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Rankine Cycles for Nuclear Power Plants

Rankine Cycles for Nuclear Power Plants. P M V Subbarao Professor Mechanical Engineering Department. Valuing the greenhouse gas emissions from A Rankine Cycle Systems ……. Life Cycle of Nuclear Fuel. Safe Disposal. Nuclear Fission & Chain Reaction. Quantity of Fuel.

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Rankine Cycles for Nuclear Power Plants

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  1. Rankine Cycles for Nuclear Power Plants P M V Subbarao Professor Mechanical Engineering Department Valuing the greenhouse gas emissions from A Rankine Cycle Systems ……

  2. Life Cycle of Nuclear Fuel Safe Disposal

  3. Nuclear Fission & Chain Reaction

  4. Quantity of Fuel • The heat value is the amount of heat released during its combustion. • It is a measure of a fuel's energy density (kJ/kg) • One uranium pellet the size of the tip of your little finger is equivalent to energy provided by: • 800 kg of coal, • 480 cubic meters natural gas, or • 570 litre of oil.

  5. The closed nuclear fuel cycle

  6. The fuel fabrication process

  7. Fuel Rod Cluster

  8. Comparison of Life-Cycle Emissions Tons of Carbon Dioxide Equivalent per Gigawatt-Hour

  9. Rankine Cycle with Boiling Water Reactor

  10. Cycle Layout for BWR Plant p=1.12MPa T=250C p=7.012MPa T=286C p=0.004246MPa T=30C p=0.004246MPa T=30C p=7.012MPa T=173C

  11. Boiling Water Reactors • The flow into the reactor from the two feedwater systems is at normal conditions about 1250 kg/s. • The pressure and temperature at this point are about 7.012MPa and 173C. • The feedwater flow mixes with the recirculation flow in the downcomer and continues to the lower plenum through the recirculation pumps. • The temperature of the water in the lower plenum is 273C. • There are 6 circulation pumps which circulate the flow in the reactor.

  12. Boiling Water Reactors • The water flows from the lower plenum through the reactor core where the water starts to boil at 286C. after about half a meter. • The steam is very moisty when it reaches the top of the core and less than 10 % of the mass flow remains after the steam and moisture separators in the top of the reactor the rest has been separated. • The separated water is then again mixed with the incoming feedwater in the downcomer. • The thermal capacity of the reactor core is 2540 MW at maximal reactor. 20m 6m

  13. Steam System

  14. Reheater system • About 23 kg/s of hot steam is taken from each of the two high pressure steam chests to the hot tube side of the reheaters. • The purpose of this system is to heat and dry the moist steam after the HPT which now contains about 14 % of moisture. • The lower part of the reheater is a moisture separator and the condensate from there is transported to the separator drainage tank. • The steam is almost completely dry after the moist separation and are ready to be reheated from 185C to 250 C by the hot steam from the high pressure steam chests.

  15. The High Pressure – Boiling Water Reactor HP-BWR • The High Pressure Boiling Water Reactor (HP-BWR) offers improved nuclear safety and less damage to the environment. • The HP-BWR is an environmentally friendly, effective alternative. • The use of the HP-BWR means improved cycle thermal efficiency up to about ~40% instead of about ~30%.

  16. Supercritical water cooled reactor

  17. Rankine cycle with Pressurized Heavy Water Reactor

  18. Pressurized Heavy Water Reactor • Fuel assemblies are placed horizontally in a tank called a calandria. • Heavy water coolant is pumped through tubes containing the fuel assemblies to pick up the heat generated from the nuclear reaction. • The coolant then moves to the steam generators to produce steam from ordinary water and back to the reactor. • Heavy water is a rare but natural form of water and is the most effective moderator used in nuclear reactors to maintain continuous fissioning. • Ordinary water is a combination of one oxygen and two hydrogen atoms (H2O).

  19. Pressurized Heavy Water Reactor • Heavy water is virtually identical, except each of the hydrogen atoms have an extra neutron. • This hydrogen isotope is called deuterium (D). Since heavy water (D2O) has almost all the extra neutrons it wants, it slows neutrons in the reactor without significantly absorbing them. • The advantage of heavy water is that is permits the use of unenriched uranium as fuel. • This means two less steps are required in the conversion process resulting in a more economical fuel source.

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