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NUCLEAR POWER PLANT

Anuclear power plantis athermal power stationin which the heat source is anuclear reactor.

As is typical in all conventional thermal power stations the heat is used to generate steam which drives asteam turbineconnected to anelectric generatorwhich produceselectricity.

historyThe science of atomic radiation, atomic change and nuclear fission was developed from 1895 to 1945, much of it in the last six of those years.

Over 1939-45, most development was focused on the atomic bomb.

From 1945 attention was given to harnessing this energy in a controlled fashion for naval propulsion and for making electricity.

Since 1956 the prime focus has been on the technological evolution of reliable nuclear power plants.

Otto Hahnwon the Nobel Prize for his discovery of nuclear fission and Enrico Fermialso receive a Nobel Prize for creating the world's first nuclear chain reaction.

In the 1940's nuclear fission was first used during World War II which prompted more research into atomic energy.

Today nuclear energy accounts for only 20% of the electricity generated in the United States.

September 3, 1948 at theX-10 Graphite ReactorinOak Ridge, Tennesseein the United States, and was the first nuclear power plant to power a light bulb.The second, larger experiment occurred on December 20, 1951 at theEBR-Iexperimental station nearArco, Idahoin the United States.

On June 27, 1954, the world'sfirst nuclear power plantto generate electricity for apower gridstarted operations at theSovietcity ofObninsk.

The world's first full scale power station,Calder Hallin England opened on October 17, 1956.

Anuclear reactor, formerly known asatomic pile, is a device used to initiate and control a sustainednuclear chain reaction.

Nuclear reactors are used atnuclear power plantsforelectricity generationand inpropulsion of ships. Heat fromnuclear fission is passed to a working fluid (water or gas), which runs throughturbines.

Today there are about 450 nuclear power reactors that are used to generate electricity in about 30 countries around the world.Since nuclear fission creates radioactivity, the reactor core is surrounded by a protective shield. This containment absorbs radiation and preventsradioactive materialfrom being released into the environment.

SYSTEMSSteam turbine

Generator

Cooling system

Feed water pump

Water Reactors-Boiling water reactor (BWR)-Pressurized water reactor(PWR)

Boiling Water Reactor

In the boiling water reactor (BWR), the water which passes over the reactor core to act asmoderatorand coolant is also the steam source for the turbine

This operating temperature gives aCarnot efficiencyof only 42% with a practical operating efficiency of around 32%, somewhat less than thePWR.

Pressurized Water Reactor

In the pressurized water reactor (PWR), the water which passes over the reactor core to act asmoderatorand coolant does not flow to the turbine, but is contained in a pressurized primary loop.

The primary loop water produces steam in the secondary loop which drives the turbine

Another advantage is that the PWR can operate at higher pressure and temperature, about 160atmospheresand about 315 C.

BWR and PWR

How does it works and How is energy created in a nuclear power plant?a nuclear-fueled power plant much like a fossil-fueled power plant water is turned into steam, which in turn drives turbine generators to produce electricity.

The difference is the source of heat. At nuclear power plants, the heat to make the steam is created when uranium atoms split called fission.

There is no combustion in a nuclear reactor

The more recent, and peaceful, use ofnuclear energyis to provide electricity for homes, offices and factories.

Nuclear power, in plants known as fission breeder reactors, heats water to very high temperatures, creating steam that drives large turbines attached to electrical generators.

Nuclear energy originates from the splitting of uranium atoms in a process called fission.

At the power plant, the fission process is used to generate heat for producing steam, which is used by a turbine to generate electricity.

InstallationIn many countries, plants are often located on the coast, in order to provide a ready source of cooling water for theessential service water system.

As a consequence the design needs to take the risk of flooding andtsunamisinto account.

TheWorld Energy Council(WEC) argues disaster risks are changing and increasing the likelihood of disasters such asearthquakes,cyclones,hurricanes,typhoons,ooding. accidents.

High temperatures, low precipitation levels and severedroughtsmay lead to fresh water shortages.

Failure to calculate the risk of flooding correctly lead to aLevel 2event on theInternational Nuclear Event Scaleduring the1999 Blayais Nuclear Power Plant flood,while flooding caused by the2011 Thoku earthquake and tsunamilead to theFukushima I nuclear

Maintenance and repairMaintenance of a Nuclear Power Plant

Extensive preventive maintenance and testing (surveillance) programs exist to ensure that nuclear safety significant equipment will function when it is supposed to.

Diesel generators, pumps, motor operated valves and air operated control valves are typically operated every one to three months.

