FY2014 Decontamination Report- A compilation of experiences to date on decontamination for the living
environment conducted by the Ministry of the Environment -(Tentative Translation)

March 2015

Ministry of the Environment

Tentative Translation< Attention >This material was translated temporarily and might be corrected in the
future.

Introduction
Radioactive materials were released by the accident at the Fukushima Daiichi
Nuclear Power Station (1FNPS) after being hit by the Great East Japan Earthquakeand ensuing Tsunami on March 11, 2011. The Government of Japan as well as
prefectural and municipal governments have been taking measures to decontaminate
the contaminated soil and wastes (hereinafter referred to as “decontamination”), in
order to reduce the impact of radioactive materials on human health and the living
environment as soon as possible.
In the efforts for the decontamination, all available resources including those fromthe central and local government offices, research institutions, and private cleaning
operators have been put together, along with the most recent scientific and technicalknowledge available from Japan and abroad. Of course it is the most important for theworld never to repeat such a disaster in the future. In the meantime, disclosing andsharing our knowledge, experiences, and lessons obtained through the decontamination
efforts at this time with domestic peers and the international community will besignificant to accelerate the decontamination work in Japan and minimize the potential
damage in future accidents in the world for the implementation of expeditious andefficient decontamination.
Therefore, in this Decontamination Report (hereinafter referred to as “the report”),
the Ministry of the Environment (MOE) has comprehensively compiled the basic policyof the decontamination and implementation framework, knowledge about the
management of decontamination projects based on the actual decontamination
operations on-site, together with the procedures, conditions and effects of individual
decontamination techniques, by mainly focusing on the decontamination operations
performed by the MOE. Thus, this report is deemed to be a fundamental document todisseminate both domestically and internationally our experiences, lessons andknowledge learned through the decontamination efforts.
The report consists of the following seven chapters:
1. Basic features of the environmental decontamination in Japan
2. Overview of decontamination methods
3. Management and treatment of decontamination wastes
4. Management of decontamination projects
5. Effects of decontamination
6. Overview, usage and conditions of decontamination technologies andverification of their effects
7. Conclusion
Chapter 1 describes the history and background of the demonstration projects, thecontamination status of decontaminated areas and features of the demonstration
projects. Chapter 2 outlines the process to establish decontamination procedures anddecontamination methods on the basis of the MOE’s document “Decontamination
Guidelines (2nd Ed., 2013)” Chapter 3 explains the management and treatment ofremoved soil and wastes derived from decontamination works with examples of
temporary storage sites, disposal and treatment of water used for decontamination
works and volume reduction for burnable wastes. Chapter 4 illustrates operation
planning for a large range of decontamination projects, including such example tasks asacquiring stakeholders’ consent, having effective communication with residents,
managing the projects and providing radiation protection, education and health care fordecontamination workers. Chapter 5 presents a wide range of area-wide
decontamination effects and their evaluation approach. Chapter 6 explainsdecontamination methods and their effects from a technical viewpoint on the basis ofdata obtained in test decontamination works in order to demonstrate findings on theeffects of individual decontamination technologies used in the full-scaledecontamination works. Chapter 7 summarizes the main points of the report.
It is the expectation of the MOE that this report will facilitate more effective andefficient decontamination works in the environmental remediation after the accident at
the 1FNPS, and contributes to preparations for potential nuclear accidents and related
research worldwide.

C o n t e n ts
1． Basic features of the environmental decontamination in Japan..................................1
1.1. History of the environmental decontamination .............................................................1
1.1.1. Specific features of the decontamination in Japan and Fukushima Prefecture...........1
1.1.2. History of the principal events associated with decontamination................................1
1.1.3. Overview of the change of the evacuation area designation.................................... 24
1.1.4. Outline of the Act on Special Measures Concerning the Handling of Environmental
Pollution by Radioactive Materials Discharged by the Nuclear Power Station Accident
Associated with the Tohoku District Off the Pacific Ocean Earthquake That Occurred
on 11 March 2011 .................................................................................................. 29
1.1.5. Overview of the Special Decontamination Area....................................................... 32
1.1.6. Overview of the demonstration model projects for decontamination ........................ 41
1.1.7. Outline of the Intensive Contamination Survey Area ............................................... 54
1.2. Features of contamination ..........................................................................................66
1.2.1. Dispersion status of radioactive materials ............................................................... 66
1.2.2. Major nuclides........................................................................................................ 69
1.3. Features of decontamination ......................................................................................73
1.3.1. Unprecedented large-scale decontamination activities............................................ 73
1.3.2. Decontamination to secure safety at an early stage and to facilitate restoration andreconstruction........................................................................................................ 76
1.3.3. Project operation with consideration of the maintenance of community and theprotection of rights ................................................................................................. 78
1.3.4. Careful response with consideration for residents’ position and feelings.................. 80
2．Overview of decontamination methods ..........................................................................81
2.1. Guidelines for Methods for Investigation and Measurement of the Status ofEnvironmental Pollution in the Intensive Contamination Survey Area .......................81
2.1.1. Basic Concept........................................................................................................ 81
2.1.2. Indicators of the Contamination Status by Radioactive Materials............................. 83
2.1.3. Methods for Investigation and Measurement to Determine the Areas to be Included ina Decontamination Plan......................................................................................... 85
2.1.4. Methods for Taking Detailed Measurements in Decontamination Zones .................. 87
2.1.5. Evaluation of Decontamination Results................................................................... 88
2.1.6. Measuring Devices and Methods of Use................................................................. 88
2.2. Guidelines Pertaining to Decontamination and Other Measures ...............................92
2.2.1. Basic Concept........................................................................................................ 92
2.2.2. Decontamination and Other Measures for Buildings and Other Structures .............. 93
2.2.3. Decontamination and Other Measures for Roads ................................................. 115
2.2.4. Decontamination and Other Measures for Soil...................................................... 125
2.2.5. Decontamination and Other Measures for Vegetation ........................................... 135
2.2.6. Decontamination Measures of Rivers and Ponds, etc. .......................................... 143
2.3. Guidelines Pertaining to the Collection and Transfer of the Removed Soil ............ 149
2.3.1. Basic Concept...................................................................................................... 149
2.3.2. Requirements for Collection and Transfer of the Removed Soil............................. 149
2.3.3. Specific Actions .................................................................................................... 149
2.4. Guidelines Pertaining to the Storage of Removed Soil ........................................... 152i2.4.1. Safety Measures and Requirements Necessary for Storage ................................. 152
2.4.2. Specific Examples of Storage Methods Chosen on the Basis of the
Facility/Management Requirements ..................................................................... 154

3． Management and treatment of decontamination wastes ......................................... 161
3.1. Temporary Storage Sites and Final Disposal .......................................................... 161
3.1.1. Waste Treatment Flow and Necessity of Temporary Storage Sites ........................ 161
3.1.2. Configurations of Temporary Storage Sites ........................................................... 163
3.1.3. Examples of Temporary Storage Sites .................................................................. 165
3.2. Wastewater Treatment ............................................................................................. 170
3.2.1. Notes of Caution for Wastewater Treatment ......................................................... 170
3.3. Volume Reduction .................................................................................................... 173
3.3.1. Necessity of Volume Reduction ............................................................................ 173
3.3.2. Volume Reduction Methods.................................................................................. 173
3.3.3. Examples of Volume Reduction............................................................................ 175
4． Management of decontamination projects ................................................................ 179
4.1. Flow of the Decontamination Process ..................................................................... 179
4.2. Contents of Decontamination Work ......................................................................... 180
4.2.1. Knowing the Air Dose Rates by Detailed Monitoring ............................................. 180
4.2.2. Decontamination Work Ordered by the Ordering Party (MOE) .............................. 183
4.2.3. Decontamination Work by Decontamination Business Operators .......................... 189
4.2.4. Securing of Necessary Resources by Decontamination Business Operators......... 205
4.3. Acquisition of Residents’ Consent ........................................................................... 215
4.3.1. Efforts Made by the Ordering Party (MOE) ........................................................... 215
4.3.2. Efforts Made by Decontamination Business Operators ......................................... 220
4.4. Communication with Local Residents and Local Municipalities .............................. 221
4.4.1. Securing Temporary Storage Sites ....................................................................... 221
4.4.2. Launching of the “Decontamination Dial 110 (Hotline)” to Receive Information about
Questionable Decontamination Work ................................................................... 221
4.4.3. Efforts Made by Decontamination Business Operators ......................................... 221
4.4.4. Provision of Wide-ranging Information to Local Residents, etc. ............................. 225
4.5. Project Management Executed by Decontamination Business Operators ............. 226
4.5.1. Schedule Control ................................................................................................. 226
4.5.2. Operational Framework for Decontamination Work............................................... 227
4.5.3. Sharing of Information and Safety Precautions ..................................................... 229
4.5.4. Hiring and Separation Management of Workers.................................................... 231
4.5.5. Protection from wildlife ......................................................................................... 231
4.6. Radiation Protection Measures ............................................................................... 232
4.6.1. Ionizing Radiation Ordinance for Decontamination ............................................... 232
4.6.2. Surface Contamination Inspection (Screening) ..................................................... 232
4.7. Education and Health Care for Decontamination Workers ..................................... 233
4.7.1. Education for Workers.......................................................................................... 233
4.7.2. Morale and Conscientiousness of Workers ........................................................... 240
4.7.3. Personal Exposure Dose Management for Workers.............................................. 241
4.7.4. Medical Checks for Ionizing Radiation and Use of Whole Body Counters ............. 242

ii

5． Effects of Decontamination ......................................................................................... 243
5.1. Evaluation Pertaining to the Goals of the Basic Policy ........................................... 243
5.1.1. Facilities Subject to Evaluation ............................................................................. 243
5.1.2. Basic Approach of Evaluation Methods................................................................. 244
5.1.3. Evaluation Methods and Results .......................................................................... 244
5.2. Overview on the Decontamination Effects............................................................... 246
5.2.1. Data for Evaluation............................................................................................... 247
5.2.2. Summary of the Results ....................................................................................... 247
5.3. Decontamination Effects in Five Areas: Public Facilities, Residential Areas, Roads,
Farmland and Forests ............................................................................................. 249
5.3.1. Public Facilities and the Like ................................................................................ 249
5.3.2. Residential Areas ................................................................................................. 250
5.3.3. Roads .................................................................................................................. 251
5.3.4. Farmland ............................................................................................................. 252
5.3.5. Forests................................................................................................................. 253
5.4. Effects at Each Target Decontamination Place ....................................................... 254
5.4.1. Outline ................................................................................................................. 255
5.4.2. Effectiveness of Decontamination Methods for Each Target Decontamination Place........................................................................................................................... 256
6． Outline of decontamination methods, applications and conditions thereof, andexamination of the effects ........................................................................................... 271
6.1. Outline of Decontamination Methods and Their Applications and Conditions ........ 271
6.1.1. Residential Areas, Schools, Parks, Large Facilities, Roads, etc. ........................... 274
6.1.2. Slopes ................................................................................................................. 334
6.1.3. Rice Fields, Dry Fields, Pastures, etc. .................................................................. 336
6.1.4. Grassland, Lawns ................................................................................................ 363
6.1.5. Forests................................................................................................................. 369
6.2. Verification of Decontamination Effects ................................................................... 382
6.2.1. Residing-restricted Areas (Areas in Which Residing is Restricted) or Evacuation
Orders Lifting Preparation Areas (Areas in Which Evacuation Orders Are Being
Prepared for Lifting) ............................................................................................. 383
6.2.2. Difficult-to-return Areas (Areas Where It Is Expected That the Residents Have
Difficulties in Returning for a Long Time) .............................................................. 398
7． Conclusion .................................................................................................................... 418

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1． Basic features of the environmental decontamination in JapanThe decontamination projects associated with the accident at the Fukushima Daiichi Nuclear Power
Station (1FNPS) of Tokyo Electric Power Co., Inc. (TEPCO) have the following basic features involving
the status of environmental pollution, geographical factors, and the stance of the national and the local
governments toward residents.
The principal radionuclide causing environmental pollution is cesium.
Decontamination should be conducted to reduce the impact on human health or the living
environment not only in housing areas and public facilities, but also in diverse and wide
areas including roads, farmlands, forests around the living space, and the like.
Decontamination should be implemented as soon as possible for early return, safety
protection and life rebuilding of residents in the evacuated areas.
Residents' opinions and their way of life should be respected; decontamination should be
conducted by paying due consideration to the protection of private rights and maintenanceof the community.

Hereinafter, the history and the background of decontamination, the status of theradioactive contamination, and features of decontamination works are given in the following
parts 1.1, 1.2 and 1.3, respectively, which led to the formation of the above characteristics.

1.1. History of the environmental decontamination
1.1.1. Specific features of the decontamination in Japan and Fukushima Prefecture
In Japan, about two-thirds of the country is occupied by forests, and the proportion of the inhabitableland areas limited to about the remaining one-third. Therefore, the population density in inhabitable land
tends to be high. In addition, as Japan is the only nation to have been hit by nuclear bombs, the Japanesepeople have a stronger interest and greater concern than the people of other countries toward the damage
caused by radiation. On the other hand, knowledge about radiation and its influence on the human health
had not been shared sufficiently among ordinary person, before the Great East Japan Earthquake.
In Fukushima Prefecture, which most strongly received the effects of the nuclear power plant accident,
the population in October 2010 was about 2 million people and the total area is approximately 14,000
square kilometers. While this is a vast land area, it is used in various forms. The utilization ratio of theland 1 is: forests, about 70 %; agricultural land, about 11%; the surface covered with water bodies, rivers
and waterways, about 3 %; and roads and residential land, about 4%. The east side of Fukushima Prefecture
faces the Pacific Ocean, and the west side is surrounded by mountains. Therefore the situation of the four
seasons is quite different between in the eastern and western regions of the prefecture. In 2014, Fukushima
City, located in the central region, had 96 snowfall days and the number of days was relatively large inJapan. Based on these specific circumstances in Japan and Fukushima Prefecture, most appropriate
decontamination activities are due to be carried out.

1.1.2. History of the principal events associated with decontamination（1） Occurrence of the accident at the nuclear power station and evacuation of residents
At 14:46 on March 11, 2011 (Japan time, hereinafter all times are this), an earthquake
occurred off the Pacific Coast of northeast Japan. The earthquake and ensuing tsunami
damaged facilities of the Fukushima Daiichi Nuclear Power Station (1FNPS) and the
Fukushima Daini Nuclear Power Station (2FNPS) of Tokyo Electric Power Co., Inc. (TEPCO),
setting the stage for an unprecedented complex nuclear accident that led to releases ofsubstantial amounts of radioactive materials to the atmosphere from the 1FNPS.
1Source: Fukushima Prefecture, "2014 edition, Recording of the main data in Fukushima Prefecture"(http://www.pref.fukushima.lg.jp/sec/11045b/26youran.html)

1Then Prime Minister Naoto Kan declared a nuclear emergency situation at 19:03 on March
11, 2011, and established the Nuclear Emergency Response Headquarters (NERH) within thePrime Minister's Office according to the Act on Special Measures Concerning Nuclear
Emergency Preparedness (Law No. 156, 1999).
In the meantime, the Fukushima Prefectural Government set up the prefectural
headquarters for disaster control. Upon receipt of the declaration of a nuclear emergency
situation at the 1FNPS, at 20:50 on March 11, 2011, the Governor of Fukushima ordered
Okuma and Futaba Towns to evacuate the residents living within the radius of 2 km from the
1FNPS.
At 21:23 on March 11, 2011, the NERH ordered the Fukushima Governor and otherrelevant authorities of the municipalities to evacuate the residents living within the radius of
3 km from the 1FNPS and to order those living within the radius of 10 km from the 1FNPS toremain indoors. Then, on March 12, 2011, the NERH ordered the Fukushima Governor andother relevant municipalities to evacuate all residents living within the radius of 20 km fromthe 1FNPS.
Later, following the hydrogen explosion at Unit 3 and others on March 14, the NERH on March 15, 2011,
ordered the Fukushima Governor and relevant authorities of the municipalities to instruct the residents
living in an area between the radius of 20 km and 30 km from the 1FNPS to remain indoors.
On March 17, 2011, the Ministry of Health, Labour and Welfare（MHLW） set the index values2 onfood and drink intake limit of radioactive materials as provisional regulation values of the Food Sanitation
Act, and began the radioactivity monitoring of foods3.
On March 19, 2011, radioactivity exceeding the provisional regulation values of radioactive materials infoods were detected in certain areas in spinach and raw milk, etc., and in response to this situation, theNERH summarized a "Monitoring plan, and a policy on setting and lifting of the food items and the areas
to be subjected to shipment restrictions, etc.". In addition, concerning the planting of rice which is a staple
grain food in the Japanese diet, the NERH presented on April 8, 2011, "The policy on planting of rice", andtook measures for foods, such as imposing planting restrictions on rice in places where the radioactivity ofthe produced rice was more likely to exceed the provisional regulation values4.
In addition, on April 21, 2011, the NERH announced to the Fukushima Governor and the mayors of otherrelated municipalities that it had designated the area located within the radius of 20 km from the 1FNPS as
the restricted area, in order to secure the complete safety of residents.
Some evacuees thought that the evacuation was a "temporary refuge of around several days" at the
beginning of the disaster occurrence. However, after about 1 month, concerns about the prolonged
evacuation life became tangible, and feelings of anger and anxiety spread among evacuees.

（2） Understanding the status of the environmental contamination based on monitoring dataand zoning of the evacuation areas
The monitoring data by the Ministry of Education, Culture, Sports, Science and Technology (MEXT)
showed areas with high accumulation of radioactive materials in the areas located beyond the radius of 20km from the 1FNPS. On April 22, 2011, the NERH announced to the mayors of local municipalities that it
had newly designated such areas located beyond the radius of 20 km from the 1FNPS as the deliberate
evacuation area. In addition, the area between the radius of 20 km and 30 km from the 1FNPS, formerly
designated as the sheltering area was designated as the “evacuation-prepared area in case of emergency,”
excluding the above “deliberate evacuation area.” The above designation requested the residents in the
deliberate evacuation area to schedule their departure from the area, and the residents in theevacuation-prepared area in case of emergency to prepare for evacuation or shelter indoors in case of
emergency. In addition, there were certain spots outside the deliberate evacuation area where substantial air
dose rates continued to be found and so the annually cumulative exposure dose one year after the accident
2Source: Ministry of Health, Labour and Welfare(MHLW),"Handling of radioactively contaminated food"(March 17, 2011)
3The provisional regulation values set on March 15, 2012 are not values established for the emergency
response after the accident, but are new values determined from the long-term perspective.
4Source: Ministry of Agriculture, Forestry and Fisheries (MAFF), “White Paper on Food, Agriculture andRural Areas: 2011" (April 24, 2012)2

was anticipated to exceed 20 mSv. On June 16, 2011, the NERH designated such locations as “specificspots recommended for evacuation,” by announcing the policy of raising awareness and supporting andpromoting the evacuation of residents5.
On August 3, 2011, the Ministry of Agriculture, Forestry and Fisheries (MAFF) published the "Basic
policy on investigation of radioactive materials in rice," and decided to investigate radioactive materials in
rice, a stable food in the Japanese diet, at two stages the “preliminary investigation" before harvesting thecrop and the "main investigation" after harvesting it 6. In addition, the MAFF carried out a survey of theradioactive contaminants that targeted a total of about 580 points in Fukushima Prefecture and fivesurrounding prefectures, and published a concentration distribution map of the radioactive materials inagricultural soil4.
On August 9, 2011, the NERH announced its concept for the review of the evacuation areas7.
The announcement stated the evacuation orders had substantial impacts on the lives ofresidents and it would be appropriate to review the orders, once the status changed because ofconfirming such as the verification of safety of nuclear reactor facilities and reduction of dose
rates through continued monitoring.
Even outside the evacuation area, contamination was found. Also, it became apparent that
evacuation had to be inevitably prolonged. Under this situation, some evacuees moved farther
from the 1FNPS. Some residents even in non-evacuation areas also moved away farther on
their own decision.
Residents were highly worried about the radioactive contamination of the living
environment. They proactively collected information about radioactive materials and thestatus of contamination by themselves because of limited availability of relevant information.
As a result, diverse information was circulated regardless of its quality via SNS and othermeans. In such a situation, prefectural, municipal, and community officials who needed todirectly communicate with residents made efforts to soothe the confusion between residents
by actively providing residents with the latest information and advice on radiation protection.
They had to so act, while responding to the disaster and confirming safety and location ofresidents, by referring to the information provided by the national and prefectural
governments and opinions of experts with whom they had personal contacts, They also lacked
sufficient information.
On September 30, 2011, MEXT announced the “Results of nuclide analyses of plutonium
and strontium”. These results showed that the effects of plutonium and strontium exposure
were much lower in comparison with that of cesium, confirming that the primary concern
should be cesium.
The total number of evacuees in the whole of Fukushima Prefecture was about 164,000 at its peak asshown in figure 1-1. The number of evacuees from the evacuation order areas reached 81,000 as of August
8, 2013. Considering that the population in Fukushima Prefecture as of October 2010 was about 2,000,000
as stated in 1.1.1, it can be understood how a lot of people evacuated.

5Source:

Nuclear Emergency Response Headquarters (NERH), “Addressing the specific spots where thecumulative exposure dose one year after the accident is expected to exceed 20 mSv” (June 16, 2011)
6 Furthermore, the concentration of radioactive cesium exceeding the provisional regulation values was
detected in rice from certain areas after the survey, so rice shipment restrictions were enforced in thoseareas.
7Source: Nuclear Emergency Response Headquarters(NERH), “Concept of the review of the evacuation areas”(August 9, 2011)3

Evacuees in whole Fukushima Prefecture
About 146,000 people

Evacuees from the evacuation order areas
About 81,000 people(11 municipalities)* approximately 164,000 at its peak(June, 2012)
Evacuation order lifting preparation area
About 33,000 people (41%)

Residence restricted area
About 23,000 people (29%)

Difficult-to-return area
About 25,000 people (31%)

Former emergency evacuation preparation area
About 21,000 million people

Hirono Town, Naraha Town,
Kawauchi Village, Tamura City,
Minamisoma City

* Approximately 28,000 people just before
lifting (September, 2011),

Other evacuees
About 44,000 people

The whole area in Fukushima
Prefecture including
Fukushima City,
Koriyama City, Iwaki City

(Remarks)
・The refugees from the whole Fukushima Prefecture are based on the damage information bulletin (Part 1031) (September 17, 2013) of the
Fukushima Prefecture “Tohoku – Pacific Ocean Earthquake, FY 2011”.
・The number of refugees from the evacuation order areas was totaled by the Assistance of Residents Affected by the Nuclear Incidents based on theinformation caught from municipalities (the number of resident registration as of August 8, 2013).
・The number of refugees from the former emergency evacuation preparation area was totaled by the Assistance of Residents Affected by the
Nuclear Incidents based on the information caught from municipalities (as of September 17, 2013).

Figure 1-1 The number of evacuees from the evacuation order areas8 .

（3） Implementation of emergency measures
1）Formulation of response policy
Upon discovery of radioactive contamination even outside the evacuation order areas,
emergency measures were also required there and various efforts were made accordingly.
Japan’s Act on Special Measures concerning Nuclear Emergency Preparedness stipulated that it was the
responsibility of the NERH to resonsd to the nuclear emergency and take post-accident measures in order toprevent the expansion of nuclear disaster and to promote the restoration activities. However, no practicallegal framework covering such points as specific methods and framework to address the release ofradioactive materials into the environment had been formulated before the accident occurred. Under thissituation, the Government immediately formulated and announced provisional policies such as criteria forthe treatment of disaster wastes9, criteria for radiation protection10, and dose criteria in schools to securechildren's living environment 11.
In addition, because radioactive materials which exceeded the provisional standard values prescribed in
the Food Sanitation Act were detected in tea leaves grown outside Fukushima Prefecture, the MAFF
stopped the shipment of those products and conducted investigations 12.

8Source: Cabinet Office, "Review of the evacuation instructions" (October 2013)

9Source: Ministry of the Environment (MOE), “Handling of disaster waste in Fukushima Prefecture for thetime being” (May 2, 2011)10Source: Nuclear Safety Commission, “The basic idea about radiation protection and decontamination” (May19, 2011)

11Source: Ministry of Education, Culture, Sports, Science and Technology (MEXT), “Tentative ideas in judging

the use of buildings and playgrounds of schools in Fukushima Prefecture” (April 19, 2011)12Source: Ministry of Agriculture, Forestry and Fisheries (MAFF), “White Paper on Food, Agriculture andRural Areas 2011" (April 24, 2012)42）Decontamination activities started by various entities
Since the contamination had expanded outside the evacuation order area, somemunicipalities started their own efforts to reduce radiation exposure. Initially, the emphasis
was placed on reduction of children's exposure to radiation.
The pioneers were Date City and Koriyama City. Date City started a demonstration test at
a school ground of former Shimooguni Elementary School from April 21, 201113. Koriyama
City began to remove topsoil of school grounds from April 27, 2011 14. In May 2011, a group of
experts on radiation from the Japan Atomic Energy Agency (JAEA), in cooperation with
Fukushima University, conducted the field survey to verify the reduction measures of air dosein schoolyards and kindergarten yards15 . As a result, two soil treatment methods were
presented: one was to collectively bury soil underground and the other was to verticallydisplace soil (upside-down plowing (deep plowing)). JAEA then continued monitoring theeffectiveness of the dose reduction activities at not only school grounds but also at school
swimming pools in municipalities. They also cooperated in the formulation of
decontamination guidelines based on their expert knowledge (In those days, the term
“decontamination” was not in common use; rather the term “dose reduction activity” wasused.)In addition, experts with knowledge of radiation played the role of decontamination
advisors for several municipalities such as Date City, Minamisoma City, and Iitate Village tostart decontamination activities (Figure 1-2 shows decontamination work in Date City).
Each municipality, whick lacked knowledge on radiation and sufficient personnel fordecontamination conducted dose reduction activities and model decontamination projects16by themselves, using available tools, in cooperation with organizations and experts withknowledge of radiation and sometimes with volunteers. These efforts mainly targeted local
facilities (or points) such as schools and specific houses. On the other hand, the notion was
gradually spread that decontamination of wide area was necessary to obtain sufficient effects
in air dose rate reduction.
Under these circumstances, to verify the effects of decontamination over relatively wide
areas with various land usage including housing, roads, agriculture, etc., the Cabinet Officeentrusted JAEA to start a demonstrative test in Date City and Minami-soma City under a“research project to formulate decontamination guidelines related to the accident at the
1FNPS”. In addition, to verify technologies for area-wide decontamination, the Fukushima
Prefecture implemented a wide-area decontamination model project. 17 In the meantime,different range and effects of decontamination among municipalities led to "sense of
unfairness" and "sense of dissatisfaction" of some residents.

13Source: Date City, “Three years of history of Date City after the Great East Japan Earthquake and Nuclear

Accident” (http://www.city.date.fukushima.jp/soshiki/9/7146.html)

14Source: Koriyama City, “History of Koriyama City after the Great East Japan Earthquake” (February 2013)15 Source:

Ministry of Education, Culture, Sports, Science and Technology (MEXT), “Air dose reduction
measures in the schoolyards and kindergarten yards based on fieldwork” (May 11, 2011)16For example, the Fukushima Prefectural Government's model project for radiation reduction measures forordinary houses
17Source: Fukushima Prefectural Government, Fukushima surface decontamination model project(https://www.pref.fukushima.lg.jp/sec/16045c/josen-mentekimoderu.html )5

Figure 1-2 Decontamination at Tominari Elementary School in Date City.

Decontamination
implementation area
Target spots for the decontamination

Residential land

Rice paddy

Area (㎡)

Roof

4,779

Wall

5,945

Garden, etc.

11,204

Rice field

11,350Field, Orchard

27,325

Surface of slope

20,705

Forest, Bamboo forest

16,339Municipal road

6,866

Land use map

Field, Orchard, etc

Forest, etc

Road

Private road, Farm road

148

Waterway

565

Others89

Total

Legend105,315

Decontamination
implementation area

Residential land,
SchoolRice paddy

ForestField, Orchard, etc.

Water storage tankOnami
elementary
schoolWater storage tank

The no n-colored section in the deco ntamination
implementa tion area shows the surface o f slope.
Route 115 o f natio nal highway

Figure 1-3 Target areas for decontamination of the area-wide decontamination model projectby Fukushima Prefecture18 .
JAEA continued enhancing its framework to support the decontamination of each municipality. In
addition, since October 2011, Fukushima Prefecture held workshops, in cooperation with JAEA, to develop
human resources for decontamination.
At the municipal level, Fukushima City created the manual mentioned in 3) and held workshops fordecontamination business operators, in order to develop human resources as well as to provide matching
opportunities for local business operators to utilize their own techniques to let them easily enter thedecontamination business19.

18Source: Fukushima Prefecture, "Fukushima Prefecture surface decontamination model project summary

version", (February 2012)19For example, through the workshop, a company specializing in painting and cleaning was found to be goodat high-pressure water cleaning, a company specializing in civil engineering was found to be good at

6

Apart from the above, regarding farmland, since May 28, 2011, MAFF took the initiative to
conduct demonstration tests, as seen in Figure 1-4, to verify decontamination technologies forfarmland soil in Iitate Village and Kawamata Town. On September 30, 2011, MAFF compiled
the publication, “Appropriate Methods for Decontamination of Farmland.” The results ofthese demonstration tests are included in the decontamination-related guidelines described in(4) 2) of this chapter.
MAFF continued efforts to develop decontamination methods. It started demonstration
project for development of farmland decontamination technologies in February 2012 20
including verification at the construction demonstration level and studies toward practicaluse in the field as shown in Figure 1-5. In February 2013, MAFF compiled the “TechnicalBook for Farmland Decontamination,” summarizing the features of each method as shown in
Figure 1-6.

Scraping top soil
using fixation agents
Itamizawa: Test area:
10 a
Cs radioactivity: 9,100
Bq/kg
Decontamination using
highly Cs absorption plants(sunflower/amaranth)
Nimaibashi: Test area: 15 a
Cs radioactivity: 7,700
Bq/kg

Decontamination bystirring soil
Itamizawa: Test
area: 4.2 a
Cs radioactivity:
15,300 Bq/kg○Demonstration tests inother areas
Upside down plowing(deepplowing)(paddy field)
Motomiya City: Test
area: 28 a Cs
radioactivity: 4,100 Bq/kg

Iitate Village
Kawamata Town

Numanodai
ra Clear
Center
Sunflower
incineration testDecontamination using
highly cesium absorption
plants (amaranth/others)
Yamakiya: Test area: 2 a
Cs radioactivity: 5,700
Bq/kg

Basic scraping of
the top soil (paddy
field)
Iitoi: Test area: 8 a
Cs radioactivity:
10,400 Bq/kg

Tearing off pasture
Iitoi: Test area: 0.5 a
Cs radioactivity:
13,600 Bq/kg

Cs radioactivity refers to the total
concentrations of cesium-134
and -137 in the soil (Bq/kg, dry soil)

Figure 1-4 Development of decontamination technologies for contaminated agricultural soil –Overview of the demonstration tests21 .

scraping of ground soil.
20Source: Ministry of Agriculture, Forestry and Fisheries (MAFF), “Results of the Demonstration Project for

Decontamination of Farmland (Interim Report)” and the “Technical Book for Farmland Decontamination”(August 31, 2012)
21Source: Ministry of Agriculture, Forestry and Fisheries (MAFF), "Development status of decontamination
technology in agriculture, forestry and fisheries" (June 16, 2012), (also the source for Figure 1-5)

7

FY2011

FY 2012FY 2013

Urgently need for Development of the
farmland decontamination basic technology

Verification at the construction
demonstration level

Efforts to further challenges toward practicaluse in the field①Scraping topsoil②Stirring/removing with water③Upside down plowing

Summarizing the construction method or
the like as a “Technical Book for
Farmland Decontamination” (Rural
Development Bureau)

Decontamination for farmland, etc

Nuclearaccident
occurrence

Ministry of Environment“Decontamination related Guidelines"
Development of decontamination work
equipment

Volumereduction

Migration
reduction

Tractor with radioprotection function
Ridges, Slopes, Farm roads, Waterway
decontamination devices
Upside down plows for decontamination

Technology development of the farmland decontamination in the high contaminated areas,
Advance of individual technology① Technology development of safe and efficient decontamination work
② Decontamination of paddy fields not being able to apply scraping top soil or upside
down plowing paddy field③ Search of the highly radioactive material absorption plants , Elucidation of theabsorption mechanism
Hillside pasture decontamination
work devices (FY2012)

Development of the prediction technology of the
dynamics of radioactive materials
Release path of the radioactive cesium fromfarmland soil and prediction of the emission

Elucidation of the migration factor of radiocesium and Development of migration reduction technology of radioactive materials to farm products
Products of nearly practical use/verification level: rice, forage crops, wheat, vegetables, fruit trees, teaProducts of study level: soybean, rapeseed

Development of volume reduction techniques for soil/crops and others containing radioactive materials[Contaminated disposal soil] Cesium removal technology by dry method (FY2011 ~),Cesium removal technology by oxalic acid (FY2012 ~)[Weed, rice straw, etc.] Pellet production equipment/Mobile carbonization apparatus(FY2011〜FY2012)

Scheduled to be introduced in stages in the field

Figure 1-5 Research plan of radioactivity decontamination measures for agriculture after the
nuclear accident.

Process

Scraping

Collecting/Tr
ansporting

Scraping~
Collecting/Tr
ansporting(continuous)

Scraping
methods

FeatureSoil watercondition

Surfacecondition

Deviceversatility

Operator
dependence

Scraping the
topsoil withbackhoe

Scraping the topsoil by moving bucket backand forth with backhoe

Wet~Dry

Rough~landleveling

High

High

Wiper

Scraping the topsoil by letting an arm swing
to a horizontal direction using the backhoe
fitted an edge to the bucket

Wet~Dry

Rough~landleveling

MiddleLow

Standardtransporting

Packing the scraped soil into theweatherproof large sandbags using backhoe
and carry it

Wet~Dry―High

Sucking

Sucking the scraped soil through suction
pump/hose using the sludge supply anddischarge car

Dry

Conveyor

Packing the scraped soil into theweatherproof large sandbags using the screw
conveyor type shaving machine

Dry

Skimmer

Scraping the topsoil with horizontally rotating
special resin plate and loading the scraped soil
into a followed truck for the non-leveling ofgroundDryland leveling

Low

MiddleTurf stripper

Scraping the topsoil by letting a lot of small
scoop-shaped blades rotate horizontally andloading the scraped soil into a truck runningparallel for the non-leveling of groundDry

land leveling

Low

MiddleRotary cutter

Scraping the topsoil using the lawnmower
with the rotary feather fixed to a backhoe andpacking the scraped soil into the weatherproof
large sandbags in the rearDryland leveling

Low

Middle――Middle

Low

―

―

―

Figure 1-6 Options of topsoil scraping methods22 .

22Source: Ministry of Agriculture, Forestry and Fisheries (MAFF), "Overview of the Technical Book of

Agricultural Land Decontamination Measures" (February 2013)83）Formulation of manuals for radiation dose reduction measures
As mentioned in 1.1.1, the knowledge of radiation and about its influences on the human body had notbeen shared sufficiently among ordinary people in Japan before the accident occurred. The accident
raised the need for general knowledge on radiation and for information on radiation protection measures
for the accident at 1FNPS, especially among people in the affected areas. Several academic organizations
with expert knowledge of radiation published Q&A-style radiation guidebooks to provide basic knowledge
and information on radiation to the public23. The Government and Fukushima Prefecture also issued somepamphlets regarding radiation.
In addition, Fukushima Prefecture, Minami-soma City, and Fukushima City publishedseveral manuals for radiation dose reduction measures24, which contributed to provide people
with knowledge not only on radiation but also on decontamination.
Based on these guidelines as well as the results of decontamination activities shown in 2) just above,some municipalities formulated and announced their first decontamination implementation plans based on
the “Basic Policy on Urgent Implementation of Decontamination” (to be explained in the following (4)) as
early as in the autumn of 201125.
The government incorporated the contents of these manuals issued by Fukushima Prefecture andmunicipalities and the knowledge obtained through decontamination activities including model projects
into the “Decontamination Technology Catalog” and the “Decontamination Guidelines” as indicated in (4)2).

23For example, “Radiation Q&A in Life Answered by Experts” issued by the Japan Health Physics Society,“The Q&A Regarding Radiation Exposure” issued by the Japan Radiological Society, and “The Q&A
Regarding the Impact of Radiation Exposure on the Human Body in Association with the 1FNPS Accident”
issued by the Japanese Radiation Research Society.
24Examples are: Guidance for Reduction of Air Dose in Living Space issued by the Fukushima Prefectural
Government (July 15, 2011), Radioactive Material Decontamination Manual issued by the Minami-soma
Municipal Government (July 2011), and the Fukushima City Decontamination Manual (1st Ed.) issued by
the Fukushima Municipal Government (September 27, 2011).
25For example, Date City Decontamination Implementation Plan (1 st Ed.) (October 2011); Fukushima City
Furusato Decontamination Implementation Plan (September 27, 2011);
Kawauchi Village Decontamination Implementation Plan (1st Ed.) e (September 28, 2011); and Minami-soma
City Decontamination Plan (1st Ed.) (November 10, 2011)9Figure 1-7 Excerpt from a brochure on radiation (left) and a guide book on decontamination(right) published by Fukushima Prefecture26 .

（4） Establishment of legal framework and decontamination guidelines
1）Framework of decontamination under the Act on Special Measures and others
While the knowledge about radiation and decontamination was gradually being collected
and assembled, as described above, Chairperson of the Environment Committee of the lower
house of the Diet presented a bill of the Act on Special Measures Concerning the Handling ofEnvironmental Pollution by Radioactive Materials Discharged by the Nuclear Power Station
Accident Associated with the Tohoku District Off the Pacific Ocean Earthquake That
Occurred on 11 March 2011 (Law No. 110, 2011) (hereinafter referred to as the Act on Special
Measures). The Act was enacted on August 26, 2011 at the upper house plenary session andpromulgated on August 30, 2011.
The NERH decided、on August 26, 2011, the Basic Policy on Urgent Implementation of
Decontamination27 as an initiative until the full enforcement of the above act (due January 1,2012).
The above basic policy stipulated: the decontamination should be operated by the national
government for the evacuation areas;, the annual additional exposure dose should be limited
to 1 mSv or lower as a long term goal in the region under existing exposure situation(currently 20 mSv or lower for the annual additional exposure); and the national government
should provide technical and financial support for local municipalities to develop andimplement their decontamination plans. In addition, a fund was created by the
supplementary budget of the Cabinet Office to let Fukushima Prefecture subsidize (at a26Source: Fukushima Prefecture, "To understand radiation correctly and behave properly" (September 2011),

and "Guidance related to radiation dose reduction measures in the living space" (July 15, 2011)27Source: Nuclear Emergency Response Headquarters (NERH), Basic Policy on Urgent Implementation of

Decontamination (August 26, 2011)10

subsidy rate of 100%) the municipalities for decontamination based on their decontaminationplans in accordance with the Urgent Implementation Policy.
The same basic policy further stipulated that the national government should continuously
provide technical information necessary for the decontamination such as, on effective
methods, their cost, and considerations due (the Decontamination Technology Catalog),
through model projects in each area, including particularly high dose areas. In this regard,
the NERH presented the “Guidelines for the Implementation of Decontamination in
Municipalities 28 ” for relevant municipalities to formulate and implement theirdecontamination plans.
On November 11, 2011, the Basic Principles on the Act on Special Measures was authorized
by the Cabinet. Taking over the concept of the Basic Policy on Urgent Implementation of
Decontamination Works, the new Basic Policy stipulated that the annual additional exposure
dose would become below 1 mSv in the long-term in the area where the annual additional
exposure dose was currently below 20 mSv, and that the national government was responsible
for treating the wastes and wastewater sludge exceeding a certain level of radioactivity.
In the meantime, on October 29, 2011, the MOE announced the “Basic Concept of theInterim Storage Facility (ISF) Necessary in Dealing with Environmental Pollution Caused byRadioactive Materials in Association with the Accident at the 1FNPS of TEPCO,” which
stipulated the policies to install the interim storage facility at one location in Fukushima
Prefecture for handling contaminated soil and wastes produced in the prefecture and to
finally dispose of such waste outside Fukushima Prefecture within 30 years after starting ofinterim storage.
On December 22, 2011, the MHLW promulgated the “Ordinance on Prevention of Ionizing
Radiation Hazards Associated with Decontamination Works to Decontaminate Soil andWastes Polluted by Radioactive Materials Resulting from the Great East Japan Earthquake”(hereinafter referred to as the Ionizing Radiation Ordinance for Decontamination), a
framework to prevent the ionizing radiation hazards associated with decontamination work.
By such legal arrangements, the legal framework for implementing decontamination workin Japan has been fixed.

2）Decontamination guidelines
On November 22, 2011, the Cabinet Office issued the “Decontamination Technology
Catalog” and on December 14, 2011, the MOE formulated and published the“Decontamination Guidelines” that systematically compiled the decontamination methods inaccordance with the Act on Special Measures. The guidelines based on the Act on Special
Measures explained in an easy-to-understand manner the processes to survey and measure
the extent of contamination, implement the decontamination, and collect, transport, and store
removed soil associated with decontamination work (See Chapter 2 for details).
On December 22, 2011, simultaneously with the announcement of the Ionizing Radiation
Ordinance for Decontamination, the MHLW formulated and announced the “Guidelines forPrevention of Radiation Hazards to Workers Engaged in Decontamination Works,” which are
the guidelines to prevent health hazards to workers associated with decontamination
operations.
On December 27, 2011, the MOE formulated and announced the “Waste Guidelines” (theguidelines for processing waste contaminated by nuclear accident-derived radioactive
materials).
In March 2012, the MOE formulated and announced the “Guidelines for Addressing
Localized Contaminated Spots by Radioactive Materials,” which are the guidelines
summarizing the efficient locating methods, in-depth survey methods, and handlingprecautions of localized contaminated spots.
Most of the guidelines were thus developed toward the end of JFY2011.ｊ
28 Source:

Nuclear Emergency Response Headquarters (NERH), Guidelines for the Implementation of
Decontamination in Municipalities (August 26, 2011)11

（5） Efforts toward the full-fledged decontamination under a unified framework
1）Decontamination projects by the Cabinet Office
In response to the establishment of the Basic Policy on Urgent Implementation of
Decontamination Works, the Cabinet Office entrusted the project for a decontamination
model to JAEA. The project primarily targeted the areas with annual additional exposure
dose exceeding 20 mSv and had the aims of establishing efficient and effective
decontamination methods and measures of radiation protection for workers (started in
November 2011; see 1.1.6 for details).
The Cabinet Office also delegated the project to demonstrate decontamination methods to
JAEA, in order to publicly solicit new decontamination technologies that can be practicableand to evaluate their effectiveness.

