Post on 16-Apr-2020
Environmental Remediation Examples and
Remediation Strategic Planning
Yasuo Onishi
(yasuo.onishi@pnnl.gov)
October 16, 2011
Pacific Northwest National Laboratory, and
Washington State University, Civil and Environmental Department
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Environmental Remediation AssessmentRemediation and other response decision making
Environmental monitoring
experiments
Assessment
Preliminary assessment to grasp the overall picture and determine critical locations, phenomena, people, etc.
use simple methods and models
Comprehensive detailed assessment for selected locations, etc.
use detailed methods and computer models
After making decisions for specific remediation and other responses
Detailed site survey
Site specific experiments
Remediation actions
Detailed assessments of prior, during and after remediation
Remediation Examples of Chernobyl CaseBetter planning and assessment
Chemical methods for contaminated Water
Zeolite
Bentonite
Activated charcoal
Mineral fertilizers (K, P, N, lime)
Physical methods to retard radionuclide movement
Clay barriers, dams, ditches, dikes
New Safe Confinement
Cleaner water supplies
New wells
Desna River
Administrative control
30-km evaluation zone
Fishing ban
Forest use ban
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Pripyat River Flooding (~ 1991 Ice Jam) and Remediation
Without the Newer East Bank Dike With the Newer East Bank Dike
90Sr Distributions if Chernobyl Shelter Should Collapses
90Sr
airborne
plume
90Sr in the
Dnieper
River
-7000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000 30000
1000
2000
3000
4000
5000
6000
7000
8000
9000
500
1000
5000
10000
50000
100000
500000
700000
3000000
7500000
15000000
Bq/m**2
-7000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000 30000
1000
2000
3000
4000
5000
6000
7000
8000
9000
500
1000
5000
10000
50000
100000
500000
700000
3000000
7500000
15000000
Bq/m**2
90Sr on
land
surface
0
100
200
300
400
500
600
700
800
1 91 181 271 361 451 541 631 721
time (days)
Sr 90
(Bq/m3)
Kiev
Kanev
Krem
Dndz
Dnepr
Kahov
137Cs Migration Prediction in Groundwater
Without NSC
After 100 years
With NSC
After 100 years
800 850 900 950 1000 1050 1100 1150
800 850 900 950 1000 1050 1100 1150
90
100
110
90
100
110
1.0E+002
1.0E+003
1.0E+004
1.0E+005
1.0E+006
1.0E+007
1.0E+008
1.0E+009
4.0E+009
Bq/m^3
800 850 900 950 1000 1050 1100 1150 1200
800 850 900 950 1000 1050 1100 1150 1200
90
100
110
90
100
110
1.0E+002
1.0E+003
1.0E+004
1.0E+005
1.0E+006
1.0E+007
1.0E+008
1.0E+009
4.0E+009
Bq/m^3
Hanford Site: Remediation and Decommissioning
• LLW and its mixed waste
• TRU (Pu, U, etc.) and its mixed waste
• HLW
Along the Columbia River,
•50 burial grounds
• 579 waste sites
• 357 excess facilities for decommission
• 9 reactors for decommission
Dismantle→ Remove waste → Treat→ Store → Dispose: in-site LLW disposal site
: ship to TRU WIPP site
: ship to HLW disposal site
100 N and 100 K-East/K-West Reactors and Trenches
100 N Reactor and a 2-km long Trench 100 K Reactors and a 2-km long Trench
1.7 billion m3 of liquid waste 4 million m3 of liquid waste
Site Remediation along the Columbia River• Removed 6 million tons of contaminated soil
• Backfilling and revegitations are the final steps.
Pump and Treat of Contaminated Groundwater
• Withdraw and treat the contaminated groundwater, and injected the
de-contaminated water back to the groundwater
• Not much effective to reduce the contamination, but it is very effective to
change the direction and velocity of the contaminated groundwater to
not to flow into areas that need to be protected
• Large-scale groundwater treatment facility is under construction in Hanford
Contaminated Soil
Physical
Separation
137Cs
TPL?Y
Clean Backfill
Lixiviant
Extraction
Wash Water 137Cs
TPL?
