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Nuclear Fuel reprocessing. Sellafield - UK. Nuclear fuel reprocessing. Why reprocess? Basic principles Description of PUREX process Industrial status. Reprocessing objectives. Recycling of fissile materials (U, Pu), Reduction of U needs) Reduction of high level waste volumes - PowerPoint PPT Presentation
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ULB 2009-2010 Nuclear Fuel Cycle Nuclear Fuel reprocessing Nuclear Fuel reprocessing Sellafield - UK
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Page 1: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Nuclear Fuel reprocessingNuclear Fuel reprocessing

Sellafield - UK

Page 2: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Nuclear fuel reprocessingNuclear fuel reprocessing

1. Why reprocess?

2. Basic principles

3. Description of PUREX process

4. Industrial status

Page 3: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Reprocessing objectivesReprocessing objectives

Recycling of fissile materials (U, Pu),

Reduction of U needs)

Reduction of high level waste volumes

Reduction of radiotoxicity and heat from the waste

Page 4: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

The Reprocessing-RecyclingThe Reprocessing-Recycling

Note: message AREVA

Page 5: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Fissile materials recyclingFissile materials recycling

Spent UOX fuel (33 GWj/t, cooling 3 years)Spent UOX fuel (33 GWj/t, cooling 3 years)

Page 6: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Element Amount (kg/tHM) U 955 Pu 10 Minor actinides 1 Np 0.4 Am 0.3 Cm 0.03 Fission products 34 Rare gases (Kr, Xe) 5 Alkali metals (Cs,Rb) 4 Alkaline-earth metals (Ba, Sr) 2 Rare earths (Y,Ln) 10 Zirconium 4 Molybdenum 3 Noble metals (Ru,Rh,Pd) 4 Technetium 1 Chalcogenides 0.5 Halides (I,Br) 0.2

Spent fuel compositionSpent fuel composition

Page 7: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

La radiotoxicité des déchetsLa radiotoxicité des déchets

Page 8: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Arguments against reprocessingArguments against reprocessing

Technological difficulty and large investments

Large, generally export, reprocessing costs

Accumulation of Pu: recycling need

Nuclear proliferation need

Transports of nuclear materials

Page 9: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Le retraitement du combustible irradiéLe retraitement du combustible irradié

1. Why reprocess?

2. Basic principles

3. Description of PUREX process

4. Industrial status

Page 10: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Reprocessing functionsReprocessing functions

1. Separation from spent fuel of U, Pu, and Fission Products (FP)+ Minor Actinides (MA)

2. Purification of U and Pu, to be re-used

3. Concentration of FP + MA for final geological disposal

Page 11: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Developed by Oak Ridge National laboratory (ORNL) and Knolls Atomic Power Laboratory (KAPL) from 1949 to 1960

Solvent extraction based on TBP

Targeted for separation of U and Pu

Used on an industrial scale in Savannah River & Hanford (USA, past), La Hague (F), Sellafield (UK), Rokkashamura (J)

PUREX: Plutonium Uranium Refining by PUREX: Plutonium Uranium Refining by EXtractionEXtraction

Page 12: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

UP3 La Hague plant

Page 13: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Nitric acidNitric acid

Due to various oxidation states of N, allows the change of actinides valences

Not too corrosive, formation of soluble metal nitrates

Stability in nitric acid medium: UVI NpV and NpVI PuIV and PuVI AmIII

Recycling of vapours in nitric acid (2NO+O2 N2O4 +H2O)

Page 14: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

U chemical propertiesU chemical properties

Electronic configuration: [Rn]5f3 6d1 7s2

6 extractible valence electrons: U metal oxidises easily in humid or hot air

Complex chemistry (5f electrons): oxidation levels III to VI

Level VI most stable (uranyle UO22+ in solution)

Uranyle nitrate solubility in various organic compounds

Page 15: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Plutonium chemical propertiesPlutonium chemical properties

Electronic configuration: [Rn]5f6 6d0 7s2

Reuslts from neutronic irradiation of U

Mix of several isotopes: 238, 239, 240, 241, 242

Oxydation levels III to VII

Levels III and IV in industrial processes

Final reprocessing product: PuO2

Page 16: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Physico-chemical aspects (1)Physico-chemical aspects (1)

Fuel rods/assemblies mechanical shearing (3-4 cm slices)

Fuel dissolution in boiling nitric acid (2h)

UO2 + 4HNO3 → UO2 (NO3)2 + 2NO2 + 2H2OUO2 + 3HNO3 → UO2 (NO3)2 + 0,5NO2 + 0,5 NO + 1,5H2O

Nitrates: Pu (NO3)4, PF (NO3)3, MA(NO3)3

Structural materials conditioning (high activity solid waste)

Nitrous vapours treatment

Volatile and gaseous FP treatment

Page 17: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Physico-chemical aspects (2)Physico-chemical aspects (2)

TBP: organic compound forming complexes with metal (M) nitrates, not soluble in water

