PRESENTATION ON NUCLEAR REACTORS

1. PRESENTATION OF INORGANIC
CHEMISTRY
Submitted by: Mehlil Hafeez
Submitted to: Maam Azhra Naveed
Topic: Nuclear Reactors

2. NUCLEAR REACTORS:
 Nuclear reactor is a device to obtain the nuclear energy in a controlled
nuclear fission reactions, usually used to generate power.
 In other words, Nuclear Reactor is an equipment for carrying out controlled
nuclear fission reactions, usually used to generate power.
 A nuclear reactor, formerly known as an atomic pile, is a device used to
initiate and control a fission nuclear chain reaction or nuclear fusion reactions.

3.  A nuclear reactor is a vessel in which a nuclear
reaction is carried out and maintained. The purpose
of a nuclear reactor is to generate electricity, propel
submarines and large ships, district heating
systems, for steam powered air craft catapult etc.
 Splitting of atoms produces lots of energy in the
form of heat. This heat is harnessed using either
water or gas and then it is used to generate steam.
The generated steam is used to drive the turbines
which are used to produce electricity.
 Nuclear reactors are used at nuclear power plants
for electricity generation.

4. PRINCIPLE OF NUCLEAR REACTORS:
 The principle involved in the functioning of a nuclear reactor is
nuclear fission. In nuclear fission, the nucleus of a heavy element is
hit by a neutron due to which it breaks into different smaller nuclei.
The resulting fragments are not of the same element hence this is a
process is called nuclear transmutation.
 The emitted neutrons may then cause new fissions, which in turn
yield more neutrons, and so forth. Such a continuous self-sustaining
series of fissions constitutes a fission chain reaction. A large amount
of energy is released in this process, and this energy is the basis of
nuclear power systems.

5. COMPONENTS OF NUCLEAR REACTOR:
 Components which are common to most types of
the nuclear reactors are:
 Fuel
 Core
 Moderator
 Control Rods
 Coolant
 Pressure fuel
 Steam generator
 Containment

6.  FUEL:
 In a conventional nuclear reactor used for power generation, the fuel is
uranium oxide. The most common fuel used in nuclear reactors is Uranium.
The Uranium are filled inside tubes to take shape of a rod, they are also
refereed as fuel rods. If the nuclear reactor is to be operated for first time then
a neutron source is needed to start the reaction. The neutron sources are
usually accompanied with elements which are known to be alpha emitters.
The alpha decay causes neutrons to be released from the source. When
reactor is operated more than one time then enough neutrons are there to
start the nuclear reaction.
 CORE:
 All reactors have a core, a central region that contains the fuel, fuel cladding,
coolant, and (where separate from the latter) moderator. The fission energy in
a nuclear reactor is produced in the core.

7.  MODERATOR:
A material that has the ability to slow down neutrons quickly and which,
at the same time, has little tendency to absorb neutrons is called a
moderator. When the neutrons are released from the core, they travel very
fast which may lead to them causing less fission. In order to increase the
rate of fission, moderators are used to slow down the neutrons so that they
may cause fission. The moderator is a material which is filled throughout the
reactor. This material can be water, graphite or heavy water.
 CONTROL ROADS:
The reactor is kept under control by trusting the positions ofthe control
rodswhich are inserted among the nuclear fuel elementin the reactor. These
control rods are usually made out of cadmium or boron,which are highly
efficientfor a neutron absorption.
 COOLANT:
The heat generated in the core of the reactor is removed by a coolant.
Water used in reactor serves both as moderator and coolant. When the
nuclear fission reaction happens in the core of the reactor a lot of heat is
generated. The function of a coolant is to remove this heat. The purpose of
the removal of heat is to not let temperature rise so high inside the reactor
that the heat melts the internals of the core and another main purpose is to
transfer the heat to water to transform it into steam.

8.  Pressure Vessel:
 It is a large robust vessel which contains the core of the reactor
along with all the internals along with the coolant and its
delivering mechanism.
 Steam Generator:
 Some reactors contain secondary systems in coolant delivery system
such as heat exchangers wherein heat is exchanged with water
which gets converted into steam. In some reactor systems the
coolant circulating around the core itself gets converted into steam.
The tubes delivering the coolants in such cases are quite robust.
 CONTAINMENT:
 It is a large structure generator. The containment walls are several
meters thick and they are made in this way to protect from the effects
of radiation in case the which contains and covers all the
components of nuclear reactor and stream reactor malfunctions.

9. EXAMPLES OF NUCLEAR REACTORS:
 PRESSURIZED HEAVY-WATER REACTOR:
A pressurized heavy-water reactor
(PHWR) is a nuclear reactor that uses
heavy water (deuterium oxide D2O) as its
coolant and neutron moderator. PHWRs
frequently use natural uranium as fuel,
but sometimes also use very low enriched
uranium. The heavy water coolant is kept
under pressure to avoid boiling, allowing it
to reach higher temperature (mostly) without
forming steam bubbles, exactly as for pressurized water reactor. While heavy
water is very expensive to isolate from ordinary water (often referred to as light
water in contrast to heavy water), its low absorption of neutrons greatly
increases the neutron economy of the reactor, avoiding the need for enriched
fuel.

10.  LIGHT WATER REACTOR:
 The light-water reactor (LWR) is a type of thermal-neutron reactor
that uses normal water, as opposed to heavy water, as both its
coolant and neutron moderator – furthermore a solid form of fissile
elements is used as fuel. Thermal-neutron reactors are the most
common type of nuclear reactor, and light-water reactors are the
most common type of thermal-neutron reactor.

11. THANK YOU