Stabilised Waste - Cement barrier - Soil interfaces 2 July 14 2009/07... · 2009. 7. 14. · cen/tc292, iso/tc190, cen/tc345, cen/tc351, sw846 percolation leaching test cen ts 14405
Post on 13-Feb-2021
0 Views
Preview:
Transcript
Stabilised Waste - Cement barrier - Soil interfacesHans van der Sloot, Hans Meeussen, Paul Seignette, Josh Arnold, David Kosson
ECN NetherlandsECN, NetherlandsVanderbilt University, Nashville
OVERVIEW
bl d fi i iProblem definitionRelease of non-interacting species (3 layer model)Scale issues Illustration of detailed chemistryChemistry of individual layersInterface reactions (diffusion in 3 layer model)Interface reactions (diffusion in 3 layer model)Carbonation and uncertaintyConclusions
214-7-2009
POSSIBLE CHANGES IN THE TANKPOSSIBLE CHANGES IN THE TANK CLOSURE SYSTEM AT LONG TERM
TANK CLOSURE
Waste
Tank heel concentrate
Concrete
concentrate
Soil
Aging and deterioration of waste form
314-7-2009
Soilof waste form
LL WASTE VAULT W t SoilC
O2 and CO2
POSSIBLE CHANGES IN THE LOW LEVEL WASTE VAULT LONG TERM
LL WASTE VAULT Waste SoilConcreteO2and CO2
Aging and
2
Aging and deterioration of waste form
Carbonation Oxidation
CO2
carbonation front
CO2
carbonation front
CO2
carbonation front oxidation front
O2
oxidation front
O2
414-7-2009
Air void (partially water filled?)carbonation frontcarbonation frontcarbonation front oxidation frontoxidation front
Effect of Boundary Conditions Boundary ConditionsEffect of Boundary Conditions and Saturation on Release from a 3-layer System
3-Layer 1-D diffusion model for
Waste form – no flux at interior boundary (left side)Clay soil – zero concentration at external boundary (right side of clay soil)
Initial Condition3 Layer, 1 D diffusion model for non-interacting, conservative species (e.g., Na)
Waste Form Concrete Clay Soil
Initial ConditionNa only in waste form at time zero at C/C0=1
Cases1. Saturated
(1) (2) (3)
100 cm 20 cm 50 cm
2. Unsaturated (tortuosity values assumed 2x for both waste form and concrete and 3.2x for soil; available porosity assumed 0.8x for waste form and concrete and 0.16 x for soil)
Waste Form Concrete
Clay Soil(compacted)
Density (g/cm3) 1.7 2.4 1.8
and 0.16 x for soil)
3. Same as (1) but with concrete layer only and C/C0=1 at waste form-concrete interface and C/C0=0 at concrete-clay soil interface
(g/cm3)
Porosity 0.4 0.1 0.35
Tortuosity (sat’d) 5 15 2
4. Same as (1) but with waste form only and C/C0=0 at waste form boundary (waste form in infinite bath)
514-7-2009
(sat d)
Transport of non interacting species in 1 2 and 3 layer system (sat unsat)Transport of non-interacting species in 1-, 2-, and 3-layer system (sat – unsat)
614-7-2009
Flux of non interacting species at the cement soil interfaceFlux of non-interacting species at the cement-soil interface
714-7-2009
Scaling to smaller dimensions with same physical conditionsScaling to smaller dimensions with same physical conditionsNa+ release from a waste through a cementitious
barrier into a clayey soil16
10
12
14
ol/l
)
4
6
8
Na+
(m
o
0
2
4
0 0 02 0 04 0 06 0 08 0 1 0 120 0.02 0.04 0.06 0.08 0.1 0.12
depth (m)Na+ t=0.05d Na+ t=0.4d Na+ t=4d Na+ t=18dNa+ t=144d Na+ t=243d Na+ t=576d Na+ t=1222d
814-7-2009
Steady state condition established within 2 years
K l f t th h titi b iK+ release from a waste through a cementitious barrier into a clayey soil
0.45
0.5
0 25
0.3
0.35
0.4
mol
/l)
0.1
0.15
0.2
0.25
K+
(m
0
0.05
0 0.02 0.04 0.06 0.08 0.1 0.12
depth (m)depth (m)K+ t=0.05d K+ t=0.4d K+ t=4d K+ t=18dK+ t=144d K+ t=243d K+ t=576d K+ t=1222d
914-7-2009
In spite of higher K level in barrier steady state condition established within 2 years
Illustration of the importance of more detailed chemistrydetailed chemistry
Geochemical speciation modeling based on pH dependence test results taking mineral precipitation, clay interaction, sorption on g p p y pironoxides, incorporation in ettringite and interaction with particulate and dissolved organic matter into account.
