station - Prof. Ghada Amer

Uranium Mining
• The decision as to which mining method to use for a particular deposit
is governed by:
1. the nature of the ore body,
2. safety and
3. economic considerations.
In the case of underground uranium mines, special precautions, consisting
primarily of increased ventilation, are required to protect against
airborne radiation exposure.

Uranium resources in Egypt
1-‫أبو‬‫زنيمة‬‫احدى‬‫مدن‬‫جنوب‬‫سيناء‬
2-‫جبل‬‫قطار‬
3-‫المسيكات‬-‫العرضية‬-‫وتقع‬‫جنوب‬
‫طريق‬‫قنا‬-‫سفاجا‬
4-‫جبل‬‫أم‬‫آر‬-‫تقع‬‫هذه‬‫المنطقة‬‫على‬‫بع‬‫د‬
180‫كم‬‫جنوب‬‫شرق‬‫أسوان‬
5-‫الصحراء‬‫الشرقية‬
6-‫الصحراء‬‫الغربية‬-‫اكتشفت‬‫في‬
‫الواحات‬‫البحرية‬‫بعض‬‫تمعدنات‬
‫اليورانيوم‬‫في‬‫جبل‬‫الهفهوف‬
7-‫سيناء‬

Processing: from ore to “yellow cake”
• Once uranium ore has been extracted in an underground or open-pit
mine, it is transported to a processing plant.
• This step allows us to obtain concentrated uranium, or "yellow cake".
Purification and concentration of uranium ore
• Once the ore has been removed from the mine, it is processed in one
of the following ways, depending on its grade:

1- Dynamic treatment
• High-grade ore (uranium content > 0.10%) is
transported to a processing plant, where it is
✓ crushed
✓ ground mechanically processed and
✓ purified with chemical solutions extracted from the
resulting liquor using organic solutions or ion exchange
resins
✓ washed and filtered
✓ precipitated and dried.

2- Acid heap leaching
• Many companies has been using this modern method for the
extraction of uranium from low-grade ores ( < 0.10%) since 2009.
• This process is called “heap” leaching because the ore is stacked up.
• It is the first time that leaching has been used in uranium mining.
The steps in the process are as follows:
1. The ore is crushed to reduce it to particles of appropriate size
2. The particles are aggregated in an agglomerator using water and
acid to enhance the permeability and stability of the heaps.
3. The ore is heaped up by stackers at the leach pads
4. An acid solution percolates through the ore heap for about 3
months
• The uranium-bearing solution drains from the heap and is collected.
The uranium is extracted from the solution using a solvent in a
chemical treatment plant.

• After drying, a solid, concentrated uranium is obtained
called "yellow cake" (due to its color and its doughy texture
at the end of the procedure) containing around 75% uranium,
or 750 kilograms per metric ton.
• The "yellow cake" is packaged and put into barrels, then sent
to conversion facilities for further chemical processing.

Uranium Metallurgy
“Yellowcake”Nuclear Power Station - Prof. Ghada Amer

Enriching Uranium for Reactor Fuel
• Increase the concentration of fissionable U-235
isotope
• Enrichment requires a physical process since
U-235 and U-238 have the same chemical
properties
• Physical processes require gases for separation
• Uranium and its oxides are solids
• Must convert uranium to UF6
• Enriched UF6 must be converted back to solid
uranium or uranium oxide

Enrichment
The two method of uranium enrichment are:
• Gaseous diffusion (older)
• Centrifugation (newer)
Both use small differences in the masses (< 1%) of the U-235F6 and
U-238F6 molecules to increase the concentration of U-235.

Gaseous diffusion

Loading uranium
hexafluoride containers
Gaseous diffusion plant
Paducah, Kentucky

Centrifuge Enrichment
Feed
Enriched
exit
Depleted
exit
U235F6is lighter and
collects in the center
(enriched)
U238F6 is heavier and
collects on the outside walls
(Depleted/Tails)
Feed to
Next Stage

1. Proven technology: Centrifuge is a proven enrichment process,
currently used in several countries.
2. Low operating costs: Its energy requirements are less than 5% of
the requirements of a comparably sized gaseous diffusion plant.
3. Modular architecture: The modularity of the centrifuge
technology allows for flexible deployment, enabling capacity to be
added in increments as demand increases.
The gas centrifuge process has
three characteristics that make it
economically attractive for
uranium enrichment:

