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Reprocessing Nuclear Fuel Cycle Uranium mining and milling Conversion Enrichment Fabrication Waste disposal Spent fuel storage Reactor Mining and Milling ore 2 - 0.1% U Reduced by chemical leaching or solvent extraction to U 3 O 8 (yellowcake)

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Nuclear fuel cycle l.jpg

Reprocessing

Nuclear Fuel Cycle

Uranium

mining

and milling

Conversion

Enrichment

Fabrication

Waste

disposal

Spent fuel

storage

Reactor


Mining and milling l.jpg
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


Enrichment l.jpg
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


Conversion capacity in t u y l.jpg
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


Fuel fabrication l.jpg
Fuel Fabrication

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


International fabrication capacity l.jpg

(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


Reactor l.jpg
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


Definitions l.jpg
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)


Fuel shuffle l.jpg
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


Slide11 l.jpg
ZONE

advantage - uniform burn-up where the flux is uniform

disadvantage - where the flux is not uniform they use higher enriched fuel to compensate


Scatter l.jpg
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


Definitions13 l.jpg
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


Definitions14 l.jpg
Definitions

  • Breeder- more than 1 fissile atom produced for every fissile atom consumed C>1

  • Converter- C=1

  • Burner-no conversion or breeding


Spent fuel storage l.jpg
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


Waste disposal l.jpg

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


The transport spectrum l.jpg

} of reprocessing

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


Reprocessing l.jpg
Reprocessing of 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 of reprocessing

  • Redox

  • Trigly

  • Butex

  • Purex-most common

  • Thorex


General process steps l.jpg
General Process Steps of reprocessing

Core

Assembly

  • Strip the cladding

  • Dissolve fuel in acid

  • Solvent extraction

  • Precipitation

  • Metal refining

  • Fuel fabrication

FP

Shear

Oxidation

Dissolve

Extract

Separate

New FUEL


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