2）Cold shutdown state of nuclear power station and rezoning of the evacuation areas
On December 16, 2011, the NERH judged that the safety of the entire power station wascomprehensively secured by the achievement of the cold shutdown state of the reactors. Thus,
it was confirmed that the target of step 2 in the roadmap, a state where “the release ofradioactive materials came under control and the radiation dose was significantly
suppressed,” was achieved.
Under this situation, on December 26, 2011, the NERH compiled the “Basic Concept andFuture Tasks in Review of the Restricted Areas and the Evacuation Order Areas after theCompletion of Step 2”; the basic concept to start a concrete review of the restricted areas andthe evacuation order areas, including the preparation for lifting the evacuation order of theareas with low dose rates by further advancing the decontamination work, with the targetedtime schedule to finish the review by March 30, 2012.
In response to the above, on January 26, 2012, the MOE announced the “Decontamination
Policy of the Special Decontamination Area” (Decontamination Roadmap),” describing theflow of decontamination projects (demonstration model projects, preliminary decontamination,and full-scale decontamination) and the processes for each area.
As for lifting of evacuation orders, it was prescribed that development of livelihood
infrastructures and restoration of municipal office functions should be promoted together
with decontamination because the objective of lifting of evacuation orders was to assure
returning of residents and reconstruction of their lives.

3）Establishment of a system toward full-scale decontamination
On August 24, 2011, before the establishment of the Act on Special Measures, the Fukushima
Decontamination Promotion Team was established mainly by the MOE in cooperation with the Cabinet
Office and JAEA to support the formulation of decontamination implementation planning by municipalities
in Fukushima Prefecture. The team started its operation in September 2011, immediately after the
promulgation of the Act on Special Measures, in cooperation with the Nuclear Emergency Response Local
Headquarters (hereafter referred to as the Local NERH)), to communicate and coordinate withmunicipalities and to help the formulation of decontamination plans (including dispatch of experts). The
team also promoted the national decontamination model projects in twelve municipalities in the restricted
area, deliberate evacuation areas, etc .
In academic and private sectors, in May 2011, the Atomic Energy Society of Japan (AESJ) establishedthe “Clean-up Subcommittee29” to actively provide support to the restoration activities of environmental
contamination by radioactive materials. In November 2011, the “Society for Remediation of Radioactive
Contamination in the Environment (SRRCE) 30 ,” which was mainly dealing with the subject of
29Source: Fukushima Special Project, Clean-up Subcommittee, Project Leader Tadashi Inoue, The objectivesof the establishment of AESJ CU Subcommittee and its activities (January 20, 2013)

30Source: The Society for Remediation of Radioactive Contamination in the Environment (SRRCE) Website(http://khjosen.org/）12

decontamination, and the “Technical Advisory Council on Remediation and Waste Management 31” byindustry groups, were established.
On January 4, 2012, upon the full enforcement of the Act on Special Measures, the MOE established the“Fukushima Environmental Restoration Office” as a base to promote decontamination and revive thenatural environment in Fukushima Prefecture. To promote decontamination in the Special Decontamination
Area, the office coordinates the operations with eleven municipalities in the same areas, implements
decontamination projects, and coordinates or cooperates with the Local NERH. In addition it consults andcoordinates plans and project details of decontamination implemented by municipalities in Fukushima,
Miyagi, and Iwate Prefectures. The office has five branches in Fukushima Prefecture to provide detailed
support to municipalities (in addition to the five branches, on December 5, 2014, the Hamadori Office for
the Interim Storage Facility was fonded to address the issues of the interim storage facility)32.
On January 20, 2012, the Decontamination Information Plaza was jointly established near Fukushima
Station by the MOE and Fukushima Prefecture to play the role of base facility to provide the general publicwith information on decontamination and radiation and to dispatch registered experts. The structure toward
full-scale decontamination was steadily being built. JAEA and AESJ dispatched expert personnel to the
Decontamination Information Plaza and the Fukushima Environmental Restoration Office.
On March 12, 2012, TEPCO established an office under the organization of the Environmental
Department in its Fukushima Office to monitor the environmental radiation by resident employees and toprovide support for the decontamination efforts in Fukushima. From April 7, 2012, the Federation ofElectric Power Companies of Japan dispatched decontamination experts to support the decontamination
activities in Fukushima, in addition to providing personnel to the Decontamination Information Plaza uponrequest.
In addition, the Japan Society of Civil Engineers (JSCE) established the “Specific Theme Committee toAddress Radioactive Waste” under the “Great East Japan Earthquake Special Committee,” to carry out
full-fledged activities from the beginning of 2012 33. In April 2012, the Japan Federation of Construction
Contractors established the Decontamination Committee under the Electric Measures Special Committee toestablish the framework to implement decontamination projects for the entire construction industry.
On January 1, 2013, TEPCO established the “Fukushima Revitalization Headquarters” and theDecontamination Promotion Office within it to provide further cooperation on decontamination.
As seen above, with the establishment of the Act on Special Measures, the efforts and roles of national,
prefectural, and municipal governments were restructured. As their roles were more clearly defined(Fig.1-8) and as their features became to be more utilized, the entire structure in Japan was optimized, andsystematic cooperation between industry and academia was accelerated.
In the meantime, from February 8, 2012, the Fukushima Prefectural Government held meetings of theStudy Committee for the Basic Concept of Environmental Recreation Strategic Base34. The committeestudied the establishment of the “Center for Environmental Recreation,” the base facility to address therestoration and recreation of the environment contaminated by radioactive materials, under close
cooperation among Fukushima Prefecture, JAEA, and the National Institute for Environmental Studies(NIES). The center is scheduled to open in FY2016 (a part of the facility is opening in FY2015) to provide
residents with information such as monitoring of environmental radioactivity, status of the environmental
decontamination for the remediation and recreation of the environment, tracking movements of radioactive
materials, research and evaluation of decontamination methods, and the results of monitoring and surveys,
and in addition to provide education, training, and exchanges to develop creative power for Fukushima's
future35.

31Source: Technical Advisory Council on Remediation and Waste Management Website(http://tacrwm.jp/01_about/01_01_objective.html)

32Source: Ministry of the Environment (MOE): "Fukushima environmental remediation office"33Source: Japan Society of Civil Engineers: JSCE Great East Japan Earthquake Special Committee - One

Year of Activities, Achievements, and Proposal (March 2012)
34Source: Fukushima Prefecture Website（https://www.pref.fukushima.lg.jp/sec/16035d/meeting-basicplan.html ）35Source: Center for Environmental Recreation Operative Strategy Meeting: Mid- and long term policy for theenvironmental recreation center (February 2015)13

Government approach

Prefecture approach

Municipalities approach

Basic Policy for Emergency Response on Decontamination Work

August 26, 2011 Nuclear Emergency
Response Headquarters, Decision

Act on Special Measures Concerning the Handling of Radioactive Pollution

August 30, 2011,Promulgation,
Enforcement of the part

East Japan earthquake recovery andreconstruction reserve fundSecuring of about ¥ 220 billion yen
September 9, Cabinet decision

Funds for decontamination and related
works

Funds fordecontamination
and related
works

Implementation of the decontamination
model project (since November)
Implementation of demonstration model
project of decontamination
technology(since November)

Implementation of Fukushima Prefecturesurface decontamination model project(since November)
Implementation of Fukushimadecontamination technology demonstration
operation (since December)Preparations
for public
infrastructure

Decontamination of public office by the
Self-Defense Forces (December 7 to 19)

Pre"Decontamination practice guidelines
by municipalities" (August 26,
determined by the Nuclear Emergency
Response Headquarters)

Budgetary
provisionDevelopment of "decontamination
technology Catalog", "decontamination
related guidelines"

Implementation of briefing session to themunicipalities about decontamination
Dispatch of experts

Development of "Decontamination
plan" in the municipalities
Formulated alreadyDevelopment of "Guidance related toradiation dose reduction measures in theliving space" (revised October 31)

Holding of "decontamination work seminar"
Publication of the "Basic policy on thecleanup activities for living area," "Suitable
methods for decontamination of farmland
and forests."

Decontamination practice guidelines bymunicipalities" (August 26, determined by
the Nuclear Emergency Response
Headquarters)

Holding of "decontamination work seminar"
Holding of "Safety and security forum"

Fukushima-City, Nihonmatsu-City,
Date-City, Motomiya-City, KooriTown, Kunimi-Town, KawamataTown, Otama-Village, Koriyama-City,
Tamura-City, Kagamiishi-Town,
Asakawa-Town, Miharu-Town,
Shirakawa-City, Nishigo-Village,
Izumizaki-Village, Nakajima-Village,
Yabuki-Town, Tanagura-Town,
Shinchi-Town, Soma-City,
Minamisoma-City, Hirono-Town,
Kawauchi-Village, Iwaki-City：25
municipalities (As of December 28,
2011)

Development of "municipal decontamination
planning manual"
Dispatch of experts and volunteers

January 1, 2012, full「Act on Special Measures Concerning the Handling of Radioactive Pollution」(full-scale decontamination start) enforcement
On January 4, 2012, opened the "Fukushimaenvironment revitalization office" inFukushima
Development of decontamination
implementation plan by government

Implementation of full-scaledecontamination by government

Fukushima Prefecture
Various approaches for thedecontamination① Financial support② Technical assistance③ Human support

Special decontamination area
・Designated areas
Designated areas of destricted area ordeliberate evacuation area (11municipalities)
Goal of the decontamination in theareas with not less than 20mSV/year
・Reduce those areas progressively andquickly
Goal of thedecontamination

Development of decontamination
implementation plan by municipalities

Implementation of full-scaledecontamination by municipalities
Priority investigation areas of pollution
situation
・Designated areas
Areas with not less than the radiationdose of 0.23μSV/year (102 areas)

Goal of the decontamination in the areas with less than 20mSV/year
・Long-term goal：less than 1mSV/year
・Annual additional exposure dose:
About 50% reduction by the end of August, 2013 compared to the end of August,2011
・Performing the decontamination in children's life environment with priority.
Annual additional exposure dose in those areas:
About 60% reduction by the end of August, 2013 compared to the end of August,2011

Goal of the decontamination in territories other than the areas with particularly high annual additional exposure dose
By the end of March, 2014, performing the action of decontamination in buildings such as housing, offices, public facilities, etc., roads,
farmland, and forests surrounding living area,
and transporting the removal soil produced from there to the temporary storage successively

Figure 1-8 Decontamination approaches by government, prefectural and municipal
authorities36 .

In October 2011, the International Atomic Energy Agency (IAEA) visited Fukushima, reviewed thedecontamination works performed by Japan and provided advice on them. The results were compiled in theform of the “Final Report by the International Mission Regarding Remediation of Large Contaminated
36Source: The nuclear disaster victims life support team by the government: “Interaction with the public,

newsletter No. 9 ‘ (News from the nuclear disaster victims life support team by the government)” (January
15, 2012)

14

Areas Off-site the Fukushima Daiichi Nuclear Power Plant.” The report described nine areas of significant
improvement and gave recommendations on twelve points to the Japanese government.
Examples of nine highlights of important progress and recommendations on twelve points
which were described in the Final Report 37 by the International Mission Regarding
Remediation of Large Contaminated Areas Off-site the Fukushima Daiichi Nuclear Power
Plant38.
【Examples of nine highlights of important progress】
The Mission Team appreciates that Japan has gone forward very quickly and allocated thenecessary legal, economic and technological resources to develop an efficient remediation
programme to bring relief to the people affected by the Fukushima Dai-ichi nuclear accident.
Priority has been given to children and the areas that they typically frequent.
The Fukushima Decontamination Promotion Team, which consists of resident staff inFukushima from the Ministry of the Environment (MOE), the Local Emergency Response
Headquarters and the Japan Atomic Energy Agency (JAEA), coordinates and shares information
with relevant ministries and agencies, and communicates with and provides technical support to
the Fukushima prefectural and relevant municipalities. The Mission Team welcomes Japan’s
efforts to establish a practical catalogue of remediation techniques
The Team considers the use of demonstration sites to test and assess various remediation
methods to be a very helpful way to support the decision-making process.

【Examples of recommendations on twelve points】
The Japanese authorities involved in the remediation strategy are encouraged to cautiously
balance the different factors that influence the net benefit of the remediation measures to ensure
dose reduction. They are encouraged to avoid over-conservatism which cannot effectively
contribute to the reduction of exposure doses. This goal could be achieved through the practicalimplementation of the Justification and Optimization principles under the prevailingcircumstances. Involving more radiation protection experts (and the Regulatory Body) in theorganizational structures that assist the decision makers might be beneficial in the fulfillment of
this objective. The IAEA is ready to support Japan in considering new and appropriate criteria.
It is appropriate to consider further strengthening coordination among the main actors, throughthe establishment of a more permanent liaison between the organizational structures of theGovernment of Japan and the prefectural and municipal authorities.
Before investing substantial time and efforts in remediating forest areas, a safety assessment
should be carried out to indicate if such action leads to a reduction of doses for the public. If not,efforts should be concentrated in areas that bring greater benefits. This safety assessment
should make use of the results of the demonstration tests.

（6） Progress of decontamination in the Special Decontamination Area and the Intensive
Contamination Survey Area
1）Progress of decontamination in the Special Decontamination Area
The decontamination in the Special Decontamination Area (see 1.1.5 for details) wasstarted from the peripheral areas of municipal offices by the Self-Defense Forces, which would
serve as the bases for full-scale decontamination activities later. Also, the decontamination of
37Source: IAEA, ”Final Report of the International Mission on Remediation of Large Contaminated Areas

Off-site the Fukushima Daiichi Nuclear Power Plant” (November 15, 2011)(http://www.mofa.go.jp/mofaj/saigai/pdfs/iaea_mission_1110_en.pdf )38Source: Excerpt from IAEA “Final Report of the International Mission on Remediation of Large
Contaminated Areas Off-site the Fukushima Daiichi Nuclear Power Plant; Draft translation (Summary
portion only)” (November 15, 2011)15

future operational bases such as other public facilities was made by the MOE. Additionally,
the decontamination model projects were started in March 2012 in the restricted area of the
Joban Expressway, an important piece of transportation infrastructure. These activities wereconducted as part of overall strategic efforts, which had the objectives of establishing effective
decontamination methods, while obtaining data to help implement smooth large-scaledecontamination, instead of just conducting large-scale decontamination without a strategy.
The progress in review of evacuation zoning differed by municipality in the Special
Decontamination Area. On March 30, 2012, zoning in parts of the restricted areas in Tamura
City, Kawauchi Village, and Minami-soma City were changed and these were newly
designated as evacuation order areas. In April 2012, the MOE formulated decontamination
implementation plans for Tamura City, Naraha Town, Kawauchi Village, and Minami-soma
City, earlier than for other municipalities. On July 25, 2012, the MOE started the firstfull-scale decontamination in the Special Decontamination Area in Tamura City. Then,although there were differences in progress among municipalities in the Special
Decontamination Area, the decontamination plans were gradually formulated, followed byfull-scale decontamination.
According to the Act on Special Measures, the consent of a large number of concerned
parties was required before starting the decontamination. It took a very long time to identify
the land owners and stakeholders, to pay attention to residents' feelings, and to provide
considerations and detailed explanations to obtain consent of all involved. Furthermore, withthe large- and full-scale decontamination works having started, the operators were required
to secure a large number of workers, provide education on labor safety and decontamination
works, and secure qualified workers. Each operator made various efforts to address thesemounting tasks. In the meantime, the national government kept collecting knowledge andinformation on new discoveries from actual decontamination works, shared the information
with the public in a timely manner, and reflected such summaries in the form of specifications
to the decontamination business operators (See Chapter 4 for details).

2）Progress of decontamination in the Intensive Contamination Survey Area
In the Intensive Contamination Survey Area (see 1.1.7 for details), some municipalities had
already conducted the decontamination before the full enforcement of the Act on Special
Measures. They utilized the knowledge obtained from their experiences and continued thedecontamination after the enforcement of this Act.
For example, based on the experience that it was important to form a consensus with local
residents before starting the decontamination, Fukushima City allowed the residents'
involvement from the planning stage of decontamination as shown in Figure 1-9. The city
established 18 “regional decontamination measure committees” consisting of officers of theautonomy promotion council, PTA, and local city council members. The city also conducted“decontamination implementation review meetings,” consisting of leaders of neighborhood
associations to confirm the flow of rainwater and surface water in each community and study
the work orders for decontamination. Minami-soma City made efforts to seek agreement
among residents to secure temporary storage sites by establishing the selection criteria forcandidate sites by themselves and explaining them to residents as shown in Table 1-1. In
Kawauchi Village, dosimeters were distributed to all families, so that residents themselves
were able to measure the dose before and after decontamination.
Such efforts to involve residents in the decontamination were also seen in several
municipalities outside Fukushima Prefecture. For example, in Kashiwa City, Chiba
Prefecture, the “Dialog Meeting toward Safe Living organized by the Association to Promote
Decontamination in Kashiwa City 39 ” was held during November 21-23, 2011, to havesufficiently long discussions with citizens. Consequently, the city formulated its
39Source: Kashiwa City Website（http://www.city.kashiwa.lg.jp/soshiki/080800/p010072.html）

16

decontamination implementation plan in March 201240. In the case of Kashiwa City, as aresult of the above efforts, the decontamination implementation plan allowed much
involvement of citizens by stipulating enhanced support for citizens and volunteers in thedecontamination implementation.
On the other hand, some municipalities were not able to establish temporary storage sites.
Some took a long time to decide the scope of decontamination and the formulation of thedecontamination implementation plan because they were not able to reach agreement withresidents.

Regional decontamination measure committee

Explanation of decontamination contents to regional decontamination measure committee

Decontamination implementation review
meeting,

Decision of decontamination order with decontamination implementation review meeting
consisting of leaders of neighborhood associations

Briefings to residents

Understanding of the common decontamination procedure through the residents briefing

Sending consent form / inquiry

Field survey / Dose measurement

Filling out consent form/inquiry and sending backInvestigation / measurement of each house by decontamination operators

Individual meeting

Decontamination operator visits all houses and has the meeting with the inhabitants fordetailed decontamination contents. The city check the contents (sentences) later and thenthe city office staff or a supervision personnel attends to the decontamination works.

Dose measurement before decontamination

Monitoring before decontamination, Notification of the measurements (quick estimation)

Decontamination work

・Decontamination work based on the decontamination management standard(The decontamination management standard which specified the decontamination worktarget is developed and the decontamination work is managed based on it so that thedifference doesn't occur to decontamination result (achievement) in eachdecontamination work)
・Supervision of the decontamination work by the decontamination manager entrusted by
the city

Figure 1-9 Procedure for housing decontamination (Fukushima City)41 .

40Source: Kashiwa City Website（http://www.city.kashiwa.lg.jp/soshiki/080800/p011077.html）
41Source: Fukushima City, "An approach to the decontamination in Fukushima City" (February 28, 2013)17

Table 1-1 Criteria for selecting candidate site for temporary storage42
Viewpoint

Items for selecting
site

Criteria for electing
site

ReasonSecuring of site area

Securing of site area
not less than
10,000m2

Production of a large
amount of removed
radioactive
substances

Securing of accessroad

Securing of accessroad not less than
two traffic lanes

Access of large
vehicles and heavy
industrial
machinery, etc.

Use of landDistance from thesurrounding housing,school and hospital,
etc.
Environment
protection

Risk of secondary
disaster
Influence of water
quality, animals andplantsCost performanceWith or without site
renovation
With or without siteacquisition

Distance between
candidate site andthe neighboringhouses, school andhospital, etc.
Outflow ofradioactive materials
and geologicalfeatureNo influence onwater quality,
animals and plants.
Preparation of sites
suitable for storage
and control of theremoved soil
Site acquisition in
the case of non-public
landLand ownerLand owners'
cooperation andunderstanding in thecase of non-public
land

Agreement with local
residents

Cooperation andunderstanding of thesurrounding
residents

Agreement

Impact on
consensus

Impact on
decontamination
work schedule andproject costs

Impact on
decontamination
work schedule（7） Efforts based on the experiences of decontamination
On October 23, 2012, the MOE compiled the “Decontamination Promotion Package,” inorder to accelerate the decontamination works and eliminate anxiety among residents. The
above package recommended measures to accelerate decontamination works, such as transfer
of authority to the Fukushima Environmental Restoration Office, expansion of outsourcing of
42Source: Minami-soma City, "The situation of the decontamination in Minami-soma City" (October 22, 2013)18

the negotiation of obtaining residents' consent to the private sector, and securing of
decontamination workers from a wide area. Moreover, it further recommended the measures
to obtain residents' consent and eliminate anxiety among residents, which was the major
problem then, such as disclosure of information about the effects and progress of
decontamination and strengthening of risk communication about decontamination.
Then, in November 2012, the “progress of decontamination in the Intensive Contamination
Survey Area” was announced, and in March 2013, the “progress of decontamination in theSpecial Decontamination Area” was announced, more publicly disclosing the overall progressof decontamination.
In the meantime, in January 2013, one year after the full enforcement of the Act on Special
Measures, upon receipt of reports about questionable decontamination operations, the MOE
immediately established the headquarters for proper decontamination promotion toinvestigate the questionable cases. At the same time, the Ministry compiled the “appropriate
decontamination program” consisting of three items: (1) enhancing established work
responsibilities of business operators through unannounced inspections; (2) building a wide
range of management systems by using effective monitoring by a third party; and (3) using
the MOE organization effectively such as designating a telephone hotline to accept reports
regarding questionable decontamination operations. Through these measures, the MOE tried
to eliminate questionable decontamination operations and recover the confidence of residents.
Furthermore, based on the knowledge to the date, the MOE formulated the second editionof the Waste Guidelines in March 2013 and the second edition of the Decontamination
Guidelines in May 2014. In April 2013, the MHLW formulated the “Guidelines to Prevent
Radiation Hazards of Workers Engaged in the Disposal of Radioactive Materials Discharged
by the Accident. Thus various guidelines were revised or expanded based on the experiencesof decontamination progress.
In addition, with accumulation of good practices, in May 2013, the Fukushima
Environmental Restoration Office compiled the “Examples of Good Practices in
Decontamination” and distributed its copies to the decontamination business operators. Thisbooklet introduced two categories of good practices with seven examples each: one category istechnical good practices such as survey measurement technologies, decontamination
technologies and decontamination operation management technologies, and the othercategory is communication good practices with the residents including the promotion ofunderstanding and risk communication (See Figure 1-10 for examples).
On June 29, 2013, the full-scale decontamination operations that were the first full-scale
project in the Special Decontamination Area were completed in Tamura City.

19

Example 1 of the approach: Measurement of the spatial dose rate in high places such as roof andrain gutters(Fukushima City, Koori Town)[Challenge]
The grasp of the accurate pollution status of target facilities is necessary to promote thedecontamination efficiently and to control its quality. In addition, the simplified measurement
technique such as without footings is required when the measurement of the spatial dose rate inhigh places such as roof and rain gutters is required.

[approach]
By attaching a radiation measurement device to the tip of the long things such as extension pole or
wash-line pole, it was done that the measurement personnel could measure the spatial dose rate inhigh places from the ground. With this method, it can be made easily to measure the spatial dose
rate in high places.
Example 1) Example of Fukushima City：
With attaching the sensor of the NaI scintillation counter to the tip of the wash-line pole, air dose
rates in the vicinity of a height of approximately 3m can be measured from the ground.
Example 2) Example of Koori Town:
With attaching a small video camera, a small radiation dose measuring instrument andcommunication a small radiation dose measuring device to the tip of the pole, the system which canreceive the picture of the video camera with a monitor at hand was built.
By photographing together the measurement instrument display screen and the surrounding
landscape with the video camera, pollution and radiation dose of the corresponding location can be
confirmed on the ground monitor (tablet screen).

[Reference photograph]
Example 2) Example of Koori-Town:○Measurement scenery

Measurement
situation of the dose in
the gutter on the roof
top

Display of themeasurements on thetablet screen

Combination status of
the video camera anda small radiation
measuring instrument

Figure 1-10 A good practice: Measurement of air dose rates in high places such as rooves andrain gutters43 .

43Source: Fukushima Environmental Restoration Office of the Ministry of the Environment "Good practices ofdecontamination " (May 2013)20

（8） Comprehensive review of the decontamination progress and review of thedecontamination implementation plans in the Special Decontamination Area
In September 2013, the MOE announced the “Comprehensive Review of theDecontamination Progress.” The review indicated the variations in progress among
municipalities, because of the time required for reaching agreement with residents andsecuring temporary storage sites, and also the weather conditions such as winter snowfalls(Figure 1-11).
In particular, it was difficult to secure the sites for temporary storage and to acquire theconsent for decontamination. Some residents were angry to have their area be selected as
temporary storage for the wastes that they were not responsible for. Some feared that thetemporary storage site ultimately would become the final disposal site without due
consultation. Some feared the accumulation of contaminated soil. Some had different opinions
about how to operate the decontamination. In all cases, because of the basic policy to fully
respect the will and consent of residents before proceeding with the decontamination, there
was no way but to build a trusting relationship and improve the understanding about
temporary storage and decontamination. In this regard, not only the national and the local
governments, but also the decontamination business operators and each worker madestrenuous and consistent efforts.

・Since the situations of decontamination were different in each municipality, there was the variation in the progress of decontamination
among municipalities. The importance of dealing with future issues based on the experience until now and promoting the decontamination inconnection with the progress of restoration was enhanced. indicated the variation in progress among municipalities,
・The original target schedule was revised to allow a flexible decontamination schedule in accordance with the situation of each municipality
after consulting with local inhabitants.
Review of the current
situations

Since the situations of decontamination were different in each municipality as described below, there
was the variation in the progress of decontamination among municipalities.

Cases which needed the time for adjustment before starting
decontamination are as follows;
・Review of the decontamination areas, development of thedecontamination plan
・Securing the site for temporary storage, Obtaining informed
consent for decontamination
・Corresponding to the concern about the influence on healthof radiation and the effect of the decontamination
・Corresponding to the worry about that a transfer destinationof the removed soil is not clear, because a plan for theestablishment of interim storage installation isn't fixed.

Cases which needed the time for the conditions of thedecontamination site are as follows;・Natural influence such as snowfall
・Addition of compensation duties
・Development of the work procedures and thedecontamination schedule in accordance with the situationof each municipality and progress of restoration.

Future challenges based on experience

Coordination with the situation of restoration

・Ensuring of workers (labor-intensive decontamination work)
・Enhancement of safety measures(beginner for many workers)
・Load to traffic and waste disposal treatment (movement of theworkers and transportation of the removed soil, processing ofwaste generated from the worker lodgings)

・Facilitation of coordination between the decontamination
work and restoration projects (infrastructure preparation,
restoration base servicing, changeover of land use, etc.)
・Review of the decontamination implementation plan based on
the returnees expected timing
・Review of the decontamination implementation plan taking
into account the differentiation of the indication of residents’
will on their intention of return and the time,

Future direction
・Revise the original target schedule, which would complete the decontamination and transfer the waste and soils to temporarystorage without exception within two years, and promote the decontamination schedule in accordance with the situation of eachmunicipality and progress of restoration.
・In that case, in addition to taking appropriate measures for acceleration and facilitation of decontamination, reconsider theoriginal schedule of the decontamination flexibly in accordance with the situation of each municipality and progress of restoration.
・In Tamura City, measures of the decontamination and related works based on the decontamination plan were completed. In
Naraha Town, Kawauchi Village and Okuma Town , completion of the decontamination will be aimed at by the end of fiscal year
2013 according to the current decontamination plan. In Minamisoma City, Iitate Village , Kawamata Town , Katsurao Village ,Namie Town and Tomioka Town , the present decontamination plan is continued to be adjusted with each municipality, and will
be changed by the end of the year. In Futaba Town, the adjustment is continued to be performed with the municipality towards
the development of the decontamination plan in connection with the consideration of the progress of restoration

Figure 1-11 Review results of the current decontamination plans, etc. in the Special
Decontamination Area44 .
44 Source:

Ministry of the Environment (MOE), “Overall review of the progress of decontamination"

21

Therefore, the original target schedule, which would “complete the decontamination and transfer thewaste and soil to temporary storage sites in all cases within two years,” was revised to allow a flexible
decontamination schedule in accordance with the situation of each municipality and progress of restoration.
Then where the progress differed by municipalities, the plans were revised to better fit with the actual
situation. Also reviewed was the conventional way of forest decontamination that had been previously
conducted in a range of about 20 meters from the forest edge. In the revision, for the forest surrounding theresidential areas in valleys with high dose rates as shown in Figure 1-12, if the dose rates in the areasurrounding the residential area was still relatively high after area-wide decontamination, effective
decontamination exceeding the 20-meter range from the forest edge was allowed on an exceptional basis.
In the meantime, the Forestry Agency, working from the viewpoint of forestry regeneration, has
implemented a demonstration project to integrally promote the forest maintenance and measures against
radioactive materials. As a demonstration project, in forests in the Intensive Contamination Survey Area,
forest maintenance practices such as thinning were mainly operated by public entities of the prefecture andmunicipalities. Also, through conducting the disposal and reducing the amounts of foliage generated fromforest maintenance, and through creating wood fences to control the diffusion of radioactive materials, theForestry Agency has conducted efforts to collect knowledge necessary for the smooth maintenance offorests in the areas affected by radioactive materials.
In December 2013, the review of each decontamination implementation plan based on thecomprehensive review was conducted and the “Review of the Decontamination Implementation Plans in
the Special Decontamination Area” was announced.

Area A (forest surrounding the residential areas)・If the effect of decontamination with the removal of the deposited organic matter such as fallen leaves, can not be obtained, it is permitted to remove
the residue of accumulated organic matter additionally in a range of 5-meter from the forest edge as a rough indication (as the outflow of sedimentis concerned, preventive measures against it such as the setting of the sandbag must be appropriately carried out depending on the situation in thefield).
・For the forests surrounding the residential areas in valleys with high dose rates , effective decontamination work beyond 20-meters from the forestedge may be exceptionally continued on the case-by-case basis, if the dose in the area surrounding the residential area was still relatively high after
the ongoing decontamination work is finished over relatively wide areas.
Area B (Forest users and workers enter on a daily basis)
・For bed log laying yard, if the continuation and restarting of cultivation are expected, it is permitted to remove the accumulated organic matter,such as fallen leaves, in the cultivated land and in the area in the reach of about 20m of its surrounding, according to the decontamination methodof forest in area A,
Area C (forest except area A and B)
・The Ministry of Environment takes a new approach based on the indications concerning the possible outflow of radioactive materials to the living
area from the area where understory vegetation is decline partially weathering.
・In the Forestry Agency, a demonstration project is advanced from the point of view of forest regeneration to the decontamination of the forest where
it is located outside of the living area and forestry was carried out, while dealing with radioactive materials.

Figure 1-12 Future direction of decontamination works in forests45 .
In the meantime, the policy for rivers and lakes was also announced. Previously, due to the shielding
effect of water, the existence of inflow sediment from the land, and the movement within the watersheds, it
was planned to study measures after accumulating investigation results and research while conducting
regular monitoring. In August 2014, the MOE announced the “summary of concept in the future measures
for rivers and lakes”. It stated that “the decontamination should be made as needed in the living zones withmany public activities and with high dose rate due to accumulation of radioactive cesium, when water isdried up and no shielding effect is expected”.
In October 2013, when the “Comprehensive review results of the progress of decontamination” wasannounced, as a follow-up to the IAEA international mission two years earlier, the IAEA follow-up mission
team visited to confirm the progress of the situation and to compile recommendations as given below.

(September 2013)
45Source: Forestry Agency: "Forest /forestry white paper in fiscal year 2013" (May 30, 2014)22

Examples of thirteen highlights of important progress and recommendations on eight
points which were shown in the “Final Report: The Follow-up IAEA International
Mission on Remediation of Large Contaminated Areas Off-Site the Fukushima Daiichi
Nuclear Power Plant”46,47【Examples of thirteen highlights of important progress】
The Team acknowledges the institutional arrangements implemented by Japan to address theremediation needs of the areas affected by TEPCO’s Fukushima Daiichi NPP accident. The Teamappreciates that Japan makes enormous efforts to implement the remediation programme inorder to reduce exposures to people in the affected areas, to enable, stimulate and support thereturn of people evacuated after the accident, and to support the affected municipalities inovercoming economic and social disruptions. The review Team recognizes the involvement of awide range of ministries and agencies, as well as institutions of the municipalities, to support
remediation by providing financial resources, technical guidance and institutional assistance.
The Team welcomes the critical evaluation of the efficiency of the removal of contaminatedmaterial compared with the reduction in dose rate offered by different methods ofdecontamination, recognizing that this is an important tool in the application of decontamination
methods. In addition, the Team notes a welcome change from guiding remediation efforts basedon surface contamination reduction, to a reduction in air dose rates. This is leading somemunicipalities to conclude that an additional 1 mSv per year is more applicable to long-term dose
reduction goals.
The Mission Team found significant progress in the development and implementation of
temporary storage facilities by municipalities and the National Government for contaminatedmaterials generated by on-going remediation activities. In addition, the Mission Team notes the
progress made towards the establishment of interim storage facilities by the National
Government with the cooperation of municipalities and local communities.

【Examples of recommendations on eight points】
Japanese institutions are encouraged to increase efforts to communicate that in remediation
situations, any level of individual radiation dose in the range of 1 to 20 mSv per year is
acceptable and in line with the international standards and with the recommendations from therelevant international organisations, e.g. ICRP, IAEA, UNSCEAR and WHO. The appropriate
application of the optimisation principle in a remediation strategy, and its practicalimplementation, requires a balance of all factors that influence the situation, with the aim ofobtaining the maximum benefit for the health and safety of the people affected. These facts haveto be considered in communication with the public, in order to achieve a more realistic perceptionof radiation and related risks among the population. The Government should strengthen its
efforts to explain to the public that an additional individual dose of 1 mSv per year is a long-term
goal, and that it cannot be achieved in a short time, e.g. solely by decontamination work. A
step-by-step approach should be taken towards achieving this long-term goal. The benefits ofthis strategy, which would allow resources to be reallocated to the recovery of essential
infrastructure to enhance living conditions, should be carefully communicated to the public. The
IAEA – and very likely also the international scientific community – is ready to support Japan inthis challenging task.

（9） The start of lifting of evacuation orders associated with the completion of full-scaledecontamination and other progresses, and follow-up decontamination
In April 2014, after the completion of full-scale decontamination in June 2013, theevacuation order was lifted on the Special Decontamination Area in Tamura City. On theother hand, in July 2014, the decontamination implementation plan was finally formulated in
Futaba Town, where the formulation had been delayed the longest. As a result, formulations
46Source: IAEA “Final Report: The Follow-up IAEA International Mission on Remediation of Large

Contaminated Areas Off-Site the Fukushima Daiichi Nuclear Power Plant” (January 23, 2014)（http://www.env.go.jp/press/file_view.php?serial=23734&hou_id=17656）
47Source: Excerpt from the draft translation (summary portion only) of the IAEA ”Final Report: The
Follow-up IAEA International Mission on Remediation of Large Contaminated Areas Off-Site the
Fukushima Daiichi Nuclear Power Plant " (January 23, 2014)23

of the decontamination plans in all municipalities in the Special Decontamination Area werecompleted (except areas where it was expected that residents will face difficulties in returning
for a long time), and decontamination and measures toward the lifting of the evacuation order
have been implemented.
The effects of the decontamination operations are reviewed by the post-monitoring to be
conducted at six to twelve months after the initial decontamination operations. If there areplaces with erosion of effectiveness of decontamination, the investigation will be conducted to
identify the cause as much as possible according to the individual situation. Then, by judging
the rationality and feasibility, the follow-up decontamination operations will be
implemented48.

1.1.3. Overview of the change of the evacuation area designation
As mentioned in 1.1.2, the designation of the evacuation areas was changed several times (Figure 1-13).
The outline of each evacuation area and the background to the modification of the designated areas areindicated here.
As of April 22, 2011
(At the time of completion of area setting
just after the accident)

August 2013
(At the time of review completion of area
setting)

As of October, 2014

Evacuation area map
As of October 1, 2014
LegendDifficult-to-return area
Residence restricted area
Evacuation order lifting
preparation area

Date City
Date City
Iitate Village

Iitate Village

Date City

Emergency
Deliberate
evacuation
Kawamata Town
evacuation area preparationarea
Kawamata Town

Minamisoma City
Iitate Village
Minamisoma City
Kawamata Town

Katsurao Village

Katsurao Village

Namie Town
Tamura City

Emergency
evacuation
preparation area

Namie Town
Futaba Town
Tamura City

Okuma Town

Okuma Town

Tomioka Town

Kawauchi Village

LegendNaraha Town

Ono Town

Katsurao Village

Restricted area

20km
Hirono Town

Fukushima
Daiichi Nuclear
Power Plant

Residence restricted area
Evacuation order lifting
preparation area

Futaba Town Fukushima

Daiichi Nuclear

Okuma Town Power Plant

Tomioka Town

Difficult-to-return area

Tamura City

Namie Town

Kawauchi Village Tomioka Town
Fukushima
Daini Nuclear
Power Plant

Fukushima
Daini Nuclear
Power Plant

Naraha Town

Naraha Town
Hirono Town

30km

Hirono Town

Figure 1-13 Change of the evacuation areas49 .

（1） Setting of the evacuation area and indoor evacuation area
In order to ensure the health and safety of the residents in the region around the FNPS,
based on the situation of the reactors, the NERH directed the Fukushima Governor and theMayors of other relevant municipalities to instruct their residents to evacuate or to shelterindoors, based on the "Act on Special Measures Concerning Nuclear Emergency
Preparedness" (hereinafter referred to as the Nuclear Emergency Preparedness Act). (Thedirections on sheltering were lifted on April 22, 2011.)

48Source: The 11th Environmental Remediation Study Meeting Material: Follow-up decontamination (March

20, 2014)

49Source: Ministry of Environment (MOE), Evacuation area maps created based on the document of the“Government Nuclear Disaster Victims Life Support Team”24

It should be noted that for the TEPCO’s 2FNPS the risk of a serious accident occurrence
decreased to a considerable degree in comparison with the situation on March 12, 2011 when
the nuclear emergency had been declared. Therefore, the evacuation area which had been set
as the area within the radius of 10 km from the 2FNPS was changed to the area within theradius of 8 km on April 21, 2011.

（2） Setting of the restricted area, deliberate evacuation area, and emergency evacuation
preparation area
In order to ensure smooth evacuation of residents step-by-step, besides the restricted area and deliberate
evacuation area, an emergency evacuation preparation area was set to deal with any future emergency.

1）Restricted area
In order to ensure the safety of the residents, the NERH announced to the Fukushima Governor and theMayors of other relevant municipalities that it set the area within the radius of 20 km from TEPCO’s
1FNPS as the restricted area based on the Nuclear Emergency Act (April 21, 2011). According to this
instruction, nobody, except those who were engaged in the emergency response measures, including such
public officials as firefighters, police officers, maritime officers, and self-defense force personnel, has anaccess to the area without the permission of the mayors after 00:00 on April 22, 2011.

2）Deliberate evacuation area
The NERH set the areas where the cumulative dose during the period of one year after the 1FNPS
accident might reach 20 mSv as the “deliberate evacuation area,” where evacuation to outside the area was
required for residents within roughly 1 month, in consideration of the impact on their health (April 22,2011).

3）Emergency evacuation preparation area
The NREH lifted the direction of indoor evacuation in the area within the radius of 20 km and 30 km
from TEPCO’s 1FNPS. On the other hand, under the accident situation which has not yet been stabilized,
there were some areas where the need for such refuge could not be excluded in an emergency. The NERH
designated such areas as the “emergency evacuation preparation area,” where the residents are required toprepare for being able to evacuate indoors or to take refuge in an emergency (April 22, 2011).

（3） Rezoning through lifting and reviewing of former designations
The NERH announced the concept for the review of the evacuation area. The announcement stated theevacuation orders had substantial impact on the lives of residents and it would be appropriate to review theevacuation orders, once a significant change occurred in the situation, for example, the verification ofsafety of nuclear reactor facilities was made or the reduction of dose was confirmed on the basis ofcontinued monitoring. It was decided that the evacuation area would be reviewed, revised and set as the
new evacuation designated areas according to their perspectives of recovery and reconstruction, based on
the results of radiation monitoring and the safety evaluation of the reactors and other factors,.

1）Lifting of the designation of emergency evacuation preparation area
Concerning the emergency evacuation-preparation area, which the NERH had designated between theradius of 20 km and 30 km from 1FNPS as the area where emergency responses such as evacuation might25

be requested in an emergency, the NERH decided the policy50 (August 9, 2011) when to lift thedesignation The policy dictated that the designation should be lifted when the following conditions become
foreseeable; safety evaluation of the nuclear power station, radiation monitoring results in detail in the area,
and restoration of public services and infrastructures in the area.
Based on this policy, the relevant municipalities started the development of their own “recovery plans”
according to their respective circumstances, in which the intentions of the residents were sufficiently
reflected and cooperation with the prefecture was taken into account. Each plan included support of theresidents’ smooth resettlement, reopening of public services such as schools and medical facilities,
restoration of public infrastructure, and, decontamination of school grounds and parks. At the stage when
the development of the individual plans was completed, the NERH decided to lift the designation of theemergency evacuation preparation area collectively and notified the relevant municipalities (September 30,2011).

2）Reviewing of restricted area and evacuation area
Based on the recognition of termination of the accident at TEPCO’s 1FNPS and the reduction in the riskof radiation exposure, the NERH decided a policy to lift the designation of the restricted areas (the areas
within the radius of 20 km from the nuclear power station) progressively, after making safety checks andcompleting the emergency restoration of infrastructures, and also after coordinating among the persons
concerned for disaster prevention and crime prevention measures, etc. In addition, for the evacuation areas(the restricted areas within the radius of 20 km, and the deliberate evacuation areas located beyond theradius of 20 km from the nuclear power station), it was decided to review those areas and to classify theminto three new areas cited below as shown in Figure 1-14, based on the radiation dose rates in those areas,
and after having discussions with the persons concerned (December 26, 2011). It is noted that the various
kinds of limitations were mitigated especially in the areas in which evacuation orders are being prepared
for lifting (the evacuation order lifting preparation area) as shown in Table 1-2.