Fuel Fabrication
• Reactor fuel is generally in the form of ceramic pellets.
• These are formed from pressed uranium oxide which is sintered
(baked) at a high temperature (over 1400°C).
• The pellets are then encased in metal tubes to form fuel rods,
which are arranged into a fuel assembly ready for introduction
into a reactor. Nuclear Power Station - Prof. Ghada Amer

UF6 Gas to UO2 Powder to Pellets

Fuel Pellets

Nuclear Fuel Assembly
Fuel
Pellet

Fuel Assemblies are Inserted in Reactor Vessel

Chapter 8
• Chain Reactions and Nuclear Reactors

Top 10 Nuclear Generating Countries, 2018
By GWh

The Evolution of Nuclear Power
Early Prototype
Reactors
Generation I
- Shipping port
- Dresden, Fermi I
- Magnox
Commercial Power
Reactors
Generation II
- LWR-PWR, BWR
- CANDU
- VVER/RBMK
1950 1960 1970 1980 1990 2000 2010 2020 2030
Generation IV
- Highly
Economical
- Enhanced
Safety
- Minimal
Waste
- Proliferation
Resistant
- ABWR
- System 80+
- AP600
- EPR
Advanced
LWRs
Generation III
Gen I Gen II Gen III Gen III+ Gen IV
Near-Term
Deployment
Generation III+
Evolutionary designs
offering improved
economics
Atoms for
Peace
TMI-2 Chernobyl

Generation IV Nuclear Energy Systems
• Six ‘most promising’ systems that offer significant
advances towards:
– Sustainability
– Economics
– Safety and reliability
– Proliferation resistance and physical
protection
• Summarizes R&D activities and priorities for the
systems
• Lays the foundation for Generation IV R&D
program plans
http://nuclear.gov/nerac/FinalRoadmapforNERACReview.pdf

IV Reactor types
• Many reactor types were considered initially; however, the list was
downsized to focus on the most promising technologies and those that
could most likely meet the goals of the Gen IV initiative.
• Three systems are nominally thermal reactors and three are fast
reactors.
• The Very High Temperature Reactor (VHTR) is also being researched
for potentially providing high quality process heat for hydrogen
production.
• The fast reactors offer the possibility of burning actinides to further
reduce waste and of being able to "breed more fuel" than they
consume.
• These systems offer significant advances in sustainability, safety and
reliability, economics, proliferation resistance (depending on
perspective) and physical protection.

A Long-Term Strategy for Nuclear Energy
1- Generation IV Thermal Reactors
• A thermal reactor is a nuclear reactor that uses slow or thermal
neutrons.
• A neutron moderator is used to slow the neutrons emitted by
fission to make them more likely to be captured by the fuel.
• Advanced, high burnup fuels
• High efficiency, advanced energy products
• Available by 2020

Thermal Systems
Example: Very High Temperature Reactor (VHTR)
– Thermal neutron spectrum and once-through cycle
– High-temperature process heat applications
– Coolant outlet temperature above 1,000oC
– Reference concept is 600 MWh with operating efficiency greater
than 50 percent
• Advanced Energy Production
– High efficiency electricity generation
– High efficiency hydrogen production via thermochemical water
cracking or high temperature electrolysis

Water
Oxygen
Hydrogen
Heat
O2
SO2
2H2O
H2
H2SO4
H20+SO2+½O2
H2SO4
HI
I2 + SO2 +2H2O
2HI + H2SO4
2HI H2 + I2
I2
900-1,100oC

Generation IV Fast Reactors
• Fast neutron systems
• Proliferation-resistant closed fuel cycles
• Minimize long-term stewardship burden
• Available by 2030 to 2040

Molten Salt Reactor - MSR
• Molten/liquid fuel
reactor
• High outlet temperatures
• Operates at atmospheric
pressure
• Flexible fuel: no covering

Supercritical Water-Cooled Reactor - SCWR
• LWR operating above the critical pressure of water, and producing
low-cost electricity.
• The U.S. program assumes:
– Direct cycle,
– Thermal spectrum,
– Light-water coolant and moderator,
– Low-enriched uranium oxide fuel,
– Base load operation.
25 MPa (supercritical)
500C (supercritical)
280C (subcritical)
Subcritical pressure
Subcritical temperature
500C (supercritical)
280C (subcritical)
Subcritical pressure
Subcritical temperatureNuclear Power Station - Prof. Ghada Amer