When you drive a car, you depend a lot on the sounds, the feel of the steering wheel and the gauges to determine if the car is running correctly.

Similarly with operating equipment at a power plant - if sounds or vibration of the equipment or the gauges and test equipment indicate a problem or degradation, actions are taken to correct the deficiency.If the equipment fails to start or run, more immediate actions are taken. In some cases, regulations called technical specifications may require the plant to be shutdown if the equipment is not corrected within a certain period of time.

Every year to two (2) years, the power plant may be shutdown for anoutage. The outage may last 30 to 60 days and depends on the amount of major maintenance to be done.

Outages are used to perform activities that cannot be done when the plant is operating:

Refueling the reactorandother preparations(removal of reactor head, upper internals, and reactor refueling)

Preventive maintenance on equipment that must run all the time, e.g.turbine-generatormust be inspected every 5 years or so,transformersmay be checked out each outage;

Modifications or replacements of major equipment, as asteam generator, that cannot be shutdown.

The maintenance personnel who maintain the equipment at the power plant must go through craft-specific training to qualify to perform the plant maintenance.

Training programs are inspected and certified by the accrediting board of the National Nuclear Training Academy.

Engineers at the power plant are often responsible for specific systems at the plant and manage the work done (preventive maintenance, repairs, and modifications) on their system.

Similarly, engineer training programs are inspected and certified by the accrediting board of the National Nuclear Training Academy.

ENVIRONMENTAL PURPOSESEnvironmental purposesWhat impact does nuclear energy have on the environment?

Nuclear powerplantsdonot emit carbon dioxide, sulfur dioxide, or nitrogen oxides as part of thepowergeneration process.

However, fossil fuel emissions are associated with the uranium mining and uranium enrichment process as well as the transport of the uranium fuel to and from thenuclear plant.

Is nuclear energy renewable or non renewable?

The material most often used innuclearpower plants is the element uranium.

Uraniumnon renewableresource.Nuclearenergy is a popular way of generating electricity around the world.

Advantages and disadvantagesADVANTAGES:

Geographical limitations- nuclear power plants don't require a lot ofspace; they do not need a large plot like a wind farm. But they have to be built near alarge body of waterfor cooling purposes - using the water as a heat sink. They are usually found on the coast so there is no risk to drinking water sources.

Nuclear power stations do not contribute tocarbon emissions- no CO2is given out - it therefore does not contribute toglobal warming.

Nuclear power stations do not producesmoke particlesto pollute the atmosphere or emit gases that contibute toacid rain.

Advantages and disadvantagesNuclear energy is by far the mostconcentrated form of energy- a lot of energy is produced from a small mass of fuel. Thisreduces transport costs- (although the fuel is radioactive and therefore each transport that does occur is expensive because of security implications).

Nuclear power isreliable. It does not depend on the weather.

Nuclear power produces asmall volume of waste(although that waste is radioactive - see below)

Advantages and disadvantagesWe cancontrol the outputfrom a nuclear power station to fit our needs. It is relatively easy to control the output - although the time factor for altering power output is not as small as for fossil fuel stations.

It is said to have along 'start up' time. It cannot respond immediately to demand. That is why electricity companies try to 'even out' demand by using tarrifs that encourage use at off peak time perids.

Advantages and disadvantagesDISADVANTAGES:

Disposal of nuclear wasteis very expensive. As it is radioactive it has to be disposed of in such a way as it will not pollute the environment.

Decommissioningof nuclear power stations is expensive and takes a long time. (In fact we have not yet decommissioned one!)

Nuclear accidentscan spread 'radiation producing particles' over a wide area, This radiation harms the cells of the body which can make humans sick or even cause death. Illness can appear or strike people years after they were exposed to nuclear radiation and genetic problems can occur too.

RADIATION

Effects of RadiationRadiationtakes place when the atomic nucleus of an unstable atom decays and starts releasing ionizing particles, known as ionizing radiation.

When these particles come into contact with organic material, such as human tissue, they will damage them if levels are high enough, causing burns andcancer. Ionizing radiation can be fatal for humans.

Effect of RadiationREM (roentgen equivalent in man)- this is a unit we use to measure radiation dosage.

We use this measurement to determine what levels of radiation are safe or dangerous for human tissue.

It is the product of the absorbed dose in rads and a weighting factor (WR), which accounts for how effective the radiation is in causing biological damage.

Effect of RadiationA sudden, short dose of up to 50 rem will probably cause no problems, except for some blood changes. 50 to 200 rem there may be illness, but fatalities are highly unlikely. A dose of between 200 and 1,000 will most likely cause serious illness - the nearer the 1,000 it is, the poorer the outlook for the human will be.

