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Low pressure reactors


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Low pressure reactors

  2. 2. Muhammad Umair Bukhari 03136050151
  3. 3. OVERVIEWI’ll discuss here:  What is nuclear energy?  Nuclear reactor  Nuclear power plant  Types of nuclear reactors and  Nuclear reactor hazards
  4. 4. What is nuclear energy?Nuclear energy produces electricity from heatthrough a process called fission. Nuclear powerplants use the heat produced by fission of certainatoms. 1. Nuclear fission nucleus of atom is split into parts, produces free neutrons and energy
  5. 5. Nuclear Reactors Nuclear Reactor  device built to sustain a controlled nuclear fission chain reaction Main Components of Nuclear Reactor: - reactor vessel - tubes of uranium - control rods - containment structure Containment control control rods structure radioactivity, absorbs contains the reaction neutrons in at least 3 feet of concrete!
  6. 6. The Nuclear Power Plant Nuclear power plant consists of all the parts needed to create electricity by usingFission occurs The heat is used nuclear energy in the reactor to heat water tovessel. Heat is create steam produced. The steam isThe steam is used to turn thecooled in the turbine in thecondenser to generator toreturn to the produceliquid phase. electricity
  7. 7. Types of Nuclear Reactors:  Thermal Reactors and Fast Reactors  Homogeneous and Heterogeneous Reactors  Low Pressure and High Pressure and ReactorsLow Pressure Reactors:  Pressure is normally 7MPa  Water boils in the core of the reactor  Low pressure reactors are working in a “DIRECT CYCLE” Most common low pressure reactors are:  Boiling Water Reactors BWR  Advanced BWR, ABWR  Economical Small Boiling Water Reactor (ESBWR)  RBMK Reactor
  8. 8. Boiling Water Reactors BWR:• Direct Boiling • UO2 Fuel• 10% Coolant = Steam • 60 – yr Service Life• 3.2% U-235 Fuel • Internalized Safety and• Lower Power Density than Recirculation Systems PWR• Corrosion Product Activated in Core• Higher Radiation Field
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  10. 10. • 1350 MWe• 77% more compact than BWR design• 39 month construction period GE TOSHIBA, Kashiwazaki-Kariwa Unit 6, Japan
  11. 11.  Early 1990s - TEPCO, 5 other utilities, GE, Hitachi and Toshiba began development 1700 MWe Goals 30% capital cost reduction Reduced construction time 20% power generation cost reduction Increased safety Increased flexibility for future fuel cycles Commercialize – latter 2010s
  12. 12.  1550 MWe (4500 MWt) Passive Condenser Systems for Heat Transfer Standard Seismic Design Improved Economics Shorter Construction Time Reduced Plant Staff and Operator Requirements
  13. 13. RBMK Reactor High Power Channel-type Reactor Graphite-moderated 1986 Chernobyl disaster Reactor pit is made of reinforced concrete Pit Dimensions 21.6 21.6 25.5 meters Vessel of the reactor, made of a cylindrical wall and top and bottom metal plates Moderator blocks are made of nuclear graphite of dimensions 250 250 500 mm There are holes with 11.4 cm (4.5 in) diameter Cylindrical core 14 m (45 ft 11 in) in diameter and 8 m (26 ft 3 in) high Maximum allowed temperature of the graphite is less or equal to 730 C (1,350 F) Top of the reactor is covered by the upper biological shield, called "Schema E" Fuel channels consist of welded zircaloy pressure tubes 8 cm (3.1 in) in inner diameter with 4 mm (0.16 in) thick walls There are 1661 fuel channels and 211 control rod channels in the reactor core UO2 pellets 1.15 cm (0.45 in) in diameter and 15 mm (0.59 in) long Emergency Core Cooling System (ECCS)
  14. 14. Nuclear Reactor Hazards Radiation effects to the workers of plant Radiation effects on environment and atmosphere Power plant is a major threat for public in case of a disaster like Chernobyl Ageing process of nuclear reactors produces:  Small leakages  Cracks  Short-circuits due to cable failure  Gradual weakening of materials  Embrittlement of the reactor pressure vessel There is also a threat of terrorism attack That attack may be from air, water or firing on plant from a distance Spent fuel pool disaster Radioactive waste storage disaster Two major nuclear reactor disasters are Three miles island and Chernobyl