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Case History: Decontamination Challenge of Iitate Village
Yuuzou MAMPUKUInstitute for Agro-Environmental Sciences, National Agriculture and Food Research Organization
3-1-1 Kannondai, Tsukuba-shi, Ibaraki, 305-8666, Japan*E-mail: manpuku@affrc.go.jp

Abstract
The nuclear power plant accident that occurred at the Fukushima Daiichi Nuclear Power Station operatedby Tokyo Electric Power Co. in the aftermath of the Great East Japan Earthquake of 2011 resulted inradioactive contamination of a substantial portion of the surrounding area, mostly in Fukushima Prefecture.
Immediately after the accident, direct contamination of crops occurred in areas where radioactive cesium
falling from the atmosphere was deposited on plant leaves or branches. As the effects of direct contamination
subsided over time, indirect contamination of crops, caused by absorption of radioactive cesium from the soil,
became a problem. The local authorities overseeing accident control in Fukushima Prefecture decided tosuspend all farming in the area, prohibiting planting of paddy fields within a 30 km radius of the Fukushima
Daiichi Nuclear Power Station with soil radiocesium concentrations of more than 5,000 Bq Kg−1. Although thedamage caused by the earthquake was relatively minor in Iitate Village in the Date district of Fukushima
Prefecture, the influence of radioactive fallout forced all of the villagers to evacuate their homes. Whiledecontamination of the entire region and environmental restoration by the government is in progress, thevillage is still confronted with various problems, including promoting public awareness of nuclear materials
and disposing of radioactively contaminated waste. The author was dispatched to Iitate Village as a specialist
for the Industry Promotion Section from April 2012 to the present (FY2020) to collaborate with staff of themunicipal government. He partook in various activities, including negotiating with relevant government
ministries, attending resident information sessions, and addressing issues of decontamination, waste disposal
and agricultural business. In this paper, the process from decontamination to resuming agricultural businessand progress toward environmental restoration with disposal of decontamination wastes is discussed in detail.
Key words :	decontamination, environmental restoration, radioactive contamination, removed soil,
resuming agricultural business

1. Details on the Nuclear Power Plant Accident
and Iitate Village
On March 11, 2011, the accident at the Fukushima
Daiichi Nuclear Power Station operated by Tokyo
Electric Power Co. (TEPCO; hereafter referred to as the
TEPCO Fukushima Daiichi nuclear accident) caused a
substantial part of the Tohoku Region to be contaminatedwith radioactive cesium, among which Fukushima
Prefecture sustained the most severe contamination. Units
1 to 3 were operating, and 4 to 6 were not, due toscheduled safety inspections when the earthquake hit thearea; although all of the active reactors scrambled
automatically, they lost all external power. The
emergency diesel generators (EDGs) went online
immediately, but all of the EDGs, except for one at Unit
6, ceased functioning due to flooding from the tsunami.
The reactor cores at Units 1 to 3 were exposed because
coolant circulation provided by the emergency core
Global Environmental Research
24/2020: 145-158
printed in Japancooling system (ECCS) failed for a certain duration,
leading to core meltdowns (Annual Report on Energy for
FY2011). Moreover, chemical reactions between steam
and zirconium on the fuel cladding tubes and otherequipment produced massive amounts of hydrogen. At
Units 1 and 3, hydrogen explosions probably caused byhydrogen leaking from the reactor containers occurred in
the upper structure of the reactor buildings. Anotherexplosion presumably caused by hydrogen occurred at
Unit 4, whose core fuel had been transferred before theaccident to the spent fuel pool for a safety inspection. As
a result of these explosions, a considerable amount ofradioactive cesium was released into the surrounding
environment (Ministry of Economy, Trade and Industry,2012).
The Japanese Government, thereafter ordered
residents within a 20 km radius to evacuate and residents
within a 20 to 30 km radius of the Fukushima Daiichi
nuclear power plant to take shelter. Leakage of©2020 AIRES

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radioactive cesium continued, and depending on winddirection and velocity, rainfall and other weather
conditions, deposition of radioactive cesium of varying
severities could be observed throughout Japan.
As a result of the TEPCO Fukushima Daiichi nuclear
accident, direct contamination occurred, in whichradioactive cesium falling from the atmosphere wasdeposited directly onto crop leaves or branches,increasing plants’ radioactive cesium concentrationlevels. On March 19, radioactive contamination beyond
the provisional regulation value (below 500 Bq Kg−1 ofradiocesium concentration) was detected in milk inFukushima Prefecture and spinach in Ibaraki Prefecture.
On March 20, vegetables and raw milk produced in six
prefectures in the Kanto and Tohoku regions also showedradioactive contamination beyond the regulation value.
While the influence of direct contamination subsided
over time, indirect contamination caused by absorption ofradioactive cesium from the soil became a problem, andthe Local Headquarters for Accident Control in
Fukushima Prefecture suspended all farming. On April 8,
the government announced the prohibition of planting
paddy fields in the area within a 30 km radius of the
Fukushima Daiichi Nuclear Power Station where readings−1of more than 5,000 Bq Kg radiocesium concentration
were found in the soil. A considerable range of crops andproducts in the area, including brown rice, herbage andgreen tea, were affected, exceeding the provisional
regulation value. A new regulatory value for radiocesium
concentration was set (100 Bq Kg−1) in April 2012, andsince 2012, all brown rice produced in Fukushima
Prefecture has undergone inspection before shipment(Ministry of Agriculture, Forestry and Fisheries, 2011;
Ministry of Health, Labour and Welfare, 2011; Fukushima
Prefecture, 2012a). In 2020, some municipalities shiftedto extraction inspection.
Iitate Village is a beautiful place located in thenorthern Abukuma Mountain range, richly blessed withnature. Forest cover accounts for approximately 75% of
its total area of 230.12 km2, and the terrain is relatively
gentle. The Manogawa River in the north, Niidagawa
River and Itoigawa River in the center, and HosokawaRiver in the south run through the village, providing
water to farm fields of approximately 2,200 ha around thesettlements. The average temperature is approximately
10°C, and the annual precipitation is approximately
1,300 mm, exhibiting a typical cool highland climate(Iitate Village, 2020).
Iitate Village did not sustain tsunami damage, but theearthquake measured just under six on the Japanese scale,causing roofing tiles to fall and roads to collapse (Fig. 1).
On the night of March 12, the Haramachi-Kawamata
town road (Prefectural Road 12) was jammed withvehicles trying to evacuate as far as possible away fromthe nuclear power plant, and a considerable number ofrefugees came to the village to take shelter. Many