Any dose over 1,000 will typically cause death.

Bataan nuclear Power PlantConstruction on the Bataan Nuclear Power Plant began in 1976.

Following the 1979Three Mile Island accidentin theUnited States, construction on the BNPP was stopped, and a subsequent safety inquiry into the plant revealed over 4,000 defects.

Among the issues raised was that it was built near major earthquake fault lines and close to the then dormantMount Pinatubo.

Anti-nuclear movement

The Bataan Nuclear Power Plant was a focal point foranti-nuclear protestsin the late 1970s and 1980s.

The project was criticised 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.

2000sDespite never having been commissioned, the plant has remained intact, including the nuclear reactor, and has continued to be maintained.

The Philippine government completed paying off its obligations on the plant in April 2007, more than 30 years after construction began.

On January 29, 2008, Energy SecretaryAngelo Reyesannounced that anInternational Atomic Energy Agency(IAEA) eight-man team led by Akira Omoto inspected the Bataan Nuclear power station on rehabilitation prospects.

In preparing their report, the IAEA made two primary recommendations.

On January 29, 2008,

First, the power plant's status must be thoroughly evaluated by technical inspections and economic evaluations.

Second, the IAEA mission advised the Philippines government on the general requirements for starting its nuclear power program, stressing that the proper infrastructure, safety standards, and knowledge be implemented.On February 1, 2010,

NAPOCOR started evaluating the financial plan ofKorea Electric Power Corporation(KEPCO), assessing that it may cost US$1 billion to rehabilitate the nuclear plant.[7]

On February 22, 2011,the Philippine government will reimburse theNational Power Corporation(NAPOCOR) 4.2 billion (US$96 million) it spent for maintaining the Bataan Nuclear Power Plant.

It requires an average of 40 million a year just to maintain it.

In May 2011,

it was announced that the plant would be turned into a tourist attraction.

Chernobyl nuclear Power PlantOn April 26, 1986, a sudden surge ofpowerduring areactorsystems test destroyed Unit 4 of thenuclear power stationatChernobyl, Ukraine, in the former Soviet Union.

The accident and the fire that followed released massive amounts of radioactive material into the environment.

The accident happened because of a combination of basic engineering deficiencies in the reactor and faulty actions of the operators: the safety systems had been switched off, and the reactor was being operated under improper, unstable conditions, a situation which allowed an uncontrollable power surge to occur.

1982 Reactor No. 1On September 9, 1982, a partial coremeltdownoccurred in Reactor No. 1 at the Chernobyl plant.

The extent of the accident was not made public until several years later. The reactor was repaired and put back into operation within months.

1986 Disaster Reactor No. 4Saturday, April 26, 1986, a disaster occurred at Reactor No. 4, which has been widely regarded as the worst accident in the history of nuclear power in the world.

As a result, Reactor No. 4 was completely destroyed Large areas of Europe were affected by the accident. The radioactive cloud spread as far away asNorway.

1991 fire Reactor No. 2The Chernobyl Nuclear Plant utilized one large, open turbine hall for all four reactors without any separating walls. Each reactor had two turbines.

On October 11, 1991, a fire broke out in the turbine hall of Reactor No.2.

The fire began in Reactor No.2's Turbine4 (-4 in Russian) while the turbine was being idled for repairs.

2013 collapse

On February 13, 2013, a 600-square-metre (6,500-square-foot) portion of the roof and wall adjacent to the covered part of the turbine hall collapsed into the entombed area of the turbine hall.

The collapse did not affect any other part of theObject Shelteror theNew Safe Confinement. No variances in radiation levels as a result of the incident were detected.

Chernobyl Nuclear Power Plantis a decommissionednuclearpower stationnear the city ofPripyat, Ukraine, 14.5km northwest of the city ofChornobyl, 16km from the UkraineBelarus border, and about

The Chernobyl disaster was the worstnuclear power plantaccident in history in terms of cost and casualties.

It is one of only two classified as a level 7 event (the maximum classification) on theInternational Nuclear Event Scale, the other being theFukushima Daiichi nuclear disasterin 2011.

The battle to contain the contamination and avert a greater catastrophe ultimately involvedover 500,000 workersand cost an estimated 18billionrubles.

During the accident itself,31 people died, and long-term effects such as cancers are still being investigated.

DecommissioningIn January 2008, the Ukraine government announced a four-stage decommissioning plan which incorporated the above waste activities and progresses towards a cleared site.

Resettlement of areas from which people were relocated is ongoing. In 2011 Chernobyl was officially declared a tourist attraction.