Nuclear Power plants

Nuclear power plants presentation

1. UNIT 3 NUCLEAR POWER PLANTS

2. Syllabus Basic s of Nuclea r Engineering , Layou t and subsystems of Nuclear Power Plants, Working of Nuclear Reactors : Boiling Water Reactor (BWR), Pressurized Water Reactor (PWR), CANada Deuterium- Uranium reactor (CANDU), Breeder, Gas Cooled and Liquid Metal Cooled Reactors. Safety measures for Nuclear Power plants.

3. Nuclear Energy 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

4. NUCLEAR POWER PLANT - LAYOUT

5. Nuclear Power plant

6. Components of Nuclear Power Plant Nuclear Fuel : Normally used nuclear fuel is uranium (U 235 ) Fuel Rods: The fuel rods hold nuclear fuel in a nuclear power plant. Neutron Source: A source of neutron is required to initiate the fission for the first time. A mixture of beryllium with plutonium is commonly used as a source of neutron. Reactor: Nuclear fission takes place in the reactor only. Nuclear fission produces large quantity of heat. The heat generated in the reactor is carried by coolant circulated through the reactor.

7. Nuclear Fission Fast Neutrons Moderator U 23 5 Moderator Fission Fragment Fission Fragment U 23 5 Fission Fragment Fission Fragment Slow Neutrons Slow Neutrons Ba Kr

8. Nuclear Fission It is a process of splitting up of nucleus of fissionable material like uranium into two or more fragments with release of enormous amount of energy. The nucleus of U 235 is bombarded with high energy neutrons U 235 + n 1 B a 14 1 +K r 9 2 +2. 5 n 1 + 200 Me V energ y . The neutrons produced are very fast and can be made to fission other nuclei of U 235 , thus setting up a chain reaction. Out of 2.5 neutrons released one neutron is used to sustain the chain reaction. 1 eV = 1.6X10 -19 joule. 1 MeV = 10 6 eV

9. Working Principle of Nuclear Power Plant The heat generated in the reactor due to the fission of the fuel is taken up by the coolant. The hot coolant then leaves the reactor and flows through the steam generator. In the steam generator the hot coolant transfers its heat to the feed water which gets converted into steam. The steam produced is passed through the turbine, which is coupled with generator. Hence the power is produced during the running of turbine. The exhaust steam from the turbine is condensed in the condenser. The condensate then flows to the steam generator through the feed pump.

10. Advantages of Nuclear Power Plant Requires less space compared to steam power plant. Fuel required is negligible compared to coal requirement. Fuel transport cost is less. Reliable in operation. Cost of erection is less. Water required is very less.

11. Disadvantages of Nuclear Power Plant Initial Cost is higher. Not suitable for varying load condition. Radioactive wastes are hazardous. Hence these are to be handled with much care. Maintenance cost is higher. Trained workers are required to operate the plant.

12. Nuclear Power Plants in India IGCAR, Kalpakkam in Chennai. Rana Pratap Sagar in Rajasthan Narora in Uttar Pradesh Kakarpur near Surat at Gujarat Kaiga Power Plant at Karnataka.

13. TYPES OF REACTORS

14. NUCLEAR REACTOR

15. CONTRO L O F NUCLEA R REACTOR 1 . Graphit e core, moderates neutro n flu x fro m fuel rods 2 . Boro n control rods t o reduce neutro n flu x for shutdown 3 . Therma l transfe r control – closed circuit water/ steam loop. Multiple water pumps nitrogen/ helium gas within containment – low thermal conductivity and oxygen exclusion – pressure gas mixture are controlled. Emergency core cooling water system (ECCS)

16. MULTIPLICATION FACTOR . Multiplication is used to determine whether the chain reaction will continue at a steady rate, increase or decrease. It is given by the relation, K = P/ ( A+E) K = Effective multiplication factor P = rate of production of neutrons A = Combined rate of absorption of neutrons E = Rate of leakage reactance

17. Pressurized water reactor (PWR) Moderator and coolant are light water (H 2 O). Cooling water circulates in two loops .Water is kept under pressure. So water heats but does not boil. Pressurizer is used to maintain constant pressure. If pressure drops, water in the pressurizer is heated up by electric heaters. If pressure increases, cooling water is injected to pressurizer.

18. Pressurized water reactor

19. The pressurized water reactor

20. Primary circuit water transfers its heat to secondary circuit water, cools down and returns to reactor vessel. Both water circuits are separate and can’t mix. Primary pressure-12 to 16 bars. Outlet temperature of coolant- 30 C. Widely used type

21. Boiling water reactor H2O is moderator and coolant. Only a part of water boils away in reactor, a mixture of water and steam leaves reactor core. Pressure is only 6 to 7 bars. Fuel UO2 Simple, low cost construction.

22. Boiling water heater

23. Boiling water heater

24. Waste disposal and safety Hydel power plant Disposal of radioactive waste from nuclear power plants and weapons facilities by recycling it into household products. In 1996, 15,000 tons of metal were received by the Association of Radioactive Metal Recyclers . Much was recycled into products without consumer knowledge. Depleted Uranium munitions for military.

