1Marie Curie Summer School on Knowledge based MaterialEstremoz Portugal 2007
Nuclear waste and vitrificationin France
Dr. Etienne Y. Vernaz,
Director of Research,
CEA / Nuclear Energy Division
Marcoule
Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 2
Summary
Nuclear Energy Fuel cycle Fuel fabrication Nuclear Reactor Spent Fuel processing Nuclear Waste
Waste treatment Vitrification of nuclear waste Waste Storage and Disposal
2Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 3
Electricity production in FranceElectricity production in France
78% nuclear 58 Pressurized Water Reactors (PWRs) 63 GWe installed
11% hydroelectric 10% thermal
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The resulting waste mass is also reduced by the same order of magnitude:
About 80% of French electricity is generated by nuclear reactors, producing 1 kg of radioactive waste per person per year, of which only 10 g consist of high-level long-lived waste.
This quantity can be compared with 10 000 kg of agricultural, industrial or household waste produced per person per year in France, about 100 kg of which are highly toxic.
In other words, the high-level waste arising from the electrical consumption of one person throughout her entire life would fit in a bottle of beer.
Specific feature of nuclear power: concentrated energySpecific feature of nuclear power: concentrated energy
Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 6
Advantages and drawbacks of concentrated energyAdvantages and drawbacks of concentrated energy
Concentrated energy production favors: Competitiveness Small volumes (materials, waste, transportation, etc.) Controlled waste: insignificant release into the
environment (contrary to greenhouse gases)
But concentrated energy requires: Intrinsically safe and controlled reactors Highly processed nuclear fuel High tech waste treatment
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Each year a 1 Each year a 1 GWeGWe plant requires plant requires
15 to 45 oil tankers15 to 45 oil tankersOILOIL 1 300 000 metric tons
6 semi6 semi--trailerstrailers
URANIUMURANIUM (PWR) 150 t natural U 150 t natural U (20 t U enriched to 4%)(20 t U enriched to 4%)
COAL COAL 2 000 000 metric tons600 trains600 trains
30 LNG tankers30 LNG tankers
GASGAS 1,8 billion m3
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Nuclear Fuel Cycle
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Uranium Resources
distributed well around theworld
Ultimate Resource ( < 130 $ / kg) estimated at about 15 millions tonsUranium 2005 : Ressources, production et demande
World consomation ~68 000 tStatic reserves evaluated at 200 years
An abondant resourceLargely spread on the earth ( 2 - 3 g/t )
Mainly two natural isotopes :238 (99,28 %) fertile material235 (0,718 %) fissile material
Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 10
MiningMining andand millingmilling Uranium is usually mined by
either surface or underground mining techniques
the mined uranium ore is sent to a mill which is usually locatedclose to the mine. At the mill theore is crushed and ground to a fine slurry which is leached in sulfuric acid to allow theseparation of uranium from thewaste rock. It is then recoveredfrom solution and precipitated as uranium oxide concentrateknown as yellow cake ,
(ammonium diuranate(NH4)2 U2 O7)
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Conversion Conversion andand enrichmentenrichmentThe vast majority of all nuclear power reactors in operation and underconstruction require enriched uranium fuel in which the proportion of the U-235 isotope has been raised from the natural level of 0.7% to about 3.5% or slightly more.Because all the enrichment process work with gaseous uranium , thefirst step is the conversion of yellow cake , into the uranium hexafluoride (UF6), that is a gaz.
Two processes are used in the world for uranium enrichment :Gazeous diffusion Ultracentrifugation
1 kg of enriched Uranium (3.5%)8kg of natural Uranium (0.7%)
7 kg of depleted uranium(0.25%)
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1. Enriched UF6 isconverted to uranium dioxide (UO2) andpressed into small pellets fritted at1700C
2. These ceramic pellets are inserted into thintubes, of a zirconium alloy (zircalloy) to form fuel rods
3. The rods are thensealed and assembled in clusters to form fuel assemblies
Fuel fabrication
Assemblage FRAMATOME
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Nuclear reactor
Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 14
Coal power plant in Gardanne (France)
Nuclear power plant (LWR)
What is the difference between a nuclearor a thermal power plant ?
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Electricity
Steam Production
The major come of the way heat is produced to make steam.