Fig. 1 A road blocked by a rockslide in Iitate Village.

villagers, including members of the village office, firefighting team, local women’s association and social
welfare council, worked nonstop at the emergency shelterto accept refugees evacuating from the Hamadori region(coastal Fukushima). The weather on March 15 was rainy,
which turned to snow during the night. The radiationlevel indicated by the radioscope located in front of the
Ichibankan Building suddenly rose drastically the same
−1
day, with the highest level reaching 44.7 μS vh at 6:20
pm. Fear spread among the people, the village authority
took various initiatives, including discussing emergency
evacuation with Kanuma City in Tochigi Prefecture,
implementing screening tests and thyroid exposure tests
for children, and holding information sessions to enhancepeople’s knowledge about radiation. However, the villageauthorities were forced to handle demands or inquiries
resulting from the daily news being discussed among the
refugees, including news about high radiation readings in
the village, an announcement from the International
Atomic Energy Agency (IAEA) regarding extremely highconcentration levels of radioactive cesium detected in thevillage’s soil on March 20, and a report on March 21 by
the national government regarding highly concentrated
radioactive cesium detected in tap water in the village.
In the course of accident response, Japan’s
government issued guidelines for a directed evacuationand the areas targeted for it on April 11. Iitate Village wasincluded in an area-update issued on April 22 and theentire village was evacuated. By June 22, the village
office functions had been relocated to shelters in Iinomachi, Fukushima City to continue attending to theaftermath of the accident (Iitate Village, 2011).

2. Contamination Level Evaluation
Various studies have been conducted in Iitate Village
involving environmental restoration to resume
agricultural business and revive agriculture in the area.
These have included assessments of soil contaminationlevels in the polluted lands, environmental air dose rateevaluations and development of decontamination
techniques for removing radioactive cesium.

Case history: decontamination challenge of Iitate Village
The Institute for Agro-Environmental Sciences(NIAES) of the National Agriculture and Food Research
Organization (NARO) has conducted radioactive cesium
monitoring studies continuously since 1959, and theinformation they had gathered was the only long-termmonitoring data regarding radioactive contamination in
farmland soil and crops produced in the soil. These
particular data were used as the control data in an
investigation of soil and contaminated crops in the area
(National Agriculture and Food Research Organization,2010). The level of radiocesium concentration in the soil
was measured in each farming field as well, and theresults were published on each prefecture’s respective
website. Later, radiocesium concentration readings infarmland soil at a depth of 15 cm were organized andpublished in a distribution map based on an air dose rate
map compiled through aircraft radiation monitoring by
the Ministry of Education, Culture, Sports, Science andTechnology, a digital farmland soil map, and actual
radiocesium concentration level measurement values. As
of November 2011, areas with high radiocesium
concentrations in the soil were distributed northwest of
the Fukushima Daiichi nuclear power plant, and in thesouth and north of the Nakadori region (inland) of

147

Fukushima Prefecture (Fig. 2). Several areas with highradiocesium concentrations (hotspots) were confirmed
locally outside of Fukushima Prefecture, and otherhotspots were confirmed within Fukushima Prefecture incities such as Fukushima or Date. From investigative
results in 2011, farmlands that exceeded the regulatory−1
standard for cultivation, set at below 5,000 Bq Kg ofradiocesium concentration in the soil, were estimated tototal approximately 8,900 ha in Fukushima Prefecture(Kohyama et al., 2013). Information was publishedindicating that radiocesium concentrations in the
farmland would steadily decrease due to the subsequentphysical decay of radioactive cesium or a phenomenon
called weathering, in which radiocesium percolates ordrains off.
Municipal governments subjected to full evacuation
suffered a severe decrease in government office functions
at that time because of the overwhelming amount ofissues requiring immediate attention, including securing
places of refuge for the people, addressing insufficient
information about radioactive cesium, and assisting
officials of Japan’s government and relevant ministries.
Resident information sessions regarding radioactive
contamination, with which no one had ever had any

Fig. 2 Soil Concentration Map of the zones directed to evacuate (total amount of cesium 134, 137 deposited on the ground surface)(as of March 11, 2013) (Nuclear Regulation Authority, 2013).

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previous experience, were also challenging. There were
instances in which the meanings of the words “radiation,”“radioactive cesium,” and “radioactivity” were confused.
In addition, explaining various technical terms in plain
language for the people was highly challenging, such asalpha ray, beta ray, gamma-ray, X-ray, neutron ray andthe “becquerel” unit that indicates the radiation emission
capacity of radioactive cesium, as well as “Sievert,” ameasure of radiation’s impact on human health. Many
residents directly linked the influence of the nuclear
power plant accident with that of the atomic bomb, andsessions were nearly in a state of total chaos. The author
also attended these resident information sessions held in
Iitate Village and other places, fielding a wide variety ofquestions regarding the relationship between theregulatory standard for radioactive concentration levels
for paddy rice cultivation and the radiation exposure of
farmers, or the credibility or certainty of information
scattered on SNS or broadcast in the news. He realized
the difficulty of explaining technical terms plainly orpresenting the current situation with the utmost care andconsideration to avoid offending the feelings of theresidents. As mentioned earlier, these sessions for the
residents involved had to be held repeatedly so that theresidents could live without anxiety.

