Download
nuclear fuel cycle n.
Skip this Video
Loading SlideShow in 5 Seconds..
Nuclear Fuel Cycle PowerPoint Presentation
Download Presentation
Nuclear Fuel Cycle

Nuclear Fuel Cycle

880 Vues Download Presentation
Télécharger la présentation

Nuclear Fuel Cycle

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Reprocessing Nuclear Fuel Cycle Uranium mining and milling Conversion Enrichment Fabrication Waste disposal Spent fuel storage Reactor

  2. Mining and Milling • ore 2 - 0.1% U • Reduced by chemical leaching or solvent extraction to U3O8 (yellowcake) • Mill tailings still contain some U and therefore emits radon. • Tailings are placed underground or capped

  3. Enrichment • Natural U is 0.72% 235 power plants use 3-5% enriched • Gaseous diffusion - most common • Gas centrifuges - 9 countries • Aerodynamic separation - too expensive • Electromagnetic separation • Laser isotope

  4. Conversion Capacity in T U/y 1. Russia 24000 2. France 14350 3. USA 14000 4. Canada 10500 5. Unit. Kingd. 6000 6. China,cont'l 400 7. Brazil 90 8. Algeria 0 9. Argentina 0 10. Armenia 0 11. Australia 0 12. Belgium 0 13. Bulgaria 0 Total = 69,340 No information available on India or Pakistan

  5. Fuel Fabrication • UF6 is converted into UO2 clad then grouped into fuel bundles

  6. (LWR, Uranium Oxide) [t U/year] nominal capacity 1. USA 3500 2. Russia 2020 3. Kazakhstan 2000 4. Japan 1674 5. France 970 6. Belgium 750 7. Germany 650 8. Sweden 600 9. Korea, Rep. 400 10. Unit. Kingd. 330 11. Spain 300 12. China,cont'l 100 13. India 25 14. Algeria 0 International Fabrication Capacity Total = 13,319

  7. Reactor • Fuel Management • Remain critical while fuel composition and reactivity changes • Shape the power density to max power output • Max. heat production from fuel • Uniform irradiation of fuel • Max productive use of neutrons

  8. Definitions • Availability - % of time over a reporting period that the plant is operational • Capacity - % of total electric power that could be produced • Efficiency - energy output per thermal energy output of the reactor Eff=W/QR (MWe/MWt)

  9. Fuel shuffle • Every year PWR-1/3 or BWR 1/4 of the core is removed and the core is reloaded • New fuel is shuffled into the core • Zone loading • Scattering loading • Modified scatter loading

  10. ZONE advantage - uniform burn-up where the flux is uniform disadvantage - where the flux is not uniform they use higher enriched fuel to compensate

  11. SCATTER Advantages 1. can be irradiated to a higher burn-up 2. less poisons for control 4 1 2 3 1 2 3 4 1 2 3 1 2 3 4 1 2 3

  12. Definitions • Burn-up - total energy released for a given amount of fuel (MWd) • Specific burn-up - energy released per unit of mass (MWd/t) or (MWd/kg) • Fractional burn-up (b) #fission/#heavy atoms

  13. Definitions • Breeder- more than 1 fissile atom produced for every fissile atom consumed C>1 • Converter- C=1 • Burner-no conversion or breeding

  14. Spent fuel storage • Still contains fuel • ~180 kg of fissile Pu and 22,000 kg of U-235 at each refueling (435 MW and 420MW) • Also contains 100’s of fission products -7 have half-lives greater than 25 yrs. • Stored on site in water then dry storage • No US permanent storage yet

  15. High level - fission products separated in the first stage of reprocessing Mine and Mill tailings Transuranic (TRU) actinides with concentrations > 100 nCi/g Low level waste - no shielding required < 100 nCi/g class A - 0.1 Ci/ft3 class B - 2 Ci/ft3 class C - 7 Ci/ft3 Intermediate level - vaguely defined between low and high !!! The DOT has its own classification. Waste Disposal

  16. } 10-3 A1 10-3 A2 solids The Transport Spectrum Highway route controlled Exempt Excepted Type A Type B 3000 A1 or 3000 A2 or 27,000 Ci whichever comes first A1 or A2 2 nCi/g Or 70 Bq/g 10-4 liquids

  17. Reprocessing • Objectives • Recover U, Pu and Th to be used as fuel • Separate radioactive and neutron- absorbing fission products • Convert the radioactive waste into suitable forms for safe storage • The US does not have reprocessing nor a long term storage facility.

  18. Types of Process • Redox • Trigly • Butex • Purex-most common • Thorex

  19. General Process Steps Core Assembly • Strip the cladding • Dissolve fuel in acid • Solvent extraction • Precipitation • Metal refining • Fuel fabrication FP Shear Oxidation Dissolve Extract Separate New FUEL