Nuclear Reactor Heat Production
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Dismantling
Solid waste
Reprocessing
Gaseous release(about 100 times less radioactivity
than a coal-fired plant of equivalent power ! ).
< 100 m3 per year of LLWILW and HLW
More than 99% of the activity generated is
confined in the spent fuel
A nuclear reactor releases extremely small amounts of radioactivity into the environment
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What Nuclear material is produced in the reactor ? Nuclear fission : A slow-moving
neutron is absorbed by the nucleus of a uranium-235 atom, which in turn splits into fast-moving lighter elements (fission products) and free neutrons.
Nuclear captureFor instance uranium-238 can capture a neutron, transforms into uranium-239, which transform into plutonium-239by 2 disintegrations
Produce Fission Products , the main ultimum waste from nuclear energy
Produce Plutonium , and some minor actinides that can beconsider as waste or as resources !
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SPENT NUCLEAR FUEL
After 4 years in the reactor, spent fuel contains:
94% uranium
1% plutonium
5% other(Fission products and minor actinides)
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Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 19
1
H2
He3
Li4
Be5
B6
C7
N8
O9
F10
Ne11
Na12
Mg13
Al14
Si15
P16
S17
Cl18
A19
K20
Ca21
Sc22
Ti23
V24
Cr25
Mn26
Fe27
Co28
Ni29
Cu30
Zn31
Ga32
Ge33
As34
Se35
Br36
Kr37
Rb38
Sr39
Y40
Zr41
Nb42
Mo43
Tc44
Ru45
Rh46
Pd47
Ag48
Cd49
In50
Sn51
Sb52
Te53
I54
Xe55
Cs56
Ba Ln72
Hf73
Ta74
W75
Re76
Os77
Ir78
Pt79
Au80
Hg81
Tl82
Pb83
Bi84
Po85
At86
Rn87
Fr88
Ra An104
Rf105
Db106
Sg107
Bh108
Hs109
Mt110
Uun
LANTHANIDES
57
La58
Ce59
Pr60
Nd61
Pm62
Sm63
Eu64
Gd65
Tb66
Dy67
Ho68
Er69
Tm70
Yb71
Lu
ACTINIDES
89
Ac90
Th91
Pa92
U93
Np94
Pu95
Am96
Cm97
Bk98
Cf99
Es100
Fm101
Md102
No103
Lr
URANIUM AND TRANSURANIC ELEMENTS ACTIVATION PRODUCTS
FISSION PRODUCTS FISSION AND ACTIVATION PRODUCTS
URANIUM ET LMENTS TRANSURANIENS
PRODUITS DE FISSION
PRODUITS DACTIVATION
PRODUITS DE FISSION et DACTIVATION
Elements formed in the spent fuel (burn-up 33 GWj/t)U : 955 kg.t-1Pu : 9.6 kg.t-1AM : 0.8 kg.t-1PF : 34 kg.t-1
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The Spent Fuel is store in a pool a few yearbefore processing
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Spent fuel is reprocessed in the La Hague plants
UP2: EDF fuel: 800 t/year UP3: Foreign fuel: 800 t/year
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Main Main stepssteps in in reprocessingreprocessing nuclearnuclear fuelfuel
Cutting the fuel assemblies
Disolving the fuel in nitric acid
Liquide / liquide extraction by TBP .
Uranium et Plutonium recovered at 99,9 % !
dissolveurroue
godets La Hague
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Reprocessed Uranium
The 235U content ofreprocessed uranium is about the same as natural uranium.
One part is recycledin some nuclearplants
One part is storedas stratgic stock waiting to be used in fast breeder reactor
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The recovered plutonium is recycled in MOX fuel
MOX fuel is a mixture of plutonium oxide and depleted uranium oxide
The MELOX plant at Marcoule
Recycling saves about 10% of the natural uranium
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Nuclear Waste conditionning
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Fission products solution vitrification :a 50 years story !
The first part of the story is solidification:from a dispersible liquid to an inert solid
First processes developed in France (1957), England and USA were batch processes
The first industrial process (AVM) started in Marcoule (France) on 1978 Glass pouring in AVM
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Why to vitrify the waste ?