3. Forms of Radiocesium Existing in the Soil
Radiocesium enters the soil and dissolves in water tobecome a monovalent cation (Cs+); thus, it is captured bynegative charges in the soil. The negative charges derived
from soil organic matter or clay minerals have different
levels of affinity for Cs+, and the composition or content
of organic matter/clay minerals differs among soils. In
this chapter, the forms of cesium in the soil, themechanism of Cs+ adsorption by negatively charged soil,
and characteristics of soil constituents, which areessential for characterizing Cs+ adsorption sites, as wellas their distribution in the soil in Japan are discussed indetail. In addition to the above, the soil distribution in
Fukushima Prefecture is thoroughly reviewed according
to the properties and types of each soil — the radiocesium
concentration levels in the farmland soil of Fukushima
Prefecture have been reported to the public accordingly.
In this report, the impact of radioactive cesium on crops
was estimated according to the soil characteristics ofFukushima Prefecture, the distribution of radiocesium
concentrations in the soil, and predictions of the behaviorof radioactive cesium in the soil of Fukushima Prefecture(Yamaguchi et al., 2012). It has been vital to provide suchinformation to the farmers and their families, but the
information available at that time was mostly academic
documents requiring scientific expertise. It was
regrettable that the relevant authorities could not provide
the local residents with such vital information in simple
and easily understandable terms.

4. Development of Decontamination Techniques
It was the first time in Japanese history for thecountry’s farmland to be contaminated with highly
concentrated radioactive cesium. According to an
investigation of the Chernobyl accident in 1986, the
IAEA reported that the soil contamination fromradioactive cesium fallout was concentrated at the surfaceof the soil (Sugiura, 2011). The same condition was
suspected in the case of Fukushima so it was expectedthat by removing the surface soil the contaminatedfarmland could be restored to a status suitable forcultivation. The National Agricultural Research Centerestablished an operating system to reduce the amount of
in-soil radioactive cesium mainly by using agricultural
machinery available on the market (e.g., power harrows
and front loaders) with consent from the farmers of Iitate
Village. It was assumed that farmers would work in theaccessible areas with simple protection, such as masks.
The Institute for Rural Engineering developed a selfpropelled top-soil stripping method for construction
machinery (Fig. 3). The decontamination techniques
mentioned above were based on land categoryclassification (e.g., paddy fields or plowed fields) andcontamination level considerations and application
policies. Details of various farmland soil decontamination
techniques were reviewed and organized into an operation
manual for radioactive cesium removal techniques(decontamination techniques) for farmland (National
Agriculture and Food Research Organization, 2011).

Preliminary survey

Crush the topsoil

Crush the topsoil

Strip the topsoil

Carry out stripped soil

Strip the topsoil

Pack in a flexible
container pack

Carry out stripped soil
Fig. 3 
Decontamination operation flowchart and images ofoperations (NARO, 2011).

Case history: decontamination challenge of Iitate Village
These systemized techniques are highly valued because
farmers themselves can implement decontamination withequipment available nearby. At the same time, heavymachinery, such as backhoes or bulldozers, was used in
actual decontamination practice. Introducing heavymachinery enhanced the efficiency of decontamination
work, yet the heavy weight and large vibrations wereconfirmed to damage the vegetation foundation layer or
rupture under drainage. In addition, the Japan Atomic
Energy Agency and other relevant authorities conducteddecontamination model verification. Subsequently,
decontamination of houses, cleansing of school buildings,
stripping of schoolyard top-soil, cleansing of roadpavement and other measures were investigated (Ministryof the Environment, 2012).
During this period, Iitate Village was designated as
one of the special areas under the direct control of thegovernment (according to the “Special Measures” of Act
No. 110 of 2012), and resident information sessions
provided by the Ministry of the Environment regarding
decontamination of houses, farmlands and wood edges
were held almost every day. Decontamination practices in
Iitate Village were implemented over an area ofapproximately 5,600 ha that included approximately
2,100 houses, 2,400 ha of farmland, 2,100 ha of forest(wood edges), and 330 ha of roads, producing
3
approximately 2,000,000 m of stripped soil, which has
been stored at 96 temporary storage sites (TSSs) in thevillage (Fig. 4). Transportation of removed soil to aninterim storage facility (ISF) began in 2016, andapproximately 730,000 m3 had been transferred outside
the village by September 2020 (Ministry of theEnvironment, 2012; Ministry of the Environment,
2016a).
The top-soil stripping method was implemented forthe entire farmland area of Iitate Village according to theresidents’ intentions. The method conducted by the
Ministry of Environment effectively decontaminated theradiocesium deposited on the top-soil of the farmland.
Uncontaminated decomposed granite available in theFig. 4 
Temporary storage site for decontaminated soil (picture
taken in August 2016; a total of 96 sites were set up in Iitate
Village).

