Nuclear Power Plant

Introduction

Nuclear fuel is any material that can be consumed to derive nuclear energy. The most common type of nuclear fuel is fissile elements that can be made to undergo nuclear fission chain reactions in a nuclear reactor.

The most common nuclear fuels are 235U and 239Pu. Not all nuclear fuels are used in fission chain reactions.

Other fuels: 238Np(Neptunium), 239U(Uranium),

241Pu(plutonium)

Worldwide Nuclear Power Reactors

• There are 440 nuclear power reactors in 31 countries.

• 30 more are under construction. • They account for 16% of the world’s

electricity. • They produce a total of 351 gigawatts (billion

watts) of electricity.

Operating Nuclear Power Plants in India

TARAPUR-1&2 RAJASTHAN-1to 6 MADRAS-1&2

NARORA-1&2 KAKRAPARA-1&2 KAIGA-1 to 4

Total Capacity 4780 MWe

TARAPUR 3&4

Reactors Under Construction

Total Capacity under construction 4800 MWe

PFBR (500 MWe) KK 1&2 (2x1000 MWe)

KAPP-3&4 (2x700 MWe)

RAPP-7&8 (2x700 MWe)

Nuclear Power Plants in India

Nuclear Power plant is a thermal power station in which the heat source is a nuclear reactor. As is typical in all conventional thermal power stations the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.

As of 16 January 2013, the IAEA report there are 439 nuclear power reactors in operation operating in 31 countries.

Nuclear power plants are usually considered to be base load stations, since fuel is a small part of the cost of production.

Enrichment Concentrates the Uranium Isotope

Uranium Is Encased in Solid Ceramic Pellets

Fuel Rods Filled With Pellets Are Grouped Into Fuel Assemblies

Comparing Uranium to Coal *1 kg of uranium-235 will generate as much energy as

3,000 tons of coal without CO2 emissions

Nuclear Fission process:-

In this process heavy nucleus is splitted and release high energy 1 fission of U-235 causes 230 mev energy

Fission products

• The fission products shown are just examples, there are a lot of different possibilities with varying probabilities

Expanding Chain Reaction

• The fission reaction produces more neutrons which can then induce fission in other Uranium atoms.

• Mouse Trap Chain Reaction

Linear Chain Reaction • Obviously, an expanding chain reaction cannot be

sustained for long (bomb). For controlled nuclear power, once we reach our desired power level we want each fission to produce exactly one additional fission

Comparing Uranium to Coal

Coal Power Plant Environmental Concerns

Nuclear Power Plant Environmental Concerns

Fission and Fusion

• Fission: A heavy nucleus is split into smaller nuclei, releasing energy

• Fusion: Two light nuclei fuse into a heavy nucleus, releasing energy – Fusion generates much more energy than

fission – Fusion of hydrogen into helium is what

provides power to the sun (and thus to the Earth)

TWO WAYS TO OBTAIN NUCLEAR ENERGY:

1. Nuclear fission 2. Nuclear fusion

• then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away.

• After about 5 years in a spent fuel pool the spent fuel is radioactively and thermally cool enough to handle, and it can be moved to dry storage casks or reprocessed.

NUCLEAR FISSION

When a neutron strikes an atom of uranium, the uranium splits into two lighter atoms and releases heat simultaneously.

Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments.

Mass-Energy conversion acc. to Einstein’s equation E=mc2

Energy from Fission

• When a neutron strikes a uranium-235 nucleus, it splits into two nuclei, releasing energy

• Example: n + 235U -> 93Kr + 141Ba + 2n • One neutron goes in, two neutrons come out

Requirements of Fission Process • The neutrons emitted in fission should have adequate

energy to cause fission of another nuclei. • The produced number of neutrons must be able not

only to sustain the fission process but should be able to increase the rate of fission.

• The process must be followed by liberation of energy. • It must be able to control the rate of fission by some

means. • Critical mass: The minimum quantity of fuel required

for any specific reactor system is called critical mass, and size associated with it is called critical size.

Nuclear Fusion

When atoms are joined together to form a larger atom is commonly referred to as nuclear fusion. The sun produces energy through nuclear fusion where the nuclei of hydrogen atoms are fused into helium atoms.

Nuclear chain Reaction

When a neutron hits a U-235 3 neutrons produced “Chain reaction is defined as a fission reaction where neutron from the previous reaction continue to propagate and repeat the reaction”

• U235 + n → fission + 2 or 3 n + 200 MeV

• MeV s Mega Electron Volt.