Fast Systems
Example: Gas-Cooled Fast Reactor (GFR)
– Fast neutron spectrum and closed fuel
cycle
– Efficient management of actinides and
conversion of fertile uranium
– Coolant outlet temperature of 850oC
– Reference concept is 600 MWth with
operating efficiency of 43 percent;
optional concept is 2,400 MWth
• Advanced Energy Production
– High efficiency electricity generation
– Good efficiency for hydrogen production
via thermochemical water cracking or
high temperature electrolysisNuclear Power Station - Prof. Ghada Amer

Lead Cooled Fast Reactor - LFR
• Deployable in remote
locations without supporting
infrastructure (output,
transportation)
• High degree of proliferation
resistance
• 15 to 30-yr core lifetime
• Passively safe under all
conditions
• Capable of self-autonomous
load following
• Natural circulation primary
• Fuel cycle flexibility
• Options for electricity,
hydrogen, process heat &
desalination
• Licensable through testing of
demonstration plant

System
Neutron
Spectrum
Coolant Temperature (°C) Fuel Cycle Size (MW)
VHTR Thermal Helium 900–1000 Open 250–300
SFR Fast Sodium 550 Closed
30–150, 300–
1500, 1000–
2000
SCWR Thermal/fast Water 510–625
Open/
closed
300–700, 1000–
1500
GFR Fast Helium 850 Closed 1200
LFR Fast Lead 480–800 Closed
20–180, 300–
1200, 600–1000
MSR Fast/thermal
Fluoride
salts
700–800 Closed 1000

http://www.nuclear.gov/AFCI_RptCong2003.pdf
January 2003
Advanced Fuel Cycle Initiative
The Path to a Proliferation-Resistant Nuclear
Future
• Develop fuel cycle technologies that:
– Enable recovery of the energy value from
commercial spent nuclear fuel
– Reduce the toxicity of high-level nuclear
waste bound for geologic disposal
– Reduce the inventories of civilian
plutonium in the U.S.
– Enable more effective use of the currently
proposed geologic repository and reduce
the cost of geologic disposal

Advanced Fuel Cycle Technologies
Application to Fast Reactors
Spent Fuel From
Commercial Plants
Direct
Disposal
Conventional
Reprocessing
PUREX
Spent
Fuel
Pu Uranium
MOX
LWRs/ALWRs
U and Pu
Actinides
Fission Products
Repository
Repository
Less U and Pu
(More Actinides
Fission Products)
Advanced, Proliferation-Resistant
Recycling
ADS Transmuter
Trace U and Pu
Trace Actinides
Less Fission Products
Repository
Gen IV Fast Reactors
Once Through
Fuel Cycle
European/Japanese
Fuel Cycle
Advanced Proliferation Resistant
Fuel Cycle
Gen IV Fuel Fabrication
LWRs/ALWRs
Gen IV Thermal Reactors
Advanced Separations

Thank you
All best
Prof. Ghada Amer

• The current methods of storage are running out of space and are
not intended for long-term use
• The USA government was required by the Nuclear Waste Policy Act
of 1982 to provide long-term storage for waste
• So far, the USA federal government has scrapped Yucca Mountain,
and it is considering alternative storage methods
• The US has more than 64,000 metric tons of nuclear waste
“Enough to cover a football field about seven yards deep”
• The half-life of the fuel is more than 1 million years
• Legal requirements: Nuclear Waste Policy Act of 1982
Fast Facts

USA Current Storage Locations

Nuclear Waste…Why?
• Most opponents of nuclear power point to
two main arguments:
• meltdowns and
• nuclear waste.
• Nuclear waste is any form of byproduct or
end product that releases radioactivity.
• How to safely dispose of nuclear waste is
essential for:
• the continued operation of nuclear
power plants,
• safety of people living around dump
sites, and
• prevention of proliferation of nuclear
materials to non-nuclear states.

