2. Nuclear Power Station
-A nuclear power plant is a thermal power station in which the heat source
comes from one or more nuclear reactors.
-As in a conventional power station the heat is used to generate steam
which drives a steam turbine connected to a generator which produces
electricity.
-Nuclear plants are generally considered charging base stations, which are
better suited to constant power output.
3. Nuclear Energy
-is the use of exothermic nuclear processes to generate useful heat
and electricity.
-is one of the cleanest fuel sources, accounting for 70 percent of all
emission-free electricity generated and emitting no carbon dioxide,
sulfur dioxide or nitrogen oxide.
4. History of Nuclear Power
• Overview of Nuclear Energy
Nuclear energy comes from mass-to-energy conversions that occur in the
splitting of atoms larger than Iron or joining atoms smaller than Iron. The
small amount of mass that is lost in either of these events follows Einstein’s
famous formula E = MC2, where M is the small amount of mass and C is the
speed of light. In the 1930s and ’40s, humans discovered this energy and
recognized its potential as a weapon. Technology developed in the
Manhattan Project successfully used this energy in a chain reaction to
create nuclear bombs. Soon after World War II ended, the newfound energy
source found a home in the propulsion of the nuclear navy, providing
submarines with engines that could run for over a year without refueling.
This technology was quickly transferred to the public sector, where
commercial power plants were developed and deployed.
• Nuclear Energy Today
Nuclear reactors produce about 20% of the electricity in the USA. There are
over 400 power reactors in the world (about 100 of these are in the USA).
They produce base-load electricity 24/7 without emitting any pollutants into
the atmosphere (this includes CO2). They do, however,
create radioactive nuclear waste that must be stored carefully.
5. History of Nuclear Power Plant
• Origins
Nuclear fission was first experimentally achieved by Enrico Fermi in 1934
when his team bombarded uranium with neutrons.
• Early years
On June 27, 1954, the USSR’s Obninsk Nuclear Power Plant became the
world’s first nuclear power plant to generate electricity for a power grid.
• Development
Installed nuclear capacity initially rose relatively quickly, rising from less
than 1 gigawatt (GW) in 1960 to 100 GW in the late 1970s and 300 GW
in the late 1980s.
6. It was the first civilian nuclear power station in the world. The plant is also known
as APS-1 Obninsk (Atomic Power Station 1 Obninsk). Construction started on
January 1, 1951, startup was on June 1, 1954, and the first grid connection was
made on June 26, 1954. For around 4 years, till opening of Siberian Nuclear
Power Station, Obninsk remained the only nuclear power reactor in the Soviet
Union; the power plant remained active until April 29, 2002 when it was finally shut
down.
7. The Shippingport Atomic Power Station in Shippingport, Pennsylvania
was the first commercial reactor in the USA and was opened in 1957..
8. Advantages
•Nuclear power plants don't require a lot of space.
•It does not produce smoke particles to pollute the
atmosphere.
•Nuclear energy is by far the most concentrated form of
energy.
•It is reliable. It does not depend on the weather. We can
control the output It is relatively easy to control the output.
•It produces a small volume of waste.
9. Disadvantages
• Disposal of nuclear waste is very expensive.
• Decommissioning of nuclear power stations is
expensive and takes a long time.
• Nuclear accidents can spread radiation producing
particles over a wide area.
11. Principal operation
• Nuclear Reactor
– A nuclear reactor is a cylindrical stout pressure vessel and houses fuel
rods of Uranium moderator and control rods. The fuel rods constitute
the fission materials and release huge amount of energy when
bombarded with slow moving neutrons. The moderator consists of
graphite rods which enclose the fuel rods. The control rods are of
Cadmium and are inserted in the reactor. Cadmium is strong neutron
absorber and thus regulates the supply of neutrons for fission. When the
control rods are pushed in deep enough, they absorb most of fission
neutrons and hence few are available for chain reaction, which therefore
stops. However, hence they are being withdrawn, more and more of
these fission neutrons cause fission and hence the intensity of chain
reaction is increased. Therefore by pulling out the control rods, power of
nuclear reactor is increased, whereas by pushing them in, it is reduced.
In actual practice, the lowering or raising of control rods is accomplished
automatically according to the requirement t of load. The heat produced
by the reactor is removed by the coolant, generally a sodium metal. The
coolant carries heat to the heat exchanger.
12. • Heat Exchanger
The coolant gives up the heat to the heat exchanger which is utilized in
raising the steam. After giving up heat, the coolant is again fed to the
reactor.