If each neutron releases two more neutrons, then the

number of fissions doubles each generation. In that

case, in 10 generations there are 1,024 fissions and in

80 generations about 6 x 10 23 (a mole) fissions.

Chain Reaction A chain reaction refers to a process in which neutrons released in fission produce an additional fission in at least one further nucleus. This nucleus in turn produces neutrons, and the process repeats. If the process is controlled it is used for nuclear power or if uncontrolled it is used for nuclear weapons A chain reaction is that process in which number of neutrons keep on multiplying rapidly(in GP) during fission till whole of the fissionable material is disintegrated. Chain reaction will continue if, for every neutron absorbed, at least one fission neutron becomes available for causing fission of another nucleus. Expressed by multiplication factor K= No. of neutrons in any particular generation/No. of neutrons in the preceding generation. If K>1, chain reaction will continue and if K<1 , cant be maintained.

Chain Reactions

• If at least one neutron from each fission strikes another nucleus, a chain reaction will result

• An assembly of uranium-235 that sustains a chain reaction is critical

Schematic diagram of a nuclear plant

control rods

fuel rods

reactor pressure vessel

water (cool)

water (hot)

water (high pressure)

water (low pressure)

coolant out

coolant in steam condenser

steam (low pressure)

turbine

electric power

steam generator

steam (high pressure)

pump

primary loop secondary loop

generator reactor core

pump

Energy Taken out by Steam Turbine

Nuclear power plant layout

• In 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. Here’s how the process works.

The Process

Nuclear Reactor Main parts:- 1.Reactor core 2.Moderator 3.Control rods 4.Coolant 5.Reflector 6.Thermal shielding

Nuclear Reactor • A Nuclear reactor is an apparatus in which nuclear fission is

produced in the form of a controlled self sustaining chain reaction. Classification of nuclear reactor 1. According to chain reacting system, neutron energies at which

the fission occurs: a. Fast reactors b. Intermediate reactor c. Slow reactors 2. Fuel moderator assembly a. Homogenous reactors: fuel and moderator are mixed to form a

homogenous material, b. Heterogeneous reactors: the fuel is used in the form of rods,

plates, lamps or wires and the moderator surrounds the each fuel element in the reactor core.

3. Fuel State a. Solid b. Liquid c. Gas 4. Fuel material a. Natural uranium with 235U(occurs in nature) b. Enriched uranium with more than 0.71% of 235U c. 239Pu, 241Pu or 239Pu(man made) Natural uranium (0.7%) and its contents increase up to 90% in enriched uranium. 5. Moderator a. Water b. Heavy water (D2O) c. Graphite d. Berylium or berylium oxide e. Hydrocarbons or Hydrides.

6. Principal product: a. Research reactor: To produce high neutron flux for research work. b. Power reactor: To produce heat c. Breeder reactor: produce fissionable material, convert fertile

material to fissionable materials. d. Production reactor: To produce isotopes, output is radioactive

material used as source of radiation and tracers. 7. Coolant: a. Air, carbon and helium cooled b. Water or other liquid cooled c. Liquid metal cooled 8. Construction of Core a. Cubical b. Spherical c. Cylindrical d. Slab e. Octagonal

Essential Component of Nuclear Reactor

1. Reactor core 2. Reflector 3. Control mechanism 4. Moderator 5. Coolants 6. Measuring instruments 7. Shielding

Nuclear Reactor

Fuel Packaging in the Core

• Rods contain uranium enriched to ~3% 235U

• Need roughly 100 tons per year for a 1 GW plant

• Uranium stays in three years, 1/3 of the fuel rods are cycled annually

The Reactor Core

• The reactor core consists of fuel rods and control rods – Fuel rods contain enriched

uranium – Control rods are inserted

between the fuel rods to absorb neutrons and slow the chain reaction

• Control rods are made of cadmium or boron, which absorb neutrons effectively

• Reactor Core :This is the main part of reactor which contain the fissionable material called reactor fuel. Fission energy is liberated in the form of heat for operating power conversion equipment. The fuel element are made of plate of rods of uranium.

• Reactor reflector :The region surrounding the reactor core is

known as reflector. Its function is to reflect back some of the neutron that leak out from the surface of core.