Sorption parameters for particulate and dissolved organic matter for U and Th based on the generic parameters derived by Milne t l 2003 f th Ni D d let al, 2003 for the Nica Donnan model.
1014-7-2009
Standardisation:
Characterisation leaching tests
GRANULAR MATERIALS
or pH DEPENDENCE TEST BATCH MODE
Standardisation: CEN/TC292, ISO/TC190, CEN/TC345, CEN/TC351, SW846
PERCOLATION LEACHING TEST CEN TS 14405 or EPA method 1314
TEST: BATCH MODE ANC, CEN/TS 14429, or EPA method 1313or, COMPUTER CONTROLLED CEN/TS
MONOLITHIC MATERIALS
CO O C / S14997
TANK LEACH TEST MONOLITH CEN/TS
15863 and EPA method 1315 and COMPACTED
GRANULAR LEACH TEST
Same as granular + GRANULAR LEACH TEST
(NEN 7347 and EPA method 1313).
Chemical speciation aspects Time dependent aspects of release
+
1114-7-2009
Chemical speciation aspects Time dependent aspects of release
LeachXS StructureLeachXS Structure
In the modeling mineral dissolution, sorption on hydrated ironoxides, clay interaction, interaction
1214-7-2009
g , p y , y ,with particulate and dissolved organic matter and incorporation in ettringite solid solution.
Cement Stabilised Waste Mix
[Th+4] as function of pH Partitioning liquid-solid, [Th+4] Th+4 fractionation in solution Th+4 fractionation in the solid phase
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
Con
cent
rati
on (
mol
/l)
1.0E-131.0E-12
1.0E-11
1.0E-101.0E-09
1.0E-08
1.0E-07
1.0E-061.0E-05
1.0E-04
Con
cent
rati
on (
mol
/l)
20%
40%
60%
80%
100%
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
p
20%
40%
60%
80%
100%
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
1.0E-091 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
[Th+4]
1.0E-141 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Free DOC-bound POM-bound Thorianite
0%1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Free DOC-bound
0%1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
POM-bound Thorianite
[UO2+] as function of pH
1.0E-04
/l)
Partitioning liquid-solid, [UO2+]
1.0E-05
1.0E-04
/l)
UO2+ fractionation in solution
100%
)
UO2+ fractionation in the solid phase
100%
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on (
mol
/
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on (
mol
/
0%
20%
40%
60%
80%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
0%
20%
40%
60%
80%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
[UO2+] Free DOC-bound POM-bound Carnotite Schoepite Free DOC-bound POM-bound Carnotite Schoepite
[Cu+2] as function of pH
1.0E-05
1.0E-04
on (
mol
/l)
Partitioning liquid-solid, [Cu+2]
1.0E-05
1.0E-04
ion
(mol
/l)
Cu+2 fractionation in solution
60%
80%
100%
of t
otal
ti
on (
%)
Cu+2 fractionation in the solid phase
60%
80%
100%
of t
otal
ti
on (
%)
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
o
SWD_SR2 (P,1,1) [Cu+2]
1.0E-08
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
Free DOC-bound POM-bound FeOxide Cu[OH]2[s]
0%
20%
40%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
oco
ncen
trat
Free DOC-bound
0%
20%
40%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
oco
ncen
trat
POM-bound FeOxide Cu[OH]2[s]
1314-7-2009
Information also relevant for stabilisation of contaminated soil
Granulated blast furnace slag – fly ash cement mortar
[Th+4] as function of pH Partitioning liquid-solid [Th+4] Th+4 fractionation in solution Th+4 fractionation in the solid phase[Th+4] as function of pH
1.0E-07
1.0E-06
1.0E-05
Con
cent
rati
on (
mol
/l)
Partitioning liquid solid, [Th+4]
1 0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
Con
cent
rati
on (
mol
/l)
Th+4 fractionation in solution
20%
40%
60%
80%
100%
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
Th+4 fractionation in the solid phase
20%
40%
60%
80%
100%
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
1.0E-081 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
[Th+4]
1.0E-14
1.0E 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
CFree DOC-bound POM-bound
0%1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Free DOC-bound
0%1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
POM-bound
[UO2+] as function of pH
1.0E-05
l)
Partitioning liquid-solid, [UO2+]
1 0E 06
1.0E-05