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village was used for soil dressing, however, and as aresult, farmers accused the Ministry of the Environmentof turning their farms into sand boxes. In addition, the cut
slopes and ridges in the farmlands were left mostly
unattended except for deep pruning of weeds, leaving
radioactive cesium in the soil. Decontamination ofhouses, farmlands, and wood edges has now been
completed in all areas except for those in the “difficultto-return zones,” and projects for resuming agriculturalbusiness and farmland maintenance and management
have gradually begun to be initiated. Approximately
3
14 million m of removed soil including thedecontamination waste (hereinafter referred to as
removed soils) was generated across the whole of
Fukushima Prefecture. The transportation of the removed
soils to the ISF has commenced across the prefecture(Ministry of the Environment, 2016a).
The removed soils will be stored for a specificduration at the ISF, and then their final disposal will be
conducted outside the prefecture, as decided by the
Cabinet Council. The Ministry of the Environment andIitate Village are currently verifying the possibility ofrecycling the removed soils-after implementing antiscattering measures or placing protective covers-for
public construction projects under the ‘Verification
Project for Recycling of Removed Soil,” as a part of the“Reconstruction and Revitalization Project for theSpecific Area of Restoration,” subject to the consent of
the village’s residents (Ministry of the Environment,2013).

5. 
Purpose and Significance of Removed Soil
Recycling
According to the Basic Guidelines for the
Reconstruction and Revitalization of Fukushima (issued
on July 13, 2012, by Cabinet decision) and other relevant
guidelines, the removed soils are to be transported to the
ISF, and the national government is to take responsibility
for their final disposal, as described in the guidelines,
which say that the government “will implement necessary
measures to complete the final disposal of theradioactively contaminated waste outside of Fukushima
Prefecture, within 30 years after the commencement ofwaste storage at the ISF.”
According to calculations by the Ministry of theEnvironment, the total amount of removed soils is3
estimated at 14,000,000 m (Ministry of the Environment,
2012; Ministry of the Environment, 2013). Some say that
it is impossible to dispose of such an immense amountbecause of the difficulty in securing final disposal sites
with adequate handling capacities. Moreover, theestimated amount does not include waste from the places
subjected to the Reconstruction and Revitalization Project
for the Specific Area of Restoration. Implementing
environmental restoration is being discussed for those150

Y. MAMPUKU

places, including the “difficult-to-return zones,” where
quantitative estimation is impossible. The estimatedamount does not include wastes with over 100,000 Bq/Kg.
As mentioned above, it is possible that the burden at the
ISF may increase. Therefore, it is necessary to formulatea method to use the removed soils partially for publicconstruction projects because the soil itself is a valuable
natural resource. However, it should not be used as it isbecause it contains radioactive cesium.
The Ministry of the Environment has been holding“Meetings for the Development of Reduction andRecycling Technology of Removed Soil Stored at ISF”
since July 2015. Referring to the investigation results of
the Working Group for the Safety Assessment ofRadiation Effects in Recycling of Removed Soil andRelevant Waste and Working Group for the Developmentof Reduction and Recycling Methods of Removed Soiland Relevant Waste Stored at ISF, the ministry hasorganized guidelines titled Basic Concept Regarding the
Safe Use of Removed Soil Recycled as the Resource(Ministry of the Environment, 2016b), which were issuedin June 2018.
“Recycled resource” has been defined at theStrategic Meetings as removed soils that have undergone
proper pre-processing and several contamination-levelreduction stages of physical processing, as well as aquality management control process to satisfy therequired criteria to be used as material at target sites.
Likewise, the term “recycle-use” is defined as using
recycled resources for strictly limited purposes, such as
public construction projects, in which the management
body or responsible party is public. These would takeforms such as embankment materials in structural
foundations, in which the material properties would not
likely be subject to alteration by humans, so that therecycled resources would be used under proper
management control, including setting radiation

concentration thresholds to reduce and minimize
secondary exposures, sealing them with protective covers,
taking anti-scattering measures, and organizing/storing
record documents. “Recycle-use” differs from less strict
counterparts like the Clearance Program, which excludes
materials from the regulatory framework of radiation
protection and grants the free distribution of recycledmaterials without restriction. “Recycle-use” as defined
here follows the regulation standard set in the Special Act
on Countermeasures Against Radiation Contamination byRadioactive Cesium Released in the nuclear power plant
Incident Due to the Great East Japan Earthquake on
March 11, 2011 (Act No. 110 of 2011), which is supposed
to be practiced under proper management. As for the
byproducts of chemical/heat processing of the removed
soils or relevant subsequential waste, such as heatprocessing ash, they are not currently included as the
subject of the Basic Concept because not all of the preand post-processing properties or the quality/possible useof those byproducts have thus far been confirmed.
To evaluate recycled resources technically, it isnecessary not only to promote technical development of
reduction/recycling technology to maximize the reductionof removed soils but also to establish a system forrecycling soil obtained from reduction processing withlow radioactive concentrations, after securing a properlevel of safety and receiving the consent of the local
residents. The Ministry of the Environment has
implemented a verification project for recycled resources(used as foundation materials for road embankments; it iscurrently continuing as an environmental monitoring
project) in Minamisoma City since 2017, and anotherverification project (of foundation material in land fordevelopment) commenced in Iitate Village in 2018 withthe understanding and cooperation of the residents ofNagadoro administrative district (Fig. 5) (Ministry of theEnvironment, 2012).

Fig. 5 Concepts on safe use of the soil from off-site decontamination work after recycling (Ministry of theEnvironment, 2016c).