Nuclear Waste Classifications
• Nuclear waste is segregated into several classifications.
1. Low level waste is not dangerous but sometimes requires
shielding during handling.
2. Intermediate level waste typically is chemical sludge and other
products from reactors.
3. High level waste consists of fissionable elements from reactor
cores and transuranic wastes.
“Transuranic waste is any waste with transuranic alpha emitting
radionuclides that have half-lives longer than 20 years”

1. Low Level Waste (LLW)
• Low level waste is any waste that could be from a high activity area.
• 90% volume of waste
• It does not necessarily carry any radioactivity.
• Split into four categories: A, B, C, and GTCC.
2. Intermediate Level Waste (ILW)
• Intermediate level waste requires shielding when being handled.
• Dependent on the amount of activity it can be buried in shallow
repositories.

3. High Level Waste (HLW)
• High level waste has a large amount of radioactive activity and is
thermally hot.
• 95% of radioactivity
• Current levels of HLW are increasing about 12,000 metric tons per year.
• Most HLW consists of Pu-238, 239, 240, 241, 242, Np-237, U-236
4. Transuranic Waste (TRUW)
• Transuranic waste consists of all waste that has radionuclides above
uranium.
• TRUWs typically have longer half-lives than other forms of waste.
• Typically a byproduct of weapons manufacturing.
• Only recognized in the United States.

Nuclear Fuel Cycle
Most nuclear waste comes from the byproducts of the
nuclear fuel cycle. The cycle typically is split into three
sections:
1. front end,
2. service period, and
3. back end.
There can be intermediate stages that include the
reprocessing of nuclear waste elements.

Creation of Nuclear Waste
•Nuclear waste is generated at all points of the fuel cycle.
•Front end waste consists primarily of low level alpha
emission waste.
•Service period waste typically includes LLW and ILW such
as contaminated reactor housings and waste from daily
operation.
•Back end waste normally is the most radioactive and
includes spent fuel rods and reactor cores.

Front End Waste
• Front end waste consists mostly of LLW
and ILW.
• The primary front end waste is
depleted uranium and radium.
– DU has several uses due to its high
density (19,050 kg/m3).
– Mix with uranium to form reactor
fuel

Service Period Waste
• Consists of mostly ILW.
• Mostly waste produced at the plant during normal
operation.
• Spent fuel rods are the most dangerous waste produced
during the service period.

Back End Waste
• Nuclear waste developed during
the back end of the fuel cycle is
the most dangerous and
includes most of the HLW
produced.
• Most back end waste emits both
gamma and beta particles.
• Also uranium-234, neptunium-
237, plutonium-238 and
americium-241are found in back
end waste.
Spent nuclear fuel in a cooling pond in North
Korea.

Waste Management (LLW)
There are several options available for the disposal of LLW
due to its lack of radioactivity.
• Waste Isolation Pilot Plant
• On-site disposal
Map of WIPP Facility

Treatment (LLW)
• Filtration
• Ion Exchange
• Evaporation
• Burning
• Compaction
• Solidification
Typical LLW treatment facility.

Waste Management (HLW)
• Most common utilized
option are reactor pools
and dry cask storage.
• Other Options for waste
management include:
– Deep Geologoical Storage
– Transmutation
– Reuse
– Launching it into space

Treatment
• Most common initial treatment of waste is vitrification.
– Waste is first mixed with sugar and then passed through a heated
tube to de-nitrite the material.
– This material is then fed into a furnace and mixed with glass.
– The molten glass mixture is poured into steel cylinders and welded
shut.
• Mid level active waste is commonly treated with ion exchange
➢ Process reduces the bulk volume of radioactive material.
➢ Typically, mixed with concrete for a solid storage form.
• Synroc is a new method for storing nuclear waste developed in 1978
by Ted Ringwood. “Attempts to hold radioactive material in a
crystalline matrix”.
• Currently in use for military waste management at Savannah River
Site.
• Can hold 50%-70% volume of waste.