9 Atomic scale containment (not a coating)9 Chemical flexibility9 Stability, Durability (leachingresistance)
Na
OSiAl
B
Zr
The mission : Create a new material with a waste
99 Volume reduction9 Organic destruction
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Complexity of fission products solutionsfrom LWR reprocessing
SrZrMoRuPmAgTb
SbCsLaPrNdGdSn
RbY
NbTcPdEuInDy
SeTeBaCeRhSmCd
Fission Products = 42.33 g/l
PNiCrNaFe
Corrosion products and additives =27.33 g/l
CmPuAmNpUActinides = 3.37 g/l
SbSnPdTcRhUMoRu
Metallic Alloys = 4.69 g/l
more than 40 different chemical elements !
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Ability to accomodate the wasteSolubility (Cr, Ru, Rh, Pd, Ce, Pu, SO4, Cl)
Phase separation (Mo, SO4, Cl, P)Devitrification (Mo, P, F, Mg, )
Maximize the waste loading
Process / Technology
Elaborate a glass from waste is a compromiseHow to formulate a HLW glass
Formulation
Ease of processingMelting temperature
Viscosity, reactivity, residence time, Electrical cond., thermal cond.
Additives needed
Glass performanceProperties for storage/disposal
Thermal stabilityChemical durability
Resistance to self irradiationMechanical properties
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GLASS FORMULATION MUST BETAILORED TO EACH APPLICATION
12.7 incl.U3O8 : 0.85.0 incl.
ThO2 : 3.6U3O8 : 0.62.8 incl.
U3O8 : 2.35.4ZnO : 2.5Remainder20.01.32.11ZrO2
520.55.70.3P2O571.05.114.915FP2O3 + Act
RussiaMayak
USAUKFranceR7/T7Oxide
10.712.010.94Fe2O3 + NiO + Cr2O3157.46.018.65Al2O3
0.20.74CaO
2513.28.011.98.510Na2O
10.412.90.917.214B2O31.68.73.14.02Li2O + K2O
50.341.055.347.045SiO2
HanfordAZ blendWVDPDWPF
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Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 31
NaO
SiB
Al
Zr
HLW-Glass formulation The goal Solubilisation of all radionuclides in an ionic and covalent network by chemical reactions at the molten state
Glass formulation = a mix of calculations and experimental measurements of the basic properties to find the best compromise between contradictory properties : Homogeneity, Viscosity Electrical resistivity Thermal conductivity Devitrification sensitivity Melting temperature,Tg, Tl, Chemical durability, R0, Rf,
The design of an operational glass domain (for the industrial scale) is based on a statistical design approach implemented at the lab scale and checked at scale one on large pilots.
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The R7T7 glass developed in France for LWR waste
Nominal Composition
SpecifiedInterval
Mass (%)min max
SiO 2 45,1 42,4 51,7B 2 O 3 13,9 12,4 16,5Al 2 O 3 4,9 3,6 6,6Na 2 O 9,8 8,1 11,0CaO 4,0 3,5 4,8
Fe 2 O 3 2,9
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Vitrification Principle
Glass Frit45% SiO218% B2O315% Na2O
Etc.
Objectif = Verre Final 45% SiO214% B2O310% Na2O15% Ox. (PF+Act.)
Etc.
Verre Final 45% SiO214% B2O310% Na2O15% Ox. (PF+Act.)
FUSION
Calcinat15% Ox. (PF+Act.)