Case history: decontamination challenge of Iitate Village

6. Concept and Awareness of the Recycle Use of
Removed Soils
The removed soils processed in the decontaminationof Iitate Village are planned to be provided for limited
use under proper management control. After undergoingappropriate pre- and post-processing or physicalprocessing such as classification, the quality of therecycled material will be modified to suit the conditionsof the target site and used strictly as structural foundationmaterial such as embankment material in publicconstruction projects, in which the management body or
responsible party is public, and in which the material
properties would not likely be subject to alteration byhumans (Ministry of the Environment, 2018a).
In final disposal outside the prefecture or otherrecycle-use of the removed soils, it will be criticallyimportant to foster a nationwide consensus and trust
regarding the concept and implementation oftechnological developments, recycle-use of removed soils
and safety measures against radiation. Conducting averification project requires detailed information
disclosure to the municipal government and local
residents. The findings and experiences obtained in theseverification projects should be reflected in future
recycling projects.
The Ministry of the Environment conducted anationwide internet survey in November 2018, targetingmen and women in their 20s to 60s (3,600 responses; 400
each in nine regions of Hokkaido, Tohoku (except for
Fukushima), Fukushima Prefecture, Kanto, Chubu, Kinki,
Chugoku, Shikoku, and Kyushu/Okinawa). The response
rate of each region corresponded to its respective
population composition ratio. The result was that morethan half of the respondents answered “Never heard of it
before” regarding the recycle-use of removed soils,
revealing that nationwide awareness of this is extremely
low (Ministry of the Environment, 2015).

7. Evaluating Amounts of Secondary Exposure
To minimize amounts of secondary exposure toresidents, facility users and construction workers in therecycle-use of removed soils, the material is to be used
for limited purposes, and all necessary measures are to betaken accordingly, including setting standard radioactive
concentration levels for recycled materials and securing
proper thicknesses of covering soil. Concentration levelsof radiocesium (134Cs+137Cs) in recycled material were
calculated under the condition of secondary exposures
not exceeding 1 mSv/y throughout the period during
which secondary exposure amounts were evaluated. In
practice, additional measures such as radiation shielding
are implemented to reduce exposure amounts further, so
as not to exceed 1/100 of the threshold (Reconstruction
Agency, 2017).

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8. Initiatives in Nagadoro, Iitate Village
The Nuclear Emergency Response Headquarters of
the Japanese Government reviewed the area that had
undergone planned evacuation in Iitate Village in June2012 and designated within it a “zone in preparation of
the lifting of the evacuation order,” “restricted residencearea,” and “difficult-to-return zone,” according to theyearly integrated radiation amount. In this particularreview, Nagadoro, a settlement in Iitate Village, wasdesignated as a “difficult-to-return zone” due to readingsof over 50 mSv/y. The Revised Act on Special Measures
for the Reconstruction and Revitalization of Fukushima
was enacted in May 2017 to establish a base forreconstruction and revitalization of the “difficult-to-returnzone.” The establishment of a special reconstruction andrevitalization base is now in progress in Nagadoro aswell.
In addition to establishment of the base, a series of
discussions among the national government, municipal
government and local residents have been conducted
repeatedly regarding the recycle-use of materials in theEnvironmental Restoration Project.
November 11, 2017: The Environmental Restoration
Project was approved in an extraordinary general
meeting of Nagadoro administrative district in Iitate
Village.
November 13, 2017: Nagadoro administrative district
informed the Mayor of Iitate Village in writing
regarding the affirmative vote at the general meeting.
November 14, 2017: The Environmental Restoration
Project was approved by the Iitate Village Council
and a conference with all village members.
November 20, 2017: The Iitate Village Council
submitted the request for implementation of theEnvironmental Restoration Project to the Ministry of
the Environment.
The request demanded that the nation and relevant
ministries provide Nagadoro with proper support,
including recycling of soil removed from the village,
environmental reformation through land development/
concentration of Nagadoro, and other necessary support
to ensure long-term land use, such as cultivation ofgardens/resource crops in the settlement after
environmental restoration through implementing findings
regarding the recycle-use of removed soils currently
being investigated by the national government.
November 22, 2017: Confirmation of the Environmental
Restoration Project Initiation among Iitate Village,
Nagadoro administrative district, and the Ministry of
the Environment
The Ministry of the Environment and Iitate Village

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agreed that both parties would work closely on theEnvironmental Restoration Project, including recyclingof the removed soils in Nagadoro, to contribute to therevitalization of not only Nagadoro but also of Iitate
Village and Fukushima Prefecture. The Ministry of theEnvironment, Iitate Village and the Naganuma settlementin the adjacent Iwase District were to collaborate andinitiate verification projects, reflecting experts’recommendations and paying utmost consideration tosafety and security in the environment.
January 28, 2018: An information session presenting
the restoration project was held during an
extraordinary general meeting of Nagadoro
administrative district in Iitate Village.
March 25, 2018: Another information session
presenting the restoration project was held during an
extraordinary general meeting of Nagadoro
administrative district in Iitate Village.
April 20, 2018: The Restoration and Revitalization
Program for Areas Requiring Special Attention wasapproved for implementation in Iitate Village.
June 3, 2018: An information session for residents on
the restoration project was held targeting theresidents of Nagadoro.
In considering residents’ feelings, verification
projects regarding the recycle-use of removed soils mustbe evaluated from every possible aspect, employing theexpertise of the “Environment Restoration Project
Organizing Committee for Restoration and Revitalizationof Nagadoro in Iitate Village” so that the project cancommence with proper care and consideration for safety
and security through efforts to review and confirm factors
causing anxiety among residents. The accomplishments averification project previously conducted in Minamisoma
City will be introduced in these projects. A series of crop
cultivation tests will be conducted as well, targeting
gardening/resource crops in response to a request from
Nagadoro (Ministry of the Environment, 2012; 2017).