• Spent fuel rods are
stored in cooling ponds
• On-site at the reactors
• Protects surroundings
from radiation
• Absorbs heat generated
during radioactive decay
Spent Fuel Pools

Spent Fuel Storage Pools

• They were only intended as a temporary solution
• They are quickly reaching full capacity
Problems with Spent Fuel Pools

Two options for storage:
• horizontal and vertical
• Surrounded by inert gas,
steel, and concrete
• Must be licensed by the
NRC
– 22 different licensed designs
• 9,000 metric tons are
stored this way
Dry Cask Storage

Dry Cask Storage on
Reactor Sites

• Even advocates admit
this is only viable for a
certain number of years
– right now they are
licensed for 50 years
• Transportation to offsite
is difficult
• Potential terrorist target
Problems with Dry Cask Storage

Deep Geological Repository
• Most common method
for handling nuclear
waste.
• Typically kept separate
from actual plants and
buried far below ground.
• First used in 1999 in the
US.
• Current research is
focusing on Yucca
Mountain. Yucca Mountain Site

• So far, rate payers have
paid in $27 billion to the
Nuclear Waste Fund
• The government has
spent $8 billion of this
money
• The site was required by
law and contract to begin
collecting waste in 1998
Government Failure:
Yucca Mountain

• Two billion years ago,
uranium in Gabon was
caught in a chain reaction
• Plutonium was produced
and trapped in the rock
• Since then, the
radioactivity has moved
only slightly and the
plutonium has devolved
into nonreactive
substances
Precedent for Yucca Mountain

• Only 3% high level
waste remains
• Results are mostly
Plutonium and some
Uranium-235
• Current capabilities: 1/3
of the world’s fuel
Reprocessing

Reprocessing – Closed Fuel Cycle
• Recovers of uranium and plutonium from spent fuel
• Reduces volume and radioactivity of waste
• France, the UK, Japan, and Russia currently reprocess spent fuel

Solidifying high-level waste in borosilicate glass
for long term storage in a repository

• In spent fuel, Plutonium is trapped
in bulky assemblies, but after
reprocessing it is stored in
powdered form
• Plutonium after reprocessing is
significantly less radioactive
• It is hard to keep track of all of the
material at a reprocessing facility
• Some storage and disposal is still
required
• Would divert funds from a
permanent storage facility
• Incredibly high price tag – perhaps
$100 billion to reprocess the
existing spent fuel
Problems with Reprocessing

• After reprocessing,
there is little security
threat
• The resulting Plutonium
can be used in MOX fuel
but not as easily in
weapons
Counter Argument to the Security
Threat from Reprocessing

Transport of Spent Fuel

Reuse of Nuclear Waste
• Research is being performed to find uses for
nuclear waste.
• Caesium-137 and strontium-90 already used
in industrial applications.
• Some waste can be used for radioisotope
thermoelectric generators (RTGs).
• Overall can reduce total HLW but not
eliminate it.

Launch it into Space
• Near infinite storage
space
• Completely removes
waste from biosphere
• Technical risks and
problems
• Political
entanglements

Conclusions
• HLW is most dangerous
byproduct of nuclear
power.
• Borosilicate glass most
common storage.
• Several venues being
researched for the safe
disposal of HLW.

Nuclear Safety
• During the fifty years that commercial power
plants have operated worldwide, there have
been three serious accidents.
• All the serious reactor incidents (Windscale,
Chernobyl, Fukushima) involved human error.
• The safety record of existing nuclear reactors
has improved over time as safety regulations
have been upgraded.

Nuclear Safety II
• There is no nuclear plant design that is totally
risk free.
• A recent MIT study based on probabilistic risk
assessment (PRA), suggests one to expect four
core damage accidents up to 2050
• They concluded that this was an unacceptably
high number – it should be 1 or less, which is
the current expected safety level.

Nuclear Safety III
• The restructuring of electricity sectors around the
world has motivated some operators to place
profits before safety.
• Excessive consideration for profits of the licensee
has played a large role in explaining the accidents
that have occurred at nuclear power plants.
• Nuclear power is least safe in environments
where satisfaction and pressure to maximize
profits are the greatest.

http://www.greenfacts.org/en/chernobyl/, Chernobyl Forum(2006)
Pathways Of Exposure To Man From
Release of Radioactive Materials

http://www.world-nuclear.org/info/chernobyl/inf07.htmNuclear Power Station - Prof. Ghada Amer

• Natural sources (81%) include radon (55%), external (cosmic, earthly),
and internal (K-40, C-14, etc.)
• Man-made sources (19%) include medical (diagnostic x-rays- 11%,
nuclear medicine- 4%), consumer products, and other (fallout, power
plants, air travel, occupational, etc.)
http://www.doh.wa.gov/ehp/rp/factsheets/factsheets-htm/fs10bkvsman.htm
NCRP Report No. 93
www.epa.gov/rpdweb00/docs/402-f-06-061.pdf

