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Nuclear power plant


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nuclear power generation
types of nuclear reactor
position in india
waste management of nuclear waste
generation of nuclear reactor
advantages and disadvantages

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Nuclear power plant

  1. 1. Introduction to Nuclear Power • It is the use of Nuclear Fission reactions to Generate Power • Nuclear energy is the world's largest source of emission-free energy • Most efficient Power Source per Unit Area • Used in 31 Countries (approx 441 reactors)1 • Accounts for about 16% of all electricity generated world wide (approx 351 Gigawatts) 1. 2003 Figures
  2. 2. Introduction to Nuclear Power The major benefits of Nuclear Power include: • No Green House Gas emissions • No Air Pollutants such as CO,SO2,NO,Hg or particulate matter, thus ensuring “Nil” contribution to Acid Rain, Global Warming etc. • Relatively low risk of “Work Related Injury” • Efficiency per capita fuel unit is very high
  3. 3. Introduction to Nuclear Power Developed Countries are shifting to Nuclear Power
  4. 4. Introduction to Nuclear Power US 97 North America Region 109 France 63 Germany 21 U. K. 12 Western Europe Region 126 Japan 44 Asia Region 66 Eastern Europe Region 11 Former Soviet U. Region 34 World Nuclear Power Production in Gigawatts
  5. 5. Introduction to Nuclear Power India Nuclear Power Production in MW Plants under operation MWe 14 reactors at 6 sites viz., Tarapur, Rawatbhata, Kalpakkam Narora, Kakrapar and Kaiga 2720 Plants under construction 2x500 at Tarapur 1000 Plants likely to commence in the current financial year 2x220, 2x1000, 1x500 2940 Future Plans 2x220,4x500,10x500,6x1000 13440 Total 20100
  6. 6. NPP IN INDIA
  7. 7. Uranium mining- World (4,7)
  8. 8. Uranium mining- India (3)
  9. 9. Advantages over coal • One gram of fissionable uranium can produce a million times more heat than one gram of coal. • For 400MW of electricity, only 20 kg of uranium fuel is required per day. In comparison, a coal burning thermal power station of the same capacity would require about 4000 tonnes of coal daily
  10. 10. Disadvantages • The problem of radioactive waste is still an unsolved one. • High risks • Nuclear power plants as well as nuclear waste could be preferred targets for terrorist attacks. • Radioactive waste is produced can be used for the production of nuclear weapons. • Uranium is a scarce resource
  11. 11. The Underlying Principle “Nuclear Fission” • In Physics, “fission” is a nuclear process, i.e., it occurs in the nucleus of an atom. Fission occurs when the Nucleus splits into two or more smaller nuclei plus some by-products. These by-products include free neutrons and photons (usually gamma rays). Fission releases substantial amounts of energy (the strong nuclear force binding energy). • The use of this energy for generation of electricity is the essence of nuclear power generation.
  12. 12. The Underlying Principle • Radioactivity was discovered by Sir James Chadwick (1932) • Later Enrico Fermi experimented and Physicist Lise Meitner and Otto Frish discovered Chain Reactions • Chicago Pile – The first controlled chain reaction was conducted in December 1942, resulted in heat Generation of 2 kW using Uranium • The Manhattan Project: – Atomic bomb – Nagasaki & Hiroshima
  13. 13. The Underlying Principle •Fission can be induced by several methods, including bombarding the nucleus of a fissile atom with a free neutron moving at the right speed •Neutron + U-235 --> fission products + more neutrons + energy •The process releases a lot of energy compared to chemical reactions. •Energy released by a fission event is approximately 200 MeV.
  14. 14. Nuclear fission process
  15. 15. How does fission work • A neutron hits a uranium nucleus. • The nucleus becomes unstable and needs to release energy. • The nucleus breaks releasing energy, neutrons and 2 smaller atoms. • The 2 smaller atoms formed are called fission fragments.
  16. 16. • When the neutrons are released during fission, they go on to hit 2/3 other uranium nuclei. • This continues and is called a chain reaction • In a nuclear reactor the chain reaction is controlled. • As the control rods are removed the chain reaction increases, and if we want to slow the reaction control rods are inserted.