30,000 bags of removed soils being held in the village’s
TSS to a stockyard designated in Nagadoro administrative
district and establish a recycling plant in the vicinity ofthe designated recycling facility (Fig. 6) (Ministry of theEnvironment, 2012; 2017).
The recycling procedure consists of two processing
phases: a pre-processing phase to break the container
bags and remove unnecessary components for farmland
development (e.g., garbage, irrelevant organic materials
and metals), and a quality control phase to manage thesoil quality according to the target use of the recycle-soil.
To maximize the amount of recycled material andreduce unnecessary organic materials or metals, the soil
will be sifted using a vibrating screen in the preprocessing phase to remove alien substances larger than aspecific size. The recycle-soils will be evaluated in thequality control phase to determine if it satisfies therequired quality standard (e.g., density, ignition loss,
moisture weight percentage and particle size distribution)
for use as embankment material in farmland development.
Those that fail to satisfy the standard will be evaluated todetermine if the quality could be improved by mixing andstirring with the soil to be used as the shielding.
The recycle-soils will then be measured by aradioactive concentration measurement/sorting device
and categorized according to their concentration levels;
those that do not meet the designated threshold will not
be used as recycled material. The soil processed in
Nagadoro will be categorized as either over 5,000 Bq Kg
or below 5,000 Bq Kg. Specifically, the soil is put into
the hopper of the radioactive concentration measurement/sorting device and lands on a conveyor (transfer speed:
35 cm/sec) equipped with a belt scale and a cesium iodide(CsI) scintillator detector (with a 1.2-second detection
interval) to measure its weight and radiation dose. Thenthe radioactive concentration measurements are sent tothe sorting device, in which the sorting chute divides thesoil into groups with over 5,000 Bq Kg and under
5,000 Bq Kg. The soil to be recycled as embankment

9. Outline of Verification ProjectThis project aims to verify various aspects ofremoving soil stored in the TSSs in the village to berecycled as embankment materials for farmland
development. The aim is to establish a technicalframework for promoting the recycle-use of materials
from the viewpoint of their management, including
examination of practical management methods forprotection from radiation during the recycling process
and assurance of quality as embankment materials forfarmland development, and securing safety from radiation
during the experimental recycle-use of soil (Ministry of
the Environment, 2012; 2017).
The first step is to transfer and store approximately

Fig. 6 Inside the recycling plant.

Case history: decontamination challenge of Iitate Village

153

Area for producing recycled soil (Nagadoro)Fig. 7 Image of the demonstration project (in Iitate Village) (Ministry of the Environment, 2018b).

Agricultural cultivation demonstration

Regeneration plant↑Warabitaira

Presentation room

Agricultural greenhouse (cultivation demonstration)↓Hiso

Fig. 8 Location of candidate area for recycling (Ministry of the Environment, 2018b).

material for farmland development will then be verified
accordingly.
The recycled material will undergo a rollingcompaction process to secure more than 50 cm ofshielding soil pressure (shielding thickness) in theconstruction of the embankment, in which the relevant
data, including hydraulic conductivity, cone index,
compaction degree, settlement of the embankment,
surface dose rate, air dose rate, soil radioactive
concentration level and other data after the compaction ofeach layer are recorded. The productivity of the actual
construction project is also estimated accordingly by
investigating key elements, such as cycle time at eachconstruction stage.
The ground at the site of the recycled material
verification project has been cured with an impervious
sheet or other materials wherever necessary to prevent
contamination of the local panel, and its rainwaterdrainage system is being properly attended by placing
required facilities such as gutters so that the level ofradioactive concentration can be measured appropriately.

Tents (100 m×30 m) have been set up at the recycledmaterial verification project site, and all work has been
conducted inside the tents to prevent infiltration of
rainwater or outflow of the removed soils. Upon resolving
technical issues, the full-scale Environmental Restoration
Project, which will encompass the farmland stretchingfrom east to west between the Hisokawa River and theprefectural road, will use the quality-controlled recycling
materials obtained by the above method (Figs. 7 and 8)(Ministry of the Environment, 2012; 2017).

10. O utline of the Cultivation Verification Project
A cultivation verification project assuming therecycle-use of materials for the planting base material has
been implemented. In this verification project, the area of
farmland development is approximately 0.1 ha, on which
various garden crops and other crops premised on the useof biomass have been tested in greenhouses. The safetyof using recycled materials is being evaluated in thesecultivation tests using shielding materials and recycled

154

Y. MAMPUKU

Fig. 9 Cultivation of ornamental plants in the greenhouse.

materials in pot culture, greenhouse cultivation (on-site),and open‐field culture (Fig. 9) (Ministry of theEnvironment 2012; 2017).The residents of Nagadoro
have also participated in the project. Their participation
seems to have had a positive effect, including a renewed
understanding of radioactive cesium and increased desire
among them to return to their homes in Nagadoro. At thesame time, however, those who have decided to return are
relatively advanced in age, posing a severe problem insustaining the community’s future.

11. Reducing Amounts of Radiocesium
Transferred to Crops
Research institutes in the prefectures of Fukushima,
Ibaraki, Tochigi and Gunma collaborated with NARO ina paddy rice cultivation experiment in 2011 to investigate
the influence of potassium fertilizer on the transfer ofradiocesium in the soil to cultivated brown rice (Ministryof Agriculture, Forestry and Fisheries, 2015) The results
showed that the transfer coefficient of radiocesium tobrown rice could be reduced, except for in soil with a lowtransfer coefficient, by applying an amount of potassium
fertilizer three times greater than the usual application.
This fertilizer was rich in clay minerals and had a highradiocesium fixation capacity. The concentration levels of
exchangeable potassium were relatively high in soil
applied to cow dung compost for a long period in addition
to a chemical fertilizer, showing a low concentration level
and transfer coefficient of radiocesium to brown rice.
Soils containing zeolite or vermiculite as clay minerals
were evaluated, and a recommendation was made to
reduce radiocesium concentration by adjusting the usual
amount of applied fertilizer in each area with a low
potassium content in the paddy field to the level at which
the amount of exchangeable potassium was around−1
25 mg-K2O (100 g) (Fig. 10). According to the above
results, a countermeasure to radioactive absorption was
implemented to increase the amount of potassium inapproximately 84,000 ha of paddy fields in Fukushima