Effects of Ionizing Radiation
• Ionizing radiation has sufficient energy to hit bound elections out of an
atom or molecule
• Includes alpha/beta particles and gamma/x-rays
• Can form highly reactive free radicals with unpaired electrons
• For example, H2O → [H2O.] + e-
• Rapidly dividing cells in the human body are particularly susceptible to
damage by free radicals
• Radiation can be used to treat certain cancers and Graves disease
of the thyroid
• However, ionizing radiation can also damage healthy cells
• Biological damage determined by:
1. radiation dose,
2. type of radiation,
3. rate of delivery, and
4. type of tissue
Chemistry in Context, Chapter 7

Radiation Units
Activity- disintegration rate of radioactive substance
• Becquerel- SI unit (Bq) = 1 disintegration per second (dps)
‫بيكريل‬:‫كمية‬‫اإلشعاع‬‫الصادرة‬‫من‬‫مادة‬‫مشعة‬‫تتحلل‬‫فيها‬‫نواة‬‫واحدة‬‫في‬‫الث‬‫انية‬
• Curie (Ci) = 3.7 x 1010 Bq = # dps from 1g Ra
1‫كوري‬‫يساوي‬‫النشاط‬‫اإلشعاعي‬‫ل‬1‫جرام‬‫من‬‫الراديوم‬-226،‫و‬‫يساوي‬37
‫جيجا‬‫بيكريل‬(‫أي‬37‫ألف‬‫مليون‬‫بيكريل‬)
Absorbed dose- energy imparted by radiation onto an absorbing
material
• Gray- SI unit (Gy) = 1 joule per kilogram
• 1 Gy = 100 rads
‫جراي‬Gray‫وحدة‬‫قياس‬‫الجرعة‬‫اإلشعاعية‬‫من‬‫األشعة‬‫المؤينة‬،‫الممتصة‬‫وتعكس‬
‫كمية‬‫الطاقة‬‫التي‬‫أودعت‬‫في‬1‫كيلوجرام‬‫من‬‫الجسم‬‫الحي‬‫أو‬‫المادة‬.

Dose Equivalent (DE)- dose in terms of biological effect
‫هي‬‫كمية‬‫الطاقة‬‫التي‬‫يحصل‬‫عليها‬‫الجسم‬(‫البشري‬)‫من‬‫األشعة‬‫المؤينة‬
‫مضروبة‬‫في‬‫معامل‬‫موازنة‬‫اإلشعاع‬،‫الذي‬‫يحدد‬‫التأثير‬‫الحيوي‬‫النسبي‬‫ل‬‫نوع‬
‫األشعة‬‫على‬‫األنسجة‬‫الحية‬.
‫وتعرف‬‫وحدة‬‫الجرعة‬‫المكافئة‬‫ب‬‫جول‬/‫كيلوجرام‬‫من‬‫الجسم‬،‫حسث‬‫أن‬‫معامل‬
‫موازنة‬‫اإلشعاع‬‫كمية‬‫مطلقة‬،‫ليس‬‫لها‬‫وحدات‬.
‫ولغرض‬‫التمييز‬‫بينها‬‫وبين‬‫جرعة‬‫الطاقة‬‫تعرف‬‫الجرعة‬‫المكافئة‬‫بالوحد‬‫ة‬
،‫زيفرت‬‫واختصارها‬‫باإلنجليزية‬(Sievert (Sv.،‫وضعت‬‫هذا‬‫التعريف‬‫الهيئة‬
‫الدولية‬‫للوقاية‬‫من‬‫اإلشعاع‬ICRP‫عام‬1990.‫وبالنسبة‬‫إلى‬‫معامل‬‫موازنة‬
‫األشعاع‬-‫ويرمز‬‫له‬‫بالرمز‬Q -
• DE = Absorbed dose X Quality factor (Q)
• Q = 1 for beta particles and gamma/x-rays
• Q = 10 for alpha particles
• Sievert- SI unit (Sv)
• 1 Sv = 100 rems
REM‫وهي‬‫اختصار‬‫للتعبير‬roentgen equivalent man‫أي‬‫مكافئ‬‫رونتجن‬‫للشخص‬