/l)
UO2+ fractionation in solution
100%
UO2+ fractionation in the solid phase
100%
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on (
mol
/l
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on (
mol
/
0%
20%
40%
60%
80%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
0%
20%
40%
60%
80%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
p
[UO2+]Free DOC-bound POM-boundEttringite Tyuyamunite Uranophane
p
Free DOC-bound
p
POM-bound Ettringite Tyuyamunite Uranophane
[Cu+2] as function of pH
1.0E-06
1.0E-05
n (m
ol/l
)
Partitioning liquid-solid, [Cu+2]
1.0E-06
1.0E-05
n (m
ol/l
)
Cu+2 fractionation in solution
60%
80%
100%
f to
tal
on (
%)
Cu+2 fractionation in the solid phase
60%
80%
100%
f to
tal
on (
%)
1.0E-09
1.0E-08
1.0E-07
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on
HOL12 (P,1,1) [Cu+2]
1.0E-09
1.0E-08
1.0E-07
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on
Free DOC-bound POM-bound FeOxide Tenorite
0%
20%
40%
60%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
oco
ncen
trat
io
Free DOC-bound
0%
20%
40%
60%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
oco
ncen
trat
io
POM-bound FeOxide Tenorite
1414-7-2009
Cement mortars and concrete not inorganic: non-negligible organic matter content!
CLAYEY SOIL
[Th+4] as function of pH Partitioning liquid-solid [Th+4] Th+4 fractionation in solution Th+4 fractionation in the solid phase[Th+4] as function of pH
1.0E-09
1.0E-08
1.0E-07
1.0E-06
Con
cent
rati
on (
mol
/l)
Partitioning liquid solid, [Th+4]
1 0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
Con
cent
rati
on (
mol
/l)
Th+4 fractionation in solution
20%
40%
60%
80%
100%
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
Th+4 fractionation in the solid phase
20%
40%
60%
80%
100%
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
1.0E-101 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
[Th+4] - L/S=10 [Th+4]-L/S=0.2
1.0E-14
1.0E 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
CFree DOC-bound POM-bound
0%1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Free DOC-bound
0%1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
POM-bound
[UO2+] as function of pH
1 0E 04
1.0E-03
l)
Partitioning liquid-solid, [UO2+]
1 0E 06
1.0E-05
)
UO2+ fractionation in solution
90%
100%
UO2+ fractionation in the solid phase
100%
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on (
mol
/l
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on (
mol
/l)
0%
10%20%
30%
40%50%
60%
70%
80%90%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
0%
20%
40%
60%
80%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
of
tota
l co
ncen
trat
ion
(%)
p
[UO2+] [UO2+] - L/S=0.2
pH
Free DOC-bound POM-bound Clay
p
Free DOC-bound
p
POM-bound Clay
[Cu+2] as function of pH
1.0E-03
1.0E-02
1.0E-01
1.0E+00
ion
(mol
/l)
Partitioning liquid-solid, [Cu+2]
1.0E-05
1.0E-04
1.0E-03
1.0E-02
n (m
ol/l
)
Cu+2 fractionation in solution
60%
80%
100%
f to
tal
on (
%)
Cu+2 fractionation in the solid phase
60%
80%
100%
f to
tal
on (
%)
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rat
Zinc_Soil (P,1,2) [Cu+2] - L/S=10Zinc_Soil (C,1,1) [Cu+2] - L/S=0.2
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Con
cent
rati
on
Free DOC-bound POM-bound FeOxide Clay
0%
20%
40%
60%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
oco
ncen
trat
io
Free DOC-bound
0%
20%
40%
60%
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
Frac
tion
oco
ncen
trat
io
POM-bound FeOxide Clay
1514-7-2009
Soil system dominated by dissolved and particulate organic matter interaction
PROFILE WASTE- CEMENTITIOUS BARRIER - SOIL
I t ifi tiDiffusion Case Stabilised Waste - CEM II GBFS-FA - Soil OXIDISED/ CARBONATEDLayer overview
Material Stabilised waste GBFS-FA-Mortar SoilLength 5 00 2 00 5 00 cm
Input specification
Length 5.00 2.00 5.00 cmPorosity frc 0.40 0.10 0.35Tortuosity 3.00 10.00 2.00Density 1.70 2.40 1.70 kg/dm³
H 10 1 11 5 6 5pH 10.1 11.5 6.5
pe 15 15 15
In the modeling mineral dissolution, sorption on hydrated ironoxides, clay interaction, interaction with particulate and dissolved organic matter and incorporation in ettringite solid solutionsolution.