Fig. 10 C orrelation between the transfer coefficient of exchangeable
potassium and radioactive cesium in the soil for brown rice
(National Agriculture and Food Research Organization,
2017b).

and other prefectures during implementation of theAgricultural Business Restoration Project in 2013
(Ministry of Agriculture, Forestry and Fisheries, 2011).
In soybean cultivation, it was also revealed that thepotassium concentration in the soil contributed tosuppression of radiocesium absorption in the same way
as observed in paddy rice cultivation, and the same target
level of exchangeable potassium was set at approximately−1
25 mg K2O100g in practice. It was reported, however,that application of potassium chloride in soybean
cultivation would prohibit root nodule adhesion;
therefore, the influence of the potassium concentration insoybean cultivation was evaluated and the reduction ofroot nodule adhesion was confirmed to be minimal at thetarget level of around 25 mg K2O100g−1, posing no ill
effect on the growth or harvest of the crop. For buckwheat
cultivation, this countermeasure was recommended witha target level of approximately 30 mg K2O100g−1(Ministry of Agriculture, Forestry and Fisheries, 2011;
Kato et al., 2015).
Pasture renovation can reduce the radiation air dose
rate at the pasture surface and the radiocesium
concentration level in newly seeded pasture. A total
renovation method combining plowing with burial ofradiocesium deep in the soil has been found highly
effective as a countermeasure in pasture cultivation.
When thorough soil turnover is accomplished, the surface
turnover by disc harrows should be enough to reduceradioactive absorption in the crop.
Potassium fertilizer has also been applied in Iitate
Village after soil decontamination. However, work
involving commuting between where the evacuatedfarmers have relocated and the village imposes a
significant burden on the farmers. Since someradiocesium remains after decontamination, continuous
practice of radioactive countermeasures, such as surface

Case history: decontamination challenge of Iitate Village
soil scraping, should be mandatory. It is vital to build asolid awareness among farmers regarding the significanceof these countermeasures. Moreover, anxieties about
radiation remain among the public, and despite thetremendous efforts of the local citizens, the damage
caused by harmful rumors falsely accusing the crops
grown in Fukushima of being contaminated withradiocesium is still problematic.

12. Dynamic Analysis of Radiocesium in
Cooking and Processing of Crops
It has been nearly ten years since the accident, andthe natural decay of radioactive cesium released to theenvironment should be progressing, yet consumers’
anxiety about the influence of radiocesium (137Cs) remains
dominant; thus the validity of the measurement standard
for radioactive concentrations in food has been evaluated.
The Food Sanitation Law defines the standard value ofradiocesium concentrations in typical food as below
100 Bq Kg−1, and it is necessary to examine the dynamismof radiocesium in the cooking and processing of the target
foods for accurate risk assessment and management(National Agriculture and Food Research Organization,
2017b). In brown rice cooking, it has been confirmed thatradiocesium is removed with the rice bran and washingwater during the polishing and boiling of brown rice(Fig. 11) (Ministry of Agriculture, Forestry and Fisheries,2015). In milled rice, the radiocesium concentration in155

polished and boiled rice has been found to be one-eighththat of brown rice, revealing the dynamics of radiocesium
during cooking and processing. Along with foodprocessing technology, a systematic procedure to easily
measure radiocesium concentrations in food has alreadybeen established in each municipality, contributing toconsumers’ safety. The radiocesium concentrations inmountain vegetables and mushrooms, however, remains
high, and residents often demand appropriate actions toresolve the situation. Relevant initiatives have been taken
since 2012 in Iitate Village so that farmers can measureradioactive concentration levels in crops they cultivatethemselves to ensure safety (Ministry of Agriculture,
Forestry and Fisheries, 2015; Ministry of Health, Labourand Welfare, 2011).

13. Environmental Restoration of Fukushima
The decontamination of the entire region of
Fukushima Prefecture, except for the “difficult-to-returnzones,” was completed by the end of 2018. A considerable
amount of contaminated soil was produced in the process,reaching a total of approximately 16,500,000 m3 inFukushima Prefecture alone. These contaminated wastes
have been stored at either TSSs set up at approximately
1,300 sites during the peak period or on residential
quarters/open ground in areas where it is difficult to set
up storage deposits (e.g., densely populated areas such as
Fukushima City or Koriyama City). All of the wastes will

Fig. 11 P ercentage of radioactive cesium removed during processing from brownrice to cooked rice(%) (National Agriculture and Food Research
Organization, 2017b).

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Y. MAMPUKU

Fig. 12 Trends in numbers of temporary storage sites in Fukushima Prefecture (quarterly for each fiscal year, published on the Ministry of
the Environment’s Environmental Remediation website) (Ministry of the Environment, 2018b).