• Control rods :The rate of reaction in a nuclear reactor is controlled by control rods. Since the neutron are responsible for the progress of chain reaction, suitable neutron absorber are required to control the rate of reaction.

a. For starting the reactor b. For maintaining at that level. To keep the production at a steady

state c. For shutting down the reactor under normal or emergency

conditions • Cadmium and Boron are used as control rods.

• Moderator :The function of a reactor is to slow down the fast neutron. The moderator should have

• High slowing down power • Non corrosiveness • High melting point for solids and low melting point for

liquids. • Chemical and radiation stability. • High thermal conductivity • Abundance in pure form. • The commonly used moderator are :

(I) Ordinary water (II) Heavy water (III) Graphite.

Nuclear Fission from Slow Neutrons and Water Moderator

Moderators • Neutrons produced during fission in the core are

moving too fast to cause a chain reaction – Note: This is not an issue with a bomb, where fissile

uranium is so tightly packed that fast moving neutrons can still do the job.

• A moderator is required to slow down the neutrons

• In Nuclear Power Plants water (light or heavy) or graphite acts as the moderator – Graphite increases efficiency but can be unstable

(Chernobyl)

Light vs. Heavy Water

• 99.99% of water molecules contain normal hydrogen (i.e. with a single proton in the nucleus)

• Water can be specially prepared so that the molecules contain deuterium (i.e. hydrogen with a proton and a neutron in the nucleus)

• Normal water is called light water while water containing deuterium is called heavy water

• Heavy water is a much better moderator but is very expensive to make

Moderator • Neutrons are slowed

down by having them collide with light atoms (Water in US reactors).

• Highest level of energy transfer occurs when the masses of the colliding particles are equal (ex: neutron and hydrogen)

Control Rods

• Control rods are made of a material that absorbs excess neutrons (usually Boron or Cadmium).

• By controlling the number of neutrons, we can control the rate of fissions

Reactor is inside a large containment building

• Coolant :The material used to remove heat produce by fission as fast as liberated is known as reactor coolant. The coolant generally pumped through the reactor in the form of liquid or gas. It is circulated throughout the reactor so as to maintain a uniform temperature.

. • Measuring Instruments: Main instrument required is for

the purpose of measuring thermal neutron flux which determines the power developed by the reactor.

• Shielding: The large steel recipient containing the core,

the control rods and the heat-transfer fluid. • All the components of the reactor are container in a solid

concrete structure that guarantees further isolation from external environment. This structure is made of concrete that is one-metre thick, covered by steel.

Shielding

• Shielding is necessary to guard personnel and delicate instruments.

• The various materials used for shielding are

Lead, Concrete, Steel and Cadmium.

• Lead is a common shielding material and is invariably employed due to its low cost.

• Concrete is another shielding material having efficiency lesser than that of lead.

• Steel is not an efficient shielding material but has good structural properties and is sometimes employed as an attenuating shield.

• Cadmium is capable of absorbing slow neutrons by a nuclear reaction.

The effectiveness of a shielding material depends mostly on the density of material

Lead - 11,300 kg/m3 Concrete - 2400 kg/m3 Steel - 7800 kg/m3 Cadmium - 8650 kg/m3

In nuclear power reactors a thermal shield of thickness of several cms of steel surrounded by about 3m thick concrete used. Water, in concrete, slows down fast neutrons while iron, barium or steel turnings are mixed in concrete to attenuate gamma rays and absorb thermal neutrons.

Power Reactors in common use

Boiling water Reactor(BWR) Pressurized water Reactor(PWR) Heavy water cooled and moderated(CANDU TYPE) Reactor Gas Cooled Reactor Liquid metal cooled Reactor

1.Boiling Water Reactor

Fuel used is rich in uranium oxide. Ordinary water is used as both moderator and coolant. Low thermal efficiency. Can’t meet sudden increase of load.

Basic Diagram of a BWR

A BWR in Practice

Boiling Water Reactor Nuclear Power Plant

• A reactor behaves in a similar manner. As the reactor water is boiled, its

volume increases, and the steam escapes at high speed through the outlet piping. The piping is designed so the steam strikes the cups on the turbine wheel; the wheel spins and its shaft turns the copper coil in the electrical generator.

Boiling Water Reactor(BWR) • Uses Enriched fuel. • The plant can safely operate using natural convection within the core or

forced circulation.

Boiling Water Reactor In Boiling Water Reactors (also known as BWRs), the water

heated by fission actually boils and turns into steam to turn the turbine generator. In both PWRs and BWRs, the steam is turned back into water and can be used again in

the process.