No observable effect (< .25 Gy)- .25 Gy is nearly 70 times average
annual radiation exposure!
“The gray (symbol: Gy) is a derived unit of ionizing radiation dose in
the International System of Units (SI). It is defined as the absorption
of one joule of radiation energy per kilogram of matter.”
White blood cell count drops (.25 to 1 Gy)
Mild radiation sickness (1 to 2 Gy absorbed dose)
• Sickness and vomiting within 24 to 48 hours
• Headache
• Fatigue
• Weakness
Physiological Effects of Severe Radiation Exposure

Moderate radiation sickness (2 to 3.5 Gy)
• Nausea and vomiting within 12 to 24 hours
• Fever
• Hair loss
• Vomiting blood, bloody stool
• Poor wound healing
• Any of the mild radiation sickness symptoms
• Can be fatal to sensitive individuals
Severe radiation sickness (3.5 to 5.5 Gy)
• Nausea and vomiting less than 1 hour after exposure
• Diarrhea
• High fever
• Any symptoms of a lower dose exposure
• About 50% fatality

Very severe radiation sickness (5.5 to 8 Gy)
• Nausea and vomiting less than 30 minutes after exposure
• Dizziness
• Disorientation
• Low blood pressure
• Any symptoms of a lower dose exposure
• > 50% fatality
Longer term or lasting radiation effects include genetic mutations,
tumors/cancer, birth defects, cataracts, etc.

www.epa.gov/rpdweb00/docs/402-k-07-006.pdfNuclear Power Station - Prof. Ghada Amer

Source Dose (mrem)
Chest X-ray 10
5-hour plane flight 3
Live within 50 miles of coal-fired
power plant for 1 year
.03
Live within 50 miles of a nuclear plant
for 1 year
.009
US Average Annual Whole Body
Radiation Dose
360
Radiation Dose Comparisons

Risks & Benefits of Nuclear Power
Risks associated with energy produced by nuclear power are
less than from coal-burning plants.Nuclear Power Station - Prof. Ghada Amer

Risks & Benefits of Nuclear Power
Coal-fired electric plants
(one 1000 MW plant)
Nuclear plants
(one 1000 MW plant)
• releases 4.5 million tons of CO2 • produces 70 ft3 of HLW/year
• produces 3.5 million ft3 of waste
ash/year
• no CO2 released
• releases 300 tons of SO2 and
~100 tons NOx/day
• no acidic oxides of sulfur and
nitrogen released
• releases Uranium and Thorium
from coal

Safety in Nuclear Power Stations
what needed
✓Water-cooled/Water-moderated Energy
Reactor
✓pressure vessel of the reactor
✓ the primary circuit piping include a very small
contents of cobalt, this results in a lower
activation of material and also a lower
irradiation of personnel

✓qualified personnel,
✓quality documentation,
✓use of operating experience,
✓technical control,
✓protection against radiation,
✓fire safety, etc.
✓each of reactor units is controlled from the
independent unit control room
✓the reactor unit chief, primary part operator
and the secondary part operator.

Unit control room

Safety system
• Basic precondition of the power station safety is:
1. a continuous removal of heat generated in the reactor
core.
2. Safety systems consist of:
a) a high-pressure and low-pressure emergency pumps,
b)sprinkler system pumps,
c)reservoirs with boric acid solution,
d)heat exchangers,
e)pressurized-water containers,
f)pipelines,
g)fittings,
h)condensing troughs and
i)towers and gas tanks.

Leakage of cooling water
✓ security systems would pump cooling water under and
over the reactor core and sprinkle the hermetic boxes.
✓ disruption of the main circulation piping → pressure of
steam generated in hermetic boxes increase → steam
into condensing troughs → condense
✓ facilities are doubled or tripled, and dimensioned in
such an extent that the leakage of radioactive
substances to environment would be reduced to a
minimum.

Fast shut-down
• 37 control rod assemblies (depend on the type)
• power supply for all the control rod assemblies
in the upper positions is discontinued
• control rod assemblies starts moving
downwards by their own mass into the reactor
core, and the fission reaction is terminated
within 12 seconds.

State Office for Nuclear Safety
• Administration and supervision
• The Radiation Monitoring Network
• The Emergency Response Cente

Thanks for your attention
I wish to see all of you in a very high
positions soon
Good Luck!

Nuclear Power Station 2020

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