Volume of transportationachived in FY2020:
approx.1648 (as of Aug. 6, 2020)

Cumulative volume of transported
approx. 8,331 (as of Aug. 6, 2020)
Volume transported on
single-year basis(103 m on bar graph)

Cumulative volume of transported
approx, 6,683 (as of the end of 2019)

Completion oftransportation ofalmost the entire amountof soil and waste planned
for the end of FY2021

Cumulative volume of transported
approx. 2,624 (as of the end of FY2018)
Cumulative volume of transported
approx. 785 (as of the end of FY2017)

Cumulative
Volume transported
3(10 m on line graph)Fig. 13 Ad-hoc policy on transportation to the ISF (Ministry of the Environment, 2018b).

be transferred to SSFs set up in Okuma Town and Futaba
Town. Transportation (Figs. 12 and 13) began in 2015
with an initial transportation test run with 46,000 m3 fromeach municipality in the prefecture. A total of 4,059,000 m3of temporarily stored soil/waste was transported to the
ISF in 2019, and as of 2019, a total of 8,509,000 m3(August 2019 under the direct control and June 2019
under the indirect control of the Ministry of theEnvironment, with information updated daily on its
website) has been transported. By the end of FY2021, thetransportation should be almost complete. Once this iscompleted, the lands used as TSSs, which were leased to
the national government, will be restored to their previous
state before use for storage deposits and returned to thelandowners) (Ministry of the Environment, 2012; 2016b).
As for the ISFs, a total of approximately 1,600 ha ofland has been allocated for their creation, and the remainsof the TSSs, including deposit/sorting facilities forcontaminated soil/waste transported from temporary
dumping sites and soil storage facilities, and other wastes,such as sorted logs or materials from dismantled
buildings, will be compacted by combustion and theresulting incineration ashes with high concentrations ofradiocesium will be sent to radioactively contaminatedwaste storage facilities. The storage time at the ISF is set
at within 30 years, after which the contents will bedisposed of at waste disposal sites set up outside
Fukushima Prefecture (the location of which is to be
decided). At the ISF, the waste is being stored in two
groups, that below and that above a threshold of
8,000 Bq Kg, to prevent rainwater infiltration withnecessary curing to limit infiltration of the groundwaterby contaminated soil particles or radiocesium. Regarding
the final disposal of radioactively contaminated waste at

Case history: decontamination challenge of Iitate Village
the ISF, relevant laws and guidelines, including the “Basic
Guidelines for the Reconstruction and Revitalization of
Fukushima” issued on July 13, 2012 (Cabinet decision),determine that “necessary measures must be taken tocomplete the final disposal of soil outside Fukushima
Prefecture within 30 years from the start of interim
storage.” Further actions will be required in the future(Ministry of the Environment, 2012).
In Iitate Village, where the author was dispatched, it
seems that the level of awareness among farmers
regarding radioactive cesium has been enhanced greatlycompared to during the farmland decontamination
measures verification project, which encompassed
approximately 40 ha of farmland in Iitate Village (in thesettlements of Nagadoro, Komiya, and Kusanomukaioshi)
and Kawamata Town (in the settlements of
Yamakiyahosoda and Yamakiyahinada), and after theevacuation order was lifted in the “zones in preparationof the lifting of the evacuation order” and “restricted
residence areas.” The residents can prepare to protect
themselves against lingering undiscovered radioactive
cesium and recover from their evacuation to the present.
Although environmental restoration by decontamination
is in progress, there remain various issues in resuming
life in the village after environmental restoration,
including some residents’ lack of desire to return to thevillage after their prolonged evacuation and discontent
with the slow reconstruction of village infrastructure. As
for resuming agricultural business in the area, a reductionin the number of residents and the increasing age of those
who wish to return and resume farming will have a great
impact, requiring close attention in the future.

14. Conclusion
A multi-perspective approach to countermeasuresagainst contamination by radioactive cesium is extremely
vital to the environmental restoration of Fukushima
Prefecture, the area most severely affected by radioactive
cesium in our country. A substantial augmentation ofcontrol technologies and data contributing to resumptionof agricultural business should be mandatory, and crosssectional initiatives to defend against radioactive cesium
must be implemented continuously in close collaboration
among the national and municipal governments, research
institutes, private corporations and other relevantorganizations.
Acknowledgments
Extremely careful yet swift actions are required in
response to radioactive cesium contamination. The author
was dispatched to Iitate Village in the Date district ofFukushima Prefecture where he served as a specialist in
the Industry Promotion Section. The author wishes toexpress profound gratitude to the following individuals

157

for their guidance and understanding:Doctor Makoto Nakatani, Vice President of NARO;
Doctor Masami Yasunaka, NARO; Dr. Takeshi Kimura,
National Federation of Agriculture Co‐operative
Associations; Professor Takuro Shinano, Hokkaido
University; Drs. Takeshi Ota, Hisaya Matsunami,
Yoshisada Nagasaka, Namiko Yoshino, Sachie Horii,
Kazunori Kohyama, Noriko Yamaguchi, Hideshi Fujiwara,
Yasuko Togamura, Mayumi Hachinohe, Tomijiro Kubota,
and Takeo Tsuchihara, NARO; Associate Professor,
Moono Shin, Fukushima University; Drs. Mutsuto Satoand Takashi Saito, Fukushima Prefecture; Drs. Masaya
Suzuki and Hirohisa Yamada, National Institute ofAdvanced Industrial Science and Technology; Prof.
Tsutomu Saito, Hokkaido University; and all the staff
members of the Iitate Village Restoration andReconstruction Division. Lastly, the author wishes toexpress gratitude from the bottom of his heart to all those
who have supported us in relevant organizations.
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Yuuzou MAMPUKU
Yuuzou Mampuku is a researcher at the Institutefor Agro-Environmental Sciences, National
Agriculture and Food Research Organization.
His research interests and specialties areenvironmental circulation system engineering andagricultural civil engineering. He has been
making efforts to restore the environment inFukushima Prefecture after the Great East Japan Earthquake.
(Received 19 October 2020, Accepted 28 December 2020)