Difficult-to-return area

Areas where annual cumulative dose might not be yet lessthan 20mSv even after five years

Residence restricted area

Areas where annual cumulative dose might exceed 20mSv
Distributionof the annual
cumulative
dose obtainedby correcting
the result of
the fourth
airborne
monitoring
survey to thepoint of
March 31,

Evacuation order lifting
preparation area

Figure 1-14 Review of the categories of evacuation areas into three designated areas based on
the annual cumulative dose estimated from air dose51 .
50Source: Nuclear Emergency Response Headquarters (NERH), "The basic concept on the review of

evacuation areas" (August 9, 2011)

51Source: Cabinet Office, "Review of the Evacuation Area" (October 2013) (Table 1-2 also the same source)

26

Areas in which evacuation orders are being prepared for lifting (hereinafter referred to“Evacuation order lifting preparation area”)

The evacuation order lifting preparation area refers to the area where it was confirmed that the annual
cumulative dose would not exceed 20 mSv in the evacuation areas as of December 26, 2011. In those areas,
the evacuation orders are still continued, but the supporting measures for recovery and reconstruction, suchas decontamination, infrastructure restoration, employment promotion, should be taken quickly, andresidents’ return as soon as possible should be the aim.
It is noted that the evacuation orders will be lifted based on sufficient consultations with authorities ofthe prefecture and municipalities, and residents, under the condition that the infrastructures indispensable todaily life are almost restored, such as electricity, gas, water and sewerage systems, main transportation
networks, and postal and communication services, and the life-related services including medical andnursing care, and at the stage in which the decontamination works mainly for the living environment ofchildren are progressed sufficiently.
When lifting the evacuation order, the circumstances of each municipality have to be consideredsufficiently. Therefore, the evacuation order should be lifted, not simultaneously in the whole area, butwhen each relevant municipality considers individually most appropriate. It can be also lifted step-by-stepeven within one municipality.
Areas in which residents are not permitted to reside (hereinafter referred to as the“Residence restricted area”)
The residence restricted area refers to the areas where the annual cumulative dose might exceed 20 mSv
among the evacuation areas as of December 26, 2011, and that subsequently require continued refuge fromthe viewpoint of reducing the dose of the residents. In those areas, decontamination works andinfrastructure restoration, etc. are carried out premeditatedly, aiming at the residents’ return andreconstructing of the community in the future.
In addition, it has been decided to shift those areas to the “evacuation order lifting preparation area,”
when it is confirmed that the annual cumulative dose that inhabitants receive will not exceed for sure 20
mSv due to the decontamination works and the natural decay of radioactive materials.
Areas where it is expected that the residents have difficulties in returning for a longtime (hereinafter referred to as the “Difficult-to-return area”)
The difficult-to-return area refers to the areas among the evacuation areas where the annual cumulative
dose might not be yet less than 20 mSv even after five years, and exceeds 50 mSv as of December 26, 2011.
According to the principle that the residence would be restricted in those areas for the future, it was decided
that the designation of those areas would not be reviewed for five years. However, even in that case,according to contamination level due to radioactive materials in the future, the contents of the planning forreconstruction and restoration in related municipalities and the situation of their implementation, it was
decided that the implementation of the review of those measures be considered.
It should be noted that the evacuation areas were reviewed and classified into three new designated areasusing air dose rates basically as mentioned above. However, the distribution of air dose rates is complicatedand is not uniform. Therefore, it was considered to be a basic principle from a practical viewpoint to avoid
division of a community and to set the whole of the administrative section unit as one area within the newly
classified areas, based on the dose level which occurs in most places within the administrative section unit.
Review of the evacuation areas was performed through coordination with the relevant local
municipalities and residents. The designation of the area classification is closely related to the timing ofreturn and the compensation. Therefore, there were some areas that needed much time for the adjustment.
As a result, it was not until August 2013 that the review of all evacuation areas was completed.

27

Table 1-2 Mitigation of the limits due to the review of the evacuation areas
After review
Beforereview

Difficult-to
Evacuation order
Residence-return
lifting
restricted area
area
preparation area

Change before and after
the review of areas

△

×

○

○

Accessible to home, etc.
(excluding thedifficult-to-returnareas) (Notes 1)

×

×

×

×

―

Special staying

×

×

○

○

Allowed to stay athome during certain
time-period(Notes 2)"Staying for the
preparations for the return
to hometown"

×

×

○

Permitted long-termstaying if certain
requirements are met.

Starting of new companies
and business activities(company invitations, etc.)

×

×

△

(Notes4)○(Notes5)

Allowed to invite newcompanies

Reoperation of existing
companies and businesses

×

×

△

○

(Notes4)(Notes5)

Farming/Forestry

×

×

△

(Notes6)(Notes6)

Access to area

Staying at home, etc.

＊Accessible
in deliberate
evacuationarea

A r e a c o ntr o lBudgetTax (forbusinesses)

Reconstruction restoration businesses

Living environment
improvementbusinesses

×

Return andrestoration
acceleration business(Notes3)×○○(Notes7)(Notes7)

○

○

―

○

○

○

Special depreciation,etc., or tax credits tocapital investment

×

×

○

○

Tax credit for salaries
to employees

×

×

○

○

Permitted reoperationof the existing
businesses
Permitted restarting ina part of the evacuation
areas

Acceleration ofreconstruction andrestoration businesses

Realization of thetreated well businessenvironment (except
for return difficult
areas)(Note 1) Allowed temporary access to the residence restricted areas and evacuation order lifting preparation
areas within the extent that municipalities recognize this. A year-round open system (temporary
access to those areas once every month (Except for January and April) on the day when inhabitantshope) is being conducted in Okuma Town, Tomioka Town, Namie Town and Futaba Town.
(Note 2) It is possible to stay overnight during a certain period of time, based on application to authorities ofthe municipalities and after the confirmation of the nuclear disaster site headquarters. The total
number of residents to stay overnight was 1,870 in New Year, Golden Week and Spring and Autumn
Equinox Festivals (implemented municipalities: Kawauchi Village, Tamura City, Minami-soma City,
Iitate Village, Katsurao Village and Kawamata Town).
(Note 3) In principle, the long-term staying applies to the evacuation order lifting preparation areas. Even in
residence restricted areas, if the requirements are met, on the basis of consultation with the chiefs ofmunicipalities and the head of nuclear disaster site response headquarters, long-term staying ispermitted.
(Note 4) For the businesses that are indispensable in the restoration and reconstruction and recognizedexceptionally, and the businesses that are not intended for residents (financial institutions, waste
disposal treatment facilities, gas stations, manufacturing industries, etc.), it is possible to start thebusiness operations after passing through the predetermined procedures.
(Note 5) As a general rule, the starting of the business to target the residents is impossible. However, forhospitals, welfare nursing facilities, restaurant businesses, retail trade and services, etc., thestarting of the preparation works for implementation of businesses such as new construction andrepair of facilities, receiving of materials and equipment, and inventory control, is possible.
(Note 6) Farming in the evacuation order lifting preparation area can be restarted based on the planting
restrictions of rice and the status of decontamination. On the other hand, in the residence restricted
areas, it is possible to carry out the maintenance and management of agricultural lands. It is also
possible to carry out the planting demonstration projects etc., aiming at restart of farming in thoseareas, which are performed under the participation of public organizations of municipalities.
(Note 7) Living environment improvement businesses are limited only if those are deemed necessary forreconstruction and restoration toward the designation of the evacuation order lifting preparation area.

28

1.1.4. Outline of the Act on Special Measures Concerning the Handling of Environmental
Pollution by Radioactive Materials Discharged by the Nuclear Power Station Accident
Associated with the Tohoku District-Off the Pacific Ocean Earthquake that Occurred on March
11, 2011（1） Act on Special Measures
1）The point of the Act on Special Measures
This Act was established to address the urgent issue of reducing promptly the impact of environmental
contamination on human health and the living environment caused by radioactive materials, which had
been released by the nuclear power plant accident associated with the Great East Japan Earthquake. It
defines that the basic principles regarding the handling of the environment pollution caused by radioactive
materials are determined in a cabinet meeting, and that the monitoring and measurement are carried out todetermine the status of the environmental contamination by accident-derived radioactive materials. It also
sets the matters relating to the disposal of wastes and the matters on measures for decontamination of soil,
etc. contaminated by radioactive materials.

2）The Basic Principles under the Act
The Basic Principles under the Act provide a decontamination framework and were approved in the
Cabinet meeting on November 11, 2011.
The following goals have been established in the Basic Principles.
The areas where the annual additional exposure dose exceeds 20 mSv are aimed to be
reduced in size step-by-step but as quickly as possible. However, it is necessary to note thata long-term approach is required for the areas where the radiation exposure dose isparticularly high.
The specific decontamination goals in these areas shall be set in the future based on theeffect of decontamination measures of soil and wastes, the results of demonstration model
projects and other development.
For the areas where the annual additional exposure dose is below 20 mSv, the following
goals are set.
The annual additional exposure dose decreases to 1 mSv/y or less in the long-term.
The annual additional exposure dose of the general public is reduced by about 50%
by the end of August 2013 as compared with that at the end of August 2011, by
including physical attenuation of radioactive materials and other factors..
It is important to restore the environment where children can live without fear.
Therefore, the goal is set to reduce the annual additional exposure dose of children
by about 60% by the end of August 2013 as compared with that at the end of
August 2011, by decontaminating their living environment such as schools andparks in high priority and including physical attenuation of radioactive materials..

These goals will be reviewed appropriately based on the effects of measures of the decontaminationof soil, etc.
In addition, for the Special Decontamination Area excluding the areas with particularly high additional
exposure dose, the schedule to complete the decontamination in those areas in approximately two years wasshown; “by the end of March 2014, measures for the decontamination of soil, etc., are carried out in
residences, offices, buildings of public facilities, roads, farmlands, forests around the living space, etc., andsoil removed by decontamination works is conveyed to the properly managed temporary storage sites one
after another”.
Further, for the areas with particularly high additional exposure dose, it was indicated that the National
Government should implement demonstration model projects first.
29

Basic Principles (Cabinet Decision 0n 11 November)
Establishment of implementation system by the Ministry of Environment and other relevant Office and Ministries ( 18 November)

Cabinet Orders and Ministerial Ordinances on requirements for the designation of areas, treatment standards, etc. (14 December promulgated)
Waste

Decontamination
Designation of Special Decontamination
Areas (Restricted Area and Deliberate
Evacuation Area)

Designation of Intensive Contamination
Survey Areas (Annual additional
exposure:1mSv or more)

Designation of Contaminated Waste
Management Areas (Restricted Area andDeliberate Evacuation Area)

Local systemestablished

Preceding decontamination by national gov.

Jan. 2012: the Act
came into full effectPreparation fordecontamination works under
the direct control of national
government.

Preparation bymunicipalities

Formulation of
Decontamination
Plan by national
government.

Formulation of
Decontamination
Plan by eachmunicipality

Formulationof Treatment
Plan bynational
government.

Designation of
Designated Waste(Over 8,000Bq/kg)

Securing temporarystorage sites

Launch of fullscale
decontamination
by national
government.
2015

Preparation for treatment under the directcontrol Of national government.

Launch of fullscale
decontamination
by municipalities

Treatment of the designatedwaste and the waste
generated in theManagement Areas bynational government.

Securing interim storage facility and starting to bring the waste from temporary storage sites in Fukushima Prefecture

Decontamination targets

Target for areas with less than 20mSv/ya. The annual additional exposure dose decreases to below 1 mSv in the long-term.

Target for areas with 20mSv or more in one
year
Reduce the size of the areas step-by-stepbut as soon as possible.

b. Reduce the annual additional exposure dose by about 50% by the end of August
2013, when compared with that at the end of August 2011.
c. Reduce the annual additional exposure dose of children by about 60% by the endof August 2013, when compared with that at the end of August 2011, bydecontaminating their living environment in high priority

Target for areas with 20mSv/y or more,

Target for the areas under the direct control of national gov. excluding the areas with particularly high annual additional exposure dose
By the end of March, 2014, the decontamination works are to be completed in residences, offices, buildings of public facilities,
roads, farmlands, forests around the living environment, etc., and soil removed by the decontamination works is conveyed to thetemporary storage sites one after another.

Figure 1-15 Outline of the Implementation of the Act on Special Measures52.

（2） Urgent implementation basic policy on decontamination
As indicated in 1.1.2.(4) 1), prior to the promulgation of the Act on Special Measures, the "Urgent
Implementation Basic Policy on Decontamination" was announced on August 26, 2011 by the NERH. In it,
the following five items were defined as the provisional targets in implementing the decontamination.

52 Document of Ministry of the Environment

30

(i)

Based on the 2007 basic recommendations of the International Commission on
Radiological Protection (ICRP) and the “basic concept” of the Japanese Nuclear
Safety Commission, the areas with the situation of emergency radiation
exposure (the annual additional exposure dose exceeds currently 20 mSv) are aimed
to be reduced in size step-by-step but as quickly as possible.

(ii) For the areas with the situation of existig exposure （the areas where the annual
additional exposure dose is 20 mSv/y or less), the aim is to reduce the annual
additional exposure dose to 1 mSv/y or less in the long term.
(iii) As a specific target of decontamination implementation in the areas contaminated byradioactive materials, it is aimed that the estimated annual exposure dose of thegeneral public be reduced by about 50% in two years.
According to the NERH provisional estimates, the estimated annual exposure dose
after two years will be reduced by about 40% compared with the estimated annual
exposure dose at present, by physical attenuation of radioactive materials and by
natural factors such as wind and rain (weathering effect).
By reducing at least approximately 10% of the exposure dose by decontamination
works, the above target of 50% reduction of the exposure dose will be achieved. In
addition, further reduction of exposure dose will be pursued.
(iv) It is important restore the environment where children who are more susceptible toradiation than adults can live in peace as before. Thus, it is aimed that the estimatedannual exposure dose of children be reduced by about 60% in two years throughthorough decontamination works in their living environment such as schools andparks.
According to the NERH provisional estimates, the estimated annual exposure dose ofchildren after two years will be reduced by about 40% compared with the estimatedannual exposure dose at present, by physical attenuation of radioactive materials
and by natural factors such as wind and rain (weathering effect).
By reducing at least approximately 20% of the exposure dose by decontamination
works, the above target of 60% reduction of the exposure dose will be achieved. In
addition, further reduction of exposure dose will be pursued.
(v) The targets mentioned above are the provisional targets being set based on limited
information in order to urgently implement the decontamination works. Thoseshould be examined and reviewed on a timely basis through detailed monitoring andaccumulation of data, survey of actual exposure dose of children, anddecontamination demonstration model projects.

In addition, the "Urgent Implementation Basic Policy on Decontamination" mentioned that for theachievement of these provisional targets, the National Government would continuously provide technicalinformation ("a technical catalogue") necessary for the decontamination works, including effective
decontamination methods, costs, precautions to make, which would be obtained through the demonstration
model projects and the approach how to proceed with decontamination of each area depending on the
difference in dose. The following four points were mentioned as the methods for "treatment of soil, etc.
produced by decontamination works".
(i)

The treatment of soil generated as a result of decontamination works, and rice straw,
compost and debris that exist in the region, are indispensable for the implementationof smooth and quick decontamination works.
(ii) For treating such soil and wastes, the National Government takes responsibility forsecuring of their disposal sites where long-term management is required, andensuring their safety. The National Government would publish a road map for theconstruction as quickly as possible.
31

(iii) However, in order to take these fundamental measures, time for securing anddevelopment of disposal sites of a certain size will be required. If we wait until suchdisposal sites are ready, it might delay quick decontamination.
(iv) Therefore, it is realistic for the time being that soil and wastes generated as a resultof decontamination works are stored in temporary storage sites in each municipality
or community. The National Government should continue all possible efforts to
support municipalities in financial and technical aspects.
The Basic Principles of the Act on Special Measures shown in 1.1.4 (1) 2), are intended to take over the"Urgent Implementation Basic Policy on Decontamination."（3） Prevention of radiation hazards due to decontamination works
The MHLW enforced the Ionizing Radiation Ordinance for Decontamination” on January 1,
2012, as a measure to reduce the radiation exposure dose of workers who were engaged insuch works as decontamination works (hereinafter referred to as "decontamination workers").
Then, in July 1, 2012, the Ionizing Radiation Ordinance for Decontamination was revised to
expand the applicable works in order to include the prevention of radiation hazards to theworkers who were engaged in restoration/reconstruction and related works.
The main features of the Ionizing Radiation Ordinance for Decontamination are given below. The
Ordinance is applied to the business operators for decontamination or works under a designated dose rate,
their employees engaged in decontamination or works, under a designated dose rate.
(1) Basic principles of prevention of radiation hazards(2) Limits and measurement of dose(3) Measures concerning the implementation of decontamination and related works(4) Prevention of contamination(5) Special education, medical examinations, and others
Further, the MHLW developed the following two guidelines in order to enable business operators andtheir workers to perform decontamination related works in accordance with the Ionizing Radiation
Ordinance for Decontamination.
Guidelines for the prevention of radiation hazards of workers engaged in decontamination
works, etc.
Guidelines for the prevention of radiation hazards of workers engaged in works under adesignated dose rate

These guidelines specify the items such as protection measures, medical examination offices and others.

1.1.5. Overview of the Special Decontamination Areas（1） Requirements and designated situations for the Special Decontamination Area
The Special Decontamination Area is specified according to the Act on Special Measures as the area
where the decontamination plans are developed by the MOE and the decontamination work is conductedunder the direct jurisdiction of the National Government. It basically corresponds to the areas that were therestricted area within the 20 km radius from the TEPCO 1FNPS and the areas that were the deliberate
evacuation area where the cumulative exposure dose for one year after the accident might exceed 20 mSv.
Specifically, as shown in Figure 1-16, the whole area of Naraha Town, Tomioka Town, Okuma Town,
Futaba Town, Namie Town, Katsurao Village and Iitate Village, and the areas that were restricted areas ordeliberate evacuation areas in Tamura City, Minami-soma City, Kawamata Town, and Kawauchi Village
correspond to the Special Decontamination Area.

32

Soma City

Date City

Iitate Village
Kawamata Town

Nihonmatsu City

Minamisoma City

Special decontamination area
Katsurao Village
Namie Town

Futaba Town

Tamura City

Okuma Town

Fukushima
DaiichiNuclearPower Plant

Tomioka Town
Kawauchi Village

Fukushima
Daini Nuclear
Power Plant

Ono Town
Naraha Town
Specialdecontamination area

Iwaki City

Hirono Town

Figure 1-16 Special Decontamination Area53 .

（2） Structure of the decontamination works in the Special Decontamination Area
The decontamination for the Special Decontamination Area was scheduled based on the following basic
policies. As shown in Figure 1-17, the decontamination implementation plans were developed at first by the
Minister of the Environment. Preliminary decontamination for municipality offices and infrastructure
facilities were conducted, while model projects were conducted by the Cabinet Office and the MOE, andthen, full-scale decontamination is performed. As shown in Figure 1-18, the decontamination works have tobe advanced while obtaining the landowners’ consents because it is necessary to enter people’s property to
conduct full-scale decontamination
It is also necessary to secure temporary storage sites because a large amount of removed soil andcontaminated wastes are generated as the decontamination works progress.

53Source: Ministry of the Environment (MOE), "Request for the cooperation for decontamination works"(February, 2012)33

January

February

March

Plan

Decontamination implementation planin special decontamination areas

Demonstration
model projects fordecontamination

Model projects by the Cabinet Office

Apri

May

June

July

after summer

High-dose areas (model project by the Ministry of Environment)＊ Lessons learnt are reflected at
any time

Government offices, community centersPrior
decontamination

Joban expressway (model project by the Ministry ofEnvironment), etc.
Infrastructure facilities such as water supply and seweragefacilities, etc.

Confirmation/grasp of stakeholders
Briefing session
for Residents

Radiation monitoring of structures, housing, etc
Full-scaledecontamination

Full-scaledecontamination

Surveying the condition of structures, housing, etc.
Reaching consensus with stakeholders
Schedule as agreed with stakeholders

Start of decontamination works
Receiving soil and wastes (at any
time)

Temporarystorage sites

Surveys, preparations and storage

DesignFigure 1-17 The short-term decontamination roadmap for Special Decontamination Area54.

Grasp of thecaretakers(owners) of
the land

60,000households
surveyResidents
briefing
session about
field surveys

Radiation
monitoring /Survey ofstructures,
housing, etc.
(field survey)

Decision of thedecontaminati
on method

Several tens of thousands ofhousing survey (5 months)

Agreement of theaccess to housing, etc.

Decontamination
works

Post radiation
monitoring

Completion/(Continuous
monitoring)

Ordered as meeting thecondition

Confirmation of
decontamination
method, Reachingconsensus withdecontamination

Report of the resultsof dose reductions

Communication with the caretakers (owners) of the land
Figure 1-18 Flow chart of the decontamination steps.

54Source: Ministry of the Environment (MOE), "Decontamination Policy for Special Decontamination Areas(Decontamination Roadmap)" (January 26, 2012)(Figure 1-18 through Figure 1-20)

34

In addition, the Special Decontamination Area is classified into three areas depending on the level of
exposure doses. Decontamination is due to start from the areas of the low exposure dose level, as shown in
Figure 1-19, because the difficulty differs depending on radiation levels. The targets of decontamination ineach area are as shown in Figure 1-20.

FY 2011

Full scale decontamination

January
Areas whichbecomeevacuation
order lifting
preparationarea(*)*Areas with
20mSv/y or
lessAreas whichbecomeresidence
restrictedarea(*)*Areas with
20mSv/y 50mSv/y・Technology
demonstration bymodel projects
・Priordecontamination ofmunicipal offices
・Monitoring dose
rates nearstructures
・Surveying thecondition of
structures
・Reaching consensus
with stakeholders＊Plan and
implementation
taking into accountsite specificfeatures of eachmunicipality

Areas whichbecome difficultto-return area(*)
*Areas morethan 50mSv/yTemporarystorage site

FY 2012
April

July

FY 2013

October

April

July

OctoberJanuary

Areas with 10 – 20mSv/y(Schools with 5 – 20mSv/y)Areas with 5 – 10mSv/yAreas with 1 – 5mSv/yAreas with 20 – 50mSv/yDecontamination works arestarted with meeting theconditions such as reaching of theagreement with residents andsecuring of the temporary storage
sites

Verification ofdose rate
reductions

Demonstration model projects

DesignJanuary

after FY 2014

Receiving and control
Surveys and preparations (schedule as agreed with local community)

Figure 1-19 Decontamination roadmap for each new evacuation order area.

35

○By around the end of this fiscal year, decontamination implementation plan for special decontamination areas will be developed.
Based on the plan, full-scale decontamination works should be performed.
○ Evacuation areas will be reviewed and classified into three new evacuation areas based on the level of air dose rate, anddecontamination will be implemented in cooperation with the perspectives of recovery and reconstruction.
○ The prospects for securing of the temporary storage sites, and the aspects of smooth securing of workers must be considered in
the plan.
○ Model projects and prior decontamination are carried out parallel. The knowledge obtained through them is reflected
appropriately .

Policy for full-scale decontamination
Areas which become evacuation order lifting preparation area(*) *Areas with 20mSv/y or less・By around the end of 2012, aiming for the decontamination of the areas with 10 ~ 20mSv / y (Schools, etc.
with 5 – 20mSv/y(1- 4μSv/h))・By around the end of March, 2013, aiming for the decontamination of the areas with 5 ~ 10mSv / y.
・By around the end of March, 2014, aiming for the decontamination of the areas with 1 ~ 5mSv / y.
・Specific targets in the areas are reflected in the plan, taking also into account the results of the model projects.
・Aiming to less than 10mSv / y for the areas with 10mSv / y or more for the time being.
Aiming at 1μSv/h or less for schools, which is a criteria of the reopening of the schools.
Areas which become residence restricted area(*) *Areas with 20mSv/y - 50mSv/y・Aiming at decontamination from FY2012 to FY2013.
・Aiming at the reduction of the size of the areas step-by-step but as soon as possible.
Areas which become difficult-to-return area (*) *Areas more than 50mSv/y・Carrying out model projects for the time being.

Implementation policies andtargets of the specificdecontamination for eachmunicipality are developed
flexibly in coordination withstakeholders.

Main steps of the full-scaledecontamination④Radiation monitoring/Surveying the condition of
structures, housing, etc.
⑤Reaching consensus for decontamination with caretakers⑥Implementation of decontamination works①Grasp of the caretakers (owners) of the land to be
decontaminated②Briefing session for Residents③Agreement of the access to housing, etc.

The development of the contents of this road map is planned and is utilized in planning and project
implementation in future

Figure 1-20 Points for the policy on the decontamination in the Special Decontamination Area.

Along with these decontamination framework in the Special Decontamination Area, the MOE carried out
detailed monitoring from November 7, 2011 through February 28, 2012, in the areas where the National
Government should perform decontamination, and the air dose rate distribution was clarified to some extent
based on the measurement results.
The Government also carried out decontamination model projects (see 1.1.6 for details), collected
knowledge about the decontamination, and then developed the common specifications of decontamination
works (“Common Specifications”) for the National Government to order decontamination works.
Furthermore, the MOE held residents’ briefing sessions prior to performing preliminary decontamination
works, and acquired the agreement of the residents before carrying out major decontamination works. At
the stage when preparations for ordering of the decontamination works had been completed, the MOE
ordered decontamination works using the Common Specifications for decontamination works.
It should be noted that not only the provision of education to decontamination workers but also theproper management of the decontamination works are important because of the large-scale of thedecontamination works. Thus, various efforts were being taken for decontamination works (See Chapter 4
for details).

（3） Review of decontamination implementation plans in the Special Decontamination Area
In the middle of fiscal year 2013 that is the last fiscal year of the original decontamination work period inSpecial Decontamination Areas, the MOE performed the “comprehensive check and review of the progressof decontamination works” (those findings were announced on September 10, 2013). The MOE discussed
future decontamination plans with each municipality based on these results, and revised thedecontamination implementation plans in the Special Decontamination Area to more realistic ones based on36Article 29, Clause 1 of the Act on Special Measures,. The outline is indicated below.

1）Outline of the comprehensive check and review
The original target schedule, in which all the decontamination works had been planned
to be completed and the wastes and soil to be transferred to temporary storage sites
without exception within two years (by the end of March, 2014), should be revised toallow a flexible decontamination schedule in accordance with the situation of eachmunicipality and progress of restoration.
At that time, the measures to accelerate decontamination and to progress smoothly
should be taken, and decontamination plans should be reviewed flexibly according to
the progress of reconstruction.
In Tamura City, decontamination works were completed in accordance with thedecontamination implementation plan. In Naraha Village, Kawauchi Village andOkuma Town, decontamination works are aimed at completion in the fiscal year 2013in accordance with the current plans and schedules. For Minami-soma City, Iitate
Village, Kawamata Town, Katsurao Village, Namie Town and Tomioka Town, the MOE
continues to coordinate planning with each municipality and will revise the current
plans and schedule of works within the year. For Futaba Town, the development of thedecontamination plan will be continued in coordination with reconstruction measuresand the situation of the town.

2）Overview of the review of the plan
For Minami-soma City, Iitate Village, Kawamata Town, Katsurao Village, Namie Town,
and Tomioka Town, the comprehensive check and review in September decided torevise their decontamination plans by around the end of 2013. The revised realisticschedules are to be established through the consultation with each community
concerned in view of current situations.
Priority is to be placed on the decontamination of residential land and its neighborhood
which is important for the residents' return. The implementation schedules of thedecontamination works in each of the municipalities are shown in Table 1-3.
Infrastructures, such as water supply, sewage systems and major roads should be
decontaminated in advance in line with the progress of reconstruction activities bycoordinating with related organizations.
In implementing the projects, measures shall be taken to accelerate and advance thedecontamination more smoothly, and to shorten the work period to the extent possible.
The project schedules shall be thoroughly managed and the progress of thedecontamination works shall be made transparent.
Based on these, the decontamination plans in the subject six municipalities have beenrevised.

37

Table 1-3 Revised decontamination schedules55
Minami-soma
City

The decontamination of residential land and its neighborhood isprioritized, aiming to be completed in the fiscal year 2015.
The decontamination works of other places aim to be completed in thefiscal year 2016. Furthermore, efforts are made to accelerate andadvance the decontamination more smoothly, and to shorten the work
period to the extent possible.

IitateVillage

The decontamination of residential land and its neighborhood isprioritized, aiming to be completed in the fiscal year 2014.
Furthermore, efforts are made to accelerate and advance thedecontamination more smoothly, and to shorten the work period to theextent possible, aiming at the completion by the end of the year 2014.
The decontamination works of other places aim to be completed in thefiscal year 2016. Furthermore, efforts are made to accelerate andadvance the decontamination more smoothly, and to shorten the work
period to the extent possible, aiming at the completion by the end of theyear 2016.

Kawamata
Town

The decontamination of residential land and its neighborhood isprioritized, aiming to be completed in the fiscal year 2014.
Furthermore, efforts are made to accelerate and advance thedecontamination more smoothly, and to shorten the work period to theextent possible, aiming at the completion in the summer of 2014.
The decontamination works of other places aim to be completed in thefiscal year 2015. Furthermore, efforts are made to accelerate andadvance the decontamination more smoothly, and to shorten the work
period to the extent possible, aiming at the completion by the end of theyear 2015.

Katsurao
Village

The decontamination of residential land and its neighborhood isprioritized, aiming to be completed in the fiscal year 2014.
Furthermore, efforts are made to accelerate and advance thedecontamination more smoothly, and to shorten the work period to theextent possible, aiming at the completion in the summer of 2014.
The decontamination works of other places aim to be completed in thefiscal year 2015. Furthermore, efforts are made to accelerate andadvance the decontamination more smoothly, and to shorten the work
period to the extent possible, aiming at the completion by the end of theyear 2015.

Namie
Town

The area-wide decontamination in the decontamination designatedareas except for the tsunami disaster areas (Minamitanashio,
Ukedokita, Ukedominami, Nakahama, Morotake) is prioritized, aiming
to be completed in the fiscal year 2015.
While taking into consideration the treatment status of disaster wastes
in the tsunami disaster areas, the decontamination of residential land
and its neighborhood is prioritized, aiming to be completed in the fiscal
year 2015. The decontamination works of other places aim to becompleted in the fiscal year 2016. Furthermore, efforts are made toaccelerate and advance the decontamination more smoothly, and to
shorten the work period to the extent possible.

TomiokaTown

The decontamination of residential land and its neighborhood isprioritized, aiming to be completed in the fiscal year 2015.
The decontamination works of other places aim to be completed in thefiscal year 2016. Furthermore, efforts are made to accelerate andadvance the decontamination more smoothly, and to shorten the work
period to the extent possible.

FutabaTown

Coordination shall be continued for the development of thedecontamination plan, taking into account the results of model projects,
picture of reconstruction plan, and the level of radiation dose, etc.

※For implementation of the decontamination works, developing the decontamination plan, securing the temporarystorage sites, reaching agreement with land owners, and securing of workers are preconditions.

55Source: Ministry of the Environment (MOE), "Review of decontamination implementation plan in s"(December 2013)38

（4） Progress of the decontamination in the Special Decontamination Area
Figure 1-21 shows the decontamination status in the Special Decontamination Area as of March 2015.
Even in Futaba Town, where the schedule of decontamination works had been delayed, thedecontamination implementation plan was developed and decontamination works are due to start soon.
Meanwhile, in Tamura City and Kawauchi Town, decontamination works were completed, and all or part ofthe evacuation orders have been lifted.
Completion/Evacuation
order lifting
Completion
Started alreadyOrdered alreadyNot ordering

Residential land almost
completion; December,
2014

Tamura City
Kawauchi Village

Special decontamination area
Difficult-to-return area

Completion of area-wide decontamination works in March, 2014

Okuma Town

Completion of area-wide decontamination works in March, 2014

Katsurao Village
Kawamata Town
Iitate Village

Residential land
Completion； July,2015

Minamisouma City

Evacuation order lifting(evacuation order lifting
preparation area); October, 2014

Completion of decontamination works in June, 2013
(Opening between the Hirono IC - Joban Tomioka IC on February 22, 2014 )(Opening between the Namie IC - Minamisoma IC on December 6, 2014 )(Opening between the Namie IC - Joban Tomioka IC on March 1, 2015 )Completion of decontamination works for residential land in July, 2014
Aiming at the completion of the works for other places in the year 2015
Completion of decontamination works for residential land in August, 2014
Aiming at the completion of the works for other places in the year 2015
Aiming at the completion of decontamination works for residential land in thefiscal year 2015
Aiming at the completion of the works for other places in the year 2016
Aiming at the completion of decontamination works for residential land in thefiscal year 2015
Aiming at the completion of the works for other places in the year 2016

Namie Town

Aiming at the completion of decontamination works for the areas except for
the tsunami disaster areas in the fiscal year 2015
For the tsunami disaster areas, aiming at the completion of decontamination
works for residential land in the fiscal year 2015
and at the completion of the works for other places in the fiscal year 2016

Tomioka Town

Aiming at the completion of decontamination works for residential land in thefiscal year 2015
Aiming at the completion of the works forother places in the year 2016

Futaba Town

Aiming at the completion of decontamination works in the fiscal year 2015

Evacuation orderlifting; April, 2014
Area-wide
completion; March,
2014

Completion of area-wide decontamination works in March, 2014
Lifting of the evacuation order in evacuation order lifting preparation area on
October 1, 2014

Naraha Town

Joban Expressway

Residential land
completion; August,2014

Completion of area-wide decontamination works in June, 2013
Lifting of the evacuation order on April 1, 2014

Figure 1-21 Overview of the progress of decontamination works under the direct control of the
National Government (as of March 2015)56 .

56Source: Ministry of the Environment (MOE), Produced based on "Progress of decontamination works under

direct control of the National Government (as of March 2015)(https://josen.env.go.jp/material/pdf/josen_gareki_progress_201503.pdf)(Table 1-4 and Table1-5 are based on
the same source)

39

Table 1-4 Progress of decontamination works under the direct control of the National
Government (1) (As of February 20, 2015)

Tamura city

Area-wide completion;

Kawauchivillage

Naraha town

Okuma town

Residential land Completion

Katsurao village

Kawamata town

Progress of decontamination
Decontami(Other than the municipalities of the work
Schedule
Size ofnation areas
Review
Evacuation
completion; as of February 20, 2015)
decontami
Populationoforder
nationTemporary
Residential Other(people)areas Decontami
lifting
Agreement(ha) (round)storageWorks
landplaces(total)nation planacquisition
sites
completion completion
securedJune, 2013
FY2013 (already
April,
400
500
H24/4
H24/4
Acquired
already
completion
completed)20144
Evacuation
order lifting
March,
securedFY2013 (alreadypreparation
400
500
H24/4
H24/4
Acquired2014
already
completed)area;
completion
October,
2014
March,
securedFY2013 (already
7,700
2,100
H24/8
H24/4
Acquired2014
Undecidedalready
completed)completion
March,
securedFY2013 (already400
400
H24/12 H24/12
Acquired2014
Undecidedalready
completed)completion2014
securedAlmostsummer
1,400
1,700
H25/3
H24/9
Working
In 2015 Undecided
alreadyacquired(already
completed)
2014
About
Almostsummer
1,200
1,600
H25/8
H24/8
Working
In 2015 Undecided
90 %acquired(already
completed)Underworking/preparations

Iitate village

6,000

5,600

H24/7

H24/5

Minami-soma
city

13,300

6,100

H24/4

H24/4

Namie town

18,800

3,300

H25/4

H24/11

Tomioka town

11,300

2,800

H25/3

H25/6

Futaba town

300

200

H25/5

H26/7

40

securedalready

About
90 %

About
80 %
About
40 %
securedalready

About
70%
About
70%
About
90 %

Adjusting Preparing

Working

In 2014(almostcompleted)In 2016

Undecided

Working

FY2015FY2016

Undecided

Working

FY2015FY2016 Undecided

Working

FY2015FY2016

Preparing

FY2015

Undecided
Undecided

Table 1-5 Progress of decontamination works under the direct control of the National
Government (2) (As of February 20, 2015) (unit :%)Naraha Kawauchi
Town
Village

IitateVillage

Kawamata Katsurao
Town
Village

100

100

100

100

100

25

100

18

100

100

100

100

100

100

38

100

56

100

100

100

100

100

100

24

100

4

100

100

100

100

68

100

100

100

99.9

100

100

100

32

100

100

100

7

100

8

100

34

100

2

Order rate

100

100

Implementation rate

100

Order rate

100

Implementation rate

Implementation rate

96

Namie
Town

Order rate

Order rate

100

Implementation rate

Implementation rate

100

Minami-soma Tomioka
City
Town

Order rate

Order rate

100

Implementation rate

Implementation rate

100

Order rate

Order rate

100

Implementation rate

Implementation rate

100

Okuma
Town

Order rate

Order rate

Residential
land
Farmland
ForestRoad

TamuraCity
Implementation rate

As of 20th
February,
2015

99.9

17

100

11

48

65

5

100

13

35

79

28

100

14

43

65

61

100

20

46

Note 1) Implementation rate is the percentage of the sizeof a completed series of decontamination
works (weeding, sediment removal, washing, etc.), to the size of decontamination objects in eachmunicipality.
Note 2) The order rate is the percentage of the contracted size to the size of decontamination
objects in each municipality.
Note 3) Size of decontamination objects, ordering size, and the size that ordering acts have been
finished may be changed with future surveys.

1.1.6. Overview of the demonstration model projects for decontamination
This section excerpts the outline of the report on the demonstration model projects for decontamination
prepared by the Cabinet Office57, which was positioned in the decontamination plans in the Special
Decontamination Area indicated in 1.1.5.(1).
Through these projects, knowledge and decontamination technologies were confirmed. In particular, thefollowing points were seen: the importance of monitoring to prevent any hot spot from being overlooked;
the importance of such obvious work environment preparations as procurement and supply of
decontamination-related goods including the securement of water supplies to push forward
decontamination works; the impact of winter weather on decontamination works; implementing effective
measures to maintain the quality of large-scale decontamination works; considering the possibility ofre-contamination; having effective strategies to prevent recontamination; and having effective measures toreduce the volume of wastes. Moreover, it was also necessary to understand the anxiety of residents todecontamination works and to make sure radiation protection for decontamination workers.
The results obtained in these projects are shown in the following (3) (4), and particularly important
findings are shown in (7).

（1） Objectives
The main objectives of the demonstration model projects for decontamination were to establish: themethods for efficient and effective decontamination; and the safety measures relating to radiation
protection of workers for the areas mainly with high radiation exposure dose in which the annual additional
exposure dose exceeds 20 mSv.
Specifically, an area of constant size for model project implementation was set in each of the 12
municipalities (Tamura City, Minami-soma City, Kawamata Town, Hirono Town, Naraha Town, Tomioka
Town, Kawauchi Village, Okuma Town, Namie Town, Katsurao Village, Iitate Village, and Futaba Town58)
belonging to restricted areas and deliberate evacuation areas. In those areas, the verification and theevaluation of the decontamination effect were carried out for the decontamination methods and57Source: Ministry of the Environment (MOE), "The overview report on the demonstration model projects fordecontamination in restricted areas and deliberate evacuation areas (Final revision)” (June, 2012)

58Futaba Town had also been included in the implementation areas of the model projects at first. However the

implementation has not been done because Futaba Town canceled the project.

41

technologies to be considered practical. And then, the data which would be utilized in the implementationof the future full-scale decontamination projects were acquired and prepared to be used immediately.
In addition, the results of these efforts were to be presented in the form of guidelines that could be usedas the reference sources by the National Government and local governments, etc. when performing
decontamination works.

（2） Implementation scheme and decontamination target areas
The target municipalities of the decontamination model projects for decontamination were divided into
three groups of A, B and C by JAEA, which was commissioned from the National Government for the
projects. In each group, Joint Ventures (JVs) performed the verification tests of decontamination
technologies based on their proposals for the decontamination submitted responding to the public call for
proposals by JAEA59.
Target areas in each group and decontamination targets are shown in Table 1-6.

59For the decontamination model project, Group A, Group B, Group C have been implemented by Taisei JV,

Kashima JV, and Obayashi JV, respectively.

42

Group A

Table 1-6 Target areas of the decontamination model projects in each municipality60
Decontamination target
Target areas for the(Total about 209 ha)Groups/Municipalities
decontamination model
projects
Main components/ features
Size
Kanebusa Elementary
Farmland, Building
Minami-Soma City
School and surrounding (Elementary School), Road, approx.
13ha
area
Forest, Residential land
Farmland, Road, Forest,
approx.
Kawamata Town
Sakashita area
Residential land
11ha
Building (Junior Highapprox.
Tsushima area
School, etc.), Road, Forest,
5ha
Residential land
Namie Town
Building (Station, Orbit,
approx.
Gongendo area
Library, etc.), Private
13ha
house, Farmland, Road
Kusano area
Building (Manufacture,
Iitate home, etc.),
approx.
Iitate Village
Base of “Patrol Team for Farmland, Private house,
17ha
Residential land, Road,
the Entire Iitate-mura”
ForestGroup B

Tamura City

Jikenjo area

Katsurao Village

Katsurao Municipal
Office and surroundingarea

Tomioka Town
Futaba Town
Hirono Town

Group C

Okuma Town

Yonomori Park
Tomioka Daini JuniorHigh School−
Chuo-dai/Nawashirogaearea

Okuma Municipal Officeand surrounding area
Ottozawa area

Naraha Town
Kawauchi Village

Kamishigeoka area
Minami Industrial
Complex
Kainosaka area

Farmland, Residential
land, Road, Forest
Farmland, Private house,
Residential land, Road,
Forest , Residential land,Road, Forest
Building (Junior HighSchool, Ground, etc.), Road
(row of cherry blossom
trees), Residential land,
Forest−Building (Government
Office, Elementary /JuniorHigh School,
Ground),Residential land,
Forest, Road
Building (Government
Office, Community Center,
Park),Residential land,
Road
Farmland, Residential
land, Road, Forest ,Farmland, Residential
land, Road, Forest
Building (Factory, etc.),
Road
Farmland, Private house,
Road, Forest

approx.
15ha
approx.
6ha
approx.
9ha
approx.
3ha−
approx.
33ha

approx.
6ha
approx.
17ha
approx.
4ha
approx.
37ha
approx.
23ha※1ha=10,000m2

60Source: Ministry of the Environment(MOE), "The overview report on the demonstration model projects fordecontamination in restricted areas and deliberate evacuation areas (Final revision)”, (June, 2012)43

（3） Overview of the results for decontamination targets
1）Residential landA) Deposition status of radioactive cesium
Large amount of radioactive cesium remain in the places where dust particles (soil) are
carried by rainwater and accumulated (such as gutters and rain spouts).
In addition, other than the places where rainwater accumulates, radioactive cesium tends
to be deposited on and remain in the soil surface layer of residential gardens, concrete slabs
on inclined surfaces, and asphalt surfaces.
Surface contamination levels of vertical outer walls, on which dust particles carried by
rainwater do not accumulate, are relatively low.
As a result of investigating the deposition and retention status of radioactive cesium fordifferent roof materials of houses (unglazed tiles, glaze tiles, cement roof tiles, galvanizediron), the largest amount of deposited radioactive cesium was for cement roof tiles. The
deterioration of the surface condition of the cement tiles is considered to have influenced
the deposition and retention.
The amount of deposited radioactive cesium was relatively small for galvanized iron andslate.
Moreover, radioactive cesium tended to be deposited and retained at specific spots on theroof.
Overlaying places of roof materials (such as tiles and galvanized iron)
Peeled portions of surface finishing (glazed or painted portions of roof tiles), rusted
or corroded portions of roof materials
Dirty areas or tree sap adhering points on the roof.
The portions of tiles to prevent snow from sliding off of a roof, such as snow guards
The dose rate of residential land was reduced overall by the decontamination works in theland. However it was found that the dose rate after the decontamination in the following
places had the tendency to be slightly higher than other places. Those places were theregions where the implementation of decontamination works was difficult, such as narrow
spaces, and around garden trees and other obstacles.

