A comparison ofremediation measures applied
after the accidents in theChernobyl and Fukushima Daiichi NPPs
Gerhard Proehl

The basis of this presentations is a presentation given at
the IRPA congress in 2016
Thank you to the co-authors• A COMPARISON OF REMEDIATION AFTER THE CHERNOBYL AND FUKUSHIMADAIICHI ACCIDENTS• B.J Howard• S. Fesenko• M. Balonov• G. Proehl• S. Nakayama

For the first five years after both accidents(but not the emergency phase)Comparison Fukushima – Chernobyl (same scale)

Fukushima compared to Chernobyl:
comparable Cs-deposition levels, but over smaller area

After Vandenhove et al., 20123Deposition and areas affected
Radionuclide

Total deposition / Area
affected

ChernobylFukushima
DaiichiCs-137

Total deposition to terrestrial 64 (Europe)and freshwater systems(PBq)

2-3 (Japan)

Area with deposition> 100 kBq/m2 (km2)~3000• Ground deposition of Cs-134 and Cs-137

Cs-134

56000

Total deposition to terrestrial 35 (Europe)and freshwater systems(PBq)
Area with deposition> 100 kBq/m2 (km2)30000

ChNPP/FDNPP~20

2-3 (Japan)~3000

IAEA 2006 Chernobyl forum; Morino 2011 Geophys. Res. Lett. 38; Yasunari 2011 PNAS 108~10Affected landscapes – focus of remediation
Chernobyl

Fukushima Daiichi

Collective and private farming,
agriculture, forests, uplands

Decision to remediateevacuated areas
Importance ofrice production
in paddy fields

Importance ofmushrooms andberries

Forestedcatchmentswith steepslopes

Comparison of the contaminated areas
FactorTiming

Chernobyl
At start of growing season

Fukushima Daiichi
Before growing season

Population density

Moderate, no pressure touse landHigh, pressure on available landTerrain

Flat, forested andagricultural

Mountainous: forested slopes
and coastal catchments

Intensity ofagriculture

Low - medium

HighKey products

Milk, meat, grain, potatoes

Rice, fruit, leafy and root crops,grain, flowers

Lateral movement
Low
across landscapePotentially highComparison of internal exposure pathways
Chernobyl

Fukushima Daiichi

Moderate to HighLow

Use of K fertiliser

Very low to moderate

High

Radiocaesium availability
for root uptake

Moderate to very highVery low to moderate

Transfer to animalproducts

Moderate to HighLow

Intake of local foodHigh to very highLow

Intake of wild foodModerate to very highLow to moderate

FactorFraction of soils with highorganic matterImportance of pathways

2012

Contributions of ingestion for both Chernobyl andFukushima vary widely, in particular for Chernobyl
Fukushima data for Kawauchi Village, Fukushima Prefecture [Yasuyuki et al., 2014] .
Chernobyl: Average data for selected rural settlements affected by the Chernobyl
accident [Jacob et al., 2001]

Goals of recovery• Reduction of dose - long term goal <1mSv/y at both sites• To enable residents of contaminated areas to return to a normal life
Chernobyl• Some 100 000 people were living in areas with > 1 mSv/y− Need to remediate to reduce their effective dose rate
− Return of people to evacuated areas• Difficult due to Sr-90 and Pu-contamination in parts of theChernobyl exclusion zone
• Low priority for return of people

Fukushima Daiichi• To re-establish an acceptable basis for a fully
functioning society in all the affected areas− Revitalisation of all contaminated areas

Interaction of long-term doses from Cs-134/Cs-137 with
agricultural practice and living habits
Fukushima

Chernobyl

Intensity of agriculture

highlow

Use of potassium fertilizer

moderate to highlow

Fraction of organic acid soils
low in nutrients

lowhigh= > Availability of cesiumin soillow to moderatehigh to very highIntake of local foodlowhigh to very high=> Contribution of ingestion
dose to total doselow

highFactor

Comparison of radiological criteria
Dose cannot be easily measured, so “operational easily measurable quantities” arederive - ambient gamma dose rates (μSv/h)- deposited activity per unit area (Bq/m2)
FactorChernobyl

Fukushima Daiichi•Comparison of radiologicalSimilarities
criteria
Long term goal of effective dose
1 mSv/yDifferences
Temporary permissible
1986 – 100mSv
levels for effective
March 2011 – 5 mSv
1987 – 30 mSv
1988-1989 – 25 mSv
annual dose
Sep 2011 - 1 mSv
1991- 1mSv

Ambient dose rate
µSv/h
Changes with time infood standard limits

2.2

corresponding to lifetime
additional dose of 350 mSv(applied in 1989)