Maqx-

+ xNO3aq- + y TBPorg [M(NO3)x y TBP]org

Formation of complexe controled by concentration in ions NO3-

Increase NO3- favours extraction of M in organic phase

Decrease NO3- favours re-extraction of M in aqueous phase

Page 18: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

(C(C44HH99))33POPO44 or PO(OC or PO(OC44HH99))33

Low solubility in aqueous phase

Affinity for U VI and Pu IV (selectivity)

Good chemical resistance to radiolysis

Density: 0.973 gcm-3 ; if 30% diluted: 0.83 gcm-3

TBP = tri-butyl phosphateTBP = tri-butyl phosphate

Twin free oxigen electrons

Page 19: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

UOUO2 2 + 2 NO+ 2 NO33 + 2TBP = UO + 2TBP = UO22(NO(NO33))22..2TBP2TBP

The The distribution coefficientdistribution coefficient (coéfficient de partage) (coéfficient de partage) DD is the ratio is the ratio of the concentration in the aqueous and organic phase: of the concentration in the aqueous and organic phase:

22

322

232

TBPNOUO2TBP)(NOUO

K

22

3aq

orgU TBPNOK

UU D

Distribution coefficient Distribution coefficient

Page 20: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Distribution coefficientDistribution coefficient

Page 21: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Extraction abilityExtraction ability

Class Ability to form complexes with TBP

Extraction ability

A) UO2+, PuO22+, Pu4+,

U4+, Zr4+, Ce4+, RuNO23+

Relatively high Very good to good

B) Pu3+, Y3+, Ce3+ Low Low to very low

C) Other FPs Very low to nil Almost nil

Page 22: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

TBP

HNOHNO33

Spent fuel

U Pu

Fissionproducts

Minor actinides

Xe, Kr, IXe, Kr, I22

PUREX PrinciplePUREX Principle

TBP en solution dans hydrocarbure (30%)

EmulsionTransfert de matièresMélange Décantation

Page 23: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Separation U - PuSeparation U - Pu

Pu4+ extracted with U (class A)

Pu3+ class B : low ability to form complexes

Mixing of organic phase with aqueous solution, containing a selective Pu reductor (concentration NO3

- must be sufficient to keep

U in organic phase)

During emulsion of the phases, Pu is reducted and goes in the aqueous phase

-

Page 24: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Purification U and PuPurification U and Pu

Impureties: FPs of class A

Extraction ability lower than U and Pu, depending on [U] and [nitric acid]

High [U]: mitigates FPextraction

High acidity: decreases Ru extractionincreases Zr, Sr extraction

Successive washing of organic phase

Concentration NO3- variable, but sufficient pour hinder the re-

extraction of U and Pu!

Page 25: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

TBP separation basic principlesTBP separation basic principles

• Sélectivity of TBP (UVI and PUIV)

• Importance of acidity: to extract UVI and PuIV: 2-3 mol/l

• To de-extract UVI: <0,02 mol/l

• Separation U-Pu: reduction PuIV to PuIII

• Separation U-Np: adjustment of the Np oxidation state to NpV

• Am is not extracted by TBP

Page 26: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Le retraitement du combustible irradiéLe retraitement du combustible irradié

1. Why reprocess?

2. Basic principles

3. Description of PUREX process

4. Industrial status

Page 27: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Shearing

Dissolution

Clearing

Extraction

Purification

Spent fuelSpent fuel

U Pu

Structural Structural elementselements

HullsHulls

Fission products & Fission products & MAMA

Insoluble residuesInsoluble residues

VitrificationVitrification

GasesGases

GasesGasesAtmospheric Atmospheric or sea or sea releaserelease

PUREX: Plutonium URanium EXtractionPUREX: Plutonium URanium EXtraction

Page 28: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

http://www.ricin.com/nuke/bg/lahague.html

The La Hague reprocessing schemeThe La Hague reprocessing scheme

Page 29: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

29

Spent fuel assemblies storage pool at Sellafield Spent fuel assemblies storage pool at Sellafield (UK)(UK)

Page 30: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Shearing of claddingShearing of cladding

Page 31: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Rotatif DissolverRotatif Dissolver

Page 32: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Caractéeristics of the dissolution solutionCaractéeristics of the dissolution solution

• Composition: U: 200 – 250 g/L Pu: 2 – 3 g/L FP: 80% of inventory MA: 100%

• Specific activity : 7,4 TBq/L (200Ci/L)

• Nitric acidity : 3 – 4 M

• Oxidation state of oxides: VI, PuIV, NpV, AmIII, CmIII

Page 33: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Extraction cycles in a reprocessing plant (example)Extraction cycles in a reprocessing plant (example)

1. Decontamination – separation cycle

M Extraction in organic phase Acid washing of the organic phase Pu Separation (reducing re-extraction) U Re-extraction in aqueous phase

2. U purification cycles (2x)

New U extraction in organic phase Washing U re-extraction in aqueous phase

3. Pu purification cycles (2x)

Solution oxidation (Pu4+) New Pu extraction in organic phase Pu re-extraction in reducing aqueous phase

Page 34: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Feed(aq)

Product(org)