Boiling Water Reactor (BWR)

• Heat generated in the core is used to generated steam through a heat exchanger

• The steam runs a turbine just like a normal power plant

2: Pressurized Water Reactor(PWR)

Advantages: Compactness Isolation of radio active system from main steam system Cheap light water used as both moderator and coolant

Disadvantages: Strong pressure vessel is required Formation of low temp. steam High losses from heat exchanger High power consumption from auxilarities

Basic Diagram of a PWR

A PWR in Practice

Pressurized water reactor(PWR) In a typical commercial pressurized light-water reactor, can use both natural and highly enriched fuels. Primary Circuit Secondary Circuit (1) the core inside the reactor vessel creates heat, (2) pressurized water in the primary coolant loop carries the heat to the steam generator. Pressurizer keep the pressure at 100kg/cm2 so that it doesn’t boil. (3) inside the steam generator, heat from the steam, and (4) the steam line directs the steam to the main turbine, causing it to turn the turbine generator, which produces electricity. The unused steam is exhausted in to the condenser where it condensed into water. The resulting water is pumped out of the condenser with a series of pumps, reheated and pumped back to the steam generators. Water acts both as coolant and moderator It produces on saturated steam

PWR

Pressurized Water Reactor Pressurized Water Reactors (also known as PWRs) keep water under

pressure so that it heats, but does not boil. This heated water is circulated through tubes in steam generators, allowing the water in the steam generators to turn to steam, which then turns the turbine generator. Water from the reactor and the water that is turned into

steam are in separate systems and do not mix.

Pressurized Water Reactor

(PWR)

Pressurized Water Reactor (PWR)

• Water in the core heated top 315°C but is not turned into steam due to high pressure in the primary loop.

• Heat exchanger used to transfer heat into secondary loop where water is turned to steam to power turbine.

• Steam used to power turbine never comes directly in contact with radioactive materials.

In the pressurized water reactor, water is heated by the nuclear fuel, but is kept under pressure in the pressure vessel, so it will not boil. The water inside the pressure vessel is piped through separate tubing to a steam generator. The steam generator acts like a heat exchanger. There is a second supply of water inside the steam generator. Heated by the water from the pressure vessel, it boils to make steam for the turbine. Other reactor designs, which use helium gas rather than water to produce steam, are also under development and may eventually be built in the United States.

PWR vs. BWR

Boiling Water Reactors (BWR)

Pressurized Water Reactors (PWR)

3.Heavy Water Cooled and Moderated (CANDU Type) Reactor

Description of CANDU type reactor

• It makes use of heavy hydrogen isotope (H1

2) as moderator • Primary and secondary cicuits are similar to PWR • It’s very expensive to separate • Control rods are not required • It has high multiplication factor and low level fuel

consumption

Advanced Reactor Designs Under Consideration

GE-Hitachi ABWR – NRC Certified (1997) Westinghouse AP1000 – NRC Certified (2005) GE-Hitachi ESBWR – Under NRC Review AREVA US-EPR – Under NRC review Mitsubishi US-APWR – Under NRC Review

Benefits of Advanced Reactor Designs

• Standardization • Simpler and Safer • Large scale power

production • Operating or under

construction elsewhere

CANDU(Canadian-Deuterium-Uranium) REACTOR

• Heavy water is used as moderator and coolant as well as neutron reflector.

• Natural Uranium(0.7% 235U) is used as fuel. • In CANDU reactor the moderator and coolant

are kept separate.

Reactor Vessel and Core: Steel cylinder with horizontal axis, length and diameter are 6m and 8m. Vessel is penetrated by 380 horizontal channels called pressure tubes. The channels contain the fuel elements, and pressurized coolant flows along the channel and around fuel elements to remove heat generated by fission. • The temperature 370deg C and high pressure 10Mpa

coolant leaving the reactor core enters the steam generator.

Fuel: Uranium Oxide as small cylinder pellets, packed in corrosion resistance zirconium alloy tube to form fuel rod.

Control and Protection system:

Vertical control system:

A Typical Breeder Reactor

• Because liquid sodium becomes radioactive, it is separated from the rest of the power plant using a heat exchanger

• High pressure gas-cooled reactors are also being researched

Liquid Metal Cooled Reactor • Sodium graphite reactor is liquid metal reactor. • Sodium works as a coolant and graphite works as moderator. • Sodium boils at 880deg C, sodium is first melted by electric heating system

and be pressurized to 7bars. The liquid sodium is then circulated by the pump.