• Steam Turbine
The steam produced in the heat exchanger is led to the steam turbine
through a valve. after doing a useful work in the turbine, the steam is
exhausted to the condenser. The condenser condense the steam which is
fed to the heat exchanger through feed water pump.
• Alternator
The steam turbine drives the alternator which converts mechanical
energy into electrical energy. The output from the alternator is delivered
to the bus bars through transformers, circuit breakers and isolators.
15. Nuclear Fission Chain Reaction
1. A uranium-235 atom absorbs a neutron, and fissions into two new atoms
(fission fragments), releasing three new neutrons and some binding energy.
2. One of those neutrons is absorbed by an atom of uranium-238, and does
not continue the reaction. Another neutron is simply lost and does not
collide with anything, also not continuing the reaction. However one neutron
does collide with an atom of uranium-235, which then fissions and releases
two neutrons and some binding energy.
3. Both of those neutrons collide with uranium-235 atoms, each of which
fission and release between one and three neutrons, and so on.
16. Nuclear Fission
In nuclear physics and nuclear chemistry, nuclear fission is either
a nuclear reaction or a radioactive decay process in which the nucleus of an
atom splits into smaller parts (lighter nuclei). The fission process often
produces free neutrons and photons (in the form of gamma rays), and
releases a very large amount of energy even by the energetic standards of
radioactive decay.
or
It is a reaction when the nucleus of an atom, having captured a neutron,
splits into two or more nuclei, and in so doing, releases a significant amount
of energy as well as more neutrons. These neutrons then go on to split
more nuclei and a chain reaction takes place.
18. Nuclear Fusion
The world needs new, cleaner ways to supply our increasing energy
demand, as concerns grow over climate change and declining supplies of
fossil fuels. Power stations using fusion would have a number of
advantages:
• No carbon emissions. The only by-products of fusion reactions are small
amounts of helium, which is an inert gas that will not add to atmospheric
pollution.
• Abundant fuels. Deuterium can be extracted from water and tritium is
produced from lithium, which is found in the earth's crust. Fuel supplies will
therefore last for millions of years.
• Energy efficiency. One kilogram of fusion fuel can provide the same amount
of energy as 10 million kilograms of fossil fuel.
• No long-lived radioactive waste. Only plant components become radioactive
and these will be safe to recycle or dispose of conventionally within 100
years.
• Safety. The small amounts of fuel used in fusion devices (about the weight
of a postage stamp at any one time) means that a large-scale nuclear
accident is not possible.
• Reliable power. Fusion power plants should provide a baseload supply of
large amounts of electricity, at costs that are estimated to be broadly similar
to other energy sources.
19. Nuclear Fusion
Fusion offers important advantages: no carbon emissions, no air
pollution, unlimited fuel, and is intrinsically safe. While fusion
technology is not at the deployment stage, the potential is
substantial. The fusion reaction is about four million times more
energetic than a chemical reaction such as the burning of coal,
oil or gas.
Fusion is a process where nuclei collide and join together to form
a heavier atom, usually deuterium and tritium. When this
happens a considerable amount of energy gets released at
extremely high temperatures: nearly 150 million degrees Celsius.
At extreme temperatures, electrons are separated from nuclei
and a gas becomes a plasma—a hot, electrically charged gas.
20. Components of Nuclear Power Station
1. Nuclear reactor
2. Control rods
3. Steam Generator
4. Steam Turbine
5. Condenser
6. Cooling Tower
22. 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. Each time an
atom splits, it releases large amounts of energy in the form of heat. 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. So basically, nuclear reactors are exotic heat
sources.
23. Inside Nuclear Reactor
Core : Here the nuclear fission process takes place.
Moderator : This reduces the speed of fast moving neutrons. Most moderators
are graphite, water or heavy water.
Coolant : They carry the intense heat generated. Water is used as a coolant,
some reactors use liquid sodium as a coolant.
Radiation shield : To protect the people working from radiation and (thermal
shielding) radiation fragments.
Fuel : The fuel used for nuclear fission is U235 isotope.
25. Nuclear Fuel use: Uranium
Uranium is a slightly radioactive metal that occurs throughout the Earth's
crust (see page on Uranium and Depleted Uranium). 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. It is, for example,
found in concentrations of about four parts per million (ppm) in granite,
which makes up 60% of the Earth's crust. In fertilizers, uranium
concentration can be as high as 400 ppm (0.04%), and some coal deposits
contain uranium at concentrations greater than 100 ppm (0.01%). Most of
the radioactivity associated with uranium in nature is in fact due to other
minerals derived from it by radioactive decay processes, and which are left
behind in mining and milling.