YSludge
Sorbent
Waste Form
N
N
134Cs and 137Cs Contaminated Soils & SedimentsA Potential Ex-Situ Remediation Scheme
Soil Washing – A Proven remediation technology for radionuclides, heavy metals & hydrocarbons
TPL: Target Performance Level
(PNNL Lixiviant: nontoxic, and
biodegradable)
Lixiviant Extraction Results
(Not-optimized)
2.00 – 0.25 mm Fraction Hanford SoilLixiviant
Formal
Conc
Initial 137Cs
Activity
(Bq/kg)
Final 137Cs
Activity
(Bq/kg)
137Cs activity
Reduction
(%)
0.25 9.6E+03 2.7E+03 72
0.50 9.6E+03 2.1E+03 78
1.00 9.6E+03 1.6E+03 83
0.25 4.2E+03 1.5E+03 64
0.50 4.2E+03 1.0E+03 76
Extractions conducted at 96 ˚C for 6 hr
PNNL Lixiviant: nontoxic, and biodegradable
137Cs-contaminated Hanford Site Crib Soils
Plutonium Migration in South Mortandad Canyon
Overland runoff Creek flow discharge
Dissolved PuTotal Pu
Sediment discharge
Particulate Pu
Construction of Web-Based Five Detailed Environmental
Remediation Distribution Maps
Distribution Map 1111: Environmental parameter map
Distribution Map 2222: Radionuclide transport parameter map
Distribution Map 3333: Radionuclide migration and fate map
Distribution Map 4444: Remediation distribution map
Distribution Map 5555: Remediation priority map
18Data connected to Web Web Page Analysis and
Decision making
Distribution Map 1111:Environmental Parameter Map
Radionuclide Concentration Distribution((((134Cs and 137Cs)
Population distribution
Geometry((((mountain, plain, river, irrigation waterway, etc.)
Land use ((((farm field, dairy farming, school, hospital, nursing home, road, park, etc.)
Land surface and geology ((((meadow, forest, concrete, sand field, clayey area, etc.))))
Groundwater and geological parameters (groundwater table height, hydraulic gradient, etc.)
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Distribution Map 2222: Radionuclide Transport Parameter Map
Weather ((((rain, snow, temperature, etc.))))
Land-surface: radionuclide migration parameters
Land sloe
Soil erosion rate
Subsurface: radionuclide migration parameters
Porosity
Hydraulic conductivity, etc.
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Distribution Map 3333: Radionuclide Migration and Fate Maps
for134Cs and 137Cs
Land Surface: Radionuclide migration amount
Radionuclide adsorption
Overland runoff amount((((rain, snow melt)
Soil erosion amount
Radionuclide migration amount on the land surface
Subsurface: Radionuclide migration amount
Radionuclide adsorption
Migration amount in unsaturated subsurface water
Migration amount in groundwater
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Distribution Map 4444: Remediation Distribution Map
Remediation technology list((((excavation, grouting, chemical extraction treatment, etc.)
Soil
River water, agricultural water, groundwater
Remediation method selection for each area shown in Map 1
Remediation area size and amount
Performance and maturity of remediation methods
Performance and maturity of waste treatment methods
Performance and maturity of waste disposal methods
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Some Remediation of CesiumSome Remediation of Cesium--Contaminated SoilContaminated Soil
Effectives depends on soil characteristics
Extract cesium from solids by washing with water or suitable extraction solutions
Ex-situ soil washing
Mature technologies.
Effectiveness depends on soil characteristics
Separate soils with high concentrations from soils with low concentrations
Physical and radiological soil separation
Applicable to shallow soil.
Excess leachate must be collected.
Risk of uncontrolled mobilization.
Effectiveness depends on soil characteristics
Leach with acid or ion exchange and a complexing agent, such as citrate
In-situ leaching
Isolates radionuclides, but restrict future land uses
Inject grout material to entrap the radionuclides in a monolith
Grouting
Isolates contaminated materials and reduces exposure
Engineered cover Isolation
Effective, but remove valuable topsoil unless replaced with new or washed soil.
Scrape upper soil layer and either wash soil or dispose.
Excavation
CommentDescriptionTechnology
Distribution Map 5: Remediation Priority Map
Environmental and human risk assessments under
Current condition
Future conditions due to radionuclide migration
Achievability of securing disposal sites
Current and future land uses
Social and cost considerations
Others
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SummaryEnvironmental remediation and its assessment examples for the Hanford, Los Alamos and Chernobyl cases were presented.
Some remediation technologies and administrative control are applicable to the Fukushima nuclear accident’s environmental remediation
Remediation strategic planning with a web-based comprehensive remediation distribution maps provides
Remediation roadmap
Scientific basis on remediation selections
Site-specific remediation method, timing, and effectiveness
waste treatment and disposal planning
Public participation of remediation decision making through webpage
Perform remediation activities methodically and quickly before cesium further will spread in the environment.
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