25. Current World Demand for Electricity

26. Future Demand Projected changes in world electricity generation by fuel, 1995 to 2020

27. Emission-Fre e Source s of Electricity 73.1% 24.2% 1.3% 1.0% 0.1%

28. Basics of a Power Plant The basic premises for the majority of power plants is to: 1) Create heat 2) Boil Water 3) Use steam to turn a turbine 4) Use turbine to turn generator 5) Produce Electricity Some other power producing technologies work differently (e.g., solar, wind, hydroelectric, …)

29. Nuclear Power Plants use the Rankine Cycle

30. Create Heat Heat may be created by: Burning coal Burning oil Other combustion Nuclear fission oil, coal or gas heat steam turbine generator electricity cold water waste heat water condenser

31. Boil Water The next process it to create steam. The steam is necessary to turn the turbine.

32. Turbine Steam turns the turbine.

33. Generator As the generator is turned, it creates electricity.

34. Heat From Fission

35. Fission Chain Reaction

36. Nuclear History 1939. Nuclear fission discovered. 1942. The world´s first nuclear chain reaction takes place in Chicago as part of the wartime Manhattan Project. 1945. The first nuclear weapons test at Alamagordo, New Mexico. 1951. Electricity was first generated from a nuclear reactor, from EBR-I (Experimental Breeder Reactor-I) at the National Reactor Testing Station in Idaho, USA. EBR-I produced about 100 kilowatts of electricity (kW(e)), enough to power the equipment in the small reactor building. 1970s. Nuclear power grows rapidly. From 1970 to 1975 growth averaged 30% per year, the same as wind power recently (1998-2001). 1987. Nuclear power now generates slightly more than 16% of all electricity in the world. 1980s. Nuclear expansion slows because of environmentalist opposition, high interest rates, energy conservation prompted by the 1973 and 1979 oil shocks, and the accidents at Three Mile Island (1979, USA) and Chernobyl (1986, Ukraine, USSR). 2004 . Nuclear power´s share of global electricity generation holds steady around 16% in the 17 years since 1987.

37. Current Commercial Nuclear Reactor Designs Pressurized Water Reactor (PWR) Boiling Water Reactor (BWR) Gas Cooled Fast Reactor Pressurized Heavy Water Reactor (CANDU) Light Water Graphite Reactor (RBMK) Fast Neutron Reactor (FBR)

38. The Current Nuclear Industry

39. Nuclear Reactors Around the World

40. PWR

41. BWR

42. CANDU-PHWR

43. PTGR

44. Hydrogen Production Hydrogen is ready to play the lead in the next generation of energy production methods. Nuclear heat sources ( i.e., a nuclear reactor ) have been proposed to aid in the separation of H from H 2 0. Hydrogen is thermochemically generated from water decomposed by nuclear heat at high temperature. The IS process is named after the initials of each element used (iodine and sulfur).

45. Hydrogen Production (cont.)

46. Closed Fuel Cycle A closed fuel cycle is one that allows for reprocessing. Benefits include: Reduction of waste stream More efficient use of fuel. Negative attributes include: Increased potential for proliferation Additional infrastructure

47. Simplification Efforts are made to simplify the design of Gen IV reactors. This leads to: Reduced capitol costs Reduced construction times Increased safety (less things can fail)

48. Increased Safety Increased safety is always a priority. Some examples of increased safety: Natural circulation in systems Reduction of piping Incorporation of pumps within reactor vessel Lower pressures in reactor vessel (liquid metal cooled reactors)

49. Gas Cooled Fast Reactor (GFR) The Gas-Cooled Fast Reactor (GFR) system features: fast-neutron-spectrum helium-cooled reactor (Brayton Cycle) closed fuel cycle (includes reprocessing)

50. Gas Cooled Fast Reactor (GFR) Like thermal-spectrum, helium-cooled reactors, the high outlet temperature of the helium coolant makes it possible to: deliver electricity produce hydrogen process heat with high efficiency. The reference reactor is a 288-MWe helium-cooled system operating with an outlet temperature of 850 degrees Celsius using a direct Brayton cycle gas turbine for high thermal efficiency.

51. Very High Temperature Reactor (VHTR) The Very-High-Temperature Reactor (VHTR) is graphite-moderated (thermal spectrum) helium-cooled reactor once-through uranium fuel cycle (no reprocessing) core outlet temperatures of 1,000 ◦C

52. Supercritical Water Cooled Reactor (SCWR) The Supercritical-Water-Coo led Reactor (SCWR) system: high-temperature high-pressure water-cooled reactor above tha t operates the thermodynamic critical point o f water (374 degree s Celsius, 22. 1 MPa, o r 705 Fahrenheit, degrees 3208 psia).

53. What is a supercritical fluid? A supercritical fluid is a material which can be either liquid or gas, used in a state above the critical temperature and critical pressure where gases and liquids can coexist. It shows unique properties that are different from those of either gases or liquids under standard conditions.

54. WASTE DISPOSAL LIQUID WASTE Dilution Concentration to small volumes and storage GASEOUS WASTE SOLID WASTE

55. Governing of Turbines

56. Governing of Turbines Governing system - regulates the turbine speed, power and participates in the grid frequency regulation. Main operator interface for starting & loading. Plays a key role on Steady state and dynamic performance

57. Governing of Turbines Need for governing system: Mismatch between load and generation results in the speed (or frequency) variation. When the load varies, the generation also has to vary to match it to keep the speed constant. Done by the governing system. Speed which is an indicator of the generation – load mismatch is used to increase or decrease the generation.

58. Pelton Wheel

59. Governing of pelton wheel

60. Governing of Francis turbine

61. Kaplan turbine

62. Governing of Kaplan turbine

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