B) Decontamination methods and results
High decontamination effect could be achieved by forcefully removing most of the deposits
in gutters and then wiping off the remaining small deposits.
It was observed that the decontamination effect on a roof varied according to the materials.
Brushing with a deck brush was effective for unglazed tiles and painted ironplates.
Manually wiping the surface was also effective for unglazed tiles.
Coating release agent had a relatively high decontamination effect compared toother methods for slate or cement roof tiles.
For cement roof tiles, decontamination effect was limited in all decontamination
methods.
Decontamination of the roof with a coating release agent provided a certain degree of
decontamination and had a merit that it did not scatter the removed substances to thesurroundings. However, it required covering the surface to be decontaminated with aprotective material for 1-3 days and the temperature must be controlled inside the coveringin winter. Therefore, its usability was limited and it was generally not practical.
Decontamination of outer walls was carried out using the methods of "hand washing","wiping off ", "high pressure water washing", and "brushing" for each material of tin, sash,
glass, and wood. Even if the decontamination methods for outer walls were different, no big
difference was confirmed in the surface contamination density after decontamination.
Decontamination of gutters was performed using “wiping off” and “high-pressure watercleaning”. No significant difference was seen in their decontamination effects. “Wiping off”
had better usability from the fact that contaminated wash water was not scattered to thesurroundings.
Decontamination of concrete (earthen floors) was carried out using high pressure water44

washing. The effect of decontamination using high pressure water washing only was
limited. When a relatively small area was targeted in the decontamination, surface cuttingwith the dust collection sander was effective for decontamination. However, it was noteffective when a large area was targeted in decontamination, and it needed a dry surface
condition. In addition, even if other methods such as metal brushes were used together withhigh pressure water washing, their effect on decontamination did not change.
For gardens, the removal of gravel, etc. under rain gutters that had become hot spots had asignificant effect for decontamination.
It was found that air dose rates inside a building were reduced after the areas surrounding
the building, and the degree of dose reduction was almost the same indoors and outdoors
regardless of the material of the building (a concrete or a wooden building). Thus, in orderto aim at reduction of indoor radiation level, decontamination of the area around thebuilding is important.

2）Large buildingsA) Deposition status of radioactive cesium
Large amounts of radioactive cesium remain in places where dust particles, which were
deposited on large buildings, have been carried by rainwater and accumulated in certain
areas (such as gutters and rainspouts). On the contrary, the amount of radioactive cesium
was relatively small in the places where dust particles were just carried by rainwater anddid not accumulate.
It was confirmed that the radiation doses were higher in the places where dust particles
were accumulated, or moss was growing, or in the drainage paths of rainwater, than those
doses in their surrounding areas.
Surface contamination levels of vertical walls of large buildings, on which dust particles
carried by rainwater did not accumulate, tended to be low compared with those of concreteslabs on inclined surfaces or asphalt surfaces. On the other hand, contaminated verticalwalls were also observed according to the movements of raindrops.

B) Decontamination methods and results
The high-pressure water washing was effective for the decontamination of concrete roof
with waterproofing.
For the roof of concrete (mortar), decontamination effect was limited in all methods of “highpressure water washing (about 10 MPa)”, “high pressure water washing and brushing”,“nano-bubble washing”, and “special solution washing such as by oxygenated water”.
The decontamination of outer walls was carried out using the methods of "wiping off " and"high pressure water washing" for each material of tin, sash, glass, and wood. Even if thedecontamination methods of the outer walls were different, no big difference was confirmedin the surface contamination density after decontamination.
“Wiping off” has better usability at a point from the fact that contaminated wash water is
not scattered to the surroundings.
It was found that the decontamination effect outside a building had influenced in reducing
the air dose rates inside. This is considered to be due to reduced radiation from theradioactive materials outside which had been detected inside.

3）FarmlandA) Deposition status of radioactive cesium
In most cases, 80% or more of the radioactive cesium inventory was present in the surface
soil layer down to a depth of about 5 cm.
It was observed that radioactive cesium penetration depth was deeper in the fields that had
been plowed just before the accident.
No remarkable difference was seen in the tendency for deposition and retention ofradioactive cesium among rice fields, crop fields and orchards.

45B) Decontamination methods and results
An effective approach involves confirming the depth distribution of radioactive cesium;
determining the practical depth and efficiency of dose reduction methods of mixed tillage,
reversal tillage, interchanging topsoil with subsoil, or topsoil stripping; and performing themost effective reduction method.
In addition, the magnitude of dose reduction efficiency was approximately in the order of"mixed tillage <reversal tillage < (or =) interchanging topsoil with subsoil ≒ topsoil
stripping".
On the other hand, the amount of removed soil was in the order of "mixed tillage ≒reversal tillage ≒ interchanging topsoil with subsoil << topsoil stripping".
The effectiveness in dose reduction by reversal tillage or interchanging topsoil with subsoil,
which does not produce soil for removal, was equivalent to that by topsoil stripping.

4）Roads
A) Deposition status of radioactive cesium
Roads (paved) tended to have low air dose rates compared with soil surface of thesurrounding farmland and bare ground, etc. This is believed due to the fact that radioactive
materials deposited on the paved surface of the roads were washed away by rainfalls after
the accident.
Depth distribution of the surface contamination density of asphalt paved surfaces inhigh-dose areas has been measured. As a result, it became clear that most of the radioactive
materials remained down to a depth around 2-3 mm from the surface for pavement face ofdense grain-size, and down to a depth around 5 mm from the surface even for porous
asphalt pavement (permeable pavements, etc.).
From the relationship between the surface dose rate and surface contamination density, thevalue of the surface contamination density may be relatively high on some roads (paved
surfaces). Radioactive cesium is unevenly distributed near the pavement surface incomparison with the soil surface of the surrounding farmland and bare ground. Thus, it isconsidered that the contribution to the surface contamination density by beta ray having ashort range distance in solids is remarkable. This also corresponds to the distribution in thedepth direction of the contamination density of radioactive materials.

B) Decontamination methods and results
As decontamination methods for paved roads, "stripping-off" had a large efficiency of dose
reduction, but generated larger quantities of removed wastes compared with other methods.
Most of the inventory of radioactive materials was found to be present in a surface layer ofasphalt, down to a depth of a few millimeters. Thus, it is possible to achieve a highdecontamination effect, while minimizing the volume of wastes generated, by surface
shaving off only this thickness.
In comparison with "stripping-off (surface removal)", "washing" has the advantage that it
does not generate wastes as in the case of surface removal or surface stripping-off. However,
the efficiency of dose reduction is not high, and the collection and disposal of wash water arenecessary.
For asphalt paved surfaces, decontamination by "surface stripping-off or surface removal(water jet, shot blasting, TS cutting machine61, etc.)" was more effective than "cleaning (dryroad sweeping, etc.)" and "washing (high-pressure washing or use of vehicles for functional
recovery, etc.)""Surface stripping-off or surface removal" methods require machines and are difficult to be
applied to areas in the vicinity of buildings and outer walls. Irregularities in the effect ofdose reduction occurred for the roads with distorted and worn surfaces.

61These were road surface cutting machines that scrape off asphalt paving or concrete paving by a rotary

blade.

465）Parks and playing grounds
A) Deposition status of radioactive cesium
The tendency was observed that more than 80% of the radioactive cesium deposited within
the depth around 5 cm from the surface in most places.
The tendency was strong that radioactive cesium deposited and remained in degradedrubber playground equipment and rusted metal playground equipment. On the other hand,
the tendency that radioactive cesium deposited and remained in metal playgroundequipment with a smooth surface was weak.

B) Decontamination methods and results
Wiping was effective in dose reduction for playground equipment with the smooth plastic
surfaces. For metal playground equipment with rusted areas, cleaning with scrubbing
brushes was effective for dose reduction, although it was limited.

6）Forests and treesA) Deposition status of radioactive cesium(Evergreen forests)
The tendency was observed that the residual radioactive cesium was remaining higher inlitter layers containing the fallen leaf layer which was formed newly during 2011
It was observed that the amounts of residual radioactive cesium were small in the bark
portions of tree trunks in comparison with other parts. It is thought that most of theradioactive cesium deposited in the leave and the branches and could not reach the trunk
part.
Radioactive concentration of fallen leaf layer formed by dropping of leaves which grew at
the time of the accident (the surface layer that was formed by the newly fallen leaves during
the year of the accident) was high compared with deciduous trees. It is thought that inevergreen trees, much more radioactive cesium deposited on the leaves, which grew at thetime of the accident, compared with other parts.
(Deciduous forests)
It was found that much radioactive cesium was depositing and remaining in the litter layer
and outer bark of the trees. It is thought that this was because not many leaves had grownat the time of the accident.
The amount of residual radioactive cesium has been compared between the fallen leaf layer
which was formed during the year of the accident and the fallen leaf layer which had been
formed before the accident under the fallen leaf layer during the year of the accident. As aresult, the former (fresh layer) had a generally smaller quantity of radioactive cesiumcompared with the latter (older layer). This is also considered to be because not many leaves
had grown at the time of the accident, most of the radioactive cesium that fell on deciduoustrees was deposited on the ground surface under the trees, and then, the accident year’s
fallen leaf layer was formed on the contaminated ground surface.

B) Decontamination methods and results
Implementing both "weeding" and "removal of the accident year’s fallen leaf layer" mayhave (limited) effects of dose reduction in evergreen forests.
On the contrary, in deciduous forests, surface contamination density was increased by
implementing both "weeding" and "removal of the accident year’s fallen leaf layer". It isconsidered that, at the time of the accident, radioactive cesium deposited on the groundsurface; The ground surface was covered afterwards by new grasses which grew thickly andthe accident year’s fallen leaves without radioactive cesium contamination; and theradiation from the ground surface was shielded by them.
It was observed that surface dose rate and surface contamination density were reduced to a47

certain extent by "removing the litter layer" in addition to "weeding" and "removal of theaccident year’s fallen leaf layer" for both deciduous forests and evergreen forests. However,
it is necessary to consider that removal of the litter layer may have impacts on forest
ecosystems, such as changes in nutrient of soil.
High-pressure water washing for trunks of trees with some barks peeled off but with noadverse effects on their growth had high decontamination effects.

（4） Outline of results for works associated with decontamination
1）Disposal of wash water
Effluent criteria were able to be satisfied by using the combined processing methods offiltration, adsorption, and coagulation/sedimentation, according to the degree ofcontamination of wash water in each spot (including the stagnant water in side ditches) or
stagnant (pond) water before the accident.

2）Volume reduction methods of removed wastes such as branches and leaves
Crushing machines could reduce volume of branches and leaves while preventing scatteringof dust with deposited radioactive materials to the surroundings by applying dust collection
measures. However the volume of logs was not reduced so much, because logs were not sobulky even before crushing.
High temperature incineration could achieve extremely large volume reduction of branches
and leaves without spreading of the radioactive materials deposited on them together withthe exhaust smoke to the outside. Furthermore, it was confirmed that cesium concentrationin the exhaust gas was sufficiently lowered below the concentration limit of radioactive
materials in air specified by the law when treating the flue gas with bag filters or HEPA
filters.
Low temperature incineration was lower in volume reduction ratios than high temperatureincineration or crushing machines.

3）Generated amount of removed wastes
Generated amount of removed wastes greatly depends on differences in thedecontamination methods rather than the differences in annual cumulative dose of
decontamination implementation areas.
If the decontamination methods such as "topsoil stripping", "weeding", "removal of
fallen leaves, etc." are selected for decontamination works, larger amount ofremoved wastes is generated.
As shown in (3) 3), the effectiveness in dose reduction by "inversion tillage" or"interchanging topsoil with subsoil" is equivalent to that by "surface soil
stripping-off". However, "inversion tillage" or " interchanging topsoil with subsoil"
does not result in the generation of waste removed soil.
More than 80% of radioactive materials can be reduced in most places by removing surface
soil to approximately 5 cm, regardless of the level of annual cumulative dose and land-use
classification. However, the thickness of the stripping that directly relates to the amount ofgenerated soil to remove should be set in consideration of both the vertical distribution ofradioactivity concentrations and the decontamination targets.
The vertical distribution of radioactive material concentrations in the ground has atendency that the reduction rate of the concentration (the rate of concentration
decrease per each 1 cm in depth) significantly decreases as it goes deeper(exponentially decreasing)For example, when 80% of the radioactive materials are included in the top 5 cm of
the ground and 90% in the top 8 cm, the additional dose reduction of 10% is
expected by removing the additional layer of 3 cm below 5 cm deep in comparison
with removing the top 5 cm for removing 80% of radioactive materials. However,
the amount of removed objects would increase by 60%..
48

Surface soil may have to be stripped off more deeply to lower the density ofradioactive materials of the topsoil below the fixed absolute value in the areas withhigh annual cumulative dose.
However, the concentration distribution of radioactive materials in theunderground depth direction may be different from that of the demonstration
model projects for decontamination implemented to date, depending on
unevenness of the ground surface and other factors. Therefore, the concentration
distribution of radioactive materials in the ground depth direction should bechecked first before starting decontamination works, and then the stripping
thickness to achieve the decontamination target needs to be determined.

4）Temporary storage sites/on-site storage sites
When installing temporary storage sites and the like, the planned sites must be
decontaminated in advance and appropriate shielding measures have to be taken after thewastes are loaded and emplaced. Therefore, air dose rates in temporary storage sites do notincrease but rather decrease after loading and emplacement of wastes, regardless of thelevel of air dose rates of the sites before installation.
Air dose rates are also reduced by covering removed wastes with sandbags filledwith uncontaminated soil.
When bringing the removed objects into the storage sites and placing them therein, theradiation influence from those with high surface dose rates can be reduced by placing
them at the center of the site, and those with lower surface dose rates are placedaround them. By doing so, the influence of radiation from the removed objects withhigh surface dose rates can be reduced by the shielding effect of the removed objects
themselves.
Types of temporary storage sites have to be selected based on the opinions of municipalities
and residents, and taking into account topographical characteristics, land use situation,
and available area of the target sites.
Aboveground storage is the easiest type for shipment of stored wastes to theInterim Storage Facility. On the other hand, when installing the storage sites onsoft ground, it is necessary to improve the foundation.
Underground storage has the advantage that the soil for the shielding can be
secured at the sites. On the other hand, it takes time to excavate the underground
portion, and measures have to be taken, for instance, for stopping groundwater
inflow.
For semi-underground storage, it is possible to increase the storage capacity evenfor a limited place of the sites. However, it takes time to excavate the underground
portion. In addition, it is necessary to apply rainwater infiltration measures at theboundaries of the aboveground portion and the underground portion.

5）Radiation exposure dose control of decontamination workers
Exposure doses of decontamination workers were studied for each decontamination target
area. The workers in areas with higher air dose rates monitored before decontamination
generally had higher exposure doses. Nevertheless, exposure doses of workers in the areas
with annual cumulative dose less than 50 mSv and with appropriate measures for exposure
control were well below the reference value of the exposure dose limit stipulated by laws
and ordinances.
On the other hand, exposure doses of workers in the areas exceeding the annual cumulative
dose of 50 mSv may exceed the exposure dose limit stipulated by laws and ordinances, if
they work continuously for five years in those areas. Therefore, in such cases, more
stringent radiation control is required, such as optimizing the combination of
decontamination methods and work procedures for dose reduction, and promoting the work
efficiency by utilizing machines.

496）Costs for each decontamination method
Costs required for the works using the decontamination methods which bring larger dose
reduction effect tend to be higher.
It should be noted that, as can be seen in the following cases, it is necessary to consider
overall factors including costs, the volume of removed wastes to be generated, andworkability in addition to the dose reduction effect, when selecting decontamination
methods.
The case in which different decontamination methods with the same level effect ofdose reduction have different features regarding costs, the generated amount ofremoved wastes, and workability.
The case in which different decontamination methods with the same level effect ofdose reduction and cost requirements have different features of workability.

（5） Results of the implementation of area-wide decontamination works in demonstration
model projects for decontamination
Decontamination works were carried out in the areas where the radiation level before
decontamination had been higher than the level to cause the annual cumulative dose of 20
mSv or more and below 30 mSv. The works cold reduce the radiation level to cause theannual cumulative dose below 20 mSv.
Decontamination works were also carried out in the areas where the air dose rate before theworks was higher than the level to cause the annual cumulative dose exceeding 40 mSv.
After the works, the air dose rate could be reduced by around 40-60%. However, it was notpossible to reduce the level to a level to enable the annual cumulative dose below 20 mSv.
Decontamination work was carried out in Ottozawa area, Okuma Town, where the air dose
rate before the works had been at the level to cause 300 mSv or more as the annual
exposure dose. After the works, the air dose rate could be reduced more than 70% in
farmland and residential places. However, the air dose rate was not able to be reduced to alevel to achieve 50 mSv/year or less for the whole area.
In some areas with lower air dose rates before decontamination, decontamination methods
that do not generate much waste were tested. Although the amount of removed wastes was
relatively small, the reduction in air dose rates was lower compared with the case in higher
air dose rate areas.

（6） Guidance on decontamination works
The findings obtained in the demonstration model projects for decontamination are summarized in the formof guidance62 and have been published for the following eight items.
Guidance on obtaining informed consent (agreement acquisition) concerning thedecontamination implementation areas, selection of temporary storage sites and theirstakeholders
Guidance on monitoring
Guidance on decontamination works
Guidance on preparation and maintenance for temporary storage sites/on-site storage sites
Guidance on screening (contamination inspection)
Guidance on the treatment of wastes generated by decontamination works
Guidance on workers’ occupational safety management
Guidance on supervision for outsourcing companies

62Source: published on JAEA home page (http://fukushima.jaea.go.jp/initiatives/cat01/entry02.html )50

（7） Important findings obtained in demonstration model projects for decontamination
1）Important findings obtained for establishment of the work environment
In restricted areas, it is important to secure site offices and rest places which serve as bases
in decontamination works and securing water for decontamination. If rest places are notsecured in time, the limitation occurs in the length of working hours in which workers canwork continuously. If water cannot be secured on site, it must be brought from outside therestricted areas. As the facilities for rest places and the like, it was effective to utilize publicgrounds and public facilities, because coordination with the persons concerned for their use
could be made in a short period of time.
Machinery and equipment to be used for decontamination works might be possible toprocure on a, lease contract, but there were cases in which to bringing them into therestricted area was refused. When procuring them on a lease contract, it is necessary toprovide sufficient information to the lease companies on the appropriate contamination
inspection of the machinery and equipment, and the appropriate decontamination methods
to apply when needed and other conditions, and to clear the concerns of these companies.
Damage conditions of houses were investigated by outsourced specialty companies. The
contents of the investigation were based upon a construction damage investigation ofdamage possibilities by decontamination works. The investigation did not include
applicable environmental conditions and construction constraints for decontamination
works, for example, investigations to determine whether it was possible to set up
scaffolding on roofs for the works were not included. Therefore, it will be an efficientapproach in the damage survey of houses for the subsequent decontamination works, notonly investigating the damage conditions, but also checking whether the houses are in suchenvironmental conditions in which appropriate decontamination methods for the houses
concerned can be applied technically, and whether there are concerns about construction
constraints for decontamination works.
For large-scale decontamination works, there may be many places where wash water is
produced. Therefore, difficulty was foreseen to set up water treatment facilities in one place
for a long term. For this reason, a water treatment system, such as a vehicle-mounted one,should be considered, which can move to the places where the wash water is generated.

2）Important findings obtained for monitoring
Regarding the monitoring to locate hot spots, there were cases which caused the residents’complaint. Such cases occurred when the hot spots could not be located in the
pre-monitoring stage and they were found later by the residents’ own measurement after
the decontamination works. Important knowledge obtained regarding monitoring is:
It is necessary to set the number of monitoring points per house in a flexible way,
not to fix it at a certain number, in order to prevent overlooking of the necessary
decontamination works.
In mesh measurements, the measurement in shorter pitches gives better accuracy,
but the workload increases instead. For optimization, a combined use of back-packtype or buggy type instruments in mesh measurements was more effective than
expanding the measurement pitches of mesh measurements for preventing theoverlooking of hotspots.
For locating hotspots, it was effective to search for a place where the air dose rate
was relatively higher than other places in the surrounding by the measurement
device with shortened time constant for higher sensitivity. A two-dimensional dose
rate distribution evaluation system, which combined a GPS device and a dosimeter,
was an effective tool for locating hotspots because of its high spatial resolution, no
requirement of high measuring skills, and less data variation of measurements,and less risks of overlooking hotspots.
Risks of overlooking hotspots could be minimized by post-work monitoring by the work
leaders as a means of work result management, in order to locate any spots with high dose
rate or high surface contamination densitiesleft behind. So was for the soil and wastes to be
removed.
513）Important findings obtained for the influence of winter weather on decontamination
Generally in the snowfall, the measured radiation dose becomes lower due to the shielding
effect of the snow on the ground. In the demonstration model projects for decontamination,
the reduction effect of dose rate due to snow was evaluated quantitatively. As the resultrough evaluation of dose rate has become feasible even when snow-covered.
Machinery and equipment for decontamination may be subjected to freezing in midwinterand the working efficiency may be significantly affected. It has been recognized that anti
freezing measures should be considered, by keeping them in shelter, for instance.
Sometimes the soil solidifiers did not work for topsoil stripping during the winter because of
low temperatures. In some other cases, the frozen layer of topsoil was stripped off up to thefrozen depth at one time, thicker than the preset thickness to strip. The amount of removed
objects thus increased. On the other hand, however, it has been recognized that the surface
soil could be stripped off effectively by using road surface cutting machines.
Following risks have been also recognized: Frozen top soil when stripped off or frozen soil
for shielding may increase the amount of seepage water after they are transferred to thetemporary storage sites; flexible container bags for shielding (hereinafter referred to as"flexible containers") may deform and subside; or the welded portion of impervious sheets
may fail. Furthermore, risks of deformation of water collection boxes have been also
noticed.

4）Important findings obtained for maintaining the quality of decontamination works
A tendency was noticed in decontamination works that the decontamination effects varied
depending on the work methods of individual workers. Particularly, in top soil stripping,soil was occasionally spilled during plowing regardless of hand work or machine work. Thishas been noticed as one of the causes for differences in the decontamination effects.
When decontaminating by top soil stripping with the stripping thickness under control,
grass roots in the actual soil surface impeded stripping off in the predetermined thickness,
Sometimes it became necessary to remove grass roots and then to strip the topsoil off
beyond the predetermined thicknesses. In the land with irregularities, it was also necessary
to strip off thicker layers than the predetermined values. In order to reduce the deviationfrom the predetermined stripping thickness, prior rolling compaction has been effective.
It has been found that both coagulating sedimentation method and filtration method had
advantages and disadvantages for the treatment of recovered wash water. For example, forthe coagulating sedimentation method, the device is simple and it is easy to use, but theprocess such as water removal from the sediment and solidification of the sediment isrequired. On the other hand, in the filtration method, residues are solid and it is easy tohandle them. However, it takes time to complete the filtration, and measures such as thereverse washing because of blocking of the filter are required. In addition, while thecoagulating sedimentation method is a batch process, the filtration method can be runcontinuously. It is difficult to recommend unconditionally which processing method can beused for recovered wash water. This is because the process to be used varies according to
the properties of treated water and the required amount of processing. As a result, the useof the processing method according to the situation or the use of a combination of processing
methods is effective for treating recovered wash water.

5）Important findings obtained for the prevention of re-contamination
The places that had been decontaminated were distinguished using colored cones and othermeans, and furthermore measures were taken to prohibit entering those places at the timethe decontamination works were being done. These actions were effective for the preventionof re-contamination.
It should be noted that, in the demonstration model projects for decontamination, daily
monitoring has been carrying out continuously at the fixed points, including the points
where individual decontamination works had been completed. As a result, during the period52

of around one month from the end of the decontamination works to the end of the projects,
hardly any situations such as a dose rate increase after the completion of decontamination
works have been observed. In other words, the influence of significant secondary
contamination have not been seen.

6）Important findings obtained for the volume reduction of wastes
Among flammable decontamination wastes, branches and leaves generated from forests
and the undergrowth of weeds such as the bamboo grass were bulky when stored in flexible
containers. Therefore, the filling efficiency of the flexible containers could not be increased.
Incineration was a very effective treatment method because the volume reduction rate washigh and spread of radioactive cesium was suppressed by installing filters for the exhaustgas. However, it is necessary to note that the equipment is relatively large-scale and theincineration ash must be handled.
Wood crushers and wood chippers were effective processing devices. This was because theirvolume reduction rate was relatively high although it depended on the processing targets,and the equipment was not large in scale. However, when wood chippers were used, it was
desirable to take measures such as laying dust sheets around the equipment because thescattering of small pieces of wood is expected.
For volume reduction of undergrowth generated from vast grasslands, compression by anundergrowth accumulation machine attached to a tractor (roll baler) was regarded as anefficient method from the viewpoint of volume reduction rate and work efficiency, although
the human power to accumulate undergrowth of weeds was required.
Volume reduction by compressing dead leaves with a heavy loader vehicle and volume
reduction by sucking off air in sealed bags with large vacuum cleaners that can be easily
carried into fields were other measures.
Soil stripped from farmland (especially pastures) and playgrounds, schoolyards, parks(especially lawn areas) included large numbers of plant roots. It is very effective from theviewpoint of control of the waste amounts that the stripped soil portions are separated into
soil and flammables (plant roots). In order to separate in this way, twisters63 and vibration
sieve machines were used. This technique cannot be evaluated with a numerical value ofseparation rate because separation depends on what are included as the non-flammables(such as soil and stones) and what are included as the flammables (such as plant roots). The
results of the separation tests of soil and plant roots were confirmed by visual inspection.
For test conditions that were good, flammables such as many roots were not included in theseparated soil. Therefore, it was possible to control the separated soil as non-flammables.
Consequently, this method was considered to be effective from the viewpoint of waste
management. When highly viscous soil was treated (clay), the soil could not be broken by
the twister and therefore a large amount of soil was separated to the root side (flammables).
Thus, it was also found that it is necessary to pay attention to the soil properties.
Combination treatment method was considered, in which grass roots that have been
separated by the twister were processed by low temperature incineration using a rotary
dryer 64 . In this case, all the wastes that were left after burning could be treated as
non-flammables.

7）Important findings obtained regarding the anxiety of residents
From local residents, including the landowners, and local governments, there were many
requests to report the progress of decontamination works and the effect of dose reduction bydecontamination. It has been found to be important to respond to these requests politely. To
promote decontamination works while building the relationship of mutual trust with local
governments and local residents, it was important that information control be implemented
63 Twister (rotary crushing mixer) (Machinery for crushing and mixing the soil with striking force of a chain

rotating at high speed)

64 Rotary (tumble) dryer (Machine for heating and drying the soil containing moisture in a rotating tube)

53

without exception to prevent release of personal information, while ensuring that the
information on the details and the results of the works were offered regularly as far as
possible.
Many concerns were voiced from residents regarding downstream contamination by washwater. Downstream contamination by wash water was found to be one of the biggest causesof uneasiness. Therefore, when decontamination works were carried out using water, it was
important to take outflow prevention measures such as providing weirs in roadside ditches
where wash water flowed into. In the case of high-pressure water washing of houses andgarden planting, it was possible to prevent secondary contamination by removing concrete
facings and surface soil under the planting and near the house after high pressure water
washing.

8）Important findings obtained for safety protection of the decontamination workers
At the places where the levels of contamination were estimated to be especially low, it wasconsidered at first that the wearing of sealed chemical protective clothing and a full-facemask was not always necessary, if post-work contamination checks of workers were
thoroughly carried out. However, in the case of actual works, some workers could not feelrelieved without wearing these protective items, and heavily equipped workers, who wore
both the sealed chemical protective clothing and the full-face mask, were found here andthere. Not only was it necessary to explain safety to workers scientifically, but also it wasalso important to remove workers’ anxiety.
For the workers, not only radiation protection but also measures to protect from pests(particularly bees and vipers) were necessary. In addition, it was found that measures toprotect workers from the danger caused by livestock and pets which had gotten free fromowners were necessary.
It was not only residents that felt uneasy as to whether decontamination was carried out
appropriately. It was found that there was a case in which workers were performing
decontamination works while feeling uneasy whether the works were being carried out
appropriately. Particularly, in the topsoil stripping by human power, it was difficult tocheck whether there was any omission of stripping or any unremoved soil by only visualinspection. Therefore, personnel qualified to make dose measurements were present in thefields during decontamination works, and the effect of dose reduction was confirmed in atimely manner. This was effective in the prevention of redoing of decontamination works
and in the prevention of excessive decontamination.

1.1.7. Outline of the Intensive Contamination Survey Areas（1） Designation of Intensive Contamination Survey Areas
Intensive Contamination Survey Areas are designated by the MOE as the areas where it is necessary toinvestigate and measure the status of the environmental contamination due to the radioactive materials
discharged in the areas by the accident mainly.
In Intensive Contamination Survey Areas, designated municipal mayors have developed theirdecontamination plans unlike those of the Special Decontamination Areas as described in 1.1.4, andmunicipalities have been implementing decontamination works steadily.

（2） Designation status of Intensive Contamination Survey Areas
The designation status of Intensive Contamination Survey Areas is not fixed because there are also someareas where the designation was lifted after the determination65. The municipalities listed in Table 1-7 are
the designated the Intensive Contamination Survey Area as of February 1, 2015. Municipalities designated65 For some municipalities, the designation of Intensive Contamination Survey Area was lifted because thedecrease in air dose rates led to the fact of the qualification for designation.

54

as the Intensive Contamination Survey Area and Special Decontamination Area are shown in Figure 1-22
through Figure 1-29, together with the progress of decontamination works in those municipalities.

55

Table 1-7 Designation status of Intensive Contamination Survey Areas (as of February 1,2015)66
Prefectures Municipalities
Fukushima
Prefecture

Fukushima City, Koriyama City, Iwaki City, Shirakawa City, Sukagawa City,
Soma City, Nihonmatsu City, Date City, Motomiya City, Koori Town, Kunimi
Town, Otama Village, Kagamiishi Town , Tenei Village, Aizubange Town,
Yugawa Village, Yanaizu Town, Aizu Misato Town, Nishigo Village , Izumizaki
Village, Nakajima Village, Yabuki Town, Tanagura Town, Yamatsuri Town,
Hanawa Town, Samegawa Village, Ishikawa Town, Tamagawa Village, Hirata
Village, Asakawa Town, Furudono Town, Miharu Town, Ono Town, Hirono
Town, Shinchi Town, Tamura City, Minami Soma City, Kawamata Town And
Kawauchi Village

Iwate
Prefecture

Ichinoseki City, Oshu City, Hiraizumi Town

MiyagiPrefecture
IbarakiPrefecture

Shiroishi City, Kakuda City, Kurihara City, Shichikashuku Town, Ogawara
Town, Marumori Town, Watari Town, Yamamoto Town
Hitachi City, Tsuchiura City, Ryugasaki City, Joso City, Hitachiota City,
Takahagi City, Kitaibaraki City, Toride City, Ushiku City, Tsukuba City,
Hitachinaka City, Kashima City, Moriya City, Inashiki City, Hokota City,
Tsukubamirai City, Tokai Village, Miho Village, Ami Town, Tone Town
Sano City, Kanuma City, Nikko City, Otawara City, Yaita City, Nasushiobara
City, Shioya Town, Nasu Town
Kiryu City, Numata City, Shibukawa City, Annaka City, Midori City,
Shimonita Town, Nakanojo Town, Takayama Village, Higashiagatsuma Town,
Kawaba Village
Misato City, Yoshikawa City

Tochigi
Prefecture
Gunma
Prefecture
SaitamaPrefecture
Chiba
Prefecture

Matsudo City, Noda City, Sakura City, Kashiwa City, Nagareyama City, AbikoCity, Kamagaya City, Inzai City, Shiroi City

66Source: Ministry of the Environment (MOE), "Decontamination information site"(the same source for Figure 1-22 to Figure 1-29)

56

Areas where decontamination is implemente d by thenational government (special decontamination areas)
Completion/Evacuation order lifting

Not ordering

Completion of decontamination works

Special decontamination areas

Started already

Difficult-to-return areas

O utsourced alreadyAreas where decontamination is implemented by eachmunicipality(intensive contamination survey areas)
Municipalities where the designation of intensive contamination survey
areas was lifted.
Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)
Other intensive contamination survey areas

Figure 1-22 Designation status of Intensive Contamination Survey Area/ Special
Decontamination Area and progress of decontamination works in Fukushima Prefecture.

Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)

Figure 1-23 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Iwate Prefecture.

57

Municipalities where the designation of intensive contamination survey
areas was lifted.
Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)

Figure 1-24 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Miyagi Prefecture.

Municipalities where the designation of intensive contamination survey
areas was lifted.
Compression of implementation of decontamination and othermeasures based on decontamination implementation plan
Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)
Other intensive contamination survey areas

Figure 1-25 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Ibaraki Prefecture.

58

Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)

Figure 1-26 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Tochigi Prefecture.

Municipalities where the designation of intensive contamination survey
areas was lifted.
Compression of implementation of decontamination and othermeasures based on decontamination implementation plan
Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)
Other intensive contamination survey areas

Figure 1-27 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Gunma Prefecture.

59

Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)

Figure 1-28 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Saitama Prefecture.

Planed already(Areas where decontamination plans were developed by eachmunicipality based on the Act on Special Measures Concerning theHandling of Radioactive Pollution)

Figure 1-29 Designation status of Intensive Contamination Survey Area and progress of
decontamination works in Chiba Prefecture.

60

（3） Implementation system of decontamination works in Intensive Contamination Survey
AreasIn Intensive Contamination Survey Areas, surveys and measurements of thecontamination status are carried out first by the mayors and other officials of the municipalities
with financial support by the National Government.
Based on the results of surveys and measurements, decontamination plans are developedby the mayors and others. In formulating the decontamination plan in each municipality, theconsultation with the Minister of the Environment is done in advance. Through thisconsultation, determinations and recommendations are made about the adequacy of plancontents, and then planning is checked whether it corresponds to the works targeted for thebudget support.
After the check has been completed, securing of temporary storage sites, reaching theconsensus with stakeholders about the decontamination works, ordering of thedecontamination works, implementing the decontamination works, and post-work
investigation and verification are carried out sequentially by each municipality, in accordancewith their own decontamination plan. All the costs for these works by each municipality arecovered with the National Government financial support.
In addition, for the implementation of decontamination works in the target areas describedin each municipality’s plan, it is prescribed in the Act on Special Measures that the National
Government has the responsibility for the land under national control, and each prefecture
has the responsibility for the land under its own control.

（4） Progress in Intensive Contamination Survey Areas
Progress of implementation of the decontamination works and other measures in Intensive
Contamination Survey Areas are described below for Fukushima Prefecture and other prefectures.

1）Fukushima Prefecture
Status of the ordering of decontamination works and the development of decontaminationplans in Fukushima Prefecture is shown in Figure 1-30. Most ordering has been completed.
However, for roads and forests (in the living space), the progress of their ordering is delayed.

61

House (number of houses)

Public facilities, etc. (number of facilities)

Number ofcompleted

204,957

Number ofcompleted

6,694

Number ofoutsourced

299,641

Number ofoutsourced

7,873

Plannednumber315,498

Plannednumber(reference) Total number planned = 431,042 houses

Road (km)Number ofcompleted
Number ofoutsourced
Plannednumber8,266(reference) Total number planned = 8,683 facilities

Farmland (paddy + field + orchard + pasture; ha)

3,550

Number ofcompleted

21,744

6,171

Number ofoutsourced

28,955

8,529

Plannednumber30,012(reference) Total number planned = 15,512km(reference) Total number planned = 34,108ha

Forest (within the range of living area) (ha)Number ofcompleted

1,098

Number ofoutsourced

1,470

Plannednumber

1,961※Planned number is the number of decontamination
works expected to be completed by the end of the
fiscal year 2014.

(reference) Total number planned = 3,314ha

Figure 1-30 Progress of decontamination works in Intensive Contamination Survey Areas in
Fukushima Prefecture (as of end of January 2015)67 .

2）Outside Fukushima Prefecture
Implementation status of decontamination and other measures in Iwate, Miyagi, Ibaraki, Tochigi, Gunma,
Saitama and Chiba Prefectures is shown in Table 1-8 through Table 1-15.
The decontamination has already been completed or almost been completed in more than 70% of themunicipalities.
Table 1-8 Completion status of implementation of decontamination and other measures basedon decontamination implementation plans outside Fukushima Prefecture68(as of end of December, 2014) (Number of municipalities)(a)Completed(b)Almost completed(c)Continued(d)Total

Iwate Prefecture

0

2

1

3

Miyagi Prefecture

0

3

5

8

Ibaraki Prefecture

11

7

1

19

Tochigi Prefecture

0

4

4

8

Gunma Prefecture

7

1

1

9

Saitama Prefecture

0

2

0

2

Chiba Prefecture

0

8

1

9

Total number

17

26

15

58

67Source: Fukushima Prefecture, "Decontamination implementation status in decontamination areas(Intensive Contamination Survey Areas) in municipalities (February 27, 2015 update) "（https://www.pref.fukushima.lg.jp/site/portal/progress201501.html
68Source: Ministry of the Environment (MOE), "Compiled of progress survey results (as of end of December,2014)" (February 13, 2015) (the same source for Table 1-9 to Table 1-15)

62

Table 1-9 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Schools and nurseryschools, etc.)(as of end of December, 2014)(Number of facilities)(a)Planned
number(b)Outsourced
number(c)Completed
numberNumber of unnecessary
decontamination works in (a),(b) and(c) [the number that decontamination
works were determined to beunnecessary by prior monitoring
results]

Iwate Prefecture

242

242

242

(54)

Miyagi Prefecture

95

95

94

(10)

Ibaraki Prefecture

329

329

329

(42)

Tochigi Prefecture

232

232

231

(5)

Gunma Prefecture

24

24

24

(7)

Saitama Prefecture

48

48

48

0

Chiba Prefecture

593

593

593

(99)

Total number

1,563

1,563

1,562

(217)

Table 1-10 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Parks and sports
facilities)(as of end of December, 2014)(a)Planned
number(Number of facilities)(b)Outsourced
number(c)Completed
numberNumber of unnecessary
decontamination works in (a),(b)and (c) [the number that
decontamination works were
determined to be unnecessary
by prior monitoring results]

Iwate Prefecture

335

335

335

(268)

Miyagi Prefecture

153

150

149

(56)

Ibaraki Prefecture

888

887

887

(335)

Tochigi Prefecture

741

736

436

(241)

Gunma Prefecture

41

41

41

(18)

Saitama Prefecture

94

94

94

0

Chiba Prefecture

1,672

1,672

1,672

(143)

Total number

3,924

3,915

3,614

(1,061)63

Table 1-11 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Housing）(as of end of December, 2014)(a)Planned
number(b)Outsourced
number(Number of houses/buildings)
Number of unnecessary
decontamination works in (a),(b)and (c) [the number that
decontamination works were
determined to be unnecessary
by prior monitoring results](c)Completed
number

Iwate Prefecture

18,621

15,321

15,321(15,207)

Miyagi Prefecture

10,228

8,503

7,350

(2,972)

Ibaraki Prefecture

47,27647,27647,266(45,143)

Tochigi Prefecture

38,05437,71834,065(13,712)

Gunma Prefecture

6,192

6,192

6,165

(4,760)Saitama Prefecture

0

0

0

0

Chiba Prefecture

19,15919,15919,159(10,919)

Total number

139,530

134,169

129,326(92,713)

Table 1-12 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Other facilities)(as of end of December, 2014)(a)Planned
number(Number of facilities)(b)Outsourced
number(c)Completed
numberNumber of unnecessary
decontamination works in (a),(b)and (c) [the number that
decontamination works were
determined to be unnecessary
by prior monitoring results]

Iwate Prefecture

3,098

2,577

2,577

(2,445)

Miyagi Prefecture

348

348

332

(180)

Ibaraki Prefecture

634

634

634

(543)

Tochigi Prefecture

402

353

223

(136)

Gunma Prefecture

123

122

122

(86)

Saitama Prefecture

8

8

8

0

Chiba Prefecture

227

227

227

(130)

Total number

4,840

4,270

4,124

(3,520)64

Table 1-13 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Roads)(as of end of December, 2014)(a)Planned
number(m)(b)Outsourced
number(c)Completed
numberNumber of unnecessary
decontamination works in (a),(b)and (c) [the number that
decontamination works were
determined to be unnecessary byprior monitoring results]

Iwate Prefecture

2,151,600

2,140,600

2,140,600(2,140,400)

Miyagi Prefecture

332,40973,232

73,232(32,726)

Ibaraki Prefecture

1,164,205

1,120,705

1,120,705(1,117,240)

Tochigi Prefecture

81,40281,40281,402(76,875)

Gunma Prefecture

203,378

203,378

203,378(201,502)

Saitama Prefecture

3,409

3,409

3,409

0

Chiba Prefecture

232,874

232,874

232,874(137,388)

Total number

4,169,277

3,855,600

3,855,600(3,706,131)

Table 1-14 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Farmland andpastures)(as of end of December, 2014)(a)Planned
number(m2)(b)Outsourced
number(c)Completed
numberNumber of unnecessary
decontamination works in (a),(b)and (c) [the number that
decontamination works were
determined to be unnecessary
by prior monitoring results]

Iwate Prefecture

0

0

0

0

Miyagi Prefecture

557,000

557,000

217,000

0

Ibaraki Prefecture

0

0

0

0

Tochigi Prefecture

12,278,300

12,278,300

12,142,000(3,755,900)

Gunma Prefecture

1,043,597

1,043,597

1,043,597(951,708)

Saitama Prefecture

0

0

0

0

Chiba Prefecture

0

0

0

0

13,878,997

13,878,897

13,402,597(4,707,608)

Total number

65

Table 1-15 Progress of implementation of decontamination and other measures based on
decontamination implementation plan outside Fukushima Prefecture (Forests (Nearby living
areas))(as of end of December, 2014)(a)Planned
number(m2)(b)Outsourced
number(c)Completed
numberNumber of unnecessary
decontamination works in (a),(b)and (c) [the number that
decontamination works were
determined to be unnecessary
by prior monitoring results]

Iwate Prefecture

0

0

0

0

Miyagi Prefecture

2,000,000

2,000,000

1,029,709(185,355)

Ibaraki Prefecture

7,186

7,186

7,186

0

Tochigi Prefecture

831,760

831,760

831,760

0Gunma Prefecture

60,15554,55553,755(38,563)

Saitama Prefecture

0

0

0

0

Chiba Prefecture

0

0

0

0

2,899,101

2,893,501

1,922,410(223,918)

Total number

1.2. Features of contamination
1.2.1. Dispersion status of radioactive materials
Radioactive materials were discharged from the damaged nuclear reactors at the 1FNPS. The total
amount of radioactive materials discharged in the period between March 11 and April 5, 2011, wasestimated to be approximately 1.5 x 1017 Bq for iodine-131 and approximately 1.3 x 1016 Bq for
cesium-137 (estimated based on the data of environmental monitoring, etc. using an atmospheric dispersion
factor)69. A massive amount of radioactive materials was dispersed into the atmosphere.
The results of various monitoring surveys confirmed that radioactive materials had dispersed into wide
areas, not only into the evacuated areas but also into areas outside those defined as evacuation areas, as aresult of the accident, as mentioned in 1.1.2. For reference, Figure 1-31 shows the result of a monitoring
survey which was done using an aircraft by the MEXT during the period between October 22 andNovember 5, 2011. As understood when compared with the evacuation area shown in Figure 1-13,
contamination was confirmed not only in the areas to which an evacuation order was made (and residents
were no longer present), but also in the areas with residents present. The dose reduction activities wereneeded in such areas.
Because radioactive materials move over time as they are carried by rainfall and other factors and theease of accumulation varies by place, depending on the shape and material of structural objects, the dose
distribution had become uneven over time compared to the condition immediately after the accident, andthere occurred some localized high-dose points called hot spots (Figure 1-33). Such unevenly contaminatedconditions in micro and macro terms led to a difference in decontamination methods by areas and buildings
and accordingly caused concerns of the residents about the existence of high radiation sources in nearby
areas, as well as affecting their sense of fairness for the level of decontamination by area and house.
Detailed explanations and appropriate responses were required to address these issues.