26. Types of Nuclear Reactor
• Pressurized Water Reactor
• Sodium Cooled Fast Reactor
• Liquid Fluoride Thorium Reactor
• Boiling Water Reactor
• Canada Deuterium-Uranium Reactors (CANDU)
• High Temperature Gas Cooled Reactor
28. Pressurized Water Reactor
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.
30. Sodium Cooled Fast Reactor
The first electricity-producing nuclear reactor in the world was SFR (the
EBR-1 in Arco, Idaho). As the name implies, 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 anything you throw at them (thorium, uranium,
plutonium, higher actinides).
32. Liquid Fluoride Thorium Reactor
LFTRs have gotten a lot of attention lately in the media. They are unique so
far in that they use molten fuel. So there's no worry of meltdown because
they’re already melted and the reactor is designed to handle that state. The
folks over at Energy from thorium are totally stoked about this technology.
34. 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.
36. 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.
38. High Temperature Gas Cooled
Reactor
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.
40. Control Rods
A control rod is a rod used in nuclear reactors to control the rate of fission
of uranium and plutonium. They are made of chemical elements capable of
absorbing many neutrons without fissioning themselves, such
as silver, indium and cadmium. Because these elements have
different capture cross sections for neutrons of varying energies, the
compositions of the control rods must be designed for the neutron spectrum
of the reactor it is supposed to control. Light water reactors (BWR, PWR)
and heavy water reactors (HWR) operate with "thermal" neutrons,
whereas breeder reactors operate with "fast" neutrons.
42. Steam Generator
Steam generators are heat exchangers used to convert water into steam
from heat produced in a nuclear reactor core.
Either ordinary water or heavy water is used as the coolant .
44. Steam Turbine
A steam turbine is a device that extracts thermal energy from
pressurized steam and uses it to do mechanical work on a rotating output
shaft. Its modern manifestation was invented by Sir Charles Parsons in
1884.
Because the turbine generates rotary motion, it is particularly suited to be
used to drive an electrical generator – about 90% of all electricity generation
in the United States (1996) is by use of steam turbines.The steam turbine is
a form of heat engine that derives much of its improvement
in thermodynamic efficiency through the use of multiple stages in the
expansion of the steam, which results in a closer approach to the
theoretically ideal, Carnot engine.
46. Condenser
Condenser is a device or unit which is used to condense vapor into liquid.
The objective of the condenser are to reduce the turbine exhaust pressure
to increase the efficiency and to recover high quality feed water in the form
of condensate and feed back it to the steam generator without any further
treatment.
The condenser has thousands of small tubes. On-line cleaning systems
inject small balls during operation. Periodically, the tubes must be cleaned
manually. During outages, the condenser tubes may be non-destructively
tested to determine if wear is occurring. Tube leakage cannot be tolerated
because the chemicals, e.g. sodium and chlorides can concentrate in the
reactor (if a BWR) or steam generator (if a PWR).
48. Cooling Tower
Remove heat from the water discharged from the condenser so that the
water can be discharged to the river or recirculated and reused.
Some power plants, usually located on lakes or rivers, use cooling towers
as a method of cooling the circulating water (the third non-radioactive cycle)
that has been heated in the condenser. During colder months and fish non-
spawning periods, the discharge from the condenser may be directed to the
river. Recirculation of the water back to the inlet to the condenser occurs
during certain fish sensitive times of the year (e.g. spring, summer, fall) so
that only a limited amount of water from the plant condenser may be
discharged to the lake or river. It is important to note that the heat
transferred in a condenser may heat the circulating water as much as 40
degrees Fahrenheit (F). In some cases, power plants may have restrictions
that prevent discharging water to the river at more than 90 degrees F. In
other cases, they may have limits of no more than 5 degrees F difference
between intake and discharge (averaged over a 24 hour period). When
Cooling Towers are used, plant efficiency usually drops. One reason is that
the Cooling Tower pumps (and fans, if used) consume a lot of power.
50. Mechanical Draft
Mechanical draft Cooling Towers have long piping runs that spray the water
downward. Large fans pull air across the dropping water to remove the
heat. As the water drops downward onto the "fill" or slats in the cooling
tower, the drops break up into a finer spray. On colder days, tall plumes of
condensation can be seen. On warmer days, only small condensation
plumes will be seen.