  17. 17. Block Schematic for Nuclear Power Plant
  18. 18. A Nuclear Power Plant is basically a Thermal Power Plant in which steam is produced in a Nuclear Reactor rather than in a Conventional Boiler
  19. 19. Nuclear Power Plant - Working Components of a Nuclear Power Plant
  20. 20. Basic Reactor Model Pump 1.Fuel 3.Controlrod 5.Steamgenerator 4. Coolant 6. 8. 7. Turbine Generator
  21. 21. Major components of Nuclear Reactor TYPE DESCRIPTION Fuel These are Fissile Elements like U235’ PU239 arranged in the form of Bundled rods Control Rods / Nuclear Poison A control rod is of chemical elements capable of absorbing many neutrons without fissioning themselves (E.g. silver, indium and cadmium) Control rods are usually inserted into guide tubes within a fuel element. A control rod is removed from or inserted into the central core of a nuclear reactor in order to control the neutron flux — increase or decrease the number of neutrons which will split further uranium atoms. This in turn affects the thermal power of the reactor, the amount of steam produced, and hence the electricity generated. Moderator Moderator is a medium which reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving U235. Commonly used moderators include regular (light) water, used in roughly 75% of the world‘s reactors, solid graphite (20%) and heavy water (D2O) (5%). Beryllium has been used in some experimental reactor types, and hydrocarbons have been suggested as a possibility. Coolant Coolant is a medium used to transfer heat generated in the Nuclear Reactor’s core to the heat exchanger to produce Steam for driving Steam Turbines. Light Water, Heavy Water, Carbon Dioxide, Nitrogen, Molten Sodium etc. are some commonly used coolants
  22. 22. Nuclear Power Reactor - Fuel Uranium Fuel Cycle
  23. 23. Types of Nuclear Reactor 1. The Boiling Water Reactor (BWR): This is the simplest of all reactors. Water absorbs heat from the reactions in the core and is directly driven to the turbines. After condensing the water is pumped back to the reactor core
  24. 24. 2. Pressurized water reactors, (PWR): In this type of reactor, the heat is dissipated from the core using highly pressurized water (about 160 bar) to achieve a high temperature and avoid boiling within the core. The cooling water transfers its heat to the secondary system in a steam generator
  25. 25. 3. Pressurized Heavy Water Reactor (PHWR), : In this type of reactors, fuel bundles are inserted into the Heat Exchanger where a heavy water moderator is circulated to provide cooling in addition to moderating neutrons. This heavy water is then circulated to the steam generator to transfer its heat and then pumped back to the reactor. The steam is a secondary circuit as above and is used to drive a turbine assembly before condensing and re-use
  26. 26. 4. The Gas Cooled Reactor (GCR) : It uses CO2 gas to remove heat from the core. This is then piped through the steam generator where heat is removed from the gas and it can then be re-circulated to the reactor. As usual steam generated is used to drive the turbine and generate electricity, condensed then recirculated. Graphite is used as a moderator to allow energy production by un-enriched uranium.
  27. 27. 5. The Light Water Graphite Reactor (LWGR): Here Graphite replaces heavy water as moderator. Light water is used to remove heat from the core for transfer to steam drums. The steam evolved in these is used subsequently to power turbines.
  28. 28. 6. The Fast Breeder Reactor (FBR): It uses a Plutonium fuel rather than Uranium. The Pu is surrounded by rods of U-238 which absorb neutrons and are transmitted into Pu-239 which undergoes fission to generate energy. As the plutonium in the core becomes depleted it creates or breeds more plutonium from the Uranium around it.
  29. 29. Nuclear Waste management • Radioactive wastes from the nuclear reactors and reprocessing plants are treated and stored at each site • High level waste is currently kept in storage facilities and will finally be put into specially engineered underground repositories. • Research on final disposal of high-level and long-lived wastes in a geological repository is in progress .
  30. 30. Technology advancements in nuclear power reactors
  31. 31. Generation II reactor • A generation II reactor is a design classification for a nuclear reactor, and refers to the class of commercial reactors built up to the end of the 1990s. • Prototypical generation II reactors include the PWR, CANDU, BWR, AGR, and VVER. (2,5)
  32. 32. Generation III reactors • Advanced Boiling Water Reactor (ABWR) — A GE design that first went online in Japan in 1996. • Advanced Pressurized Water Reactor (APWR) — developed by Mitsubishi Heavy Industries. • Enhanced CANDU 6 (EC6) — developed by Atomic Energy of Canada Limited. • VVER-1000/392 (PWR) — in various modifications into AES-91 and AES-92. (2,5)
  33. 33. Generation IV reactor • Generation I V reactors(Gen IV) are a set of theoretical nuclear reactor designs currently being researched. • commercial construction before 2030, with the exception of a version of the Very High Temperature Reactor (VHTR) called the Next Generation Nuclear Plant (NGNP). • Research into these reactor types was officially started by the Generation IV International Forum (GIF) (2,5)
  34. 34. Goals of Gen IV • Improve nuclear safety. • Improve proliferation Resistance. • Minimize waste and natural resource utilization. • Decrease the cost to build and run such plants. • Increase life time of nuclear reactors.
