Nuclear Fuel Cycle

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

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(No Transcript)
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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

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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
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Fuel Fabrication

• UF6 is converted into UO2 clad then grouped into
  fuel bundles

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International Fabrication Capacity

• (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

Total 13,319
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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

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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
• EffW/QR (MWe/MWt)

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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

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

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Definitions

• Breeder- more than 1 fissile atom produced for
  every fissile atom consumed Cgt1
• Converter- C1
• Burner-no conversion or breeding

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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 100s of fission products -7 have
  half-lives greater than 25 yrs.
• Stored on site in water then dry storage
• No US permanent storage yet

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Waste Disposal

• High level - fission products separated in the
  first stage of reprocessing
• Mine and Mill tailings
• Transuranic (TRU)
• actinides with concentrations
• gt 100 nCi/g

• Low level waste - no shielding required
• lt 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.

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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
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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.

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Types of Process

• Redox
• Trigly
• Butex
• Purex-most common
• Thorex

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General Process Steps
Core Assembly

• Strip the cladding
• Dissolve fuel in acid
• Solvent extraction
• Precipitation
• Metal refining
• Fuel fabrication

FP
Shear
Oxidation
Dissolve
Separate
Extract
New FUEL