51. Natural Draft
This photo shows a single natural draft cooling tower as used at a European
plant. Natural draft towers are typically about 400 ft (120 m) high, depending
on the differential pressure between the cold outside air and the hot humid
air on the inside of the tower as the driving force. No fans are used.Whether
the natural or mechanical draft towers are used depends on climatic and
operating requirement conditions.
52. Top 10 Location of Nuclear Power Station
• Fukushima I And II
• Kashiwazaki And Kariwa, Japan
• Yeonggwang, South Korea
• Zaporozhye, Ukraine
• Nord, France
• Paluel, Upper Normandy, France
• Cattenom, Lorraine, France
• Bruce County, Ontario, Canada
• Ohi, Fukui, Japan
• Wintersburg, Arizona, USA
65. Akademik Lomonosov
• Russia will begin to operate the world's first floating nuclear power plant in
just three years time.
• The specially-made ship with a nuclear power plant on-board will provide
energy, heat and drinking water to relatively inaccessible areas of the vast
country.
• The director of Russia's largest shipbuilders, the Baltic Plant, announced
that the unique ship should be operational by 2016 at the 6th International
Naval Show in St Petersburg.
• The first ship will be called Akademik Lomonosov and is intended to be the
first of small fleet of floating nuclear plants in Russia.
• It is designed to provide energy to big industrial companies, cut-off port
cities and offshore oil and gas platforms.
• The ship's power-generating capabilities were based on nuclear reactors
which are already on-board ice breaker ships in the chilly region that have
operated successfully for over half a century.
68. Bataan Nuclear Power Plant
Bataan Nuclear Power Plant is a nuclear power plant, completed but never
fueled, on Bataan Peninsula, 100 kilometers (62 mi) west of Manila in
the Philippines. It is located on a 3.57 square kilometer government
reservation at Napot Point in Morong, Bataan. It was the Philippines' only
attempt at building a nuclear power plant.
The Bataan Nuclear Power Plant was a focal point for anti-nuclear
protests in the late 1970s and 1980s. The project was criticized for being a
potential threat to public health, especially since the plant was located in an
earthquake zone, and because a volcano formation was found near the
location of the plant.
71. Three Mile Island
After shutting down the fission reaction, the TMI-2 reactor's fuel core
became uncovered and more than one third of the fuel melted.
Inadequate instrumentation and training programs at the time hampered
operators' ability to respond to the accident.
The accident was accompanied by communications problems that led to
conflicting information available to the public, contributing to the public's
fears
A small amount of radiation was released from the plant. The releases were
not serious and were not health hazards. This was confirmed by thousands
of environmental and other samples and measurements taken during the
accident.
The containment building worked as designed. Despite melting of about
one-third of the fuel core, the reactor vessel itself maintained its integrity
and contained the damaged fuel.
73. Chernobyl
The Chernobyl accident in 1986 was the result of a flawed reactor design
that was operated with inadequately trained personnel.
The resulting steam explosion and fires released at least 5% of the
radioactive reactor core into the atmosphere and downwind – some 5200
PBq (I-131 eq).
Two Chernobyl plant workers died on the night of the accident, and a further
28 people died within a few weeks as a result of acute radiation poisoning.
UNSCEAR says that apart from increased thyroid cancers, "there is no
evidence of a major public health impact attributable to radiation exposure
20 years after the accident.―
Resettlement of areas from which people were relocated is ongoing.
75. Fukushima Daiichi
Following a major earthquake, a 15-metre tsunami disabled the power
supply and cooling of three Fukushima Daiichi reactors, causing a nuclear
accident on 11 March 2011. All three cores largely melted in the first three
days.
The accident was rated 7 on the INES scale, due to high radioactive
releases over days 4 to 6, eventually a total of some 940 PBq (I-131 eq).
Four reactors are written off – 2719 MWe net.
After two weeks the three reactors (units 1-3) were stable with water
addition but no proper heat sink for removal of decay heat from fuel. By July
they were being cooled with recycled water from the new treatment plant.
Reactor temperatures had fallen to below 80ºC at the end of October, and
official 'cold shutdown condition' was announced in mid December.
76. Fukushima Daiichi
Apart from cooling, the basic ongoing task was to prevent release of
radioactive materials, particularly in contaminated water leaked from the
three units.
There have been no deaths or cases of radiation sickness from the nuclear
accident, but over 100,000 people had to be evacuated from their homes to
ensure this. Government nervousness delays their return.