  35. 35. Reactor types Thermal reactors • 1. Very-high- temperature reactor (VHTR) • 2. Supercritical- water-cooled reactor (SCWR) Fast reactors • 1. Gas-cooled fast reactor (GFR) • 2. Sodium-cooled fast reactor (SFR) • 3. Lead-cooled fast reactor (LFR)
  36. 36. • VHTR:- Concept uses a graphite-moderated core with a once- through uranium fuel cycle, using helium or molten salt as the coolant. • SCWR:- Concept that uses supercritical water as the working fluid. It could operate at much higher temperatures than both current PWRs and BWRs. • MSR:- Nuclear reactor where the coolant is a molten salt. Nuclear fuel dissolved in the molten fluoride salt as UF4 or ThF4.
  37. 37. • FR:- Fast-neutron spectrum and closed fuel cycle. The reactor is helium-cooled. Based on Brayton cycle gas turbine. • SFR:- Builds on two closely related existing projects, the liquid metal fast breeder reactor and the Integral Fast Reactor. • LFR:-fast-neutron-spectrum lead or lead/bismuth eutectic (LBE) liquid-metal-cooled reactor with a closed fuel cycle.
  38. 38. Advantages • Nuclear waste that lasts a few centuries instead of millennia. • 100-300 times more energy yield from the same amount of nuclear fuel. • The ability to consume existing nuclear waste in the production of electricity.
  39. 39. Facts of disaster • 6-7 % heat still decay out from core even in shutdown condition which is must to remove. • In emergency shutdown back up gens ets take 60-75 seconds to achieve full load. • Test was conducted with night shift workers instead of trained day shift workers. • Production of xenon reduced the stable power level required for test causing withrawal of more control rods. • Human error by Er. Toptunov who inserted control rods in the core.
  40. 40. • To increase power output control rods were removed instantly in large number causing rise in temperature and hence massive power spike occurred which damaged the fuel rods also . • As power was around 700 mw actual test begins and turbine generator went off and ext. gensets resumed the working of ECCS. • Due to some alarm triggering 4 of 8 main circulation pumps went off air causing serious steam voids in coolant process thus increasing the temperature of core.
  41. 41. • To reduce the increased power output control rods are allowed to get in the core which was already damaged. So only1/3 part of rods was in the core. • Consequently power output rose up to 33GW(10 times of peak output). • Hydrogen blast took place first blowing off the secondary containment and then flammable graphite blasted with huge impact involving radioactive core also.
  42. 42. Fukushima Daiichi Event Unit 1 439 MW 11 March 2011 (2,5)
  43. 43. Fukushima Event  The Fukushima nuclear facilities were damaged in a magnitude 8.9 earthquake on March 11 (Japan time), centered offshore of the Sendai region, which contains the capital Tokyo.  Plant designed for magnitude 8.2 earthquake. An 8.9 magnitude quake is 7 times in greater in magnitude.  Serious secondary effects followed including a significant tsunami, significant aftershocks and a major fire at a fossil fuel installation.
  44. 44. Waste Management Disposal of waste of nuclear power plant Nuclear power plant wastes can be classified • Low level radioactive waste • High level radioactive waste
  45. 45. Waste Management • It includes cooling water pipes,radiation suits,discarded fuel elements cans and gloves • Low level radioactive waste are easy to dispose off • Low level radioactive wastes are stored under sea bed and large stable geologic formations on land Low level radioactive waste
  46. 46. Waste Management High level radioactive waste • It includes materials from the core of the nuclear reactor. • Plutonium, Uranium, Control rods and other radioactive elements made during fission • Difficult to dispose
  47. 47. Waste Management • These radioactive materials are stored in shielded storage vaults • Shielded vaults are stored in deep salt mines • Sometimes high level nuclear waste can be sunk to the bottom of the sea & oceans • Fired into the sun or into a long term stable orbit. • Transmutation High level radioactive waste disposal
  48. 48. • Necessary to guard personnel and delicate instruments • Materials used are lead, Concrete, Steel and cadmium • Water is used to slow down fast neutrons • Boron and steel are employed for absorption of thermal neutrons • Heavy metals like lead is required to act as thermal shield and to absorb gama rays Waste Management Shielding of Nuclear reactor