Typically 44100 variables, 192565 expressions, 118 equations
1614-7-2009
PROFILE WASTE- CEMENTITIOUS BARRIER - SOIL
Distribution profile for Al+3 after 6 days Distribution profile for Ca+2 after 6 daysp y
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
on (
mol
/l)
Stabilised Waste Concrete Soil
p y
1.0E-02
1.0E-01
1.0E+00
1.0E+01
1.0E+02
tion
(m
ol/l
)
Stabilised Waste Concrete Soil
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
Con
cent
rati
o
1.0E-06
1.0E-05
1.0E-04
1.0E-03
0.00 0.01 0.03 0.04 0.05 0.06 0.08 0.09 0.10 0.11
Con
cent
ra
1.0E-090.00 0.01 0.03 0.04 0.05 0.06 0.08 0.09 0.10 0.11
depth (m)
Free DOC-bound POM-bound Clay Ettringite AA_Gibbsite Albite[low] Kaolinite
depth (m)Free DOC-boundPOM-bound ClayEttringite AA_2CaO_Fe2O3_SiO2_8H2O[s]AA_Calcite AA_Gypsum
Distribution profile for Sr+2 after 6 days
1.0E-01S bili d W C S il
Distribution profile for Na+ after 6 days
1.0E+02Stabilised Waste Concrete Soil
1.0E-04
1.0E-03
1.0E-02
rati
on (
mol
/l)
Stabilised Waste Concrete Soil
1.0E-02
1.0E-01
1.0E+00
1.0E+01
trat
ion
(mol
/l)
Stabilised Waste Concrete Soil
1.0E-08
1.0E-07
1.0E-06
1.0E-05
0.00 0.01 0.03 0.04 0.05 0.06 0.08 0.09 0.10 0.11
Con
cent
r
1.0E-06
1.0E-05
1.0E-04
1.0E-03
0.00 0.01 0.03 0.04 0.05 0.06 0.08 0.09 0.10 0.11
depth (m)
Con
cent
1714-7-2009
depth (m)
Free DOC-bound POM-bound FeOxide Clay Ettringite BaSrSO4[50%Ba] Strontianite
depth (m)
Free DOC-bound POM-bound Clay Albite[low]
PROFILE WASTE- CEMENTITIOUS BARRIER - SOIL
Distribution profile for Th+4 after 6 days
1.0E-04
1.0E-03
Stabilised Waste Concrete Soil
Distribution profile for UO2+ after 6 days
1.0E-03
1.0E-02
Stabilised Waste Concrete Soil
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
entr
atio
n (m
ol/l
)
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
entr
atio
n (m
ol/l
)1.0E-13
1.0E-12
1.0E-11
1.0E-10
0.00 0.01 0.03 0.04 0.05 0.06 0.08 0.09 0.10 0.11
Con
ce
1.0E-13
1.0E-12
1.0E-11
1.0E-10
1.0E-09
0.00 0.01 0.03 0.04 0.05 0.06 0.08 0.09 0.10 0.11
Con
ce
depth (m)
DOC-bound POM-bound Thorianite
depth (m)
Free DOC-bound POM-bound Carnotite
Association with DOC important for release
1814-7-2009
p
Predominance diagrams
Projected very long t
Technetium
term condition –carbonated and a doxidised
Initial condition –alkaline and reducing
1914-7-2009
Carbonation leads to alterations in the releaseCarbonation leads to alterations in the release behaviour as a result of the pH change that is brought about
CarbonationCarbonationThe effect of carbonation on release is illustrated by
CO2CO2CO2
modeling, including an evaluation of uncertainty in the model prediction.