69 Source: JAEA, "Summary of Estimation of Release Amounts of 131I and 137Cs Accidentally Discharged from

Fukushima Daiichi Nuclear Power Plant into the Atmosphere” (May 12, 2011)66

Legend

Air dose rates at the height of 1 m
above the ground surface(μSv/h)[Converted to the values as of 5
November]Areas where air dose
rate is not measured* Air dose rate due to natural radionuclides is included in this map.

Figure 1-31 Result of the Fourth Airborne Monitoring Survey (October to November 2011) by
MEXT (Air dose rates at the height of 1 m above the ground surface within an 80 km zone
from the 1FNPS)70 .

70Source: Ministry of Education, Culture, Sports, Science and Technology (MEXT), “Result of the Fourth

Airborne Monitoring Survey by MEXT” (December 16, 2011) (the same source for Figure 1-32)

67

Legend

Total accumulation of Cs-134 and137 on the ground surface (Bq/m2)[Converted to the values as of 5
November]Areas where air dose
rate is not measured

Figure 1-32 Result of the Fourth Airborne Monitoring Survey (October to November 2011)by MEXT (Total accumulation of 134Cs and 137Cs on the ground surface within an 80 km zone
from the 1FNPS).

68

Aizubange Town

Place where rainwater flows and drops

Bottom of downspout

Onami district, Fukushima-City

Exit of downspout

Place where rainwater flows

Figure 1-33 Monitoring of contamination status with gamma camera images at the hotspot
locations71 .

1.2.2. Major nuclides
Released radioactive materials included xenon-133, tellurium-132, strontium and plutonium in addition
to cesium and iodine.
Among them, strontium and plutonium were monitored from June 6 through June 14 and from June 27
through July 8, 2011 by the MEXT). As a result, plutonium-238 and plutonium-(239+240) were detected in
the northwest direction within the radius of 45 km from TEPCO’s 1FNPS, as shown in Figure 1-34.
However, the amount was within the monitoring level of the deposition quantity of plutonium due toatmospheric nuclear tests which had been monitored nationwide for 11 years before the accident, except for
one place (1.4 times of the maximum amount of plutonium monitored before the accident). Relatively highamount of strontium-89 and -90 has also been monitored on the ground surface in the northwest direction
from the 1FNPS. However, those quantities indicated a tendency to decrease as the distance got away fromthe power station. Based on these measurements, cumulative effective doses of 50 years were calculated forevery radionuclide which was deposited on the soil. As a result of these analyses, it was confirmed that the

71Source: "Discussion meeting with well-informed persons about decontamination ~Considering futurefrom the former knowledge in National Government and 4 cities ~ Fact book" (June 20, 2014
edition)(http://josen.env.go.jp/material/pdf/session_140615/session_140615_03_140620.pdf)

69

influences of radiation exposure due to the nuclides other than radioactive cesium are very small comparedwith those of radioactive cesium that was released in large quantities72.
Furthermore, as the half-lives of iodine 131, Xenon 133 and tellurium 132 are short with approximately
eight days, five days and three days, respectively, the influence of radioactive exposure due to these
nuclides becomes small after the early days of the accident. Therefore when considering person's radiation
exposure at present, important nuclides have become two of cesium 134 (half-life; about 2.1 years) andcesium 137 (half-life; about 30.2 years).

72According to the "Results of nuclide analyses of plutonium and strontium by the Ministry of Education,

Culture, Sports, Science and Technology (MEXT)", those are as follows. Cumulative effective doses of 50 years
have been analyzed in each place where the highest values were detected in the deposition amounts ofplutonium-238, plutonium-(239+240), and strontium-89 and -90. For them, plutonium-238 was 0.027 mSv,
plutonium-(239+240) was 0.12 mSv. Strontium-89 was 0.61μSv (0.00061 mSv), and strontium-90 was 0.12
mSv.
On the other hand, those values of cesium-134 and -137 were 71mSv and 2.0Sv (2,000mSv), respectively, ineach place where the highest values were detected for the deposition amounts of cesium-134 and -137.
In addition, in these analyses, the effect of dose reduction by decontamination is not included, and it isassumed to have stayed the same at the same place for 50 years.

70Legend
Deliberate
evacuation
area

Emergency
evacuation
preparationarea

Accumulation of Pu-238
and Pu-239+240 on the
ground surface(Bq/m2)(As of June 14)
Detection of Pu-238 andPu-239+240
Detection of Pu-238 only
Detection of Pu-239+240 only
Upper: Measured value of Pu-238
Lower: Measured value of Pu-239+240(2Km mesh)
10Km mesh(2Km mesh)

Places where plutonium 238 and 239+240 are considered to have been deposited newly due to the accident of Fukushima
Daiichi nuclear power plant

Figure 1-34 Measurement results of 238Pu and 239+240Pu on the ground surface73 .

73Source: Ministry of Education, Culture, Sports, Science and Technology (MEXT),"Results of nuclide analyses of plutonium and strontium by the Ministry of Education, Culture, Sports,
Science and Technology (MEXT)" (September 30, 2011) (the same source for Figure 1-36)

71

Legend
Deliberate
evacuation
area

Emergency
evacuation
preparationarea

Accumulation of Sr-89 andSr-90 on the ground surface(Bq/m2) (As of June 14)

Detection of Sr-89 and Sr-90
Detection of Sr-90 only
Upper: Measured value of Sr-89
Lower: Measured value of Sr-90(2Km mesh)
10Km mesh(2Km mesh)

Places where strontium 89 and Sr-90 are considered to have been deposited newly due to the accident of Fukushima Daiichi
nuclear power plant

Figure 1-35 Measurement results of 89Sr and 90Sr on the ground surface.

72

1.3. Features of decontamination
1.3.1. Unprecedented large-scale decontamination activities
Since radioactive materials have been dispersed across a wide area, decontamination works in Japan
associated with the accident at the 1FNPS have to be done in vast areas as indicated in 1.1.2 and 1.1.3: it isan extremely large-scale project that has not been seen before. We are also required to promote large-scaledecontamination projects that no one has ever done before, while obtaining the consents of related persons,such as owners of residential land. Moreover, we faced a large number of problems, as we did not haveenough time for planning. To solve these problems, various measures were taken and considerable efforts
were made.

（1） Establishment of strategic decontamination process
1）Implementation of large-scale decontamination with strategic decontamination process
The areas subjected to decontamination are extremely broad. There are several tens of
thousands to hundreds of thousands of residential land lots from which it is necessary toobtain consent, which means the number of involved persons such as owners is enormousand a great amount of time and manpower is required to obtain their consent. Therefore,
it is not necessarily efficient to hastily start a large amount of decontamination works at
one time before putting in place the system for decontamination.
To address such a situation, we implemented the “Demonstration model project fordecontamination” especially in the Special Decontamination Areas where the residents
had been evacuated and no restored infrastructures had been put in place. Throughdecontaminating local government offices and public facilities first, while confirming andaccumulating achievements and technical knowledge, we formed bases fordecontamination and restoration/reconstruction works, which led to smooth large-scaledecontamination (full-scale decontamination) works later.
In the full-scale decontamination, the strategic efforts by building bases were seen as
with the case of preliminary decontamination: these efforts were intended to increase thespeed of decontamination works as much as possible and improve the workplace safety of
the workers by first decontaminating the workers’ base for taking a rest.

2）Decontamination plan based on the weather
The weather varies greatly from season to season in Japan.
The demonstration model project for decontamination has proved that especially in winter it isdifficult to get accurate values of air dose rate due to the shielding effect of falling and accumulated
snow and there is a reduction in decontamination efficiency, increase in weight and volume of waste
due to the attachment of snow and problems in using cars, etc., as indicated in 1.1.6 (7). Therefore, it
has become a general rule not to perform decontamination forcedly during the time of snowfall andaccumulation in the full-scale decontamination.
Also, in the rainy and typhoon seasons, there are many concerns, including those for measuring
error, outflow of materials removed by decontamination, problems in recovering decontamination
waste water and concerns about worsening of the labor environment for decontamination workers.
Therefore, we make it a rule to stop the decontamination works under certain conditions of wind andrain.
Because we sometimes need to postpone the schedule of decontamination due to weather conditions,
we need to plan work schedules taking into account these impacts.
Although high temperature and solar insulation in summer do not affect the decontamination work
itself, they may result in a harsh working environment and have impacts on the health ofdecontamination workers. To address such a situation, we decided to work on decontamination withdue considerations for prevention of heat stroke and response to sudden illness depending on theweather, including wearing of protective clothing with cold packs and avoidance of working during73hours when temperatures are the highest, as well as raising the awareness of workers about heatstroke.

（2） Securing decontamination workers1）Securing the quantity of decontamination workers
While the decontamination work does not necessarily require a high level of skill, it has to be donewith consideration for the level of radiation dose and conditions of the decontamination objectives.
Also, only a very limited part can be done by machine. As a result, we need a large number ofworkers: the numbers of local workers that can be employed are not sufficient to secure the required
number of decontamination workers, and we needed to recruit widely from outside Fukushima
Prefecture.
However, the Great East Japan Earthquake which sled to the accident at the nuclear power station,
inflicted massive damage on the Tohoku region, mainly to Miyagi, Iwate and Fukushima Prefectures
as mentioned in 1.1.2 There have been large-scale restoration/reconstruction projects after theearthquake underway in Miyagi and Iwate Prefectures, and there has been a great demand forconstruction workers doing decontamination and other works also in the prefectures other than
Fukushima. Therefore, it has been very difficult to secure the required number of decontamination
workers.
Furthermore, many workers were required for works to be done on the site of the 1FNPS, which
added to the difficulty to secure the necessary number of decontamination workers.
Therefore, the MOE and local governments have worked to reduce concerns for becoming adecontamination worker, by introducing the details of decontamination work in an easy-to-understandway. In addition, they tried to secure decontamination workers by implementing various measures,
including payment of a special allowance in the Special Decontamination Areas.

2）Securing the quality of decontamination workers
Although decontamination work does not necessarily require a high level of skill, sufficient effects
may not be obtained if workers do not know the principle of decontamination and do not follow acertain procedure. Moreover, since radiation is not visible unlike ordinary contamination and dust, it
has the feature that we cannot tell whether a sufficient decontamination effect is obtained or notwithout measurement. If appropriate decontamination work is not done, it could lead to not only an
increase of removed substances, but also problems with residents. Therefore, securing the quality, as
well as the quantity, was required in recruiting decontamination workers.
On the other hand, it was difficult to secure a large number of workers who had knowledge andexperience in decontamination and radiation from the outset, because general citizens were notfamiliar with the knowledge of radiation, let alone decontamination, in Japan before the Great East
Japan Earthquake as mentioned in 1.1.1 Therefore, we had no choice but to nurture the knowledge of
decontamination through education. The efforts were made to provide many workers with education
about decontamination. For example, decontamination business operators provided the special
education and the newcomer education based on the Ionizing Radiation Ordinance fordecontamination to workers before starting decontamination work, as well as regular education andtraining on safety. They also implemented accident prevention activities and mutual checking ofradiation protection measures among workers on the site of work every morning before starting
decontamination work. In addition to the above, they themselves extracted and presented example
cases of successes and failures at work sites. The MHLW transmitted animated materials for special
education about decontamination on YouTube and Fukushima Prefecture and MOE held training
sessions on decontamination work for decontamination workers and site supervisors. These efforts
helped decontamination business operators perform educational activities more smoothly and easily.
Furthermore, decontamination workers are required to be of sufficient quality in terms ofconsideration to related persons and local residents as shown in 1.3.3, as well as in terms ofknowledge about decontamination. Especially, those from outside the decontamination area wererequired to exhibit behavior and awareness worthy of getting the trust of related persons and residents.
Moreover, the work of decontamination is unlikely to give a sense of accomplishment to workers,
74unlike civil engineering work and construction which are actions of making structural objects. A highlevel of patience is also required for decontamination workers to continue the work without degradingits quality, because they have to continue relatively monotonous work of decontamination endlessly
while placing extra effort on radiation protection. Therefore, how to maintain the motivation of theworkers was a critical issue.
The workers from the disaster-affected areas could maintain their motivation when they saw the
improved appearance as a result of their work such as mowing and they could feel their hometowns
were being restored. However, it is not always true for the workers from outside the areas. To maintainand secure their motivation, various efforts were made, including making repetitive communications
about what their efforts would bring about, showing the effects of their work by comparing the data
before and after decontamination, and conveying voices of appreciation and encouragement from thelocal people.

（3） Preparation of project environment
To perform this great amount of unprecedented decontamination work, it is also important to
prepare uniform procedures and systems to order and perform the work smoothly as a project, as wellas the strategic process as shown in (1) above and the securing of the quantity and quality of workers
as shown in (2) above.
Since there were a limited number of personnel at the MOE who had the experience of
implementing public works as a direct control project, they used the existing rules and systems that
had been established by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) and theMAFF, while obtaining help from personnel of the two ministries who had many experiences of doing
such works. Thus, the MOE temporarily created the common specifications and other rules(hereinafter referred to as the “Common Specifications”) that were required to implement thedecontamination and other construction works as a direct control project by searching for a way andstarting the decontamination work. After that, they continued to improve the specifications
step-by-step according to the actual conditions of the decontamination sites through a trial and error
process. As a result of these efforts, they established the rules from the framework of the entire
decontamination work to specific construction work implementation methods to a certain extent toenable a quick start of the decontamination works. They also strove to ensure the quality of works.
On the other hand, while we can create design documents for conventional civil engineering workin advance, we have to place an order based on approximate figures for decontamination, because
orders are placed before consent forms are collected. Therefore, we needed to agree on a construction
unit price in advance so that we could adjust an account after implementing decontamination work.
Also, although we need to provide documents about unit price for each decontamination objective at
the time of placing an order, it was difficult to accurately determine the unit prices74 in advance.
Therefore, we estimated the unit prices to allow quick order placement by setting up a team, which
included staff members from the MLIT and the MAFF who had many experiences in placing orders
for civil engineering work, based on the results of decontamination that had been implemented
independently under the model project of the Cabinet Office, as well as by Fukushima Prefecture andmunicipalities. The situation assumed under the model project may not always apply to the actual sitesof decontamination, because there are different conditions such as the existence of newly growing
trees after the earthquake. Therefore, we promoted a PDCA (Plan-Do-Check-Act) cycle energetically,
through changing actual work depending on the condition of the site and providing feedback about theresults. There were also some cases in which we had to do work on the site that had not been specified
in the decontamination guidelines or the Common Specifications. In such cases, the work was done
through trial and error and discussions between the supervising officials from the National
Government and the decontamination business operators. Such knowledge was shared among thesupervising officials to be reflected in the Common Specifications and other documents whenappropriate.
If we try to respond easily to the request of related persons, it may cause a risk of excessive
decontamination. The excessive decontamination would increase the total amount of removed
74Unit price represents a quantified amount of time and effort that is required for a certain task.

75

materials, as well as cause a feeling of unfairness among other related persons. To prevent these
problems, we standardized the judgment on reasonableness for the entire project, and included it as a
new rule in the standard procedures, if it could be theorized or generalized to ensure consistency.
In addition, the National Government improved the environment for decontamination work on thesite, as well as created a good project environment by preparing documents. For example, there is aconcern that the amount of daily life waste disposal and sewage treatment might exceed the existing
disposal/treatment capacity, as a result of a significant number of workers being expected to comefrom other local communities and prefectures. We worked to avoid such a shortage of treatment
capacity by ensuring exchange and confirmation of information between the National Government andlocal governments in advance, without fully leaving the response to decontamination business
operators.

1.3.2. Decontamination to secure safety at an early stage and to facilitate restoration andreconstruction（1） Acceleration of project through sharing information and promoting PDCA cycle
Since early stage securing of safety and restoration/reconstruction was required, we had to start thedecontamination project without sufficient lead-time for conducting sufficient policy preparation.
Therefore, we focused on the PDCA cycle and incorporated information that had not been prepared or
known in the preparation stage moment to moment to compensate for the lack of time at the
preparation stage. A part of such efforts is mentioned in Section 1.3.1.(3).
In large-scale decontamination works that are performed in multiple municipalities, implementationof an individual PDCA cycle only may cause isolated optimization. The system for information
sharing is critical for implementing a PDCA cycle that can contribute to the optimization of
decontamination work as a whole. The governmental organizations that played a central role in theinformation sharing were the Fukushima Environment Restoration Office for Fukushima Prefecture,
Iwate Prefecture and Miyagi Prefecture, and the Kanto Region Environment Office for Tochigi
Prefecture, Ibaraki Prefecture, Gunma Prefecture, Chiba Prefecture and Saitama Prefecture.

（2） Improvement of decontamination speed through setting up of temporary storage sites
In order to perform decontamination work smoothly, it is desirable to secure a disposal site forremoved soil and other materials generated by decontamination work before starting actual work.
There is a limited amount of large land space in Japan that may be used immediately as shown in 1.1.1.
If we started decontamination work after we had secured disposal sites for significant amounts ofremoved soils and other materials, it would take much time and it was clear that the start ofdecontamination would be delayed.
To solve this problem, we decided to secure so called “temporary storage sites” used to store
removed soils and materials temporarily before bringing them to the disposal facility (interim storage
facility), to promote the decontamination work, while making efforts to secure the disposal facility.
However, there were many cases in which the setting up of a temporary storage site was not decided
easily due to a limited amount of land. Many different efforts were made to set up temporary storagesites.
The reasons why the setting up of temporary storage sites was not advanced easily include thefollowing.
Difficulty of setting up sites on public lands
There were sufficient areas of national forests75, and it was not so difficult to form
a consensus about making national forests as candidate sites for temporary storage.
However, many such forests were preserved as protected forests under the Forest
75The area of national forests in Fukushima Prefecture amounts to approximately 400 thousand ha, while theentire area of Fukushima Prefecture is approximately 1 million 400 thousand ha.

76Act and the procedures for cancellation of protected forests were required. It tookmuch time to conduct studies and perform cancellation procedures.
Since the national forests are located in mountainous areas, we need land
reclamation to make them flat. In addition, there are some cases in which
preparation and improvement of access roads are required and the disposal of soil
from such work also has to be stored. As a result, we could not utilize the area ofreclaimed land effectively, and it resulted in taking much time for land reclamation,etc.
Difficulty in forming consensus with residents living in the vicinity
The residents became angry and felt frustrated, because temporary storage sites
were set up not on the premises of TEPCO or national land, but on sites in thevicinity of the residents who were suffering from evacuation and anxieties fromradiation. That became a major obstacle to the formation of consensus.
The residents were worried that the temporary storage site might become a final
disposal site.
There was a concern that accumulation of soil contaminated with radioactive
materials might enhance the impact of radiation.
Residents had a feeling of rejection of storing even contaminated materials thatwere generated outside their own lands.

To address such problems, the National Government, municipalities and decontamination business
operators advanced the following efforts, which led to dispelling the concerns and setting up
temporary storage sites by municipalities.
Seeking candidate lands in the local area
In the case where it was difficult to secure an appropriate temporary storage site
within the national land, this fact was communicated honestly to the municipal
governments and residents and understanding for securing a temporary storagesite in the region was requested. We worked to seek practical solutions jointly withthe local community.
Elimination and mitigation of concerns and frustrations
In response to the opinions that the temporary storage site should be set up within
the premises of TEPCO and the national land, we did not turn down such opinions
immediately, but explained that it was not practical when looking at it objectively,
after considering the practicality of using each premise, and requesting andnegotiating with other governmental agencies in some cases. We also worked toeliminate and mitigate frustrations of the residents by making an in-depth
explanation that to secure the site in their community would result in advancing
decontamination more quickly.
In response to the concerns about the safety of the temporary storage site, we madethe following explanations to eliminate and mitigate concerns of the residents: theoutmost part would be covered by uncontaminated soil; and accumulated soils
would have lower risk once they were accumulated and sufficient safety measures
were taken compared to the case in which removed soil was stored on the site.
In addition, there was also an effort to help the residents realize the safety of atemporary storage site through their building a system for monitoring the
temporary storage site as in the case of Kawamata Town.
In response to the feeling of rejection of storing contaminated materials that weregenerated outside their own lands, we explained patiently that setting up thefacility would result in advancing decontamination more quickly. Also, we sought
the cooperation of heads of district and neighborhood associations, who were closer
77

to the residents in terms of psychological distance, and asked them to consider
setting up a temporary storage site in each administrative district.
In the case of Fukushima Prefecture, in response to the concerns that thetemporary storage site might become a disposal facility eventually, the MOE wasin the forefront of the efforts to prepare for interim storage facilities as much as
possible and to appeal with such an attitude to eliminate and mitigate concerns of
the residents.
Transmission of information on actual status
Since the residents did not have an image of a temporary storage site especially in
the initial stage, we worked to create a concrete image of the facility, by providing
explanations with leaflets and holding tours on the site of a temporary storage sitethat was actually set up, in order to reduce psychological resistance against thefacility.
Since decontamination work advanced quickly in the areas where the temporarystorage site was set up, we made appeals with such results to make the residents
recognize the necessity and the importance of the temporary storage site, in orderto accelerate the setting up of a temporary storage site also in the areas where thefacility had not been set up.
Flexible response appropriate for the situation of each area
When it was difficult to set up a temporary storage site by any means, we
responded in a flexible way according to the situation of each area, such as
operation with storage of removed soil and materials on the site, and not sticking
to setting up the temporary storage site as an absolute requirement.

Furthermore, we reduced the amount of generated removed soil and materials through avoiding
excessive decontamination as mentioned above in the first place in order to reduce the amount ofremoved soil and materials that were to be brought into the temporary storage site. We also reduced
the volume of removed soil and materials by cutting, crushing, compressing or burning them.

1.3.3. Project operation with consideration of the maintenance of community and theprotection of rights（1） Maintenance of community
This decontamination project derived from the 1FNPS accident focused on residents’ returning totheir previous lives as early as possible. Therefore, we were required to promote it without damaging
the local communities to ensure later life there, not just to remove contaminated soil and materials.
To achieve this goal, we employed a method to perform decontamination work by an administrative
unit, such as a district; that is to say “Decontamination of the entire community,” not to advancedecontamination work for each related person after obtaining the consent. This decontamination
method has a disadvantage for the residents who agreed on performing decontamination work earlier,because it starts after obtaining the consent from all the residents of an administrative unit, such as the
district.
Despite such a disadvantage, we needed to promote decontamination work focusing on the local
communities that had already existed, given the healthy maintenance of each community after
decontamination, in addition to the fact that there was no sufficient decontamination result without
decontamination for the whole area.
As to setting up the temporary storage site as shown in Section 1.3.2.(2), many residents said thatthey agreed to accept the removed contaminated soil from inside their community, but not those fromother communities. It can be said that the unit of the local community, such as a district, was one of
the important units in Japan to advance decontamination.
This concept was also used in setting evacuation areas. In order to avoid separation of a local
78

community or district, we did not use the annual exposed dose as sole criteria for setting a border of anevacuation area. We were careful so that the border of an evacuation area did not divide a district unit,
while making the exposure dose the fundamental criterion.

（2） Protection of rights and consideration of lifestyle
This decontamination project focused on residents’ returning to their previous lives as early as
possible. Therefore, we did a minimum amount of scraping and replacement of roof materials so as to
avoid damages to properties owned by the residents as much as possible. In the case of the residents
engaged in farming, the agricultural land was inseparable from their lives: they had cultivated andnurtured their land over a long period of time. Therefore, when a farming family requested it, we tried
to select an appropriate decontamination method as much as possible to avoid stripping, etc. andworked to maintain the functions of agricultural soils.
Some residents said, “I want a full replacement.” We patiently provided explanations and werecommitted to protect their properties and agricultural lands that were very important for farming
households.
Also, ancestral shrines and garden trees they had grown over years were irreplaceable for the
residents’ lives. If such shrines and garden trees were removed or cut because they were contaminated,that might cause emotional distress to the residents and lead to degradation of quality of their lives.
Therefore, we worked with the residents to coordinate whether decontamination was done or not, as
well as choosing the detailed decontamination method based on a comprehensive judgment on the
degree of decontamination and the importance for the residents, while listening to their opinions.

（3） Obtaining consent securely
In implementing this decontamination project, we adhered to obtaining consent from the residents
before starting decontamination. We were determined not to perform decontamination forcibly,
ignoring the intention of the residents.
This was very important not only in terms of the importance of obtaining consent from the residents
from a viewpoint of protecting the right of the residents76 as mentioned in (2) above, because
decontamination could damage or change the properties and agricultural lands of the residents, butalso in terms of sharing and agreeing on the decontamination plan with the residents, because there
were different objectives and methods of decontamination.
Therefore, we obtained the consent of the residents while giving them in-depth explanations andpreparing detailed drawings and materials about decontamination procedures for eachdecontamination objective.
On the other hand, as mentioned above, there are currently several tens of thousands of displaced
people from the evacuation area and more than one hundred thousand including those that fled fromoutside the evacuation area. To obtain residents’ consent to decontamination, it is necessary to identify
related persons who have the rights over targets of decontamination and obtain consent regardless ofwhether they are living there or have evacuated the area. However, there are a great number ofdecontamination targets: the number of residences to be covered by decontamination solely amounts
to from several tens of thousands to several hundred thousand. Especially for the Special
Decontamination Areas, where all the residents have evacuated, we need to identify the number ofrelated persons by checking with registry books and other materials, then identify where they haveevacuated to and explain the current situation and the method of decontamination to them to obtainconsent. Also, in the case that one person owns multiple land plots or buildings, name-baseaggregation is required to organize the data. As a result, a great amount of manpower was required toobtain their consent.
Moreover, we could not always obtain the consent after a one-time explanation/discussion. There
were many cases in which we finally obtained the consent after we had listened carefully to the76In addition to obtaining consent from residents on the possibility of damages to their properties in theprocess of implementation of agreed-on decontamination methods, we needed to agree on the conditions of
their properties before decontamination so that we could confirm whether damages and loss discovered
after decontamination had been caused by decontamination work or not.

79

requests of the residents, considered such requests and answered their questions again and again.
Especially in the Special Decontamination Areas from where the residents had already evacuated, it
was more difficult to obtain the consent, because the residents could not confirm whether there wasany inappropriate decontamination work or damage to the buildings for themselves. Therefore, we
confirmed their consent on the site and allowed them to be present at the decontamination to observe
decontamination work so that the residents could confirm the work with their own eyes. We also
provided instruction and education to decontamination business operators and workers, who would
obtain the consent from related persons, to respond to such persons sincerely so that they could build a
relationship of trust with them.
Although those efforts were made, the degree of consent varied by individual and by area. As aresult, the progress of decontamination varied by area, and the areas in which decontamination wasunderway and those in which it was not were distributed in a patchy fashion.

1.3.4. Careful response with consideration for residents’ position and feelings
Anxieties and concerns of the local residents are not always related to decontamination. Especiallyin the Special Decontamination Area, the residents did not necessarily have a positive attitude toward
discussing decontamination solely, because the review of the area that served as a base for thedecontamination plan was related to the compensation criteria. Therefore, we made careful responses
giving thought to situations and feelings of residents of the area, such as bringing staff members who
could provide explanations about the review of the area and compensation when we had a briefing
session about decontamination.
Also, the residents had a feeling of non-acceptance toward effluent water, as they had an image that
contamination was also transferred when water flowed from the premises of their residences to outside,although it was unlikely that effluent water generated as a result of decontamination in the Intensive
Contamination Survey Area had a higher level of radioactive concentration. Therefore, we took
necessary measures in response to the request of the residents, such as recovery of effluent water.
Furthermore, we also gave consideration to their feelings about visiting their residences: In theseasons when there were many requests for overnight stay, such as the year-end and New Yearholidays and the Bon period for visiting their ancestors’ graves, we also conducted decontamination
prior to these periods.
In addition, the fact that many decontamination workers come to the community from outsidemeans an increase of strangers in the community to the local residents, and they are likely to beconcerned about the change of the community’s atmosphere, deterioration of public security andgeneration of traffic jams. To address such concerns, we made many efforts to build a relationship oftrust between the local residents and the decontamination workers.

80

2． Overview of decontamination methods
As explained in the previous chapter, the Act on Special Measures Concerning the Handlingof Environmental Pollution by Radioactive Materials Discharged by the Nuclear Power Station Accident
Associated with the Tohoku District Off the Pacific Ocean Earthquake That Occurred on 11 March 2011
(hereafter referred to as the “Act on Special Measures”) designated the Special
Decontamination Areas for the National Government to decontaminate and the Intensive
Contamination Survey Areas for the local municipalities to decontaminate. In order toachieve the additional exposure dose of 1 mSv/y or less as the long-term goal, thedecontamination was planned to be implemented in the following order.
(i) Investigate and measure the status of contamination and designate the areas in which
decontamination and other measures are to be implemented (Articles 34 and 36)(ii) Formulate the decontamination plan and implement decontamination based on the plan
(Article 40)(iii) Collect, transfer and store the removed soil, generated by the decontamination andrelated works (Article 41)
The Ministry of the Environment (MOE) formulated the “Decontamination Guidelines (1stEdition)” in December 2011 to explain these processes in a concrete manner. The guidelines
are divided into the following four parts and each part corresponds to one of the above (i) to(iii).
Part 1: Guidelines for the Methods for Investigation and Measurement of the Status ofEnvironment Pollution in the Intensive Contamination Survey Areas (corresponding to(i))
Part 2: Guidelines Pertaining to Decontamination and Other Measures (corresponding
to (ii))Part 3: Guidelines Pertaining to the Collection and Transfer of Removed Soil(corresponding to (iii))
Part 4: Guidelines Pertaining to the Storage of Removed Soil (corresponding to (iii))
While the guidelines mainly cover the decontamination by municipalities, they also coverdecontamination by the National Government. Decontamination in accordance with theseguidelines is deemed to be appropriate for the situations found in Japan.
The guidelines were revised in May 2013. Further, a supplement was added in December
2014 based on the opinions of specialists and local governments and it included the responses
to improper decontamination, ways for conducting more effective decontamination, as well as
giving the knowledge obtained and the new technologies made available since December 2011.
The four parts are outlined and explained below based on the revised 2nd Edition77.

2.1. Guidelines for Methods for Investigation and Measurement of the Status ofEnvironmental Pollution in the Intensive Contamination Survey Area
2.1.1. Basic Concept
The “Guidelines for Methods for Investigation and Measurement of the Status ofEnvironmental Pollution in Intensive Contamination Survey Areas” corresponds to Part 1 of
the Decontamination Guidelines. As shown in Figure 2-1, this part explains the following
items: (i) the investigation and measurement of the status of environmental pollution by theaccident-derived radioactive materials in the Intensive Contamination Survey Areas; (ii)77Source: Ministry of the environment (MOE), “Decontamination Guidelines (2nd Edition)” (supplement added,

December 2014) (http://josen.env.go.jp/material/pdf/josen-gl-full_ver2_supplement1412.pdf)
Fig.2-41 and Table 2-1 to Table 2-57 are from the same source.

81

Fig.2-1

todetails of the measurement methods necessary for decontamination and related works, andstorage of removed soil in the decontamination implemented areas; and (iii) the methods fordetermining accuracy of measurement.
Measurements are needed to determine the appropriate decontamination measures and tomonitor storage sites of removed soil as mentioned above, and in this context they also relate
to other parts of the Decontamination Guidelines. This correlation is illustrated in Figure 2-2.

<Implementation Items><Necessary Investigations and Measurements>① Designate intensive contamination survey area

Investigations and measurements to determine
whether or not a municipality② Determine decontamination zones where
decontamination and other measures will be
carried out

Investigations and measurements on theenvironmental contamination status within theintensive contamination survey areas③ Implement detailed measurements in thedecontamination zones

Detailed measurements designed to determine if it
is necessary to conduct decontamination in
individual facilities, as well as to decide on themethods for decontamination④ Implement decontamination and other measures
based upon the decontamination plans

Perform measurements before and after thedecontamination measures⑤ Collect, transfer, and store the removed soil
generated, in association with decontaminationand other measures

Monitor the air dose rate and the radioactivity
concentrations when the removed soil is being
stored⑥ Cancel the intensive contamination survey area
designation

Investigations and measurements to determine
whether or not a municipality meets thedesignation requirements*In addition to the above, continuous investigations andmeasurements must also be carried out where appropriate forthe sake of monitoring the changes in the dose rate

Figure 2-1 Implementation items and necessary investigations and measurements forcarrying out decontamination.

82

2.Indicators of
the Status ofContamination
by Radioactive
Materials

1.Basic Concept

6.Measuring
Apparatuses
and Methods of
Use

＊2

＊1

Riversand ponds

Air dose
rate

Vegetation

4.Methods for Taking Detailed Measurements
in Decontamination Zones

Soil

Air dose
rate

Roads

3. Methods for Investigating and Measuring to Determine
the Areas to be Included in a Decontamination Plan

Buildings
and Otherstructures

Part 1:
Guidelines for
Methods for
InvestigatingandMeasuring the
Status ofEnvironmental
Pollution in
Intensive
Contamination
Survey Areas

5.Assessments oftheDecontamination
Results

Determine the decontamination methods
Part 2:
Guidelines
Pertaining to
Decontaminati
on and Other
Measures

Surfacedose rate

Measure to confirm the decontamination results(before decontamination)

Air doserate

Surfacecontamination
density

Implement the decontamination work

Measure to confirm the decontamination results(after decontamination)

Air doserate

Surfacedose rate
Surfacecontamination
density

Assessments of the decontamination results

Part 3:
Guidelines
Pertaining to
the Collection
and Transferof theRemoved Soil

Part 4:
Guidelines
Pertaining to
the Storage of
Removed Soil

Air dose
rate

Collect and transfer the removed soilStore the removed soil
Air dose
rate

Monitor the radiation dose

*1: If “4. Detailed Measurements in Decontamination Zones” concurrently serve as “Measure to confirm the decontamination results (before
decontamination)”, then measurements of surface dose rate and surface contamination density shall also be performed.
*2: Those parts related to “5. Assessments of the Decontamination Results” and “6. Measuring Apparatuses and Methods of Use” areindicated with a ”●“

Figure 2-2 Descriptive actions related to measurements in the Decontamination Guidelines

2.1.2. Indicators of the Contamination Status by Radioactive Materials
The indicators of the contamination status by radioactive materials use the air dose rates
as the indicators of the contamination status in the living environment and the surface
contamination densities and surface dose rates as the indicators of the contamination statusof the objects subject to decontamination in order to grasp the contamination status byradioactive materials. Table 2-1 summarizes the indicators together with measurement
methods.

83

Table 2-1 Summary of indicators of the contamination status by radioactive materials
Assessment

Status of contamination in living Status of contamination of objects

perspectives

spacescategory

No. 1 measurement points(①)
No. 2 measurements points(②)
Determine the decisions of
Determine the scope for thedecontamination zones
decontaminationinindividual
Determine if it is necessary tofacilities and determine the amount
conduct
decontaminationof radioactive materials (extent ofwithin individual facilities in
the contamination) in conjunction
the decontamination zones
with the detailed measurements
throughdetailed
carriedout
withinthemeasurements
inthedecontamination zones
zones(determine by using
Confirm the degree to which themean dose rate)contamination of the objects subject
Determine the comprehensive
to decontamination has abated due
results of the decontamination
to the decontamination and otherwithin the individual facilities
measuresfrom the decontamination andother measures (however,attention must be paid to thefact that this is affected bybackground radiation*3)
Monitor the radiation dosewhen the removed soil isstoredAir dose rate (1 m*1)
Surface
Surface dose rate (1Measurement
objective

Indicator

subject to decontamination(measurement

contamination cm)

position)

densityUse(1 cm)

collimatora Vary the
distance
andExamples ofmeasuring

NaI scintillation survey meterCsI scintillation survey meter

apparatus
Methods forusing themeasurement
results

Determinethedecontamination zones
Assess the improvements inthe contamination status inliving spaces through thedecontamination work

GM
meter

surveymeasure*2
NaI
scintillation
survey meter
CsI
scintillation
survey meter

Determine the decontamination
methods
Assess the extent to which theradioactive materials have abatedthrough the decontamination work

*1: For the contamination status in living spaces, in principle, measurements should be taken at aheight of 1 m from the ground (it would also be fine to measure at a height of 50 cm atelementary and lower level schools, as well as special-needs schools, with consideration for theliving spaces of infants and schoolchildren in the lower grades).
*2: The surface dose rate of the target object is to be measured at positions at the object’s surface
and at heights of 50 cm and 1 m, and then the measured values are to be compared.

842.1.3. Methods for Investigation and Measurement to Determine the Areas to be Included ina Decontamination Plan
（1） Basic concept
The methods for investigation and measurement to determine the areas to be included in
the decontamination plan stipulate that the decontamination areas (areas to be included in adecontamination plan) are in principle divided by the unit of zones such as an a village section,a municipal block, or other units, where the dose rate is 0.23 μSv/hour78 or higher, which isthe condition for decontamination planning. But regarding the living environment forchildren, such as schools and parks, it is allowed to divide the decontamination zones basedon each facility rather than on an area such as municipal blocks.

（2） Methods for investigation and measurements by zone units
The methods for investigation and measurements by zone units are used to judge whether azone meets the decontamination planning requirements and then to select suitablemeasurement methods based on the judgement. Two examples are given. The first is based on
the measurement results at various points (Figure 2-3) and the second is based on themeasurement results at schools and in parks (Figure 2-4).

1）Designation based on the measurement results at various points
Specific locations and number of points for measurement in a zone are first chosen inconsideration of the following points, depending on the form of existing land use andthe situation of the surrounding.
The locations of measurement are chosen in a manner that the general tendency inthe zone can be represented.
Special locations such as the base area of trees, street drains and other locations
where high dose rates may be recognized should not be chosen, because themeasurements are intended to grasp the average dose rate in the zone.
More locations should be chosen in a living space where, for instance, there aremany buildings.
Investigations and measurements may not always be needed in zones where
people’s exposure dose cannot be naturally reduced, such as forests.
Efficient investigations and measurements should be employed as needed, forexample, measurements by using monitoring vehicles.
Once the measurements are completed at all points in the zone, the average dose rateof the zone is calculated based on all the results of the zone.
Based on the average dose rate, the judgment is derived whether that zone meets thedecontamination planning requirements.

78The air dose rate per hour which is equivalent to the additional annual exposure dose per year of 1 mSv.

This is calculated as follows: 0.19 μSv/h×（8 h＋0.4×16 h）×365 days= 1 mSv per year. The dose rate of 0.4
μSv/h due to exposure from the ground is added to 0.19 μSv/h and then air dose rate per hour of 0.23 μSv isobtained. (Refer to “Basis of the additional annual exposure dose of 1 mSv per year" (October 10, 2011): The
first joint review meeting of the environment restoration review committee and the hazardous waste safety
evaluation review committee.)85

Certain area in a municipality

SchoolPark

Plant/building★= Measurement point

Figure 2-3 Example of the determination of whether the area meets the decontamination
planning requirements based on the measurement results at various points.

2）Designation based on the measurement results at schools and in parks
Specific locations and number of points for measurement in a zone are first chosen inconsideration of the following points.
Measurements are to be made mainly in the living environment of children, suchas schools and parks in the zone.
Special locations such as the base area of trees, street drains and other locations
where high dose rates may be recognized should not be chosen, because themeasurements are intended to grasp the average dose rate in the zone.
Measurements are to be done at about five points in each school or park.
Once the measurements are completed at all points in the zone, the average dose rateof the zone is calculated based on all the results of the zone.
Based on the average dose rate, the judgment is derived whether that zone meets thedecontamination planning requirements
Certain area in a municipality

Park

SchoolPlant/building★: Measurement point

Figure 2-4 Example of the determination of whether the municipal area meets thedecontamination planning requirements based on the measurement results for schools and parks.

86

（3） Methods for investigation and measurement of the living environment of children, suchas schools and parks
Concerning the living environment for children such as schools and parks, it is allowed todesignate a decontamination planning zone on a facility basis, as mentioned in (1) above. This
subsection presents the decision criteria to judge whether each facility (zone) meets theplanning requirements (Figure 2-5).
Specific locations and number of points for measurement in a facility are first chosen inconsideration of the following points.
Special locations such as the base area of trees, street drains and other locations
where high dose rates may be recognized should not be chosen, because themeasurements are intended to grasp the average dose rate in the facility.
Measurements are to be done at about five points in each facility.
Once the measurements are completed at all points in the facility, the average dose rateof the facility is calculated based on all the results of the facility.
Based on the average dose rate, the judgment is made whether that facility meets thedecontamination planning requirements.

Certain area in a municipality
Facility-by-facility determination
Park

SchoolFacility-by-facility determination

Plant/building★= Measurement point

Figure 2-5 Example of the determination of whether the area meets the decontamination
planning requirements based on the measurement results only from facilities used bychildren, such as schools and parks.

2.1.4. Methods for Taking Detailed Measurements in Decontamination Zones
The methods for detailed measurements in decontamination zones elaborates on thethings to record in the measurements in detail. It also stipulates that the detailed
measurements be included as part of the pre-decontamination work measurements.
The locations to be decontaminated and decontamination methods are described in Section
2.2, “Guidelines Pertaining to Decontamination and Other Measures”, and are not explained
here.

87

2.1.5. Evaluation of Decontamination Results
The evaluation of decontamination results stipulates that the decontamination results canlargely be evaluated by two ways: evaluation of air dose rates in the living environments inthe decontamination zone as a whole and the individual targeted facilities; and evaluation of
surface concentration densities of the objects subject to decontamination in the individual
decontamination works. The former evaluation is expressed in terms of reduction rate of the
air dose rate, while the latter evaluation may be expressed in terms of decontamination factor(DF) as well as the reduction rate.
Reduction rate [%] = (1- Radiation dose after decontamination ／Radiation dose before
decontamination)×100
Decontamination factor [-] = Surface contamination density before decontamination／
Surface contamination density after decontamination

2.1.6. Measuring Devices and Methods of Use
The measuring devices and methods of use explains the measurements necessary for thewhole scope of activities covered by the Decontamination Guidelines, including not only themeasurements for formulating decontamination plans but also measurements for confirming
the results of radiation reduction through the decontamination works and other relevantmeasurements.

