NUCLEAR FUELNuclear fuel is any material that can beconsumed to derive nuclear energy. The mostcommon type of nuclear fuel is fissile elementsthat can be made to undergo nuclear fission chainreactions in a nuclear reactorThe most common nuclear fuels are 235U and239Pu. Not all nuclear fuels are used in fissionchain reactions
NUCLEAR FISSIONWhen a neutron strikes an atom of uranium, theuranium splits ingto two lighter atoms and releasesheat simultaneously.Fission of heavy elements is an exothermic reactionwhich can release large amounts of energy both aselectromagnetic radiation and as kinetic energy of thefragments
NUCLEAR CHAIN REACTIONSA chain reaction refers to a process in which neutronsreleased in fission produce an additional fission in at leastone further nucleus. This nucleus in turn produces neutrons,and the process repeats. If the process is controlled it isused for nuclear power or if uncontrolled it is used fornuclear weapons
U235 + n → fission + 2 or 3 n + 200 MeVIf each neutron releases two more neutrons, then thenumber of fissions doubles each generation. In thatcase, in 10 generations there are 1,024 fissions and in80 generations about 6 x 10 23 (a mole) fissions.
NUCLEAR REACTORA nuclear reactor is a device in which nuclear chainreactions are initiated, controlled, and sustained at asteady rate, as opposed to a nuclear bomb, in whichthe chain reaction occurs in a fraction of a second andis uncontrolled causing an explotion.
CONTROL RODSControl rods made of a material that absorbsneutrtons are inserted into the bundle using amechanism that can rise or lower the control rods.. The control rods essentially contain neutronabsorbers like, boron, cadmium or indium.
STEAM GENERATORSSteam generators are heat exchangers used toconvert water into steam from heat produced in anuclear reactor core.Either ordinary water or heavy water is used as thecoolant .
STEAM TURBINEA steam turbine is a mechanical device that extractsthermal energy from pressurized steam, and converts itinto useful mechanical Various high-performance alloys and superalloyshave been used for steam generator tubing.
COOLANT PUMPThe coolant pump pressurizes the coolant topressures of the orderof 155bar.The pressue of the coolant loop is maintained almostconstant with the help of the pump and a pressurizerunit .
FEED PUMPSteam coming out of the turbine, flowsthrough the condenser for condensation andrecirculated for the next cycle of operation.The feed pump circulates the condensedwater in the working fluid loop.
CONDENSERCondenser is a device or unit which is used tocondense vapor into liquid.The objective of the condenser are to reduce theturbine exhaust pressure to increase the efficiency andto recover high qyuality feed water in the form ofcondensate & feed back it to the steam generatorwithout any further treatment.
COOLING TOWERCooling towers are heat removal devices used totransfer process waste heat to the atmosphere.Water cirulating throughthe codeser is taken to thecooling tower for cooling and reuse
ADVANTAGESNuclear power generation does emit relatively low amountsof carbon dioxide (CO2). The emissions of green house gasesand therefore the contribution of nuclear power plants toglobal warming is therefore relatively little.This technology is readily available, it does not have to bedeveloped first.It is possible to generate a high amount of electrical energyin one single plant
DISADVANTAGESThe problem of radioactive waste is still an unsolved one.High risks: It is technically impossible to build a plant with100% security.The energy source for nuclear energy is Uranium. Uraniumis a scarce resource, its supply is estimated to last only for thenext 30 to 60 years depending on the actual demand.
DISADVANTAGESNuclear power plants as well as nuclear waste couldbe preferred targets for terrorist attacks..During the operation of nuclear power plants,radioactive waste is produced, which in turn can beused for the production of nuclear weapons.