Waste(aq)

Fresh solvent(org) Fresh solvent

Aqueous feed

Loaded solvent Loaded solvent meets most meets most

concentrated concentrated aqueous solutionaqueous solution

Fresh solvent meets Fresh solvent meets depleted aqueous depleted aqueous

solutionsolution

Counter current: maximising loading & extractionCounter current: maximising loading & extraction

Page 35: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

FeedFeed(aq)(aq)

ProductProduct(org)(org)

WasteWaste(aq)(aq)

ccff ccpp

cw

Fresh solventFresh solvent(org)(org)

c = 0c = 0

1

i

n

orgnc

orgnc

org1c

orgic

org0c

org1-ic

org1-nc

aq0c

aq2c

aq1ic

aq1c

aqic

aqnc

Multi-stage extractionMulti-stage extraction

Page 36: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Solvent extraction devicesSolvent extraction devices

Page 37: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Solvent extraction devicesSolvent extraction devices

Page 38: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Laboratory scale centrifugal contactors (ITU)Laboratory scale centrifugal contactors (ITU)

Page 39: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Pulsed ColumnPulsed Column

Page 40: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Solvent extraction devicesSolvent extraction devices

Page 41: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Recovery rate and decontamination factorRecovery rate and decontamination factor

• Residual materials recovery rate: Pu:99,88%

• Decontamination factor: Impureties in inlet product divided by impureties in outlet product

• β, γ impurities: U: 1,5 106; Pu: 7 107

• Separation factor U-Pu: 106

Page 42: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

42

Technological constraints of reprocessingTechnological constraints of reprocessing

• High activities

• Heat release

• Under-criticity to be guaranteed, verifications

• Corrosion resistance (stainless steels, zirconium)

• Maintenance of equipement

• Controls of materials fluxes

Page 43: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

U and Pu conditioningU and Pu conditioning

Aqueous solution of Uranyl nitrate [UO2 (NO3)2] at 250 – 300 g U / l

Denitration and transformation into UO3 or UO2 (fabrication plant)

Aqueous solution of Pu nitrate: [Pu (NO3)2] at 50-150 g Pu / l

Oxidation of Pu in Pu 4+, mixing to oxalic acid which precipitates Pu as oxalate

Calcination and storage of PuO2 or transport to MOX plant

Page 44: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Plutonium Conversion : calcinationPlutonium Conversion : calcination

Page 45: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

High decontamination factors

High selectivity for U and Pu

Low cost

Easy scale up

Room temperature process

Radiolytic degradation of organic phase

TBP not incinerable yielding solid radioactive waste

Some fission products are not (fully) soluble (Zr, noble metals particles)

Pure plutonium produced

Advantages and disadvantages of PUREXAdvantages and disadvantages of PUREX

Page 46: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Bitumen: e.g. for residues from evaporation or spent organic ion exchangers

Cement: for low radioactive waste

Glass: for high level liquid waste

Ceramics: alternatives for HLLW (not industrial)

Waste formsWaste forms

Page 47: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Borosilicate glass matrix

HLW concentrate is calcined

Mixed with glass frit and heated at 1100 oC

Liquid poured in a stainless steel canister

Canister is welded shut

Vitrification of HLWVitrification of HLW

Page 48: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Concentration (wt%)

R7/T7

(Cogema) Magnox (BNFL)

SiO2 47.2 47.2 B2O3 14.9 16.9 Al2O3 4.4 4.8 CaO 4.1 - MgO - 5.3 Na2O 10.6 8.4 Others 18.8 17.4

Silica is the main glass-forming component

Boron oxide reduces thermal expansion and improves chemical durability

Vitrification of HLWVitrification of HLW

Page 49: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Vitrification of HLWVitrification of HLW

Page 50: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Waste treatmentWaste treatment

Page 51: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

Le retraitement du combustible irradiéLe retraitement du combustible irradié

1. Why reprocess?

2. Basic principles

3. Description of PUREX process

4. Industrial status

Page 52: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

52

Reprocessing capacities in the worldReprocessing capacities in the world

LWR fuel: France, La Hague 1700

  UK, Sellafield (THORP) 900

  Russia, Ozersk (Mayak) 400

  Japan 14

  total approx 3000

Other nuclear fuels: UK, Sellafield 1500

  India 275

  total approx 1750

Total civil capacity   4750

NEA 2004NEA 2004

Page 53: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

53

Rokkasho-Mura (Japan)Rokkasho-Mura (Japan)

Page 54: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

AREVA La Hague Reprocessing PlantsAREVA La Hague Reprocessing Plants

Page 55: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

55

UP3 plant in La Hague

Page 56: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

56

Marcoule R&D

Page 57: Nuclear Fuel reprocessing

ULB 2009-2010Nuclear Fuel Cycle

ConclusionConclusion

Reprocessing: strategic option

based on nitric dissolution, séparation by organic extraction

Reprocessing-Recycling strategy, in LWRs, but preferably in fast reactors

Technical and commercial success

3 main sites: FR, UK, JP

Thank you for your attention!


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