Working

• Breeder Reactor : Almost same as Liquid Metal Cooled Reactor

Advantages and disadvantages of Nuclear Power plants

Advantages of Nuclear Power

•Nuclear power plants do not emit carbon dioxide. No products are burned. Emissions released by a nuclear power plant are water vapor.

•There is a large supply of nuclear fuel (Uranium) and costs are low to retrieve it.

•Nuclear can provide power quickly when other sources are down.

The NEED Project

ADVANTAGES Clean Plentiful Supply High energy content in uranium

•Small fuel pellet •Can provide base load power •Energy savings in transportation

Operating cost is low after construction

Nuclear power generation does emit relatively low amounts of carbon dioxide (CO2). The

emissions of green house gases and therefore the contribution of nuclear power plants to

global warming is therefore relatively little.

This technology is readily available, it does not have to be developed first.

It is possible to generate a high amount of electrical energy in one single plant

Advantages of Nuclear Power • Nuclear electricity is reliable and relatively cheap

(with an average generating cost of 2.9 cents per kW/h) once the reactor is in place and operating.

• Large reserves of Uranium in United States - Fuel for nuclear power plants will not run out for tens of thousands of years

• Nuclear power plants contribute no greenhouse gasses and few atmospheric pollutants

Disadvantages of Nuclear Power

• Uranium is ultimately a nonrenewable resource. • Nuclear power plants are extremely costly to build. • The slight possibility that nuclear power plants can

have catastrophic failures. • Large environmental impact during the mining and

processing stages of uranium are numerous. • Nuclear waste (Spent nuclear fuel) is extremely

hazardous and must be stored safely for thousands of years.

DISADVANTAGES

The problem of radioactive waste is still an unsolved one.

High risks: It is technically impossible to build a plant with 100% security.

The energy source for nuclear energy is Uranium. Uranium is a scarce resource, its supply is estimated to last only for the next 30 to 60 years depending on the actual demand.

Nuclear power plants as well as nuclear waste could be preferred targets for

terrorist attacks..

During the operation of nuclear power plants, radioactive waste is produced,

which in turn can be used for the production of nuclear weapons.

Nuclear Plant Site selection • Proximity to load center

• Population distribution • Land Use: not agricultural • Meteorology: wind direction • Geology: bearing capacity of soil • Seismology: low seismic activity • Hydrology: Near a water source

Safety Measures for Nuclear Power Plants Three main sources of radioactive contamination are: • Fission of nuclei or nuclear fuels • The effect of neutron fluxes on the heat carried in

the primary cooling system and on the ambient air.

• Damage of shell of fuel elements. All the above can cause health hazards to workers , communing and natural surroundings.

Safety Measures • A nuclear power plant should be constructed away from

human habitation.(160km radius) • The materials used for construction should be of required

standards. • Waste water should be purified. • Should have a proper safety system, plant could be shut

down when required. • While disposing off the wastes it should be ensured that it

doesn’t contaminate the river or sea.

Nuclear Waste Disposal • Geological Disposal • The process of geological disposal centers on

burrowing nuclear waste into the ground to the point where it is out of human reach.

• The waste needs to be properly protected to stop any material from leaking out. Seepage from the waste could contaminate the water table if the burial location is above or below the water level. Furthermore, the waste needs to be properly fastened to the burial site and also structurally supported in the event of a major seismic event, which could result in immediate contamination.

• Reprocessing • Reprocessing has also emerged as a viable

long term method for dealing with waste. As the name implies, the process involves taking waste and separating the useful components from those that aren’t as useful. Specifically, it involves taking the fissionable material out from the irradiated nuclear fuel..

Production of Plutonium (Pu) in Nuclear Reactors

• 239Pu is produced in nuclear reactors by the absorption of a neutron on 238U, followed by two beta decays

• 239Pu also fissions by absorbing a thermal neutron, and on average produces 1/3 of the energy in a fuel cycle.

• 239Pu is relatively stable, with a half life of 24 thousand years.