（1） Measuring devices and methods of use
Among the measuring devices and methods of use, scintillation survey meters (scintillation
counters) are used for dose rate measurement and GM survey meters (GM counters) are used
for surface contamination density measurement.

（2） Maintenance of measuring devices
Regarding maintenance of measuring devices, users should note that the measuring devices
may give incorrect readings for such reasons as changes in the sensitivity of detectors causedby the measuring environment or degradation of any components in the electrical circuit. It isstressed that the measuring devices should be periodically calibrated and adjusted.

（3） Methods of use of measuring devices
The methods of use of measuring devices identifies the precautions to be taken formeasurements using scintillation survey meters and GM survey meters, as summarized inTable 2-2. Furthermore, examples of the format of recording sheets for measurements arepresented in Figure 2-6 and Figure 2-7.

88

Table 2-2 Summary of measuring devices and methods of use
Category
No. 1 measurement point（①） No. 2 measurement point（②）
Purposeof Contamination
statusof Contamination status of objects subject tomeasurements living spaces
decontamination
ObjectGamma rays
Gamma rays
Beta rays
measured
Examplesof
NaI scintillation survey meter
GM survey metermeasuringCsI scintillation survey meter
apparatuses
Calibration
Measuring apparatuses shall be calibrated at least once a year inaccordance with JIS.(Agent performing the calibration work)
Businesses registered in accordance with the Measurement Act
Measuring apparatus manufacturer
Daily check
The remaining battery level, breakage of cables and connectors, and statusof high voltage application shall be checked, and inspections of switch
operability, etc. shall be carried out.
Measurements shall be performed at the same places where thebackground radiation does not vary substantially, and it shall be
confirmed that there are no large variations by comparing with pastvalues.
If it is difficult to perform the calibrations more than once a year as
described in the above section, this can be substituted by a method(adjustment) to compare the results with those obtained in the same
location where measurements were also taken by using a separate
measuring apparatus that has been fully calibrated and checked (thisexcludes GM survey meters).
Prevention of
The body and detecting element of the measuring apparatus shall becontaminationpreferably covered with a thin plastic sheet, etc.
The plastic sheet, etc. shall be replaced with new material when it getsdirty or breaks.
Measurement
The air dose rate shall be [Usinga
Measurements
measured at a height of 1 m collimator]
shall only be takenfrom the ground.
The air dose rate
roughly1 cm away
The air dose rates on roads
shallbefrom the surface.
and pedestrian overpasses
measured at anearschoolsmaybeheight of roughly
measured at a height of 50
1 cm (a height
cm from the ground forwhere about one
elementary
schoolsandfinger will fit
below,
aswell
asbetweenthespecial-needs schools, with
detector element
consideration for the living
and
the
space
of
infantsandmeasurement
schoolchildren in the
point) from theLower grades.
surface of themeasurement
point while using
a collimator toshieldagainstexternal gamma
rays.
[Measurements byvaryingthedistance]
The air dose rateshallbemeasured from89

Records

positions on thesurface and atheights of 50 cm
and 1 m awayfrom it, and themeasured values
shallbecompared.
Prior to measurement, it shall be confirmed whether the background valueof the measuring apparatus is being displayed abnormally (no indicators
appear, or indicators are unusually high or low).
When measuring the air dose rate, the measurements shall be taken withthe detecting element parallel to the ground surface and as far away as
possible from the body.
The power to the measuring apparatus shall be turned on and the reading(measured value) shall be read off after waiting until the reading
stabilizes. In doing so, with measuring apparatuses on which a time
constant can be set, the measurer shall wait until a period of time that isthree times longer than the time constant has elapsed before performing
the measurements.
If the readings on the measuring apparatus disappear, switch the range
and take the measurements, and if the readings disappear in the
maximum range, either interpret those readings as being in the maximum
range or higher, or use another type of measuring apparatus to take themeasurements.
If readings vary, the average value shall be read.
The measurer shall record the air dose rate, etc. at each measurement point
shown in the conceptual diagram, etc., along with the date and time of
measurement and the measuring apparatus used (see Figures 1-14 through1-18).

90

Manufacturer: ModeCity:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination

After Decontamination

Date measured

Mon., April 22, 2013

Fri., April 26, 2013

Time measured

9:20~9:40

13:20~13:40

Measurer

Josen Taro

Josen Taro

WeatherCloudyClea

Air Dose Rate Measurement Results Entry Section
BeforeDecontamination

Measurement
heightAfter Decontamination

Measurement
height①-1 measurement point

3.0

μSv/h

1m 50cm

0.51

μSv/h

1m 50cm①-2 measurement point

0.55

μSv/h

1m 50cm

0.16

μSv/h

1m 50cm①-3 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-4 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-5 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-6 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-7 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-8 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-9 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-10 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm

Notes(Example)

Garden①－１x

Building①－2xGardenParking lot*The arrows indicate the direction of
the measurements.

Figure 2-6 Entry sample of an air dose rate record sheet.

91

Manufacturer: ModeCity:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination
Date measured

Day: ( ) Month:

After Decontamination

Year

Day: ( ) Month:YearTime measured
Measurer
Weather
Air Dose Rate Measurement Results Entry Section
BeforeDecontamination

Collimator①-1 measurement point

cpm

Yes Nocpm

Yes No①-2 measurement point

cpm

Yes Nocpm

Yes No①-3 measurement point

cpm

Yes Nocpm

Yes No①-4 measurement point

cpm

Yes Nocpm

Yes No①-5 measurement point

cpm

Yes Nocpm

Yes No①-6 measurement point

cpm

Yes Nocpm

Yes No①-7 measurement point

cpm

Yes Nocpm

Yes No①-8 measurement point

cpm

Yes Nocpm

Yes No①-9 measurement point

cpm

Yes Nocpm

Yes No①-10 measurement point

cpm

Yes Nocpm

Yes NoAfter Decontamination

Collimator

Notes

Figure 2-7 Example of a surface contamination density record sheet.

2.2. Guidelines Pertaining to Decontamination and Other Measures
2.2.1. Basic Concept（1） Role of the Guidelines
The Decontamination Guidelines use example cases to explain in a concrete fashion the
Ordinance of the Ministry of the Environment (MOE) pertaining to standards for themeasures for decontamination of the soil, etc. provided in Article 40, Paragraph 1 of the Act on
92

Special Measures.
Each municipality will formulate a decontamination plan based on prioritization andfeasibility in light of the actual conditions in individual areas. Appropriate decontamination
methods will be selected as needed from among those listed in these guidelines to advance thedecontamination work based on individual decontamination plans.
At present, the methods given in these guidelines are deemed to be appropriate for
implementing decontamination and related procedures, but decontamination work and newtechnologies are currently being developed and verified by various stakeholders. These
guidelines will be revised as needed in light of trends in the development and verification ofthis knowledge and these technologies.

（2） Important points in implementing decontamination and other measures
This section explains the four aspects that are important in implementing decontamination
measures. The radioactivity of radioactive materials decays naturally as time passes. In
addition, the appropriate responses must be taken by fully considering the changes in thecontamination status as a result of factors like the radioactive materials migrating due torainwater and other factors.
Measures shall be taken to prevent dispersion and outflow, as well as offensive odors,
noise, and vibrations, and records of the quantities of removed soil and other necessary
measures should be taken with respect to preserving of health of surrounding residents
and conserving the living environment.
To effectively reduce the radiation doses due to contamination, those locations that arecontaminated at comparatively high concentrations that contribute substantially to theradiation dose must be identified, and appropriate methods of decontamination must
be used in accordance with the characteristics of the contamination. The effectivenessof these methods must also be confirmed by measurements before and after thedecontamination to effectively reduce the radiation doses in the living environment.
The removed soil, etc. must be separated from other objects to ensure that there is nodanger that it mixes with other objects, and the removed soil must also be separated
from other decontamination wastes to the extent possible.
It is important to strive to minimize the quantity of removed soil, etc. generated duringdecontamination. It is also important to ensure that the contamination does not spread
as a result of the decontamination work. For example, washing activities using waterproduce drainage that contains radioactive materials. The workers carrying out
decontamination and other measures should, to the extent possible, remove in advance
those radioactive materials that can be removed by methods other than washing withwater, properly treat wastewater, and find other ways to avoid affecting outflow
destinations due to cleaning, etc. as much as possible. Moreover, periodic monitoringshould be performed after the applicable measures are implemented when deemednecessary on account of the actual conditions in the area.

2.2.2. Decontamination and Other Measures for Buildings and Other Structures
This section explains preparation, prior measurements, decontamination methods,
post-work measures, and subsequent measurements and records, as shown in Figure 2-8 ofthe basic flow pertaining to decontamination and other measures for houses, buildings,
agricultural facilities, and other structures.

93

(1)Measures to reduce public exposure in connection with the work

1.Preparation

2.PriorMeasurements(2)Equipment and materials(1) Determination of measurement points(2) Measurement methods

Measures to prevent the spread of contamination through dispersion, outflows, and so forthfollowing the decontamination (institute the necessary measures for each instance of
decontamination work)

3.Decontamination
Methods

Decontami
nationwork
proceeds
from highareas tolow areas(1) Decontamination of roofs and other areas(2) Decontamination of rainwater gutter(3) Decontamination of exterior walls(4) Decontamination of fences, walls ,benches, playground equipment, etc.
(5) Decontamination of gardens and other areas(6) Decontamination of street drains, etc.

(1) Handling the removed soil, etc.

4.Post-Work
Measures(2) Wastewater treatment(3) Cleaning equipment, etc.

5.Subsequent Measurements and Records

Figure 2-8 Basic flow for decontamination and other measures for buildings and otherstructures.

（1） Preparation
Before performing decontamination work, in addition to preparing the equipment required
for the work, preparations must be made to ensure safety of workers and the general public toprevent their exposure to hazards, such as by inhaling dust generated duringdecontamination work; these preparations are summarized in Table 2-3.

94

Table 2-3 Preparation for decontamination and other measures
Measures to
Restriction of
Reduce Public
entry
Exposure inConnection with
Decontamination
Work

Signage

Preparation of
Equipment andMaterials
Preparation of
Equipment andMaterials

Generalequipment

Equipment forcleaning withwater

Equipment forcleaning metal
surfaces
Equipment forcleaning wood
surfaces
Equipment forwork in highplacesGeneralequipment

Equipment forcleaning withwater

In cases where the general public is deemed likely to enter
the area, the area shall be cordoned off with pylons orrope, etc. to prevent people from unnecessarily
approaching the work site, and the entry of people andvehicles shall be restricted
In cases where radioactive materials may be dispersed inconnection with the decontamination work, the perimeterof the decontamination area shall be fenced in with sheets,
etc., water shall be sprayed, or other such measures shallbe taken to prevent dispersion and the area shall becordoned off with rope, etc.
In cases where the general public is deemed likely to enter
the area, signs, etc. shall be put up to alert the public that
decontamination work is being performed.
Examples：Mower, hand shovel, grass sickle, broom, bamboo-rake,
dustpan, tongs, shovel, small shovel, metal rake, compact
heavy machinery for scraping away topsoil, garbage bags
(bags for burnable matter, burlap sacks for soil and sand(sandbags)), vehicles for transporting collected removed soil,
etc. to the on-site storage location (truck, two-wheeled cart,etc.), ladder
Examples：Hose, shower nozzle, high pressure water cleaner, brushes(scrub brush, brush for cleaning vehicles, brush for cleaninghigh places), scrubbing brushes (circular scrubber, steel wool
brush, etc.), wire brushes, tools for pushing away water(broom, scraper, etc.), bucket, detergent, dust cloth, sponges,
paper towels
Examples：Brush, sandpaper, cloth, removing agents
Examples：Brush, sandpaper, power sander, cloth, steam cleaner, waterhigh pressure washer, tools for pushing away water (broom,
scraper, etc.)
Examples：Scaffold, mobile lift, aerial vehicle
Examples：Mower, hand shovel, grass sickle, broom, bamboo rake,
dustpan, tongs, shovel, small shovel, metal rake, compact
heavy machinery for scraping away topsoil, garbage bags
(bags for burnable matter, burlap sacks for soil and sand(sandbags)), vehicles for transporting collected removed soil,
etc. to the on-site storage location (truck, two-wheeled cart,etc.), ladder
Examples：Hose, shower nozzle, high pressure water cleaner, brushes(scrub brush, brush for cleaning vehicles, brush for cleaninghigh places), scrubbing brushes (circular scrubber, steel wool
brush, etc.), wire brushes, tools for pushing away water(broom, scraper, etc.), bucket, detergent, dust cloth, sponges,
paper towels

95

（2） Prior measurements
The air dose rate, etc. should be measured and recorded at the same location and by thesame method both before and after decontamination work in order to confirm
decontamination effects. The method of measurement for the air dose rate, etc. before
decontamination work is explained below.

1）Determination of measurement points
Before decontamination work, determining the location where the air dose rate, etc. ismeasured (thereafter refer to as “measurement point”; Table 2-4) and preparing a diagram(Figure 2-9) with the areas to be measured, are done, and the structures to be used as
markers, etc., are described and diagram examples are presented. In addition, it is explainedthat hotspots and their ambient areas can be excluded from the measurement points, if theresidents are not expected to stay there for a relatively long time
Table 2-4 Reasoning behind the measurement points for air dose rates and other measures forthe decontamination of buildings and other structures
Measurement No. 1 measurement points(①)
No. 2 measurement points (②)
point
Measurement Air dose rate in living spaces
Surface contamination density, etc.
targetfor objects subject to decontamination
Reasoning
For detached housing, in gardens
Measurement points for roofs,
behindtheand other outdoor locations,rooftops, and the sides of buildings
measurement
approximately
two
to
five
shall be set near the center of eachpointsmeasurement points shall be set
surface.
from among places where people
Measurement points for gardens
are deemed likely to spend
and other grounds shall be set near
relatively large amounts of time.
their centers. (Choose places along
For collective housing, public
the centerline for grounds that are
facilities, and so forth, in gardens
long and thin or otherwise notand other outdoor locations,square.)approximately five measurement
Measurement points for fences andpoints shall be set from amongwalls shall be set at intervals thatplaces where people are deemedenable the distribution of the air
likely to spend relatively large
dose
rate,
etc.
to
be
amounts of time.
ascertained.[Example] Pitch of 5 to
10 m
Measurement points for benches,playground equipment, etc. shall be
set at places people will be incontact with.

96

Garden①②② WallBuilding②② Under eaves

Rooftop② Wall ② Under ② Rainwater
guttereaves

Parking lot①②②

GardenRoad①:Contamination status for living spaces(air dose rate: approximately two to five measurement points)②:Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)
Figure 2-9 Example schematic diagram for reporting measurement points for use indecontamination and other measures for buildings and other structures.

2）Measuring methods
It is recommended that for the measurement point marked as ① the apparatuses such as
NaI scintillation survey meters which are able to measure gamma rays should be used and forthe measurement point marked as ② GM survey meters should be used.

（3） Decontamination methods
The flow of overall decontamination work is shown in Figure 2-10; basic features include
implementing decontamination work from higher locations to lower locations and preventing
contamination from spreading or being released. Individual decontamination measures forroofs, rainwater gutters, exterior walls, fences, ditches, gardens, street drains, etc. aredescribed in terms of the items such as basic flow, necessary measures for priordecontamination work and decontamination methods and notes of caution.

97

Decontamination methods

Measures to prevent the spread of contamination through dispersion, outflows, and so forth following the decontamination<Examples of decontamination stages>(1)Decontamination of roofs and other areas

Decontamination work proceeds from high to low areas

Removal of fallen leaves, sediment, and soforth through manual labor(2)Decontamination of rainwater gutter
Decontamina
tion results

Not effective(3)Decontamination of exterior walls
Effective(4)Decontamination of fences, walls, benches,playground equipment, etc.

Cleaning via discharged water(for target objects for whichcleaning by water is possible)(Proceed to the decontaminationof low areas)
Conduct the decontamination from(1) –(6) as needed.

(5)Decontamination of gardens and other areas(6)Decontamination of street drains, etc.

Figure 2-10 Basic flow for the decontamination of buildings and other structures.

1）Decontamination of roofs
The flow of decontamination for roofs is shown in Figure 2-11. The necessary measuresprior to the decontamination work are shown in Table 2-5. The decontamination methods areshown in Table 2-6.

98

Decontamination of roofs and other areas

Measures to prevent the spread of contamination throughdispersion, outflows, and so forth following thedecontamination

Remove sediment (fallen leaves, moss, dirt, etc.)
Removal via manual labor
WipingWork that is being considered for implementation inregions where the air dose rate is comparatively highWashing away items that could not becompletely taken away through theremoval of sediment with water at the end
is effective

Cases where the results of decontamination cannot be adequately observed
Cleaning
Brush cleaning
High pressure water washing[Precautions]・Take steps to prevent dispersal and outflows of the water and othermaterials
・Perform the cleaning in a partial manner and check to confirm if thedecontamination has been effective before carrying out full-scalecleaning・Pay attention to the fact that this may break roofs

Wastewater treatment (*where needed)
In cases where adequate decontamination results are not observed on
concrete rooftops and the like, and this is acknowledged to be a necessaryand effective way of reducing the radiation dose
Scraping away

[Precautions]・Take measures to prevent the dispersion of dust

Figure 2-11 Basic flow for the decontamination of roofs and other areas.

Table 2-5 Necessary measures prior to the decontamination of roofs and other areas
Category
Decontamination methods and notes of caution
Safety measures
When performing work in high places, appropriate safetymeasures shall be taken, such as erecting scaffolding andallocating aerial vehicles.
Prevention ofIf sidewalks and buildings are immediately adjacent, curing shalldispersion
be performed to prevent dispersion of water, etc.
Using a method of water recovery-type high pressure watercleaning is also effective for preventing the dispersal ofradioactive materials.
Ensuring drainage
When using water to clean, the channel for cleaning water to flow
channels andshall be checked beforehand and the drainage channel cleaned inwastewater
advance to enable smooth drainage.
treatment
See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

99

Table 2-6 Decontamination methods for roofs and other areas and notes of caution
Category
Decontamination methods and notes of caution
RemovalDecontamination
Fallen leaves, moss, mud, and other sediments shall beofthrough manual
removed by hand by people wearing rubber gloves and by
sediments labor
shovel, etc.
WipingWiping shall be performed carefully through the use of
paper towels or dust cloths that have been dampened
with water.
All sides of folded paper towels, dust cloths, etc. used in
wiping work shall be used. However, none of the surfacesthat have already been used for decontamination (wiping)shall be touched with bare hands as these surfaces may
have radiocaesium on them.
Consideration shall be given to preventing thecontamination from re-adhering by such means as wiping
it down with a new side of the cloth for each wipe
according to the contamination status.
In some cases the results of the decontamination will besmaller due to effects from roofing materials like cement
tiles, matte clay tiles, and painted steel sheets, as well asfrom rust.
When rust is present, the rust itself must be removed bybeing wiped away.
Cleaning
Brush cleaning
Cleaning shall be thoroughly performed by using scrub
brushes, scrubbing brushes, etc.
Cleaning shall be performed from high places to low ones
so as to avoid dispersing water to the surroundings.
Rotary brushes shall not be used as they are not suitable
for thatched or tiled roofs.
Highpressure
Any possibility of breakage or damage to roofs, etc. fromwater cleaninghigh pressure water cleaning shall be checked in advance(obtaining advice from a specialist is recommended).
To prevent dispersion of soil, etc. by water pressure,cleaning shall be performed at low pressure initially andthe pressure shall be raised gradually while checking theflow of cleaning water and the dispersion conditions.
To achieve a decontamination effect, the spray nozzle
shall be brought near the place to be decontaminated.
Special attention shall be paid to cleaning the overlapping
sections
Scraping
Blast work
Abrasive materials shall be shot at the surface with aaway
shot blaster and scraped away from said surface
uniformly.
In order to prevent dust from arising, curing, etc. shall be
performed to prevent dispersion of dust to thesurroundings and the dust shall be collected.
For blast work, curing shall be performed to ensure thatabrasive materials and the like do not travel outside ofthe decontamination work area. What is more, after theabrasive materials and other materials have been used
they shall be collected in a manner that ensures that they
will not scatter the radioactive materials adhering tothem to the surroundings.
Scraping away
Dispersion to the surroundings shall be prevented when
scraping away contamination. (Example: use of dust
collectors, sprinkling in advance, setting up simple plastic
housings, etc.)1002）Decontamination for rainwater gutters
The flow of decontamination work for rainwater gutters is shown in Figure 2-12. The
necessary measures prior to the decontamination work are shown in Table 2-7. The
decontamination methods and notes of caution are shown in Table 2-8.
rainwater gutter

Measures to prevent the spread of contamination throughdispersion, outflows, and so forth following thedecontamination

Remove sediment (fallen leaves, etc.)

Washing away items that could not becompletely taken away through the removalof sediment with water at the end iseffective

Removal via manual labor
WipingCases where the results of decontamination cannot be adequately observed
Cleaning[Precautions]・Take steps to prevent dispersal and outflows of thewater and other materials
・Perform the cleaning in a partial manner and check to
confirm if the decontamination has been effective
before carrying out full-scale cleaning
・Pay attention to the fact that this may break rainwater
guttering

Brush cleaning
High pressure water washingWork that is being considered for
implementation in regions where the air
dose rate is comparatively highWastewater treatment (*where needed)

Figure 2-12 Basic flow for the decontamination of rainwater gutters.

Table 2-7 Necessary measures prior to the decontamination of rainwater gutters
Category
Decontamination methods and notes of caution
Prevention
If sidewalks and buildings are immediately adjacent, curing shall beofperformed to prevent dispersion of water, etc.
dispersion
Ensuring
When using water to clean, the channel for cleaning water to flow shall bedrainagechecked beforehand and the drainage channel cleaned in advance tochannels
enable smooth drainage.
andSediment in rainwater gutter shall be removed prior to cleaning with
wastewater
water.
treatment
See “4. (2) Wastewater Treatment” regarding the treatment of wastewater.
Damage to the end-flow sections of rainwater gutter or places where they
are directly discharged into garden plots may result in high doses, so
consideration shall be given to the decontamination of gardens and similarsites.

101

Table 2-8 Decontamination methods for rainwater gutters and notes of caution
Category
Decontamination methods and notes of caution
RemovalDecontamination
Fallen leaves, moss, mud, and other sediments shall beofthrough manual
removed by hand by people wearing rubber gloves and by
sediments labor
shovel, etc.
WipingWiping shall be performed carefully through the use of
paper towels or dust cloths that have been dampened
with water.
All sides of folded paper towels, dust cloths, etc. used in
wiping work shall be used. However, none of the surfacesthat have already been used for decontamination(wiping) shall be touched with bare hands as thesesurfaces may have radiocaesium on them.
Consideration shall be given to preventing thecontamination from re-adhering by such means as wiping
it down with a new side of the cloth for each wipe
according to the contamination status.
Since large quantities of radioactive materials
accumulate on the sediments in rainwater gutter, it iseffective to remove said sediments.
Cleaning
Brush cleaning
Cleaning shall be thoroughly performed by using scrub
brushes, scrubbing brushes, etc.
Sediment in downspouts (especially bend sections) tends
to get overlooked, so these should be cleaned with a wirebrush.
Cleaning shall be performed from high places to low ones
so as to avoid dispersing water to the surroundings.
HighpressureHigh pressure water cleaners shall be used to clean via
water cleaningpressure washing with a water pressure of generally 5
MPa or less and around 2 liters of water used per 1 m toensure that rainwater gutter is not destroyed. This is
primarily for narrow places where people cannot reachand other sections where it is difficult to perform wiping
work.
•The spray nozzle shall be brought near to the place
being decontaminated (about 20 cm) in order to get
results from the cleaning, and the cleaning shall be
performed at the appropriate speed of movement.
•Washing shall be performed from the upstream to thedownstream of the drainage slope to ensure that water
does not disperse to the surroundings.

3）Decontamination for exterior walls
The flow of decontamination for exterior walls is shown in Figure 2-13. The necessary
measures prior to the decontamination work are shown in Table 2-9. The decontamination
methods and notes of caution are shown in Table 2-10.

102Decontamination of exterior walls
There is no need to carry out
decontamination in cases where thesurface contamination concentration is
sufficiently low.

Measures to prevent the spread of contamination throughdispersion, outflows, and so forth following thedecontamination

WipingCases where the results of decontamination cannot be adequately observed
Cleaning[Precautions]・Take steps to prevent dispersal and outflows of thewater and other materials
・Perform the cleaning in a partial manner and checkto confirm if the decontamination has been effective
before carrying out full-scale cleaning
・Pay attention to the fact that this may break exterior
walls

Brush cleaning
High pressure water washingWork that is being considered for
implementation in regions where the air
dose rate is comparatively highWastewater treatment (*where needed)

Figure 2-13 Basic flow for the decontamination of exterior walls.

Table 2-9 Necessary measures prior to the decontamination of exterior walls
Category
Decontamination methods and points to notes of caution
Prevention ofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent dispersion of water, etc.
Ensuring
When using water to clean, the channel for cleaning water to flow shalldrainage
be checked beforehand and the drainage channel cleaned in advance tochannels andenable smooth drainage.
wastewater
See “4. (2) Wastewater Treatment” regarding the treatment oftreatment
wastewater.

103

Table 2-10 Decontamination methods for exterior walls and notes of caution
Category
Decontamination methods and notes of caution
RemovalWipingWiping shall be performed carefully through the use of paperoftowels or dust cloths that have been dampened with water.
sediments
All sides of folded paper towels, dust cloths, etc. used in wiping
work shall be used. However, none of the surfaces that havealready been used for decontamination (wiping) shall be touchedwith bare hands as these surfaces may have radiocaesium on
them.
Consideration shall be given to preventing the contaminationfrom re-adhering by such means as wiping it down with a newside of the cloth for each wipe according to the contamination
status.
Cleaning
Brush
Cleaning shall be thoroughly performed by using scrub brushes,
cleaning
scrubbing brushes, etc.
Cleaning shall be performed from high places to low ones so as to
avoid dispersing water to the surroundings.
High
To prevent dispersion of soil, etc. by water pressure, cleaningpressure
shall be performed at low pressure initially and the pressure
watershall be raised gradually while checking the flow of cleaningcleaning
water and the dispersion conditions.
The spray nozzle shall be brought near to the place being
decontaminated (about 20 cm) in order to get results from thecleaning, and the cleaning shall be performed at the appropriate
speed of movement.
Attention must be paid to the fact that there is the possibility ofdamaging the property, such as by causing walls to peel, or
having water seep indoors.

4）Decontamination for fences, outside walls, benches, and playground equipment, etc.
The flow of decontamination for fences, outside walls, benches, and playground equipment,
etc., is shown in Figure 2-14. The necessary measures prior to the decontamination work areshown in Table 2-11. The decontamination methods and notes of caution are shown in Table
2-12.

104

Decontamination of fences, outside wall, benches, playground equipment, etc.
Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following thedecontamination

For rusted sections, it is effective to
remove the rust with sandpaper, andthen wipe the sections off with a cloth,etc.

WipingWooden and other surfaces thatare difficult to decontaminate
by wiping them down

Joints of metals that are
difficult to clean by wiping

High pressure water washing

Steam cleaning

Scraping away

Wastewater treatment (*where needed)[Precautions]・Take steps to prevent dispersal and outflows of the water and othermaterials
・Perform the cleaning in a partial manner and check to confirm if
the decontamination has been effective before carrying out fullscale cleaning

Work that is being considered for
implementation in regions where theair dose rate is comparatively highFigure 2-14 Basic flow for the decontamination of fences, outside walls, benches, playgroundequipment, etc.

Table 2-11 Necessary measures prior to the decontamination of fences, outside walls, benches,playground equipment, etc.
Category
Decontamination methods and notes of caution
Prevention ofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent dispersion of water, etc.
Ensuring
When using water to clean, the channel for cleaning water to flow shalldrainage
be checked beforehand and the drainage channel cleaned in advance tochannels andenable smooth drainage.
wastewater
See “4. (2) Wastewater Treatment” regarding the treatment oftreatment
wastewater.

105

Table 2-12 Decontamination methods for fences, outside walls, benches, playgroundequipment, etc. and notes of caution
Category
Decontamination methods and notes of caution
WipingAll sides of folded paper towels, dust cloths, etc. used in wiping work
shall be used. However, none of the surfaces that have already beenused for decontamination (wiping) shall be touched with bare hands asthese surfaces may have radiocaesium on them.
Consideration shall be given to preventing the contamination fromre-adhering by such means as wiping it down with a new side of thecloth for each wipe according to the contamination status.
The rust on metal playground equipment shall be removed through theuse of sandpaper, a metal brush, or the like before it is thoroughly
wiped down.
Once a side of a paper towel or dust cloth has been used on
decontamination (wiping) or a brush, waste cloth, or sandpaper has
been used for wiping there is the possibility that it will haveradiocaesium adhering to it, and so it must not be touched directly by
hand.
High pressure
High pressure water cleaning shall be performed on the joints ofwater cleaning
playground equipment and the like that are difficult to wipe down.
(metal joints)
To prevent dispersion of soil, etc. by water pressure, cleaning shall be
performed at low pressure initially and the pressure shall be raised
gradually while checking the flow of cleaning water and the dispersion
conditions.
The spray nozzle shall be brought near to the place being
decontaminated (about 20 cm) in order to get results from the cleaning,
and the cleaning shall be performed at the appropriate speed of
movement.
Steam
Wooden playground equipment shall be cleaned using a steam cleaner.
cleaning
Scraping away
The surface wood of wooden playground equipment shall be scraped(woodenaway with electric power tools or the like.
playground
Dust collectors, etc. shall be used when scraping off wooden surfaces,
equipment,
etc. to prevent dispersion to the surroundings.
etc.)5）Decontamination of gardens, etc.
The flow of decontamination for gardens and other similar areas is shown in Figure 2-15.
The necessary measures prior to the decontamination work are shown in Table 2-13. The
decontamination methods and notes of caution are shown in Table 2-14.

106Decontamination of gardens and other areas.

Measures to prevent the spread of contamination throughdispersion, outflows, and so forth following the decontamination*Hotspots
Locations where the soil has been contaminated in ahighly concentrated manner by rainwater andwastewater containing radioactive materials where
there is a high probability that radiocesium has become
concentrated compared to the surrounding areas

Deep plowing or removal of soil and other materials at hotspots*
Removal of underbrush
Cases where the results of decontamination cannot be adequately observed

Work that is being considered for implementation in regions where the air
Soil gardens, etc.
Grave land crushed stone gardens, etc.
Lawn gardens, etc.
Gardens, parking lots, and harddose
rate is comparativelyhighpacked floors paved with
Deep plowing
Scraping away of topsoil
Covering the soil surface

High pressure water cleaning of gravel
and crushed stone
Removal of gravel andcrushed stones
Wastewater treatment(*where needed)[Precautions]
・When scraping away the topsoil and removing gravel and crushed stones,
it is necessary to confirm in advance the depth of the contamination fromthe surface layer and establish the optimal depth for the scraping away
and removal in advance.

concrete or asphalt

See “V. 3 (1)Decontaminationof Lawns”

See “III. Decontamination
and Other Measures forRoads”

Work that is being considered for
implementation in regions where the air
dose rate is comparatively highFigure 2-15 Basic flow for the decontamination of gardens and other similar areas.

Table 2-13 Necessary measures prior to the decontamination of gardens and other similar
areas
Category
Decontamination methods and notes of caution
Prevention ofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent dispersion of water, etc.

107Gravel and crushed stone gardens,etc.

Table 2-14 Decontamination methods for gardens and other similar areas and notes of caution
Category
Decontamination methods and notes of caution
Deep plowing or
Fallen leaves, moss, mud, and other sediments shall be removed byremoval of soil andhand by people wearing rubber gloves and by shovel, etc.
other substances at
The soil at hotspots below rainwater gutter and the like shall be deep
hotspots
plowed or removed. When this is implemented attention must be paid
to the depth of the contamination.
In cases where it is difficult to perform deep plowing at a location,such as with soil that has been packed into rainwater chambers andthe like, consideration shall be given to performing deep plowing in
the vicinity of said rainwater chambers.
Removal of
Before performing the deep plowing and the scraping away of topsoil,
underbrush, etc.
conduct weed removal and weeding on any weeds that would pose ahindrance to the work using a shoulder-type mower or human power.
In some cases the shielding effect for the beta rays by grass may be
reduced by the grass cutting, and so the reduction rate may drop.
Deep plowing
About 10 cm of topsoil shall be uniformly scraped away andtemporarily piled on top of a plastic sheet or the like.
About 20 cm of subsoil shall be uniformly scraped away and piled on
top of a separate location from the topsoil.
After the topsoil has been uniformly spread out, the subsoil shall be
uniformly spread on top of it and the land will be leveled. It shall be
restored to its original height at a compactness that is about the sameas it was before.
Scraping
A bamboo winnow or similar instrument shall be used to uniformly
away surface
scrape away the garden topsoil.
soil
Attention shall be paid to the fact that due to the planted vegetation
and unevenness relative to the ground there may be reduced certainty
with the decontamination work.
Covering the
The surface soil shall be covered with soil that does not containsurface soilradiocaesium.
High
A shovel or the like shall be used to place the gravel or crushed stones
pressure
into a water tank and then perform high pressure water cleaning.
water
To prevent dispersion of soil, etc. by water pressure when performing
cleaningofhigh pressure water cleaning, cleaning shall be performed at low
gravelandpressure initially and the pressure shall be raised gradually whilecrushedchecking the flow of cleaning water and the dispersion conditions.
stonesSee “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.
Removal of
The gravel or crushed stones shall be uniformly removed with a shovel
gravelandor the like.
crushedWhen gravel or crushed stones are removed, the area shall be coveredstonesby using the same type of gravel or crushed stones as before asneeded, and it shall be covered to the same standing height as before
and to about the same compactness as before.

Gravel and crushed stonegardens, etc.

6）Decontamination for street drains, etc.
The flow of decontamination for street drains, etc. is shown in Figure 2-16. The necessary
measures prior to the decontamination work are shown in Table 2-15. The decontamination
methods and notes of caution are shown in Table 2-16.

108Decontamination of street drains, etc.
Measures to prevent the spread of contamination throughdispersion, outflows, and so forth following thedecontamination

Remove sediment (fallen leaves, soil, etc.)
Removal via manual labor, etc.
Cases where the results of decontamination
cannot be adequately observed
Cleaning[[Precautions]・Take steps to prevent dispersal and outflows of thewater and other materials

Brush cleaning
High pressure water washing

Wastewater treatment (*where needed)

Work that is being considered for
implementation in regions where the air
dose rate is comparatively highFigure 2-16 Basic flow for the decontamination of street drains, etc.

Table 2-15 Necessary measures prior to the decontamination of street drains, etc.
Category
Decontamination methods and points to notes of caution
Prevention ofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent dispersion of water, etc.
Ensuring
When using water to clean, the channel for cleaning water to flow shalldrainage
be checked beforehand and the drainage channel cleaned in advance tochannels andenable smooth drainage.
wastewater
See “4. (2) Wastewater Treatment” regarding the treatment oftreatment
wastewater.

109

Table 2-16 Decontamination methods for street drains, etc. and notes of caution
Category
Decontamination methods and notes of caution
Removal of Decontamination
Fallen leaves, moss, mud, and other sediments that are
sediments
through manual
easy to remove shall be removed in advance by shovel,
labor
etc.
When the concrete joints of street drains are deep, aspatula or the like shall be used to remove the sedimentsfrom the joints.
When performing deep plowing at rainwater chambers it
will be difficult to carry this out in such locations, and so
deep plowing shall be carried out in the vicinity of saidrainwater chambers.
In cases where sediment gets clogged in rainwaterchambers and water overflows out of street drains likewhen it rains contamination will sometimes spread tothe surroundings. In such cases the ground surface of thesurroundings shall be measured and decontamination
work shall be carried out in accordance with theconfiguration of the ground surface.
Cleaning
Brush cleaning
Cleaning shall be thoroughly performed by using a deckbrush or broom.
Cleaning shall be performed from high places to low ones
so as to avoid dispersing water to the surroundings.
High pressure
To prevent dispersion of soil, etc. by water pressure,water cleaningcleaning shall be performed at low pressure initially andthe pressure shall be raised gradually while checking theflow of cleaning water and the dispersion conditions.
The spray nozzle shall be brought near to the place being
decontaminated (about 20 cm) in order to get resultsfrom the cleaning, and the cleaning shall be performed at
the appropriate speed of movement.

（4） Post–work measures
This section explains handling the removed soil, etc., wastewater treatment, and cleaning
equipment used, etc. as post-work measures.

1）Handling the removed soil, etc.
The removed soil, etc. is appropriately handled and transferred to an on-site storage or atemporary storage site. The basic flow of handling the removed soil, etc. is shown in Figure2-17. The methods of handling and notes of caution are explained in Table 2-17.

110

Handling the removed soil, etc.
Removed soil

Decontamination waste(vegetation, protective equipment, etc.)

Measures necessary to prevent dispersion
Implement the appropriate response inaccordance with the “Waste Guidelines”
Measure and record the radiation dose

On-site storage or transfer to temporarystorage sites*See “Part 4: Guidelines Pertaining to the Storage of Removed
Soil” and “Part 3: Guidelines Pertaining to the Collection
and Transfer of Removed Soil”

Figure 2-17 Basic flow for handling the removed soil, etc.
Table 2-17 Methods for the handling of removed soil, etc. and notes of caution
Category
Decontamination methods and notes of caution
Handling
To prevent dispersion, the removed soil, etc. shall be placed in bags or
the removed
other containers and closed or sealed, or wrapped in sheets or similarsoil, etc.
material.
The removed soil, etc. shall be separated from decontamination waste to
the extent possible and placed in separate bags or other containers toensure there is no mixing. Please refer to the Guidelines on the Storage of
Decontamination Waste (promulgated at the end of December 2011) for
details on the handling of waste.
The air dose rate at the surface (from 1 cm away) of each container or setof multiple containers holding the removed soil, etc. shall be measured,and the radiation dose of the removed soil, etc. generated by thedecontamination work shall be recorded and displayed in a manner thatroughly indicates the dose level (range).
Vegetation and the disposable masks, etc. used in the decontamination
work shall be treated and disposed of as decontamination waste inaccordance with the Waste Guidelines (March 2013, Vol.2) and otherrelevant statutes.

2）Wastewater treatment
In cases where wastewater is generated as a result of decontamination, wastewater
treatment should be carried out as needed. The flow of wastewater treatment is shown in
Figure 2-18. The necessary measures prior to the wastewater treatment are shown in Table
2-18. The methods for treatment and notes of caution are shown in Table 2-19.
For decontamination in decontamination zones (zones subject to the decontamination plansestablished by municipalities) there is essentially no need to treat wastewater in cases wheresediments are removed. However, it is a basic principle that wastewater treatment should be
carried out in situations where the wastewater is highly turbid or the wastewater has been
recovered from water recovery-type high pressure water washing.

111

Wastewater treatment
Decontamination of roofs, rainwater gutter, roads, etc.

Cases where the removal of
sediments and wiping iscarried out and wastewater
treatment is not carried out

Cases where wastewater
treatment is carried out

Water recovery-type highpressure water cleaning

Cases where the destination thewastewater flows to is the soil

Filtration
treatment via soil

Sedimentation treatmentusing street drains

Sedimentation treatment using
water tanks

Scraping awayand deep
plowing of soil

Water collection (damming
street drains withsandbags)

Collect water (plastic
containers, temporary pools,
attached tanks for water
recovery-type high pressure
water cleaning, etc.)

Soil particles
withRadioactive
cesiumadhering tothem arestopped by thesoil and the soil
is removed.

Water collection
via rainwaterchambers is also
possible
Sedimentation ofsuspended solids (soilparticles, etc.)(Supernatantliquid)Sedimentation of suspended
solids (soil particles, etc.)(Supernatantliquid)Collection of
the sediment

Collection of
the sediment
Discharge

Discharge

Use
coagulants
as needed

Discharge

Since Radioactive cesium adheres to things like soil particles it
is crucial to remove the particulate matter within thewastewater.

Figure 2-18 Basic flow for wastewater treatment.

Table 2-18 Necessary measures prior to the wastewater treatment
Category
Decontamination methods and notes of caution
Ensuring drainage
channels andwastewater
treatment

The channel down which the wastewater will flow shall bechecked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.

112

Table 2-19 Methods for wastewater treatment and notes of caution
Category
Decontamination methods and notes of caution
Filtration
When the area under rainwater gutter consists of soil, radiation
treatment via soil
shall be captured by flushing wastewater generated on rooftops
down to the soil via the rainwater gutter, and then said top layer ofsoil shall be removed after the decontamination of the rooftop.
Sedimentation
Water shall be collected in plastic containers or temporary pools,
treatment
using
then sedimenting out the particulate matter, and discharging thewater tanks
water from the supernatant liquid while collecting the sediment(agents to cause the liquid to undergo coagulating sedimentation
shall be used).
The water in the supernatant liquid shall be checked to make surethere is no turbidity.
A simple filter will be installed and filtration shall be carried out asneeded.
Sedimentation
The water shall be collected by damming up the street drains using
treatment
using
sandbags, then sedimenting out the particulate matter, andstreet drains
discharging the supernatant liquid while collecting the sediment.
The water in the supernatant liquid shall be checked to make surethere is no turbidity.
A simple filter will be installed and filtration shall be carried out asneeded.

3) Cleaning equipment used, etc.
With regard to the post-work cleaning of the equipment used and handling consumablematerials for decontamination, as a general rule, the Ministry of Health, Labour andWelfare’s “Ordinance on the Prevention of Ionizing Radiation Hazards Related to
Decontamination Work of Soil Contaminated by Radioactive Materials Resulting from theGreat East Japan Earthquake” and “Guidelines for Prevention of Radiation Hazards forWorkers Engaged in Decontamination and Other Works” are to be followed. Moreover, it isimportant to keep in mind the items listed in Table 2-20.