Solution
Calcination
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HT melting = RN solubilisation in a ionic and covalent network by chemical reactions at the molten state
Glass Frit Calcine
Impregnation of the Calcine
Partial dissolutionLocal saturation
Crystal precipitation
Agitation
Dilution
Crystal dissolution
Homogenization of the molten liquid
GLASS
REE silicates
(Si, Ca, Nd, La, Ce)
(Ce,Zr)O2
Spinelles (Fe, Ni, Cr, Mn)
RuO2
Pd
Chemical reactivity during melting
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Two-step calciner / hot crucible vitrification process
The French Vitrification process
Dust scrubberGlass melter
Container
Calciner
Liquid waste
Additives
Glass frit
Recycling
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Hot cells vitrification lines
La Hague Vitrification Plants
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Thermal Power
~ 2 kw
Glass Volume150 litres
Glass Mass400 kg
Height1,3 m
Diameter0,43 m
The Glass Container
Internationallyapproved
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stockage chaud
chemine 100C
air ambiant 25C
110C 45C
40C
La Hague Glass interim storage( air cooling )
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Vitrified wasteforms are currently stored at the production site
La HagueMarcoule
Total number of glass containers produced in France > 13000 (18 000 t spent fuel)
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Cold Crucible Induction Melter Technology
The Near Term Future of Radwaste VitrificationIncreasing waste loading
Increasing glass throughputsNew matrix (glass-ceramics)
Higher Temprature, Corrosives glass compositions
Cold Cap
Molten glass
CCIM
Cold glasslayer
Inductor
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Cold Crucible in Operation
Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 42
Waste+
Glassprecursor
OxygenOxygen
CathodeAnode
Burned gases exhaust
HF Current
MoltenglassInductor
PlasmaMetallicCooled
walls
The Emerging processes :Plasma combustion & Vitrification
This process is a novel combination of two innovative technologies:
VITRIFICATION:
Glass melting by direct induction in a metal cold crucible
COMBUSTION:
Oxygen arc plasma transferred between two aerial torches above the molten glass.
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The EMERGING PROCESSES :PLASMA COMBUSTION & VITRIFICATION
Three Operations in one Apparatus :
Combustion/incineration.
Vitrification.
Gas postcombustion.
Waste
Gastreatment
Glass
Ar/O2 Ar/O2
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The three main waste conditionningprocesses
1. Vitrification of Fission product solution
2. Compaction of cladding wastes (Hulls)
3. Cimentation oftechnological waste
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Cladding waste is compacted
Etienne Y. Vernaz Nuclear waste and vitrification Marie Curie Summer School Estremoz Portugal 2007, 46
Most technological waste is LLW suitable for surface disposalSome ILW is placed in interim storage at the production sites
Technological wastes are cemented
Homogeneous liquid or powdered wasteHeterogeneous solid waste
1088
974
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Ultimate reprocessing waste forms Ultimate reprocessing waste forms
The fission product solution, which also contains the minor actinides and about 0.1% U and Pu, is vitrified
The hulls and end pieces are rinsed and then compacted
Technological waste is grouted in cement
Today, the volume of reprocessing waste produced each year by a 1 GWe reactor is:
2.5 m3 HLW (glass) 5 m3 ILW (mainly compacted hulls) 12 m3 LLW (cemented)
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Classification of solid nuclear waste in FranceNuclear waste are sorted over the period and the activity
C - WasteInterim storageHigh Activity (HLW)
B - waste :Interim storage Interim
storageIntermediate level
waste (ILW)
Stockage ddi ltude pour les dchets
radifres et graphitesA - Waste1Dedicated surface
disposal ( Soulaine )
Low Activity (LLW)
Mine residues1Dedicated surface disposal (Morvilliers)Very low activity
(VLLW)
Longue Live Priode > 30 ans
Short live Period < 30 ans
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Type vol% ActivityCumulative volume
(m3) until 2020
LLW 95%
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Calendar :
2015 : safety assessment deposit for a geological disposal site
2020 : starting a prototype reactor for transmutation
2025 : industrial opening of underground disposal
HLW and ILW DisposalIn France geological disposal is retained as reference solution
for the management of long life waste (ILW and HLW) ( french policy act n 2006-739 of June 29 ,2006)
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An underground laboratory was built at at Bure (Northern France),at a depth of 500 m in a clay formation
The clay layer investigated here has favorable properties for radioactive waste containment:
- highly stable for the last 150 million years, unfractured- very low permeability- transport of chemical elements controlled by diffusion at an extremely low rate
Underground laboratory
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Final conclusions
We know what to do with nuclear waste !
High tech processes have been developed and optimized for each waste category
Vitrification of PF solution is a major step in this process They are available today at affordable cost for society This cost is taken into account in the price per kWh
and EDF has already constituted reserves French and international studies have demonstrated
that with suitable processing the environmental impact of nuclear waste will remain negligible, even over the long term
The CEAs considerable research potential ensures that further progress will be made in the futur.
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