Down in CIS countries,
stable in EU countries

0.19(excl. natural background)corresponding to annual
additional dose of 1 mSv

Down (decreasing)Classification of contamination in Chernobyl
Cs-137 (kBq/m2) Designation••

Below 37

Not contaminated37 - 185

Remediation for areas
with “sensitive soils” (eg.
wet peat, acid sandy)

185 - 555

Remediation applied forsandy soils and light loam
soils

555 - 1480

Full scale remediation>1480

No economic activity

Set definition of contaminated land at 37kBq/m2
Identified settlements where annual dose rate was > 1 mSv
Izrael 1990

Fukushima designation of remediation areas
Special Decontamination Area (SDA)(Evacuated areas)

Intensive Contamination Survey
Area (ICSA) (Not evacuated areas)

Coloured areas
were remediated• SDA 1 (Green) : additional exposure rate lower than 20 mSv/year(Evacuation orders are ready to be lifted)• SDA 2 (Yellow): additional exposure rate between 20-50 mSv/year(Residents are not permitted to live)• DA 3 (Red): additional exposure rate higher than 50 mSv/year (Residents have difficulties in
returning for a long time)• ICSA: additional exposure rate higher than 1 mSv/yearComparison of remediation approachAspectChernobyl

Fukushima Daiichi

Similarities
Restrictions and food monitoring
Radiological criteria

Food standards, [RCs] soil, ambient dose rate
Decontamination of residential areas
Differences

Key focus

External and internal dose

External dose

Remediatedareas

All settlements with average
dose > 1 mSv/y

ICSA and evacuated areas - SDA 1,2,3Approach• Rapid implementation• Priorities• Focus on measures with a high− Social and cultural factors
effectiveness in dose reduction− Dose reduction even in less affected• Cost-benefit analysis
areas• Sufficient financial resources available

CostForest

High
Providing advice on behaviour

Very highDecontamination on the border of forests

Remedial measures applied - residential
Remediation measure
Decontamination of residential areas
High pressure water hosing
Removal of deposits from the roof,
gutters etc
Wiping roofs and walls
Vacuum sanding
Topsoil removal
Removal of plants
Removal of deposits in road ditches
Decontamination of gardens/trees
Topsoil removal
Paring fruit trees
High pressure water hosing
MowingRemoving leaves

Chernobyl Fukushima
Daiichi


Effectiveness of remediation: 2-4 fold reduction in external ambient dose rate

Important countermeasures
Fukushima Daiichi

Chernobyl• Use of uncontaminated feedstuff beforeslaughter• Radical improvement:
Deep ploughing, re-sowing, lime, K-fertilizer

Use of “PrussianBlue” to reduce
Cs-resorption inthe gut• Removal of plants, topsoil• Soil hardener• Draining suspended soil from paddies• Deep ploughing• Use of extra K-fertilizer

Testing top soil
removal after using
soil hardener(Courtesy from MAFFJAEA-NARO )Live monitoring

Comparison of agriculture remediation measures
Remediation measure

Chernobyl

FukushimaDaiichiAnimal products

Clean feeding
AFCF to animals
Live monitoring of domestic animals
Agricultural land
Radical improvement – ploughing, reseeding,
additional fertilisation
Soil removal
Tillage reversal
Soil treatment with additional K and P
Soil amendment with liming
Application of sorbents and organic fertilisers
Drainage of wet peats
Paddy fields puddling and removal of suspended
sediment
Removal of plants
Soil hardening and removal
Forest remediation• Restrictions−access, harvesting of food products, collection of firewood• Local monitoring
Chernobyl

Providing information and advice• Spatial variation of contamination• Which mushrooms to avoid• Where and when to collect wood, wild
products and hunt game animals• Tree felling schedules

Fukushima Daiichi• Remove surface material from 20 mborder• Action level for use of wood formushroom production

Wastegeneration
andmanagement

Chernobyl• Decontamination of ca. 1000 settlements andwaste buried nearby• Selection of remediation options which did notgenerate waste

Fukushima• Decontaminating ICSA and SDA• Huge generation of waste• High costs• Radiological consequences− Consequences of the FDNPP accident are much lower than ofChernobyl− The scale of remediation activities is comparable

SU • Remediation− For both accidents, the long term goal of remediation is an individual
annual effective dose of 1 mSv/a
M − additional
Radiological criteria for remediation in Japan are lower than those inthe USSR
M − In Japan, reduction of limits for food and other remediation actionlevels
A − Therefore, relatively higher costs in Japan− Decision to remediate evacuated land in JapanR • Chernobyl− The consideration of dose saved and the related cost was an importantYpart of the remediation strategy.
• Fukushima− For remediation of affected areas radiological and social and culturalconsiderations had high priority