113

Table 2-20 Methods for cleaning equipment and handling materials and notes of caution
Category
Details
Cleaning
Heavy machinery, vehicles, and other objects used for which there is theequipment
possibility that a great deal of contaminated soil is adhering to themandshall be checked to confirm the extent to which said soil is adhering tomaterials
them. Those objects to which a great deal of contaminated soil isadhering shall be cleaned in a designated location, and other measures
shall be taken to ensure that the contaminated soil, etc. is not spreadaround indiscriminately.
Likewise for shovels and other tools, shoes, and work clothes to whichlots of contaminated soil is adhering, these shall be checked to confirm
the extent to which said soil is adhering to them. Those objects to which agreat deal of contaminated soil is adhering shall be cleaned in adesignated location, and other measures shall be taken to ensure thatthe contaminated soil, etc. is not spread around indiscriminately.
The wastewater generated by the cleaning shall be treated as needed byreferring to “(2) Wastewater Treatment.”
When cleaning, the workers shall take care to ensure that they are notbathed in the spray from this.
In addition, even equipment or materials with a low possibility ofcontamination shall be checked to confirm whether or not contaminatedsoil is adhering to them.
The equipment, materials, and work clothes used shall be washed,cleaned, and reused to the extent possible.
[Washing/cleaning examples]
Steam cleaning is effective for cleaning machinery, but scrubbing it downwith brushes and a detergent is also sufficient.
Normal methods are sufficient for washing work clothes and otherclothing.
When carrying the clothing, etc. used in decontamination work, it shallbe placed in a box or bag, etc. to minimize dispersal of the attachedmatter.
When going indoors after decontamination work, mud shall be removed
from shoes, clothing shall be changed, and other measures shall be taken
to avoid bringing indoors dust attached to the workers.

（5） Subsequent measurements and records
To confirm the decontamination effect, the air dose rate, etc. after completion of thedecontamination work should be measured and recorded as shown in Table 2-21.
Table 2-21 Subsequent measurements and records for the decontamination of buildings andother structures
Measurement of
The air dose rate, etc. shall be measured at each measurement point.
air dose rate, etc.
Measurements shall be carried out in the same location as the priormeasurements and under the same conditions to the extent possible.
For the measuring apparatus, the same apparatus as was used for theprior measurements shall be used to the extent possible.
Recordkeeping
The air dose rate, etc. at each measurement point, places where
decontamination work was performed, decontamination date, names ofthe decontaminators, type of objects decontaminated, decontamination
methods, total decontamination area (of soil, etc.), the approximate
weight of the removed soil, etc., and the status of storage and disposal.
The equipment used in decontamination and the method of disposal
after use.
See “Part 4: Guidelines Pertaining to the Storage of Removed Soil” fordetails on the items to record with regard to the storage of removed soil.
114

2.2.3. Decontamination and Other Measures for Roads
This section explains preparation, prior measurements, decontamination methods,
post-work measures, and subsequent measurements and records, in the basic flow shownin Figure 2-19, pertaining to measures for decontamination of the paved surfaces of roads(including sidewalks), street drains, curbs, guardrails, and pedestrian overpasses.

1.Preparation

2.PriorMeasurements(1)Measures to reduce public exposure in connection with the work
(2)Equipment and materials(1) Determination of measurement points(2) Measurement methods

Measures to prevent the spread of contamination through dispersion,
outflows, and so forth following the decontamination (institute thenecessary measures for each instance of decontamination work)
3.Decontamination
Methods(1) Decontamination of paved surfaces(2) Decontamination of unpaved roads(3) Decontamination of roadsides and street drains(1) Handling the removed soil, etc.
4.Post-Work
Measures(2) Wastewater treatment(3) Cleaning equipment, etc.

5.Subsequent Measurements and Records

Figure 2-19 Basic flow for the decontamination and other measures for roads.

115

（1） Preparation
Before performing decontamination work, in addition to preparing the equipment required
for the work, preparations must be made to ensure safety of workers and the general public toprevent their exposure to hazards, such as by inhaling dust generated duringdecontamination work; these preparations are summarized in Table 2-22.
Table 2-22 Preparation for decontamination and other measures for roads
Measures to
Reduce Public
Exposure inConnection with
Decontamination
Work

Restriction ofentry

Signage

Preparation of
Equipment andMaterials

Generalequipment

Equipment forcleaning withwater

Equipment for
scraping off

Equipment
for removal of
topsoilEquipment forcovering thesoil surface

In cases where the general public is deemed likely toenter the area, the area shall be cordoned off withpylons or rope, etc. to prevent people from
unnecessarily approaching the work site, and theentry of people and vehicles shall be restricted.
In cases where radioactive materials may bedispersed in connection with the decontamination
work, the perimeter of the decontamination area
shall be fenced in with sheets, etc., water shall be
sprayed, or other such measures shall be taken toprevent dispersion and the area shall be cordoned off
with rope, etc.
In cases where the general public is deemed likely toenter the area, signs, etc. shall be put up to alert the
public that decontamination work is being performed
generalExamples:Mower,
hand
shovel,grass
sickle,broom,
bamboo-rake, dustpan, tongs, shovel, small shovel,
metal rake, compact heavy machinery for scraping
away topsoil, garbage bags (bags for burnable matter,burlap sacks for soil and sand (sandbags)), vehicles fortransporting collected removed soil, etc. to the on-sitestorage location (truck, two-wheeled cart, wheelbarrow,etc.), aerial vehicle, ladder, road sweeper
Examples:Hose for water discharge, high pressure water cleaner,drainage pavement functional recovery car, brushes(scrub brush, brush for cleaning vehicles, etc.), tools forpushing away water (broom, scraper, etc.), bucket,
detergent, dustcloth, sponge, paper towels
Examples:Shot blaster, surface cutter, vibration drill, needle gun,grinding machine, equipment for scraping away, ultrahigh pressure water cleaner, equipment needed toprevent dispersion(dust collector, curing material)
Examples:Backhoe, bulldozer, hydraulic shovel
Examples:Self-propelled surface compaction roller, plywood forsurface compaction, sprinkling equipment（2） Prior measurements
The air dose rate, etc. should be measured and recorded at the same location and by thesame method both before and after decontamination work in order to confirm
116decontamination effects. The method of measurement for the air dose rate, etc. before
decontamination work is explained below.

1）Determination of measurement points
Before decontamination work, the measurement points (Table 2-23) at which the air doserate, etc. are to be measured should be decided and a schematic diagram illustrating therange of the measured objects, the measurement points, structures to be used as markers, etc.
should be made (Figure 2-20). In addition, in setting these measurement points, hotspots andtheir ambient areas that contribute insubstantially to the radiation dose in the living space
are not to be used as measurement points unless the users, etc. are deemed likely to spend
relatively large amounts of time there.
Table 2-23 Reasoning behind the measurement points for air dose rates and and othermeasures and the decontamination of roads
Measurement
No. 1 measurement points（①）
No. 2 measurement points(②)
pointsObjects subject
Surface contamination density, etc.
to
Air dose rate in living spaces
for objects subject tomeasurement
decontamination
Reasoning
Measurement points shall be
Measurement points shall be set atbehind theset at intervals that allow theintervals that allow the air dose
measurement
air dose rate distribution to be
rate, etc. distribution to be
pointsascertained near the centerline
ascertained for each road surface,of sidewalks.
road shoulder, street drain, andIf there are no sidewalks,
sidewalk.
appropriate points shall be(Example)Pitch of approx. 10 –30
determined by confirming themusage status of the road.
(Example)Pitch of approx. 10–30 m

10m to 30 m
Sidewalk

Shoulder

①②

①②

②

②
Road

②

②

②

①:Contamination status for living spaces②:Contamination status for objects subject to decontamination(surface contamination density, surface dose rate

Figure 2-20 Example schematic diagram for reporting measurement points for use indecontamination and other measures for roads.

1172）Measurement methods
It is recommended that for the measurement point marked as ① the apparatuses such as
NaI scintillation survey meters which are able to measure gamma rays should be used and forthe measurement point marked as ②, GM survey meters should be used.
（3） Decontamination methods
This section explains the flow of the overall decontamination work for roads (Figure 2-21)
that is efficiently focused on the places with comparatively high concentrations of radioactive
materials that contribute substantially to the radiation dose. When water is used indecontamination work on roads or for similar work, radioactive materials may migrate to theroadsides or street drains. Therefore, when using water, it is more efficient to first remove thesediments from the roadsides and street drains, then clean the roads, and finally clean theroadsides and street drains again. Decontamination methods for roadsides and street drains,
as well as paved surfaces and unpaved roads are described in terms of the items such as basic
flow, necessary measures for prior decontamination work and decontamination methods andnotes of caution.
Decontamination methods

Measures to prevent the spread of contamination through dispersion, outflows,
and so forth following the decontamination(1)Decontamination of paved surfaces(2)Decontamination of unpaved roads(3)Decontamination of roadsides and street drains

Wastewater treatment(* as needed)<Examples of decontamination stages>
Removal of fallen leaves, sediment, and soforth through manual labor

Conduct thedecontamination from (1) –(3) as needed.

Decontamination
results

Effective

Non effective
Cleaning via discharged
water (for target objects
for which cleaning bywater is possible)(Proceed to the decontamination of low areas)

Figure 2-21 Basic flow for the decontamination of roads.

1181）Decontamination of paved surfaces
This section explains the flow of decontamination for paved surfaces of roads (andsidewalks) as shown in Figure 2-22. The necessary measures prior to the decontamination
work are in Table 2-24. The decontamination methods and notes of caution are in Table 2-25.
Decontamination of paved roads
Measures to prevent the spread of contamination
through dispersion, outflows, and so forthfollowing the decontamination
Remove sediment (fallen leaves, moss, dirt, etc.)
Removal via manual labor

Washing away items that
could not be completely taken
away through the removal of
sediment with water at theend is effective

Cases where the results of decontamination cannot beadequately observed0[Precautions]・Take steps to prevent dispersal andoutflows of the water and other materials
・Perform the cleaning in a partial mannerand check to confirm if thedecontamination has been effective before
carrying out full-scale cleaning

Cleaning
Brush cleaning
High pressure water cleaning

Wastewater treatment(*where needed)
In cases where adequate decontamination results are not observed,
and this is acknowledged to be a necessary and effective way of
reducing the radiation dose
[Precautions]・Take measures to prevent the dispersionof dustScraping away
Blast work
Ultra high pressure water cleaning
Scraping away

Wastewater treatment (* as needed)

Work that is being considered
for implementation in regions
where the air dose rate iscomparatively highFigure 2-22 Basic flow for the decontamination of paved surfaces.
Table 2-24 Necessary measures prior to the decontamination of paved surfaces
Category
Decontamination methods and notes of caution
SafetyIf traffic cannot be stopped when the decontamination work is carried
management
out, then adequate safety management shall be undertaken throughmeasures like allocating traffic controllers or the like.
Prevention of
When carrying out decontamination work that uses water, measuresdispersion
shall be taken to prevent the dispersion of the cleaning water.
Ensuring
Sediment on roads, on roadsides, and in street drains shall be removed
drainage
before cleaning with water.
channels andWhen using water to clean, the channel for cleaning water to flow shallwastewater
be checked beforehand and the drainage channel cleaned in advance totreatment
enable smooth drainage.
See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

119

Table 2-25 Decontamination methods for paved surfaces and notes of caution
Category
Decontamination methods and notes of caution
RemovalRemovalFallen leaves, moss, mud, and other sediments shall beofthroughremoved by hand by people wearing rubber gloves, shovel, or
sediments manualroad sweeper, etc.
labor
Cleaning
Brush
Cleaning shall be performed from high places to low ones so as
cleaning
to avoid dispersing water to the surroundings.
With drainage pavement functional recovery cars, attention
must be paid to the fact that in some cases their cleaning anddrainage recovery functions may decline on surfaces where
distortion or wear has occurred due to the effects ofearthquakes, etc.
High
To prevent dispersion of soil, etc. by water pressure, cleaningpressure
shall be performed at low pressure initially and the pressure
watershall be raised gradually while checking the flow of cleaningcleaning
water and the dispersion conditions.
Water recovery-type high pressure water cleaning is also
effective.
To achieve a decontamination effect, the spray nozzle shall be
brought near the place to be decontaminated.
When decontamination is carried out over a wide range,
attention must be paid to ensure that no variance occurs
between the work methods at different points (height of thenozzle over the ground, work time per unit of surface area, etc.)
Scraping
Blast work
Abrasive materials shall be shot at the surface with a shotaway
blaster and scraped away from said surface uniformly.
In order to prevent dust from arising, curing, etc. shall be
performed to prevent dispersion of dust to the surroundings
and the dust shall be collected.
For blast work, curing shall be performed to ensure thatabrasive materials and the like do not travel outside of thedecontamination work zone. What is more, after the abrasive
materials and other materials have been used they shall becollected in a manner that ensures that they will not scatterthe radioactive materials adhering to them to thesurroundings.
When scraping away material on interlocking concrete blocks,
attention must be paid to the fact that scrapings andradioactive materials may be left behind in the gaps between
the blocks.
Ultra-highUltra-high pressure water cleaner (cleaning waterpressure
recovery-type) of 150 MPa or higher shall be used for scraping
water
material away on paved surfaces.
cleaning
A powerful vacuum truck shall be used to collect any scrapingsthat arise.
Scraping
A surface cutter or the like shall be used to scrape away theaway
paved surface.
Dispersion to the surroundings shall be prevented when
scraping away contamination.
(Example: use of dust collectors, sprinkling in advance, setting
up simple plastic housings, etc.)1202）Decontamination of unpaved roads
The flow of decontamination for unpaved surfaces of roads is shown in Figure 2-23. The
necessary measures prior to the decontamination work are in Table 2-26. The
decontamination methods and notes of caution are in Table 2-27.

Decontamination of unpaved roads

Measures to prevent the spread of contamination
through dispersion, outflows, and so forthfollowing the decontamination
Remove sediments (fallen leaves, moss, dirt, etc.)
Removal via manual labor
Cases where the results of decontamination cannot
be adequately observed

Soil roads, etc.

Gravel and crushed stone roads, etc.

Slopes of roads

Deep plowing

Pressure wash gravel andcrushed stones

Remove underbrush, etc.

Remove gravel andcrushed stones

scraping away the topsoil

scraping away the topsoil
Covering the soil surface

Wastewater
treatment(* as needed)[Precautions]
・When scraping away the topsoil and removing gravel andcrushed stones, it is necessary to confirm in advance thedepth of the contamination from the surface layer andestablish the optimal depth for scraping away and removal
in advance.

Work that is being
considered for
implementation in regions
where the air dose rate iscomparatively highFigure 2-23 Basic flow for the decontamination of unpaved roads.

Table 2-26 Necessary measures prior to the decontamination of unpaved roads
Category
Decontamination methods and notes of caution
Prevention ofdispersion

When scraping away the topsoil when it comes to dried soil, efforts canbe made to prevent the dispersion of dust by scattering solidification
agents over the area in advance to solidify the soil surface.

121

Table 2-27 Decontamination methods for unpaved roads and notes of caution
Category
Decontamination methods and notes of caution
Removalofsediments

Removalthroughmanuallabor

Soil with fallen leaves, moss, mud, and other sediments shall be
removed by hand by people wearing rubber gloves and by shovel,
etc.

Soil
roads, etc.

Deepplowing

About 10 cm of topsoil shall be uniformly scraped away andtemporarily piled on top of a plastic sheet or the like.
About 20 cm of subsoil shall be uniformly scraped away andpiled on top of a separate location from the topsoil.
After the topsoil has been uniformly spread out, the subsoil shallbe uniformly spread on top of it and the land will be leveled. It
shall be restored to its original height at a compactness that isabout the same as it was before.

Scraping
away
topsoilA backhoe or the like shall be used to uniformly scrape away thesurface.
Dispersion to the surroundings shall be prevented when
scraping away contamination.
(Example: use of dust collectors, sprinkling in advance, setting
up simple plastic housings, etc.)

Covering
the surface
soil

The surface soil shall be covered with soil that does not containradiocaesium.

Highpressurewater
cleaning ofgravel andcrushedstones

A backhoe or the like shall be used to place the gravel or crushedstones into a water tank and then high pressure water cleaning
will be performed.
To prevent dispersion of soil, etc. by water pressure when
performing high pressure water cleaning, cleaning shall be
performed at low pressure initially and the pressure shall beraised gradually while checking the flow of cleaning water andthe dispersion conditions.
See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Removal ofgravel andcrushedstonesThe gravel or crushed stones shall be uniformly removed with abackhoe or the like.
When gravel or crushed stones are removed, the area shall becovered by using the same type of gravel or crushed stones as
before, and it shall be covered to the same standing height as
before and to about the same compactness as before.
Attention shall be paid to the fact that because of the large air
gaps when covering with crushed stones, density adjustments
shall be performed via the appropriate surface compaction.

Removal ofunderbrush

Weed removal and weeding shall be conducted using ashoulder-type mower or human power.

Removal of
topsoil

Human power, a backhoe, or the like shall be used to uniformly
scrape away the surface.
Dispersion to the surroundings shall be prevented when
scraping away contamination.

Gravelandcrushedstoneroads, etc.

Slopes of
roads

122

3）Decontamination of roadsides and street drains
The flow of decontamination for roadsides and street drains is shown in Figure 2-24. The
necessary measures prior to the decontamination work are in Table 2-28. The
decontamination methods and notes of caution are in Table 2-29.

Decontamination of roadsides and street drains
Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following
the decontamination

Remove sediments (fallen leaves, etc.)
Removal via manual labor

Cases where the results of decontamination cannot beadequately observed
Cleaning[Precautions]・ Take steps to prevent
dispersal and outflows of
the water and othermaterials

Brush cleaning
High pressure water cleaning

Wastewater treatment(*where needed)

Work that is being considered
for implementation in regions
where the air dose rate iscomparatively highFigure 2-24 Basic flow for the decontamination of roadsides and street drains.

123

Table 2-28 Necessary measures prior to the decontamination of roadsides and street drains
Category
Prevention of dispersion
Ensuring
drainagechannels
andwastewater treatment

Decontamination methods and notes of caution
If sidewalks and buildings are immediately adjacent, curing
shall be performed to prevent dispersion of water, etc.
When using water to clean, the channel for cleaning water toflow shall be checked beforehand and the drainage channel
cleaned in advance to enable smooth drainage.
See “4. (2) Wastewater Treatment” regarding the treatmentof wastewater.

Table 2-29 Decontamination methods for roadsides and street drains and notes of caution
Category
Decontamination methods and notes of caution
RemovalRemovalFallen leaves, moss, mud, and other sediments that are easy toofthroughremove shall be removed in advance by shovel, etc.
sediments manual
When the concrete joints of street drains are deep, a spatula or
labor
the like
Cleaning

Brushcleaning
Highpressurewater
cleaning

Cleaning shall be thoroughly performed by using scrub brushes
or scrubbing brushes.
Cleaning shall be performed from high places to low ones so as
to avoid dispersing water to the surroundings.
To prevent dispersion of soil, etc. by water pressure, cleaning
shall be performed at low pressure initially and the pressure
shall be raised gradually while checking the flow of cleaningwater and the dispersion conditions.
To achieve a decontamination effect, the spray nozzle shall be
brought near the place to be decontaminated.

（4） Post–work measures
This section explains handling the removed soil, etc., wastewater treatment, and cleaning
equipment used, etc. as post-work measures.The details appear in 2.2.2.(4) of this report.

（5） Subsequent measurements and records
To confirm the decontamination effect, the air dose rate, etc. should be measured after
completion of the decontamination work and recorded as shown in Table 2-30.

124

Table 2-30 Subsequent measurements and records for the decontamination of roads
Measurementof air doserate, etc.
Recordkeeping

The air dose rate, etc. shall be measured at each measurement point.
Measurements shall be carried out in the same location as the priormeasurements and under the same conditions to the extent possible.
For the measuring apparatus, the same apparatus as was used for theprior measurements shall be used to the extent possible.
The air dose rate, etc. at each measurement point, places where
decontamination work was performed, decontamination date, names ofthe decontaminators, type of objects decontaminated, decontamination
methods, total decontamination area (of soil, etc.), the approximate
weight of the removed soil, etc., and the status of storage and disposal.
The equipment used in decontamination and the method of disposal
after use.
See “Part 4: Guidelines Pertaining to the Storage of Removed Soil” fordetails on the items to record with regard to the storage of removed soil.

2.2.4. Decontamination and Other Measures for Soil
This section explains preparation, prior measurements, decontamination methods,
post-work measures, and subsequent measurements and records, in the basic flow (Figure2-25), pertaining to decontamination and other measures for soil in schoolyards, kindergarten
yards, parks, farmland, and other comparatively large land spaces.

1.Preparation

2.PriorMeasurements

3.Decontamination
Methods(1)Measures to reduce public exposure in connection with the work
(2)Equipment and materials(1) Determination of measurement points(2) Measurement methods

Measures to prevent the spread of contamination through dispersion,
outflows, and so forth following the decontamination (institute thenecessary measures for each instance of decontamination work)(1)Decontamination of the soil at schoolyards,
kindergarten yards, and parks

4.Post-Work
Measures(2)Decontaminationof farmland(1) Handling the removed soil, etc.
(2) Wastewater treatment

5.Subsequent Measurements and Records

Figure 2-25 Basic flow for decontamination and other measures for soil.

125

（1） Preparation
Before performing decontamination work, in addition to preparing the equipment required
for the work, preparations must be made to ensure safety of workers and the general public toprevent their exposure to hazards, such as by inhaling dust generated duringdecontamination work; these preparations are summarized in Table 2-31.
Table 2-31 Preparation for decontamination and other measures for soil
Measures to
Restriction of entry
In cases where the general public is deemed
Reduce Public
likely to enter the area, the area shall be
Exposure incordoned off with pylons or rope, etc. toConnection withprevent
peoplefrom
unnecessarily
Decontamination
approaching the work site, and the entry ofWorkpeople and vehicles shall be restricted.
In cases where radioactive materials may bedispersedinconnection
withthedecontamination work, the perimeter of thedecontamination area shall be fenced in withsheets, etc., water shall be sprayed, or othersuch measures shall be taken to prevent
dispersion and the area shall be cordoned off
with rope, etc.
Signage
In cases where the general public is deemed
likely to enter the area, signs, etc. shall be put
up to alert the public that decontamination
work is being performed.
Preparation ofGeneral equipment
Examples:decontamination
Mower, hand shovel, grass sickle, broom, bamboo
equipment andrake, dustpan, tongs, shovel, small shovel, metalmaterials
rake, compact heavy machinery for scraping
away topsoil, garbage bags (bags for burnable
matter, burlap sacks for soil and sand(sandbags), large sandbags, flexible containers),
vehicles for transporting collected removed soil,
etc. to the on-site storage location or temporarystorage site(truck, two-wheeled cart, etc.), aerial
vehicle, ladder
Equipment for
Examples:cleaning with water
Hose for water dischargeequipment for
Examples:removal of topsoil
Bulldozer, hydraulic shovel
Equipment for
Examples:covering soil
Self-propelled surface compaction roller, plywood
surfacesfor surface compaction, sprinkling equipment
Decontamination equipment foruse on farmland

Equipment
for scraping
away topsoil

Equipment
for mixing
with water
Equipment
for inversion
tillage anddeep tillage

Examples:Equipment required for scraping away topsoil,
inversion tillage, and deep tillage (bulldozer,
hydraulic shovel, tractor, vertical harrow andother attachments, rear blade, front loader),backhoe, grader, crane, vacuum car, mower, highpressure water cleaner, chipping machine,
hammer knife mower, flexible containers
Examples :Tractor, vertical harrow and other attachments,
drainage pump, backhoe, crane, mower, water
shielding sheets, flexible containers
Examples:Tractor, deep-tillage plow, deep-tillage rotary,
mower

126

（2） Prior measurements
The air dose rate, etc. should be measured and recorded at the same location and by thesame method both before and after decontamination work in order to confirm
decontamination effects. The method of measurement for the air dose rate, etc. before
decontamination work is explained below.

1）Determination of measurement points
Before decontamination work, the measurement points (Table 2-32) at which the air doserate, etc. are to be measured should be decided and a schematic diagram illustrating therange of the measured objects, the measurement points, structures to be used as markers, etc.
should be made (Figure 2-26). In addition, in setting these measurement points, hotspots andtheir ambient areas that contribute insubstantially to the radiation dose in the living spaceshould not be used as measurement points unless the users, etc. are deemed likely to spend
relatively large amounts of time there..
Table 2-32 Reasoning behind the measurement points for air dose rates and other measures
for the decontamination of soil
Measurement No. 1 measurement points(①)
No. 2 measurement
point
points（②）
Measurement Air dose rate in living spaces
Surfacetargetcontamination
density,etc.
forobjects subject todecontamination
Reasoning•Measurement points shall be set at intervals that Same as with No. 1
behind theallow the air dose rate distribution to be measurement points.
measurement
ascertained.
(①)
points【Schools (school buildings, schoolyards)】
For schoolyards, the schoolyards shall be divided
up into meshes of about 10 –30 m andmeasurements shall be conducted at one spot ineach mesh (in cases where there will presumably
be little variance in the air dose rate,measurements
may
also
be
taken
in
approximately five locations that have been
uniformly dispersed). The need to conductdecontamination and the contents of this shall be
determined based on the mean values from this.
For school buildings, measurements shall be
carried out in approximately five measurement
points at places where people are deemed likely tospend relatively large amounts of time in thevicinity around school buildings. The need to
conduct decontamination and the contents of thisshall be determined based on the mean values
from this. For the school building as a whole,measurements can be carried out at multiple
points in places where people are deemed likely tospend relatively large amounts of time (roughly
the total from the several measurement points inthe schoolyard and school building mentioned
above), and the need to conduct decontaminationand the contents of this can be determined basedon the mean values from this.
127

【Farmland and pastureland】
Farmland and pastureland shall be divided up
into meshes of about 10 –30 m and measurements
shall be conducted at one spot in each mesh.
However, changes can be made to this in cases
where said land has a vast surface area according
to the conditions. The need to conductdecontamination and the contents of this shall be
determined based on the mean values from this.

Planted trees
1m

1m
②

①
②

Building②

Schoolyard
① ②

10 m

① ②

① ②

① ②

① ②

① ②

① ②

① ②

① ②

①
②

Planted
trees
① ②

10 m
①:Contamination status for living spaces②:Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)

Figure 2-26 Example of a schematic diagram for reporting measurement points for use indecontamination and other measures for soil (schoolyards).

2）Measurement methods
It is recommended that for the measurement point marked as ① the apparatuses such as
NaI scintillation survey meters which are able to measure gamma rays should be used and forthe measurement point marked as ②, GM survey meters should be used．Table 2-33 presents
measurement methods specifically for radiocesium concentration in farmland soil.

128

Table 2-33 Measurement methods for the radiocesium concentration in farmland soil
Measuring
Estimates from germanium semiconductor detectors, NaI scintillation
apparatus
spectrometers, LaBr3(Lanthanum bromide) scintillation spectrometers,
usedand air dose rate
Calibration
At least once a year, calibration shall be performed using standard
radiation sources with known amounts of radioactivity.
Daily check
The remaining battery level, breakage of cables and connectors, andstatus of high voltage application shall be checked, and inspections ofswitch operability, etc. shall be carried out.
Measurements shall be performed at the same places where thebackground radiation does not vary substantially, and it shall be
confirmed that there are no large variations by comparing with pastvalues.
Prevention of•The body and detecting element of the measuring apparatus shall becontamination
covered with thin plastic sheet, etc.
The plastic sheet, etc. shall be replaced with new material when it getsdirty or breaks.
Measurement
For rice fields, soil shall be extracted from the surface of themeasurement point down to 15 cm deep in the ground, and after the soil
has been dried the radiocaesium concentration in the soil shall bemeasured using a germanium semiconductor detector.
For dry fields, soil shall be extracted from the surface of themeasurement point down to the depth of the plow layer (15 to 30 cm),and after the soil has been dried the radiocaesium concentration in thesoil shall be measured using a germanium semiconductor detector.
Records
The measurer shall record the air dose rate, etc. and radiocaesium
concentration at each measurement point shown in the conceptual
diagram, etc., along with the date and time of measurement and themeasuring apparatus used.

（3） Decontamination methods
This section explains the flow of the overall decontamination work for soil (Figure 2-27)
that is efficiently focused on the places with comparatively high concentrations of radioactive
materials that contribute substantially to the radiation dose. The arrangement of the overall
schedule should be made so as to avoid undertaking decontamination of two or more large
areas within a municipality at the same time whenever possible. The methods ofdecontamination for soil in schoolyards, kindergarten yards, and parks, as well as farmland
are described in terms of the items such as basic flow, necessary measures for priordecontamination work and decontamination methods and notes of caution.
Decontamination methods

Measures to prevent the spread of contamination through dispersion,
outflows, and so forth following the decontamination(2) Decontamination of farmland
・Farmland (fields) that has not been
plowed・Farmland (fields) that has been
plowed・Agricultural water facilities
・Orchards
・Pastureland(1)Decontamination of schoolyards,
kindergarten yards, and parks
Conduct the decontaminationfrom (1) –(2) as needed.

Figure 2-27 Basic flow for the decontamination of soil.
1291）Decontamination of soil in schoolyards, kindergarten yards, and parks
The flow of decontamination for soil in schoolyards, kindergarten yards and parks is shownin Figure 2-28. The necessary measures prior to the decontamination work are in Table 2-34.
The decontamination methods and notes of caution are in Table 2-35.
Decontamination of schoolyards, kindergarten yards, and parks*Hotspots
Locations where the soil has been
contaminated in a highly concentrated
manner by rainwater and wastewatercontaining radioactive materials where there
is a high probability that radiocesium has
become concentrated compared to thesurrounding areas.

Measures to prevent the spread ofcontamination through dispersion, outflows,
and so forth following the decontamination
Removal of soil and other materials at
hotspots*

Cases where the results of decontamination
cannot be adequately observed
For artificial
turf
Deep plowing

Scraping away the topsoil

Covering the soil surface

Deep plowing
has theadvantage thatit does notproduceremoved soil.

Adding soil, etc.
(as needed)

Covering the soil surface
has the advantage that it
does not produce
removed soil.

Removal of infill
material from
artificial turf

When the depth that mustbe scraped away is shallow
it is effective to use
solidification agents.

[Precautions]
・When scraping away the
topsoil, it is necessary toconfirm in advance thedepth of thecontamination from thesurface layer andestablish the optimal
depth to be scraped away
in advance.

Figure 2-28 Basic flow for the decontamination of schoolyards, kindergarten yards, and parks.
Table 2-34 Necessary measures prior to the decontamination of schoolyards, kindergarten
yards, and parks
Category
Decontamination methods and notes of caution
Prevention of
When scraping away the topsoil when it comes to dried soil, efforts can bedispersion
made to prevent the dispersion of dust by scattering solidification agentsover the area in advance to solidify the soil surface.

130

Table 2-35 Decontamination methods for schoolyards, kindergarten yards, and parks andnotes of caution
Category
Decontamination methods and notes of caution
Removal of
Fallen leaves, moss, mud, and other sediments shall be removed by hand by
sediments
people wearing rubber gloves and by shovel, etc.
Deep
About 10 cm of topsoil shall be uniformly scraped away and temporarily
plowing
piled on top of a plastic sheet or the like.
About 20 cm of subsoil shall be uniformly scraped away and piled on top of aseparate location from the topsoil.
After the topsoil has been uniformly spread out, the subsoil shall be
uniformly spread on top of it and the land will be leveled. It shall be
restored to its original height at a compactness that is about the same as it
was before.
Scraping
A backhoe or the like shall be used to uniformly scrape away the surface.
away
The remaining topsoil can be confirmed by means of sprinkling lime aroundtopsoilin advance.
Scraping away by using a surface cutter or hammer knife mower is aneffective method for covering vast areas.
Dispersion to the surroundings shall be prevented when scraping away
contamination.
(Example: use of dust collectors, sprinkling in advance, setting up simple
plastic housings, etc.)
Covering
The surface soil shall be covered with soil that does not containthe surface
radiocaesium.
soil
Attention shall be paid to the fact that because of the large air gaps when
covering with crushed stones, density adjustments shall be performed via
the appropriate surface compaction.
Removal of
The infill material found in artificial turf and the like shall be taken out via
infillmachinery that can absorb and remove said infill material.
material
fromartificial
turf2）Decontamination of farmland
The flow of decontamination for farmland is shown in Figure 2-29. The necessary measuresprior to the decontamination work are in Table 2-36. The decontamination methods and notesof caution are in Table 2-37.

131

Decontamination of farmland (fields)
Farmland (fields) that has notbeen plowed

Agitation/remov
al of soil bywater

Scraping away
topsoil[Precautions]
・When scraping away the topsoil, it
is necessary to confirm in advancethe depth of the contaminationfrom the surface layer andestablish the optimal depth to be
scraped away in advance.

Inversion tillage

Inversiontillage

Inversiontillage

Deep tillage

It is permissible to carry out inversion tillage, which does not
generate removable materials (soil)for farmland that has aconcentration of 5,000 Bq/kg or less of radiocesium in thesoil[Precautions]
・When inversion tillage is carried out, the water table must
be measured in advance and its depth must be taken into
account.

Decontamination of agricultural water facilities
Agricultural water facilities
Removal of sediments
Decontamination of orchards

Decontamination of pastureland
Pastureland

Orchards
Cleaning of tree bark

Cleaning of tree
bark

Pruning

Scraping away topsoil

Inversion tillage/plowing

Scraping away topsoil[Precautions]
・When inversion tillage
is carried out, thewater table must be
measured in advanceand its depth must be
taken into account.

[Precautions]
・When scraping away
the topsoil, it isnecessary to confirm inadvance the depth ofthe contamination fromthe surface layer andestablish the optimal
depth to be scraped
away in advance.

[Precautions]
・When scraping away the topsoil, it isnecessary to confirm in advance the depthof the contamination from the surface
layer and establish the optimal depth to be
scraped away in advance.

Work that is being considered for
implementation in regions where the air
dose rate is comparatively highFigure 2-29 Basic flow of decontamination of farmland

132

Table 2-36 Necessary measures prior to the decontamination of farmland
Category
Decontamination methods and notes of caution
Prevention of dispersion
When scraping away the topsoil when it comes to dried soil,
efforts can be made to prevent the dispersion of dust by
scattering solidification agents over the area in advance tosolidify the soil surface.

Table 2-37 Decontamination methods for farmland and notes of caution
Category
Decontamination methods and notes of caution
Unplowed
Scraping
A backhoe or the like shall be used to scrape away the surface.
away topsoil
The remaining topsoil can be confirmed by means of sprinkling
lime around in advance.
Soil agitation
After the upper layer of soil has been agitated (shallow
or removal by
puddled), the turbid water with fine soil particles floating in it
water
shall be forcefully drained via a pump. Then solid-liquid
separation shall be performed in a grit chamber or similar
device that has been covered with a plastic sheet to collect thesoil particles.
Inversion
A plow shall be used to invert the soil so that the contaminatedtillagesoil in the top layer is moved to the bottom layer and theuncontaminated soil from the bottom layer is placed on the top
layer.
The tillage depth for inversion tillage shall be 30 cm inprincipal. However, in cases where soil that is not suitable foruse as the plow layer will come to the surface, such as soil that
contains pebbles, then the tillage depth shall be set shallowly
after first confirming that adequate decontamination results
will be obtained from this.
The water table shall be measured and its depth taken into
account when performing inversion tillage as needed.
Attention must be paid to the fact that small tractors cannot be
used to agitate the soil in cases where the topsoil is frozen due
to cold temperatures.
PlowedInversion(Same as above)tillage
Deep tillage
A deep tillage rotary tiller shall be used to deeply till cultivatedland about two times. The tillage depth of deep tillage shall be
about 30 cm in principal.
Water
Removal of
Mud and other sediments that have accumulated in
facilities
sediments
agricultural drainage canals and other such facilities shall be
removed through the use of a shovel or the like.
Orchards
DebarkingTree bark shall be removed by primarily concentrating on the
top sand sides of main trunks and main branches.
A dedicated chipping tool shall be used to scrape away so as totake off tree bark that has grown old.
Cleaning tree
Tree species that do not have a configuration in which old treebark
bark can be removed from their branches and trunks (peachtrees, cherry trees, etc.) shall be subject to cleaning.
When cleaning bark or debarking with the use of a highpressure water cleaner, radiocaesium tends to easily disperse
together with the water, and so the use of these procedures
shall be avoided during the growing season and be carried out
during dormant stages.

133Pruning

Scraping
away topsoil

Pastureland

Inversiontillageplowing/

Scraping
away topsoil

Old branches to which it is thought that radiocaesium isdirectly
Adhering shall be removed.
The branches shall be removed during the tree’s dormant stage
so that this does not affect its growth.
The soil shall be removed by human power or via an earth
blade on a small backhoe. Or a rotary tiller shall be attached toa small tractor and the soil shall be lightly tilled, after which
the topsoil shall be removed by a method such as gathering up
the topsoil through the use of a front loader (without a claw) on
a tractor.
A plow shall be used to invert the soil so that the contaminatedsoil in the top layer is moved to the bottom layer and theuncontaminated soil from the bottom layer is placed on the top
layer.
The tillage depth for inversion tillage shall be 30 cm inprincipal. However, in cases where soil that is not suitable foruse as the plow layer will come to the surface, such as soil that
contains pebbles, then the tillage depth shall be set shallowly
after first confirming that adequate decontamination results
will be obtained from this.
The water table shall be measured and its depth taken into
account when performing inversion tillage as needed.
Attention must be paid to the fact that small tractors cannot be
used to agitate the soil in cases where the topsoil is frozen due
to cold temperatures.
•A backhoe or the like shall be used to scrape away the surface.

（4） Post–work measures
This section explains handling the removed soil, etc., and cleaning equipment used, etc. as
post-work measures. Handling the removed soil, etc. is described in 2.2.2 (4) 1) of this reportand cleaning equipment used, etc.is described in 2.2.2 (4) 3) of this report.

（5） Subsequent measurements and records
To confirm the decontamination effect, the air dose rate, etc. should be measured after
completion of the decontamination work and recorded as shown in Table 2-38.
Table 2-38 Subsequent measurements and records for the decontamination of soil
Measurement of air dose
The air dose rate, etc. and radiocaesium concentration in therate, etc. and radiocaesium
soil (in the case of farmland) shall be measured at eachconcentration, etc.
measurement point.
Measurements shall be carried out in the same location as
the prior measurements and under the same conditions to
the extent possible.
For the measuring apparatus, the same apparatus as wasused for the prior measurements shall be used to the extent
possible.
Recordkeeping
Air dose rate, etc. and radiocaesium concentration in the soilateachmeasurement
point,
placesforwhichdecontamination
work
wasperformed,
dateof
decontamination, names of decontaminators, types of objects
subject to decontamination, method of decontamination, total
134

area decontaminated (soil, etc.), the approximate weight of
the removed soil, etc., and the status of storage and disposal.
The equipment used in decontamination and the method of
disposal after use.
See “Part 4: Guidelines Pertaining to the Storage of Removed
Soil” for details on the items to record with regard to thestorage of removed soil.

2.2.5. Decontamination and Other Measures for Vegetation
This section explains preparation, prior measurements, decontamination methods,
post-work measures, and subsequent measurements and records, in the basic flow (Figure2-30), pertaining to the decontamination and other measures for vegetation.

1.Preparation

2.PriorMeasurements(1)Measures to reduce public exposure in connection with the work
(2)Equipment and materials(1) Determination of measurement points(2) Measurement methods

Measures to prevent the spread of contamination through dispersion, outflows,
and so forth following the decontamination (institute the necessary measuresfor each instance of decontamination work)
3.Decontamination
Methods(1)Decontaminationof lawns

4.Post-Work
Measures(2)Decontamination oftrees in living spaces,such as roadside trees
and the like(3)Decontaminationof forests(1) Handling the removed soil, etc.
(2) Wastewater treatment

5.Subsequent Measurements and Records

Figure 2-30 Basic flow for decontamination and other measures for vegetation.

135

（1） Preparation
Before performing decontamination work, in addition to preparing the equipment required
for the work, preparations must be made to ensure safety of workers and the general public toprevent their exposure to hazards, such as by inhaling dust generated duringdecontamination work; these preparations are summarized in Table 2-39.
Table 2-39 Preparation for measures on decontamination work for vegetation
Measuresto Restrictionof
In cases where the general public is deemed likely to
reduce public entry
enter the area, the area shall be cordoned off with
exposureinpylons or rope, etc. to prevent people from unnecessarily
connection withapproaching the work site, and the entry of people anddecontamination
vehicles shall be restricted.
work
In cases where radioactive materials may be dispersedin connection with the decontamination work, theperimeter of the decontamination area shall be fenced
in with sheets, etc., water shall be sprayed, or othersuch measures shall be taken to prevent dispersion andthe area shall be cordoned off with rope, etc.
Signage
In cases where the general public is deemed likely toenter the area, signs, etc. shall be put up to alert the
public that decontamination work is being performed
Preparation ofGeneralExamples：Equipment andequipment
Mower, hand shovel, grass sickle, broom, bamboo rake, dustpan,
Materials
tongs, shovel, small shovel, metal rake, compact heavy machinery
for scraping away topsoil, garbage bags (bags for burnable matter,burlap sacks for soil and sand (sandbags)), vehicles fortransporting collected removed soil, etc. to the on-site storage
location (truck, two-wheeled cart, etc.)
equipment
for Examples：
pruning trees
Hatchet, pruner, chainsaw, stepladder, mobile lift, and saw（2） Prior measurements
The air dose rate, etc. should be measured and recorded at the same location and by thesame method both before and after decontamination work in order to confirm
decontamination effects. The method of measurement for the air dose rate, etc. before
decontamination work is explained below.

1）Determination of measurement points
Before decontamination work, the measurement points (Table 2-40) at which the air doserate, etc. are to be measured should be decided and a schematic diagram illustrating therange of the measured objects, the measurement points, structures to be used as markers, etc.
should be made (Figure 2-31). In addition, in setting these measurement points, hotspots andtheir ambient areas that contribute insubstantially to the radiation dose in the living spaceshould not be used as measurement points unless the users, etc. are deemed likely to spend
relatively large amounts of time there.

136

Table 2-40 Reasoning behind the measurement points for air dose rates and other measures
for the decontamination of vegetation
Measurement No. 1 measurement points（①）
No. 2 measurement points（②）
point
Measurement Air dose rate in living spaces
Surface contamination density, etc. fortargetobjects subject to decontamination
Reasoning
Measurement points shall be set at
Same as with No. 1 measurement
behindtheintervals that allow the air dosepoints（①） for lawns.
measurement
rate distribution to be ascertained.
For roadside trees, measurement
pointsLawns
points shall be established within
Lawns shall be divided up intoa range that will presumably bemeshes of about 10 –30 m andaffected by the roadside tree
measurements shall be conducted(example: a position that is about 1
at one spot in each mesh.
m away from the side of theForests
roadside tree).
Measurements shall be conducted
For forests, the points shall be as
at one spot about every 20 –50 mwith No. 1 measurement points.
near the forest edge and thegeographical center of the forest
where work will be performed.

Lawn
① ②

50m

① ②

① ②

Forest edge
Scope ofdecontamination
Approximately
20m

②

②

②

Forest①:Contamination status for living spaces②:Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)

Figure 2-31 Example schematic diagram for reporting measurement points for use indecontamination and other measures for vegetation (forests).

2）Measurement methods
It is recommended that for the measurement point marked as ① the apparatuses such as
NaI scintillation survey meters which are able to measure gamma rays should be used and for
the No. 2 measurement point marked as ②,GM survey meters should be used..

