Nuclear power station by Romeo Aguilera Jr

NUCLEAR POWER PLANT

Presented by:Romeo B. Aguilera Jr.

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.

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.

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.

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.

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.

The Shippingport Atomic Power Station in Shippingport, Pennsylvania was the first commercial reactor in the USA and was opened in 1957..

http://en.wikipedia.org/wiki/File:Shippingport_Reactor.jpg

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.

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.

Schematic Diagram

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.

• 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.

Classification by type of Nuclear Reaction

•Nuclear Fission•Nuclear Fusion

Nuclear Fission Chain Reaction

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.

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.

Nuclear Fusion

Nuclear FusionThe 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.

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.

Components of Nuclear Power Station

1. Nuclear reactor

2. Control rods

3. Steam Generator

4. Steam Turbine

5. Condenser

6. Cooling Tower

1. Nuclear Reactor

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.

Inside Nuclear ReactorCore : 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.

Nuclear Fuel Cycle

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.

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

Pressurized Water Reactor

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.

Sodium Cooled Fast Reactor

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).

Liquid Fluoride Thorium Reactor

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.

Boiling Water Reactor

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.

Canada Deuterium-Uranium Reactors (CANDU)

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.

High Temperature Gas Cooled Reactor

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.

2. Control Rods

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.

3. Steam Generator

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 .

4. Steam Turbine

Steam TurbineA 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.

5. Condenser

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).

6. Cooling Tower

Cooling TowerRemove 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.

Types of Cooling Tower

• Mechanical Draft

• Natural Draft

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.

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.

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

Fukushima I And II

Total power output: 8,814 MWe

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


First Floating Nuclear Power Plant

Akademik Lomonosov

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.

Nuclear Power Plant in the Philippines

Bataan Nuclear Power Plant

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.

Nuclear Power Plants (Disaster)

Three Mile Island

Three Mile IslandAfter 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.

Chernobyl

ChernobylThe 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.

Fukushima Daiichi

Fukushima DaiichiFollowing 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.

Fukushima DaiichiApart 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.