• It is used in nuclear weapons • It can be bred for nuclear reactors

Nuclear Weapons to Reactor Fuel

• We are buying highly enriched uranium (20% 235U) from the former Soviet Union’s nuclear weapons for 20 years from 1993--2013

• Converting it to low enriched uranium (3% 235U) for reactor fuel

• It will satisfy 9 years of US reactor fuel demand

• It comes from 6,855 Soviet nuclear warheads so far

Steam relief to Wet well following rise of pressure in the Pressure Vessel

Pressurisation of wetwell & Opening of drywell - Partial core uncovery – metal water reaction – hydrogen - clad damage – steam, non-condensibles, fission

gases come to dry well

Drywell Pressurization

Drywell pressurisation – venting - Accumulation of H2 gas in secondary containment and pressure build-up

Attainment of explosive H2 concentration in secondary containment – BURSTING & release (Units 1&3)

Attainment of explosive H2 concentration in Wetwell – BURSTING & release (Unit-2)

How a Nuclear Reactor works • 235U fissions by absorbing a neutron and producing 2 to 3 neutrons,

which initiate on average one more fission to make a controlled chain reaction

• Normal water is used as a moderator to slow the neutrons since slow neutrons take longer to pass by a U nucleus and have more time to be absorbed

• The protons in the hydrogen in the water have the same mass as the neutron and stop them by a billiard ball effect

• The extra neutrons are taken up by protons to form deuterons • 235U is enriched from its 0.7% in nature to about 3% to produce the

reaction, and is contained in rods in the water • Boron control rods are inserted to absorb neutrons when it is time to

shut down the reactor • The hot water is boiled or sent through a heat exchanger to produce

steam. The steam then powers turbines.

Safety in Indian PHWRs

Reactor Safety

Safe Shutdown Decay Heat Removal

Containment

Systems & Features

• Fast Acting

• Independent

• Passive

(Shut off Rods, Control Rods and Poison Injection for Long term shutdown)

Systems & Features

• Active & Passive

• Backup Systems

[Emergency Core Cooling System (ECCS), Suppression Pool, Inventory in Calandria & Calandria Vault, Fire water injection into Steam Generators]

Systems & Features

• Double Containment

•Inner Containment design for Design Basis Accident (DBA) pressure

• Secondary Containment under negative pressure

•Engineered Safety Features (ESF)

Indian Nuclear Program: The Present Status

• 12 PHWR & 2 BWR now under operation • 4 PHWR and 2 LWR under commission • 2950 MW generation & 3000 MW under commission • Successful experiments with Fast Breeder Test Reactor (FBTR) • Prototype Fast Breeder Reactor (PFBR) for 500MWe under

construction • Advanced Heavy Water Reactor (AHWR) using (Pu-Th) O2

MOX for 300MWe: advanced stage of design approval; construction soon to begin.

MAKING INDIA A NUCLEAR POWER • India 1948:-It was pt.

Jawaharlal Nehru initiated India’s Nuclear energy program

• India 1967:-It was Indira Gandhi initiated India’s Nuclear weapons program

INDIA AFTER 2000 • India 2005:-It was Dr.

Manmohan Singh signed 123 agreement.

• India 2009:-Manmohan Singh is again interested to increase India’s civilian Nuclear energy

India has signed “Civil Nuclear Trade Agreement”.

CONTROL RODS Control rods made of a material that absorbs neutrons are

inserted into the bundle using a mechanism that can rise or

lower the control rods.

. The control rods essentially contain neutron absorbers

like, boron, cadmium or indium.

STEAM GENERATORS 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.

STEAM TURBINE

A steam turbine is a mechanical device that extracts

thermal energy from pressurized steam, and converts it into

useful mechanical

Various high-performance alloys and super alloys have

been used for steam generator tubing.

COOLANT PUMP

The coolant pump pressurizes the coolant to pressures of

the orderof 155bar.

The pressue of the coolant loop is maintained almost

constant with the help of the pump and a pressurizer unit.

FEED PUMP

Steam coming out of the turbine, flows through

the condenser for condensation and recirculated

for the next cycle of operation.

The feed pump circulates the condensed water

in the working fluid loop.

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 & feed back it to the steam generator

without any further treatment.

COOLING TOWER

Cooling towers are heat removal devices used to transfer

process waste heat to the atmosphere.

Water cirulating throughthe codeser is taken to the cooling

tower for cooling and reuse

Future of Nuclear Power • India has adequate deposits of fissionable material Thorium

which can be eventually used for generation of power.The future of nuclear power plant is quiet bright

• Following three factors need discussion 1. Cost of Power Generation 2. Availability of nuclear fuel, breeder reactor. 3. Safety of nuclear plants. List of Nuclear plants in India http://www.npcil.nic.in/main/allprojectoperationdisplay.aspx Tarapur, Rana Pratap Sagar , Kalpakkam, Narora, Kakrapar