CO2CO2CO2The data are placed in perspective to actually measured test data for > 70
carbonation frontcarbonation frontcarbonation front different cement mortars (Portland as well as different types of blended cements)
2014-7-2009
Stochastically varied input parameters for modeling of pH dependence leaching test data for cement mortars
• Total available concentration (10%)
• pH (0.1 unit)p ( )
• Pe (2 units)
• All reaction constants (15%)
• Ionic strength (20%)
• Gaussian distribution
• 2000 simulations in the pH range 2-13
2114-7-2009
2000 simulations in the pH range 2 13
Solubility of Ca in cement mortars as function of pH
With CarbonateWithout Carbonate100000000100000000
10000000
a] (µ
g/l)
10000000
a] (µ
g/l)
1000000
[Ca
1000000
[Ca
1000002 4 6 8 10 12
pH
1000002 4 6 8 10 12
pH
2214-7-2009
Solubility of SO4 as S in cement mortars as function of pH
Without Carbonate With Carbonate
100000
1000000
100000
1000000
10000
100000
S] (µ
g/l)
10000
100000
[S] (
µg/l)
1000[S
1000
[
1002 4 6 8 10 12
pH
1002 4 6 8 10 12
pH
2314-7-2009
Ettringite
Solubility of Si in cement mortars as function of pH
Without Carbonate With Carbonate
1000000
10000000
1000000
10000000
10000
100000
[Si]
(µg/
l)
10000
100000
[Si]
(µg/
l)
100
1000
2 4 6 8 10 12100
1000
2 4 6 8 10 12 2 4 6 8 10 12pH
2 4 6 8 10 12pH
2414-7-2009
CONCLUSIONSCONCLUSIONS- Both physical and chemical changes in the waste form and cement barrier are of importance to properly assess release to thebarrier are of importance to properly assess release to the environmental.
- For non-reacting species a steady state condition of release through the barrier develops within a few years for saturated conditions Forthe barrier develops within a few years for saturated conditions. For unsaturated conditions this takes in the order of a hundred years.
- Carbonation and oxidation lead to important changes in release b h i f b A h l d i f i ibehaviour of substances. As these processes lead to moving fronts it is difficult to capture the release in a Kd describing contaminant behaviour of the entire waste form, the barrier or the soil.
2514-7-2009
CONCLUSIONSCONCLUSIONS- Gaining insight in more detailed chemical interactions is of importance as mobilisation in the form of dissolved complexes mayimportance as mobilisation in the form of dissolved complexes may occur. Currently, organic matter interaction is not considered.
- The binding potential of hydrated ironoxide (formed in situ upon oxidation of reduced Fe in both waste and barrier) for radionuclides ofoxidation of reduced Fe in both waste and barrier) for radionuclides of interest is important for retention within the containment under oxidised/carbonated conditions.
U d Th i h d l li i d d f h- U and Th in the present model runs are preliminary and need further verification by measurement of actual release behaviour from size reduced stabilised waste. In case of U and Th, this is possible with stable isotopes For Tc this is obviously not possiblestable isotopes. For Tc this is obviously not possible.
- Therefore, carrying out a pH dependence test on cement stabilised radioactive waste is highly recommended to provide better insight in
2614-7-2009
release controlling processes.
CONCLUSIONSCONCLUSIONS- More detailed chemical characterization provides the means to design for retention of contaminants in the waste or the design of adesign for retention of contaminants in the waste or the design of a chemical barrier in addition to physical containment.
- Although calculation times with complex chemistry are long compared to Kd type calculations it is possible to model release under definedto Kd type calculations, it is possible to model release under defined conditions along the projected path as defined in a pe – pH diagram (resulting from carbonation and oxidation). More complete consideration of chemical processes also provides more robustconsideration of chemical processes also provides more robust understanding of non-linear process coupling and for improved design.
- Optimization of calculation efficiency. Balance complex models with simplified models Preferably justified simplification based onsimplified models. Preferably justified simplification based on understanding the underlying processes.
2714-7-2009
top related