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

1

Radionuclide Pathways to Man

2

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

Dnieper River Watershed and Chernobyl Nuclear Accident Contamination

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

5

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

Chernobyl Plant

At Accident

Present

NSC

construction

set-up

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

Cesium-137 Concentration on the Land Surface (in 80-km)

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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

21

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

22

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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