Remediation of Off-site Affected
Areas
Shunsuke Kondo
ChairmanJapan Atomic Energy Commission
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Highly Contaminated Areas
30km(mSv/y)20km

Fukushima
Dai-ichi NPP(Source: Ministry of Education, Culture, Sports, Science & Technology)

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Measures for Remediation• In order to decrease existing and potential annual exposures, we should
pursue;– Reducing the number of exposed people– Modifying pathways of contaminant to a people– Removing existing sources by decontamination.

• Optimizing the intervention, we should consider avertable doses,
radiological risks, environmental effects, risks to workers, economic costs,
the generation of secondary waste, anxiety on the people affected, social
disruption arising from the restriction, etc.
• The priority choices for the Government to pursue areA)
B)
C)

Restriction of inhabiting in the area where expected annual additional doseis larger than 20 mSv;
Strict shipping control for agricultural products, animal products and marine
products through radiological surveys andStep-by-step decontamination of the land.
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Strategy for Decontamination
I.

Reduce the size of the areas where estimated annual additional
exposure is larger than 20 mSv through step by stepdecontamination activities.
– As entrance in such areas is restricted, the Government should promote
decontamination activities in cooperation with the municipal governments
concerned.
– If the municipal governments desire to decontaminate their area swiftly, thegovernment should cooperate them to plan and promote the activities
financially, dispatching experts.
– Before removing the restriction of entrance, it is also necessary to restore
safe operation of public services essential for living.

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Strategy for Decontamination (2)II. Reduce the annual additional exposure in the areas where it iscurrently below 20 mSv to below 1 mSv on a long term basis.
– Realize at least 50% reduction of the annual additional exposure in such areas in twoyears and pursue further reduction incessantly.
– Pursue exhaustive decontamination of children's’ environment (schools, play grounds,etc.), aiming at reducing the annual additional exposure to 1 mSv as soon as possible
and pursue further reduction incessantly.
– Pursue regional decontamination in the case of highly contaminated areas and spotwise decontamination in the case of relatively low contamination area, identifying hot
spots such as those locations where sludge in the drains or gutters has collected.

III. In the area where annual additional exposure is below 1 mSv, focus
decontamination activities on the hot spots.

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Key Issues in Discharging the Government’s
Responsibilities for Decontamination• Assure the fund for decontamination.
• Promote radiological surveys relevant to area characterization andconfirmation of the achievement of decontamination.
• Prepare remediation technologies and infrastructure, and support
the optimization of remediation strategy and plan.
• Assure safety of activities and safe management of waste.
• Cooperate with local governments in the planning and execution ofremediation activities.
• Ensure public participation in all activities associated withremediation processes, standing close to the people living in theaffected areas and sharing their anxiety.
68Current Situation• Evacuation Area ( >20 mSv/y)– The Government is to start at least one demonstration
decontamination project in every municipal area with aview to demonstrating decontamination approaches andestablishing safety guideline for their widespreadimplementation.
– Based on the results of such projects, the Government willplan and promote a large scale decontamination activity
before the end of the year in cooperation with themunicipal governments so that people can return to homeas soon as possible.
– With regard to agricultural land, Ministry of Agriculture,
Forestry and Fisheries has promoted activities to verify theeffectiveness of various decontamination technologies tobe applied to contaminated agricultural fields.
69Current Situation• Inhabitation Area (1-20 mSv/y)– Municipal governments are leading the planning and theexecution of decontamination activities, setting goals,
deciding the objectives and methods of decontamination,actors and places for temporary storage ofdecontamination waste.
– Asking experts for advise, municipalities have been
conducting activities to decontaminate housings andschools including play grounds, establishing“Decontamination guideline” based on such demonstration
activities: the Government and professional societies also
have presented instruction manuals for decontamination ofresidents’ living spaces.
70Activities to Reduce Dose Rate in
School and School Route<Detailed survey in site>
Soil under trees, sideditch, outlet of rainwater
pipe, etc.

<School route>
Cleaning of walkway,side ditch, etc.
Removal of soil,weed, etc.

(Source: Fukushima Prefecture)<Schoolhouse>
Cleaning by highpressured water(roof, veranda,wall, etc.)<Detailed survey in site>
Play Equipment, flower
bed, pet house, etc.

<Playground>Removal of surface soil
Removal of dirt in side
ditch
<Detailed survey on school route>
Driving dose measurement withGPS record

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Demonstration of Decontamination in School(unit: μSv/h)

Decontaminatedarea

Decontamination Decontamination methods
BeforeAfter

Scupper on roofof school building

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1.9

Removal of soil and fallen leaves, cleaningby scrubber and high-pressured water

End of rainwater
pipe

40

4.2
3.7

Removal of soil and moss + water washing

Overgrown
walkway

25

3.8
1.2

Removal of soil and grass + cleaning by
high-pressured waterSide ditch

13

1.6

Removal of soil and grass(Measured position: 1cm height from soil surface)

Dose measurement(Source: Cabinet Office based on Materials in Atomic Energy Commission Meeting)

Cleaning by high-pressured water72

Decontamination of Swimming Pool Water
Decontaminating method of Swimming pool water• Mixture of Zeolite and flocculant with pool water• Precipitation and agglomeration of zeolite with suspended solids

Bag filter

Pump
Flocculant
ZeoliteTank(Source: Japan Atomic Energy Agency)

Pump
Counteractive(if needed)

Measurement of radioactiveconcentration and pH insupernatant water

Measurement ofradioactive concentration

Water drain73

Decontamination of Roof of Private
House
Preparation ofdecontamination

Cleaning by high-pressured water

Cleaning by high-pressured water
Decontamination(Back of rainwater pipe)
Before: 40-50 kcpm
After: less than 10kcpm
BeforeEnd of rainwater pipe near ①

45 - 65

End of rainwater pipe near ②

50 – 170

Average

10 - 35(Source: Cabinet Office based on Materials in Atomic Energy Commission Meeting)After1474

Generation of Contaminated Waste by
DecontaminationWaste from School

Waste from private house
Soil bag around waste forshieldingContaminated soil buried inplayground

Waste from three private houses(Source: Cabinet Office based on Materials in Atomic Energy Commission Meeting)75

Concept of Managing Waste fromDecontamination Activities
Temporary storage•Soil package•Flexible container•Bulk container

Temporary storage

Interim storage
facility•Garden plant•Soil•Mud•Fallen leaves
Temporary storage•House•Water and sewerage•Street gutter•Farm land
•Pasture

Final disposal facility
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Conclusion• Decontamination activities have been started in residential
area and school area in particular, asking experts foradvice.
• As for high dose area, demonstration decontamination
activities have been started and the Government andmunicipalities hope that a large scale decontamination
activities will be executed based on the knowledge andexperience obtained in these activities.
• It is recognized as a matter of utmost importance to agree
upon the locations for temporary storage of the waste
including contaminated soil to be generated in these
activities with municipalities beforehand.
77I would like to express our deepest gratitude to
you all for a wide array of support andsuggestions.
As we should intensify the decontamination ofhighly contaminated area from now on, yourcontinued support will be most helpful.

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