137

（3） Decontamination Methods
The flow of decontamination for vegetation is explained in Figure 2-32. The necessary
measures prior to the decontamination work are in Table 2-41. The decontamination methods
and notes of caution are in Table 2-42.

Decontamination methods

Measures to prevent the spread of contamination through dispersion, outflows, and so forthfollowing the decontamination (institute the necessary measures for each instance of
decontamination work)(1)Decontamination of
lawns(2)Decontamination of trees in living spaces,such as roadside trees and the like(3)Decontamination offorests

Figure 2-32 Basic flow for the decontamination of vegetation.

1）Decontamination of lawns
The flow of decontamination for lawns is in Figure 2-32. The necessary measures prior to
the decontamination work are in Table 2-41. The decontamination methods and notes ofcaution are in Table 2-42.

Decontamination of lawns

Work that is being considered for
implementation in regions where theair dose rate is comparatively highMeasures to prevent the spread ofcontamination through dispersion, outflows,
and so forth following the decontamination

Cases where it isclear that adequate
decontamination
results cannot be
obtained
Deep trimming

Grass removal[Precautions]・Measures to prevent the inhalation of dust
shall be taken.
・Determinations on the decontamination
results from deep trimming shall be madevia tests and experiments, etc.

[Precautions]・Deep trimming shall first be carried out inan experimental manner, with

Figure 2-33 Basic flow for the decontamination of lawns.

138

Table 2-41 Necessary measures prior to the decontamination of lawns
Category
Decontamination methods and notes of caution
Prevention ofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent the dispersion of dust, etc.
Table 2-42 Decontamination methods for lawns and notes of caution
Category
Decontamination methods and notes of caution
Deep trimming

If large mowers will fit, then deep trimming shall be carried out usinglarge mowers (shallow cutting down to approximately 3 cm, which is alevel from which the grass can recover).
If large mowers will not fit, then the deep trimming of lawns shall be
carried out using a hand guided mower (sod cutter, etc.)

Grass removal

The flat claw for a backhoe bucket shall be installed and the grass andsod shall be removed (about 5 cm).

2）Decontamination of trees in living spaces, such as roadside trees and the like
The flow of decontamination for trees in living spaces, such as roadside trees and the like is
explained in Figure 2-34. The necessary measures prior to the decontamination work are in
Table 2-43. The decontamination methods and notes of caution are in Table 2-44.

Decontamination of trees in living spaces, such as roadside trees and the likeWork that is being considered
for implementation in regions
where the air dose rate iscomparatively highMeasures to prevent the spread ofcontamination through dispersion, outflows,
and so forth following the decontamination

Removal of sediments, etc.
Cases where the results of decontamination cannot beadequately observed
When branches
and other suchparts arecontaminatedPruning branches, etc.

Scraping away the topsoil[Precautions]・You must not harm the rootstock.
・You must not dig too deeply.

Consideration shall be given to carrying out
decontamination via cutting down trees andhigh pressure water clean in gas needed.

Figure 2-34 Basic flow for the decontamination of trees in living spaces, such as roadside trees
and the like.

139

Table 2-43 Necessary measures prior to the decontamination of trees in living spaces, such as
roadside trees and the like
Category
Decontamination methods and notes of caution
PreventionofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent the dispersion of dust, etc.
Table 2-44 Decontamination methods for trees in living spaces, such as roadside trees and thelike and notes of caution
Category
Decontamination methods and notes of caution
RemovalofFallen leaves, moss, mud, and other sediments shall be removed by
sediments
hand by people wearing rubber gloves and by shovel, etc.
Scraping away
Accumulated fallen leaves and soil shall be picked up by using a shovel
topsoilor rake, etc.
RemovalofDelimbing and pruning shall be carried out on roadside trees by using abranches, etc.
pruner and branch cutter to an extent that does not give rise to any
pronounced impact for the growth of trees according to the tree species
and their delimbing period.

3）Decontamination of forests
The flow of decontamination for forests is explained in Figure 2-35. The necessary measuresprior to the decontamination work are in Table 2-45. The decontamination methods and notesof caution are in Table 2-46.

140Decontamination of forest(near the living spaces)
Determination of decontamination areas(determination of decontamination effect by pilot
implementation as needed)[caution]・Pilot implementation shall be performed
Pilot implementation of removal of organic
step by step with interval of 5m in thesediments of fallen leaves and the likerange of 20m from the edge of forests. The
effective range of removal of organic
sediments such as fallen leaves ,etc. shallIn the case without
be determined with confirming
an adequate effects
decontamination effect for reducing
radiation exposure dose in the living
environment
・The necessity for implementing removal of
Pilot implementation of removal of organicorganic sediment residues shall be
sediment residues
adequately considered.

Measures to prevent the spread ofcontamination through dispersion, outflows,
and so forth following thedecontamination(including cutting)[caution]
Removal of organic sediments on fallen
leaves and the like shall be implemented in
the effective range on reducing air dose in
the living environment.( Removal of organic
sediments such as fallen leaves and the like iseffective in the range of 5m~10m from theedge of forests)
Take note that removal of organic sediments
such as fallen leaves and the like shall be
implemented to aim at the range of 5m fromthe edge of forests and not to over-disclose
the root of trees.

Removal of leaves of standing trees(asneeded)Removal of organic
sediments on fallen
leaves and the like

Removal of organic
sediments on fallen
leaves and the likeand removal oforganic sedimentresidues[caution]
Prevention from running-off soil shall beespecially considered in case of removal oforganic sediment residues.

Prevention measures for running–off
soil ,etc.

Figure 2-35 Basic flow of decontamination of forests (near living spaces).

Table 2-45 Necessary measures prior to the decontamination of forests
Category
Necessary measures prior to the decontamination
PreventionofIf sidewalks and buildings are immediately adjacent, curing shall bedispersion
performed to prevent the dispersion of dust, etc.
Cutting
The cutting of weeds, shrubs, and other vegetation shall be carried out
using a chainsaw or shoulder-type mower, etc.

141

Table 2-46 Decontamination methods for forests and notes of caution
Category
Decontamination measures and notices of caution
Removal oforganic
sediment

Organic sediment shall be removed by bamboo-rake, etc.
Masks shall be worn to avoid inhaling suspended particulates produced
during removal work.

Removal oforganic
sediment
residue

Organic sediment residue shall be removed by bamboo-broom, etc.if
radiation dose is not effectively able to be reduced in the living environment
after removal of organic sediment.
Masks shall be worn to avoid inhaling suspended particulates produced
during removal work.

Removal ofbranches
and leaves(only forevergreentrees)

In case that a large contribution of radiation materials on the standing trees
at the very edges of the peripheral areas around forests to radiation
exposure dose in the living environment is deemed , the pruning and cuttingof branches and leaves of standing trees at the very edges of the peripheral
areas around forests shall be carried out to an extent that does not give riseto any pronounced impact for the growth of trees and the fallen branches
and leaves shall be collected,
Generally, the very edges of the peripheral areas around forests contain alarge volume of leaves affixed to trees, and so there is the possibility that acomparatively large amount of radioactive materials are adhering to them.
Therefore, branches and leaves should be removed from as high up a
position as possible (up to about half the length of the tree canopy).
Masks shall be worn to avoid inhaling suspended particulates produced
during removal work.

Prevention
measures ofrunning off soil

Prevention of running-off soil shall be made by setting sandbags and fences
at appropriate locations such as the very edges of the peripheral areas
around forests.

（4） Post–work measures
This section explains handling the removed soil, etc., and cleaning equipment used, etc. as
post-work measures. Handling the removed soil, etc.is described in 2.2.2 (4) 1) of this reportand cleaning equipment used, etc. is described in 2.2.2 (4) 3) of this report.

（5） Subsequent measurements and records
To confirm the decontamination effect, the air dose rate, etc. should be measured after
completion of the decontamination work and recorded as shown in Table 2-47.

142

Table 2-47 Subsequent measurements and records for the decontamination of forests
Measurement of
The air dose rate, etc. shall be measured at each measurement point.
air dose rate, etc.
Measurements shall be carried out in the same location as the priormeasurements and under the same conditions to the extent possible.
For the measuring apparatus, the same apparatus as was used for theprior measurements shall be used to the extent possible.
Recordkeeping
The air dose rate, etc. at each measurement point, places where
decontamination work was performed, decontamination date, names ofthe decontaminators, type of objects decontaminated, decontamination
methods, total decontamination area (of soil, etc.), the approximate
weight of the removed soil, etc., and the status of storage and disposal.
The equipment used in decontamination and the method of disposal
after use.
See “Part 4: Guidelines Pertaining to the Storage of Removed Soil” fordetails on the items to record with regard to the storage of removed soil.

2.2.6. Decontamination Measures of Rivers and Ponds, etc.
This section explains the basic policy for decontamination measures of rives and ponds, etc.
that is, the exposure from radioactive materials in the sediments of rivers and ponds, etc.
with a very large amount of water which has an effective shielding effect makes very little
contribution to the radiation level of ambient areas. In the case of the seasonal water dried-up
condition (which negates the expected shielding effect), for the living spaces where the air
dose rate from accumulated radioactive cesium deposited on the sediments is high and many
activities of the general public are carried out, the decontamination measures should be
implemented as needed. The objectives for decontamination measures are the facilities which
the general public often utilizes, such as facilities which are located near riverbeds and areas
where there are sediments of rivers and ponds. For the former decontamination measures, theprovisions for other specific places may be applied as shown in Table 2-48.
Table 2-48 Specific implementation methods for decontamination work, etc. for facilities
located near riverbeds which the general public often utilizes.
objectives
Referred sections in “Decontamination Guidelines”
Fences・walls, benches 2.2.2. (3) 4) Decontamination of fences・walls, benches and playing tools
and playing tools
Parts paved by
2.2.3. (3) 1) Dcontamination of paved surfaces ,etc.
concrete,asphalt ,etc.
Parts of soil,etc. on
2.2.3. (3) 2) Decontamination of unpaved roads, etc.
ground surface
2.2.4. (3) 1) Decontamination of soil of schoolgrounds,kindergaraten,parks
Parts of lawns on
2.2.5. (3) 1) Decontamiantion of lawns
ground surface
On the other hand, the sediments of rivers and ponds (reservoirs) should be
decontaminated only if the air dose rate increases significantly due to seasonal water dry-up
in reservoirs located near living spaces such as residential areas and parks. For
decontamination of sediments in reservoirs, the basic flow of decontamination measures isshown in Figure 2-36 and they consist of preparation, prior measurements, decontamination
methods, post-work measures, and subsequent measurements and records.

143

1.Preparation

2.PriorMeasurements(1) Measures to reduce public exposure in connection with the work
(2) Equipment and materials(1) Determination of measurement points(2) Measurement methods

Measures to prevent the spread of contamination through dispersion, outflows,
and so forth following the decontamination (institute the necessary measuresfor each instance of decontamination work)
3.Decontamination
Methods(1) Decontamination of hot spots(2) Scraping away of decontamination of farmland(3) Covering the soil surface

4.Post-Work
Measures(1) Handling the removed soil, etc.
(2) Wastewater treatment

5.Subsequent Measurements and Records

Figure 2-36 Basic flow of decontamination measures of sediments in reservoirs.

（1） Preparation
Before performing decontamination work, in addition to preparing the equipment required
for the work, preparations must be made to ensure safety of workers and the general public toprevent their exposure to hazards, such as by inhaling dust generated duringdecontamination work; these preparations are summarized in Table 2-49.

144

Table 2-49 Preparation of decontamination measures for sediments in reservoirs
Measures to
Restriction of
In cases where the general public is deemed likely to
Reduce Public
entry
enter the area, the area shall be cordoned off with
Exposure inpylons or rope, etc. to prevent people from
Connection with
unnecessarily approaching the work site, and the entry
Decontaminationof people and vehicles shall be restricted
Work
In cases where radioactive materials may be dispersedin connection with the decontamination work, theperimeter of the decontamination area shall be fenced
in with sheets, etc., water shall be sprayed, or othersuch measures shall be taken to prevent dispersion andthe area shall be cordoned off with rope, etc.
Signage
In cases where the general public is deemed likely toenter the area, signs, etc. shall be put up to alert the
public that decontamination work is being performed.
Preparation ofGeneralExamples：equipment ,etc.
equipment
Mower, hand shovel, grass sickle, broom, bamboo rake, dustpan,
tongs, shovel, small shovel, metal rake, compact heavy machinery
for scraping away topsoil, garbage bags (bags for burnable matter,burlap sacks for soil and sand (sandbags)), large sandbags, flexible
containers vehicles for transporting collected removed soil, etc. tothe on-site storage location (truck, two-wheeled cart, etc.), ladder
Equipment for
Examples:scraping away
tractor, vertical harrow and other attachments, rear blade, front
sediments
loader, backhoe, grader, crane, vacuum car, mower, chipping
machine, hammer knife mower, flexible containers, bulldozer,
hydraulic shovel, backhoe
Equipment for
Examples:covering
Self-propelled surface compaction roller, plywood for surface
sediments
compaction, sprinkling equipment, bulldozer, hydraulic shovel（2） Prior measurements
The air dose rate, etc. should be measured and recorded at the same location and by thesame method both before and after decontamination work in order to confirm
decontamination effects. The method of measurement for the air dose rate, etc. before
decontamination work is explained below.

1）Determination of measurement points
Before decontamination work, the measurement points (Table 2-50) at which the air doserate, etc. are to be measured should be decided and a schematic diagram illustrating therange of the measured objects, themeasurement points, structures to be used as markers, etc.
should be made (Figure 2-37). In addition, in setting these measurement points, hotspots andtheir ambient areas that contribute insubstantially to the radiation dose in the living spaceshould not be used as measurement points unless the users, etc. are deemed likely to spend
relatively large amounts of time there..

145

Table 2-50 Reasoning behind the measurement points for air dose rates and other measures
for the decontamination of sediments in reservoirs
Measurement point
No. 1 measurement points(①）
No. 2 measurement points （②）
Measurement target
Air dose rate in living spaces
Surface contamination density,
etc. for objects subject todecontamination
Reasoning behind
The measurement points shall
The measurement shall bethemeasurement
be determined with the distancemade at a point per the
pointsbetween the points where thedistance-intervalof
distribution of the air dose rate
approximately 20m~50m, in theis able to confirm.
dried-upreservoir
whose
In the case that the air doseradiation exposure affects therate of the living spaces is
air dose rate in the living
significantly
affectedbyspaces near the reservoir.
radiation
exposure
fromdried-upreservoir,themeasurement shall be made
at
a
point
per
the
distance-intervalofapproximately 20m~50m, in the
peripheral
parts
of
the
reservoir, when the basin of thereservoir is disclosed.

Linear living spaces such as roads
and promenades, etc.

Facial living spaces such as open
spaces and resident areas, etc.

Decontamination areas :the area in the living spaces
on which the exposure doseis affected by radiation
The disclosed part of wet
basin in the reservoir

The covered partby water in thereservoir

Non-living spaces＊If the living environment will in future be deemed to be affected due to increase of the air dose ratefrom radiation exposure by in-flow and out-flow of the reservoir after decontamination,
decontamination of sediment in the reservoir may , as needed, be implemented and the measuring
points shall be determined according to the decontamination area .
①：Status of decontamination on the living space②：Status of decontamination of decontamination objects

Figure 2-37 Example diagram on measurement points for decontamination of sediments in areservoir.
1462）Measurement methods
It is recommended that for the measurement point marked as ① the apparatuses such as
NaI scintillation survey meters which are able to measure gamma rays should be used and forthe measurement point marked as ②, GM survey meters should be used.
（3） Decontamination methods
This section explains that the decontamination methods should be implemented so as toprevent contamination expansion due to dispersion and outflow of radioactive substances
caused by the decontamination work. The decontamination flow for the reservoir is shown in
Figure 2-38. The necessary measures prior to the decontamination work are in Table 2-51.
The decontamination methods and notes of caution are in Table 2-52.
Decontamination of sediments in the reservoir

Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following
the decontamination

Decontamination of hotspots ＊(removal of soil, etc.
and water plant)

Scraping away sediments＊Hotspots
The spot where radioactive
ceseum is deemed todeposit more than on thesurrounding area

Covering sediments[caution]
Before scraping away sediments, it isnecessary to confirm depth ofcontamination from the surface anddetermine the most appropriate depth ofscraping[caution]
The merit of covering sediments is not tocause generating of removed soil. Before
covering it is necessary to confirm
possibility of neither obstruction of thereservoir nor of intrusion and coming–off
and determine the most appropriate depthof covering

Figure 2-38 Basic flow of decontamination of sediments in reservoirs.
Table 2-51 Necessary prior measures for decontamination of sediments in reservoirs
category
Necessary prior-measures
Prevention ofdispersion

If sidewalks and buildings are immediately adjacent, curing shall be
performed to prevent the dispersion of dust, etc.
If scraping topsoil of dried-up soil, prevention measure of dispersion ofsoil dust shall be implemented. There are the measures of solidifying
the surface of the soil in advance by dispersing solidifying materials,etc.

147

Table 2-52 Decontamination methods for sediments in reservoirs and notes of caution
Category
Decontamination methods and notices of caution
Decontaminationof hotspots

Sediments and water plants shall be removed by hand withrubber-gloves and scoop.it is recommended that top sediment is scraped
every approximately several centimeter with measuring
surfacecontamination density etc.

Scraping andremoval of
sediments

Before scraping sediments it is necessary to confirm depth ofcontamination from the surface and determine the most appropriate
depth of scraping
It is recommended that for a small area in the appropriate location of thereservoir, top sediment shall be scraped every several centimeter depthof sediments with measuring surface contamination density and thedepth to be scraped shall be determined.
Sediments shall be scraped by backhoe, etc.
It is able to confirm whether the residue of top sediments not to be
removed exist by dispersing in advance calcium arsenate ,etc.

Covering
sediments

Sediments shall be covered by soil without radiocaesium while it shallbe taken account into that covering layers over the sediments are run-off
and the sediments are disclosed by the water flow after re-filling
water ,etc.

（4） Post–work measures
This section explains handling the removed soil, etc., and cleaning equipment used, etc. as
post-work measures. Handling the removed soil, etc. is described in 2.2.2 (4) 1) of this reportwastewater treatment, in 2.2.2 (4) 2) of this report and cleaning equipment used, etc., in 2.2.2(4) 3) of this report.

（5） Subsequent measures and records
To confirm the decontamination effect, the air dose rate, etc. should be measured after
completion of the decontamination work and recorded as shown in Table 2-53.
Table 2-53 Subsequent measurements and records of decontamination for sediments inreservoirs
Measurement of
The air dose rate, etc. and radiocaesium concentration in the soil (in the
air dose rate, etc.
case of farmland) shall be measured at each measurement point.
Measurements shall be carried out in the same location as the priormeasurements and under the same conditions to the extent possible.
For the measuring apparatus, the same apparatus as was used for theprior measurements shall be used to the extent possible.
Recordkeeping
Air dose rate, etc. and radiocaesium concentration in the soil at eachmeasurement point, places for which decontamination work was
performed, date of decontamination, names of decontaminators, typesof objects subject to decontamination, method of decontamination, total
area decontaminated (soil, etc.), the approximate weight of the removed
soil, etc., and the status of storage and disposal.
The equipment used in decontamination and the method of disposal
after use.
See “Part 4: Guidelines Pertaining to the Storage of Removed Soil” fordetails on the items to record with regard to the storage of removed soil.
1482.3. Guidelines Pertaining to the Collection and Transfer of the Removed Soil
2.3.1. Basic Concept
The “Guidelines Pertaining to the Collection and Transfer of the Removed Soil” use theexample cases to explain in a concrete fashion the Ordinance of the Ministry of theEnvironment pertaining to standards for the collection and transfer of the removed soil
provided in Article 41, Paragraph 1 of the Act on Special Measures.
When collecting and transferring the removed soil, safety measures are required to prevent
radioactive materials contained in the removed soil from damaging human health and theliving environment. The specific, necessary actions include 1) preventing the radioactive
materials from dispersing or outflowing when the removed soil is loaded, unloaded, ortransferred, and 2) preventing the public from being exposed to radiation emitted from theremoved soil while it is being collected or transferred.
These guidelines organize and describe the requirements for collecting and transferring theremoved soil as well as specific actions to be taken in accordance with the safety measures
mentioned above while also referring to the existing rules related to the transfer ofradioactive materials79.

2.3.2. Requirements for Collection and Transfer of the Removed Soil
This section explains four types of requirements for collection and transfer of the removed
soil.
Requirements for Preventing Dispersion, Outflow, and Leakage
Requirements for Radiological Protection
Requirements for the Transfer Route
Other Requirements

2.3.3. Specific Actions
Specific actions are necessary to collect and transfer the removed soil by using trucks inview of the requirements listed in 2.3.2.
Preventing Dispersion, Outflow, and Leakage
When collecting and transferring the removed soil, it is put into flexible container
bags, flexible containers, or drums with a lid, or wrapped in plastic sheets, etc. No
other special measures are necessary if the soil is transferred by box trucks.
If the removed soil contains sharp or heavy materials such as relatively largestones, the containers should be prevented from being torn, for example by using
containers with an inner liner.
Before the transfer of removed soil with a high water content, it is dehydrated asmuch as possible and measures are taken such as putting the soil in impermeablecontainers or laying down waterproof sheets.
When using non-waterproof containers, measures should be taken such as covering
the removed soil with waterproof sheets to prevent rainwater from permeating thesoil during collection and transfer. No such measures are necessary when using
79The ministerial ordinances based on the Act on the Regulation of Nuclear Source Materials, Nuclear Fuel

Materials and Reactors (hereinafter the “Reactor Regulation Act”), which includes the “Rules Related to theTransfer of Nuclear Fuel Materials Outside Plants or Operating Sites (hereinafter the “external transfer
rules”)” and “Rules for Transferring Nuclear Fuel Materials by Vehicles (hereinafter the “vehicle transfer
rules for nuclear fuel materials”),” as well as the ministerial ordinance based on the Act on the Prevention ofRadiation Hazards Due to Radioisotopes, etc. (hereinafter the “Prevention Act”), which includes the “Rules forTransferring Radioisotopes by Vehicles (hereinafter the “vehicle transfer rules for radioisotopes”)”.

149box trucks.
All containers should be visually checked for tears or cracks and the mouths of any
flexible bags or flexible containers should be securely close to prevent the contentsfrom being discharged if they collapse or fall over, or a fire breaks out. Drums
should be selected that have locking mechanisms.
Before driving a truck from an on-site storage area or a temporary storage site forremoved soil on public roads, the exterior and tires of the truck should be washed if
any soil is adhering to the truck. If water is used for washing, the drainage channel
for the washing water should be checked in advance to ensure smooth drainage
and if necessary, it should be cleared.
Fire extinguishers should be kept in the trucks as a means of controlling any fires.
Moreover, for the handling of any removed soil that has spilled out, the following
items should be prepared: cleanup implements, bags for collection, barrier ropes ortapes to indicate the areas where people should not enter, flashlights, andcommunication devices such as mobile phones. If the carrier is a business operator,
it is recommended a measuring apparatus be carried to check for radioactive
contamination (calibrated scintillation survey meter).
Shielding
When transferring the removed soil from areas where the radioactive dose rate
exceeds 200 mSv/year, a calibrated scintillation survey meter (hereinafter referred
to as the “measuring apparatus”) should be used to measure the air dose ratearound the truck after it is loaded with containers.
The measuring apparatus should be covered with a plastic bag to avoid
contamination.
The detecting element should be held parallel to the ground surface during
measurement.
After turning on the power of the measuring apparatus, it is necessary to wait
until the readings become stable. After that, readings should be taken five times
and the average of these values will be the measured value.
The measurements should be taken at a point 1 m from the front, rear, and bothsides of the vehicle. If there is an open cargo area, the vertical planes of theexternal outline of the carried objects should be used instead of both sides of thevehicle.
Measurements should be conducted at the point where the highest air dose rate isobserved after implementing an initial screening on each surface of the vehicle. If
the point of the highest air dose rate is unknown, the measurements should betaken at the center of each surface.
Care should be taken that the maximum measured values (dose equivalent rates
at 1 cm) does not exceed 100 μSv/hour, and the results should be recorded.
If the maximum dose exceeds 100 μSv/hour, the amount of the removed soil to betransferred should be decreased or shielding materials should be added to thecontainers holding the soil or to the truck itself.
Loading limitations
If the removed soil is loaded together with other wastes on a truck, the two should
be distinguished from each other during the collection and transfer.
SignageCollection and transfer of the removed soil using trucks shall be conducted in thefollowing manner.

150

A. The following information should be displayed on the exterior of the truck.
(1) Precautions to the effect that the truck is being used to collect or transfer
removed soil.
(2) Name of the person or entity in charge of the collection or transfer.
B. The information provided in items (1) and (2) above should be indicated using
signage with easily identified colors and letters. The letter size of the
precautions as provided under (1) should be not less than 140 points as specified
in JIS Z 8305, and the letter size of the precautions as provided under (2) should
be not less than 90 points as specified in JIS Z 8305.
Transfer during the night should be avoided as much as possible. This is because
visibility generally deteriorates at night, and so for example it would be harder to
see the signage that is being displayed.
Other matters
Documents showing the following information should be kept in the truck.
(These apply when any of the national, prefectural, and municipal governments
conducts or commissions a carrier to conduct the collection or transfer of theremoved soil.)
As a document to prove this fact, a copy of the contract between thegovernment and the contractor (concerned party).
Name and address of the person in charge of the collection or transfer and thename of the representative if the carrier is a corporation.
Amount of the removed soil to be collected or transferred.
Date on which collection or transfer is started.
Names, addresses, and contacts of the sites where the removed soil is being
loaded for the collection or transfer, and of the destination where the soil isbeing transferred to.
Cautions pertaining to handling the removed soil.
Emergency measures in case of an accident.
(When the carrier (primary contractor) that has been commissioned by the
National Government to collect or transfer the removed soil commissions suchwork to another carrier)
As a document to prove this fact, a copy of the contract between the primarycontractor and the carrier (subcontractor).
A document proving the fact that said subcontractor is the person who has
been listed as those to whom the said primary contractor intends to
subcontract the work of collection and transfer of the removed soil under thecontract document pertaining to the agreement made between the National
Government and the primary contractor.
Name and address of the person in charge of the collection or transfer and thename of the representative if the carrier is a corporation.
Amount of the removed soil to be collected or transferred.
Date on which collection or transfer is started.
Names, addresses, and contacts for the site where the removed soil is being
loaded for collection or transfer and of the destination where the soil is beingtransferred to.
Cautions pertaining to handling the removed soil.
Emergency measures in case of an accident.

151

The carrier should load and unload the removed soil by its own workers or instruct
other workers to do this.
If there are records on the decontamination work, the document showing the air
dose rate on the surface of each bag or container should be kept in the truck.
When selecting the transfer route, residential areas, shopping streets, schoolroutes, and narrow roads should be avoided to the extent possible in order toprevent damage to human health and the living environment as well as to reduce
any other effects on local residents. Moreover, the removed soil transfer by vehicles
should be done while following the legally permitted speeds and avoiding the peaktimes for heavy traffic and the time periods when children are going to or
returning from schools or kindergartens. When the removed soil is being loaded
onto the truck, low-noise heavy machinery should be used to reduce noise.
The following items should be recorded: the amounts of the removed soil collectedor transferred; the dates on which each arrangement for the collection or transferof the removed soil starts and ends; the name of the person in charge of thecollection or transfer; the names and addresses of the sites where the removed soil
is loaded and unloaded; and the registration or vehicle number of the truck used
for the collection or transfer. The resulting records should be retained for five years
from the date when the collection or transfer ends.

2.4. Guidelines Pertaining to the Storage of Removed Soil
These guidelines use example cases to explain in a concrete fashion the Ordinance of the
Ministry of the Environment pertaining to standards for the storage of the removed soil
provided in Article 41, Paragraph 1 of the Act on Special Measures．
Facility Design
Construction of storage facilities (hereinafter “facilities”) that can ensure safety according
to the radioactivity concentration and amount of the removed soil
Safety Management
Carrying out proper safety management of the removed soil during and after its delivery.
Taking measures if any problems occur.

2.4.1. Safety Measures and Requirements Necessary for Storage
This section describes organization of the facilities and management requirements based on
the safety measures that are considered to be necessary and commonly applied when storing
the removed soil (Figure 2-39).

152

Containers

Water shielding layer
Earth mound

Fence

Fence

Sandbags

Drain ditch

Collection tank(This is used to check forradioactive materials asnecessary)

Monitoring of radioactive materials in
the groundwater(*Figure is an image of Temporary Storage site)

4 Basic diagram of the safety measures for on-site and temporary storage sites① Prevent radioactive materials from dispersing, outflowing, or penetrating the ground(e.g. water shielding layer and containers)② Block radiation by shielding(e.g. earth mounds and sandbags)③ Install fences to prevent intrusion(e.g. fence)④ Monitor the air dose rate and groundwater continuously(e.g. monitoring of radioactive materials)⑤ Take prompt measures when any abnormality is found.
Note: ③ and ④ apply only to temporary storage sites.

Figure 2-39 Basic diagram of the safety measures for on-site and temporary storage sites.

（1） Facility requirements
The seven following facility requirements are explained.
Shielding and isolation
Prevention of dispersion of the removed soil
Prevention of penetration of rainwater, etc.
Prevention of outflow of the removed soil and radioactive materials
Prevention of effects from substances other than radioactive materials
Resistance to earthquakes, etc.
Other necessary measures（2） Management requirements
The four following management requirements are explained.
Restriction of entry
Monitoring the radiation dose and carrying out repairs of the facilities
Keeping records (Table 2-54 lists the items to be recorded)
Confirmation that the vacant site is not contaminated after the removed soil that had
been stored there was taken away

153

Table 2-54 Items to record pertaining to the storage of removed soil
Category
Items
Basic matters
Amount of removed soil stored
Dates on which the storage starts for each batch of removed soil stored
Dates on which the storage ends for each batch of removed soil stored
Names and addresses of the receiving sites*
Names and addresses of the destinations of the removed soil after the
storage
Information on
Names of the persons in charge of delivering the removed soildeliveryandNames of the persons in charge of receiving the removed soil
receipt
Registration or vehicle number of any trucks(In case where such trucks were used for the transfer pertaining to thedelivery)
Maintenance
Details of the measurement, inspection, and testing carried out toand control ofmaintain and control the place for storage
storage sites
Measurement
Position of the site boundary (fence) and position of the measurementof the air dosepointsrate
Dates measured
Measuring methods
Measuring apparatuses used for the measurements
Measurement results (background and air dose rate along the siteboundary)
Name of the inspector
Radioactive
Air dose rate on the surface of each container
concentration(On the surface of each container with the removed soil, or each group ofof the removed
multiple containers)
soil, etc.

2.4.2. Specific Examples of Storage Methods Chosen on the Basis of the
Facility/Management Requirements
This section describes two types of relatively small-sized on-site storage facilities bothabove ground and underground and two types of large-sized on-site storage facilities bothabove ground and underground in terms of facility specifications and safety management asshown in Table 2-55.
In addition, this section shows two types of both small-sized and large-sized temporarystorage sites above ground and two patterns of temporary storage site both underground andon sloped ground in terms of facility specifications and safety management as shown in Table
2-55.

154

Storagesite
On-sitestorage

Temporary
Storage site

Table 2-55 Examples of storage methods
Overground/
Summarized contents of storage site
undergroundoverground
Mound(2 × 2 × 1m) of removed soil generated during the decontaminationof an area whose air dose rate is about 1μSv/hour as as an example ofon-site storage over the ground
Mound (20 × 20 × 1 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1μSv/hour as as an
example of on-site storage over the groundundergroundPit (2 × 2 × 0.5 m) of removed soil generated during the decontaminationof an area whose air dose rate is about 1μSv/hour as as an example ofon-site storage under the groundPit (20 × 20 × 1 m) of removed soil generated during the decontaminationof an area whose air dose rate is about 1μSv/hour as as an example ofon-site storage under the groundoverground
Mound(20 × 20 ×2 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1μSv/hour as as an
example of on-site storage under the ground
Mound (100 × 100 ×2 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1μSv/hour as as an
example of on-site storage under the groundundergroundPit (50 × 50 × 2 m) of removed soil generated during the decontaminationof an area whose air dose rate is about 1μSv/hour as as an example ofon-site storage under the ground
Sloped ground Mound (20 × 20 × 2 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1μSv/hour as as an
example of on-site storage on the sloped groundTwo examples are presented here. The first is a pit (2 × 2 × 0.5 m) containing removed soil
produced during the decontamination of an area whose air dose rate is about 1 μSv/hour; it isexplained as an example of on-site storage underground. The second is a mound (20 ×20 × 2m) of removed soil produced during the decontamination of an area whose air dose rate isabout 1 μSv/hour; it is explained as an example of a temporary storage site above groundPit (2 × 2 × 0.5 m) of removed soil produced during the decontamination of an area
whose air dose rate is about 1 μSv/hour as an example of on-site storage underground(Figure 2-40)
An example of facility specifications and safety management details for the example on-sitestorage is shown in Table 2-56.

155

Earth mound(at least 30 cm)
At least
1 m*

Sandbags

Water shielding layer* Shielding distance(0) m if the covering with soil
exceeds 30 cm in thickness

Figure 2-40 Example of on-site storage underground - Pit (2 × 2 × 0.5 m) containing removed
soil produced during the decontamination of an area whose air dose rate is about 1 μSv/hour
Table 2-56 Example of facility specifications and safety management details for anunderground pit (2 × 2 × 0.5 m) on-site storage of removed soil produced during thedecontamination of an area whose air dose rate is about 1μSv/hour
Shieldingisolation

andAfter the delivery of the removed soil, shield it by putting sandbags
containing uncontaminated soil on the top or cover it with soil. The
sandbag or covering with soil shall be at least 30 cm thick. In this case,
it is not necessary to maintain an isolation distance from residentialbuildings, such as private houses.
If the top surface is not shielded, place the removed soil at least 1 m
away from residential buildings such as private houses.

Prevention
dispersionof

To prevent any radioactive material from dispersing, put the removed
soil in sandbags or flexible containers whose openings can be closed,and close them securely. If the removed soil is not put into any
containers such as sandbags, wrap it in a dustproof sheet.

Preventionofpenetrationofrainwater, etc.

Cover the removed soil with a waterproof sheet and fix the ends so thatthe sheet cannot be blown by the wind as needed. For fixing, sandbags
and blocks can be used.
Raise the center to prevent rainwater from accumulating on the surfaceof the sheet as needed.

Prevention
outflow

Spread a waterproof sheet over areas where the removed soil is placed.
No special measures are necessary if the removed soil is stored inwaterproof flexible containers, etc.
When placing the removed soil, take care not to damage the waterproof
sheet, etc.

Monitoringof

After completing covering with soil, etc. for the removed soil, use acalibrated scintillation survey meter to measure the air dose rate at the156

center (one spot) and places 1 m apart from four spots on the outer
perimeter of the area where the removed soil has been placed and at aheight of 1 m (four spots), and record the results.
If it is impossible to conduct such measurements at a place 1m apartfrom the outer perimeter, select other measurement points.
Record the measurement points by drawing a rough sketch to identify
the place of measurement.
Record keeping

Keep the records of measurement results of the air dose rates until theremoved soil is taken out.

Mound (20 ×20 × 2 m) of removed soil produced during the decontamination of an area
whose air dose rate is about 1 μSv/hour as an example of a temporary storage site
above ground (See Figure 2-41)
An example of facility specifications and safety management details for an example
temporary storage site is shown in Table 2-57.

Earth mound(at least 30 cm thick)Flexible containers(containing the removed soil)
Water shielding layer

Fence

At least 4m

At least 4m

Sandbag

Rainwaterdrain

Water shielding
sheetCollection tank(for checking radioactive
materials as necessary)

Collection/
drainage pipe

Protective layer(water collection
assistant layer)

Water table

Monitoring of radioactive
materials in the groundwater

Figure 2-41 Example of temporary storage site above ground – Mound (20 ×20 ×2 m) above
ground in temporary storage site of removed soil produced during the decontamination of anarea whose air dose rate is about 1 μSv/hour157

Table 2-57 Example of facility specifications and safety management details on a mound (20×20 ×2 m) above ground in a temporary storage site of removed soil produced during thedecontamination of an area whose air dose rate is about 1μSv/hour
Shieldingisolation

andWhen the delivery work extends over a lengthy period of time, keep theremoved soil at least 4 m away from residential buildings such asprivate houses from the viewpoint of curbing the public’s additional
exposure dose to not more than 1 mSv per year during the delivery.
During the delivery of the removed soil, shield it by putting flexible
containers, etc. containing uncontaminated soil on the side or cover itwith soil. The sandbag or covering with soil shall be at least 30 cm
thick.
After the delivery of the removed soil, shield it by putting sandbags
containing uncontaminated soil on the top or cover it with soil. The
sandbag or covering with soil shall be at least 30 cm thick.

Prevention
dispersion

ofWhen delivering removed soil, to prevent any radioactive material fromdispersing, put the removed soil into a flexible container, and close it
securely. If the removed soil is not put into any containers such as
flexible containers, wrap it in a dustproof sheet.

Preventionofpenetrationofrainwater, etc.

During and after the delivery of the removed soil, cover it with aweatherproof and waterproof sheet such as a water shielding sheet toprevent the soil from being exposed to the rain as much as possible. Fix
the end of the water shielding sheet so that it cannot be blown by thewind. For fixing, sandbags and blocks can be used. No special measures
are necessary if the removed soil is stored in waterproof containers or
kept in a facility with a roof.
Raise the center to prevent rainwater from accumulating on the water
shielding sheet, etc.
•Arrange the removed soil so that it is positioned higher than the water
shielding sheet, etc. for good drainage.
Install drainage facilities during the delivery to discharge any
accumulated rainwater.

Prevention
outflow

Spread a weatherproof and waterproof sheet such as water shielding
sheet over areas where the removed soil is placed.
When placing the removed soil, take care not to damage the waterproof
sheet, etc.
Installation of water shielding layer such as laying waterproof sheet
can be omitted if the removed soil is stored in waterproof containers
and a waterproof cover is properly applied to prevent rainwater fromcoming in.

Backgroundmeasurementof

Air dose rate
Before the delivery of the removed soil, use a calibrated scintillation
survey meter to measure the air dose rate at points along the siteboundary and at 1 m height on both sunny and rainy days, and record
the results.
The measurement points shall have an interval of about 2 m along thesite boundary and include the points on the site boundary nearest to
the place of storage of removed soil.
If it is impossible to conduct such measurements at a place 4 m apartfrom the outer perimeter, select other measurement points.
Record the measurement points by putting a mark on the ground or
drawing a rough sketch to identify the place of measurement.
Derive the approximations for the upper limit of variation from the158measured air dose rate values (at tens of points) and the following
equation:m + 3×√{(s1-m)2+(s2-m)2+・・+(sk-m)2+・・+(sN-m)2}/Ｎ
where S1, S2, . . .Sk… SN: Measured values,
m: Average of the measured values, and
N: Number of the measured values.
Radioactivity concentration of the groundwater
Before the delivery of the removed soil, dig a water sampling hole near
the planned temporary storage site, sample the groundwater, measure
the radiocaesium concentration of the sample, and record the results.
For the installation of the water sampling hole, prevent the intermixingof topsoil and surface water. In addition, implement measures toprevent the intermixing of topsoil and the like as needed.
Radioactivity concentration of the leachate (if necessary)
This is not a standard for storage, but if measuring he leachate, install
pipes into the protective layer to sample the leachate, and install acollection tank (e.g. working water tank or concrete measuring tank) on
the outside of the temporary storage site to collect the sampledleachate.
Radioactivity concentration of soil
Before the delivery of the removed soil, sample soil in the planned
temporary storage site, measure the radiocaesium concentration of thesample, and record the results.
The measurement points shall be at the center and four corners of thearea in which removed soil is placed.
Monitoring

Record keeping

Air dose rate
After the delivery of the removed soil starts, use a calibrated
scintillation survey meter, to measure the air dose rate at a height of 1
m at four spots including a spot nearest to the place of storage ofremoved soil among the background measurement points, and record
the results.
Take such measurements at least once a week.
Radioactivity concentration of the groundwater
After the delivery of the removed soil starts, sample the groundwaterfrom the sampling hole, measure the radiocaesium concentration of thesample, and record the results.
Samples of the groundwater should be taken when there is no turbidity.
Take such measurements at least once a month.
Radioactivity concentration of the leachate (if necessary)
After the delivery of the removed soil starts, check whether water isaccumulated in the collection tank at least once a month.
If water has accumulated, sample the leachate and measure theconcentration of radiocaesium, etc. in the sampled leachate.
Keep the following records until the period of operation of the facility
ends.
The amount of the removed soil stored, dates on which the storage
starts and ends for each batch of the removed soil stored, and thenames and addresses of the receiving site and destinations of theremoved soil after the storage.
The names of the persons in charge of receiving and delivering theremoved soil concerning such removed soil received, and theregistration or vehicle number of any truck in case where such truck
was used for the transfer pertaining to the delivery.
The results of an air dose rate measurement and water quality test
(measurement of the radioactivity concentration of groundwater).
159

Confirm that the measured values of the air dose rate and theradiocaesium concentration of the groundwater are within theallowable variation range of the background values. (Note that during
the delivery of the removed soil, the measured air dose rate shall not
exceed the allowable variation range plus air dose rate equivalent to 1
mSv/year.)If the measured value is observed to be exceeding the allowablevariance range, etc., identify the cause. If it is found that the temporarystorage site2 is the cause of such problem, take any necessary
measures, such as adding shielding materials, repairing the facility, or
collecting the removed soil.

RepairofConstruct fences (e.g. ropes, nets, or iron wire) at the periphery of thearea at least 4 m away from the temporary storage site.
Install signboards at least 60 cm × 60 cm in visually obvious places toindicate precaution to the effect that the area is the place of storage ofthe removed soil, the contact details in the event of an emergency, andthe height of the piled-up removed soil.

Vacant site check

After the period of storage ends and the removed soil is taken out of thetemporary storage site, measure the Cs-134 and Cs-137 concentrationof soil at the vacant site and confirm that the resulting values arewithin the variation range of the background concentration.
The measurement points shall be at the center and four corners of thearea in which removed soil had been placed.
If the measured value is observed to be exceeding the allowablevariation range, decontaminate the site.

Restriction
entry

160

3． Management and treatment of decontamination wastes
3.1. Temporary Storage Sites and Final Disposal
3.1.1. Waste Treatment Flow and Necessity of Temporary Storage Sites
As shown in Chapter 1, the “Urgent Implementation Basic Policy on Decontamination” (“Urgent
Implimentation Policy” in this document) (announced on August 26, 2011 by the Nuclear Emergency
Response Headquarters (NERH); hereafter referred to as the “Basic Policy on Decontamination”)
prescribes that, concerning the following description about the disposal of wastes and soil contaminated byradioactive materials: “The National Government shall be responsible for securing disposal sites that
require long-term management as well as safety of such sites, and will create and announce a roadmap toconstruct such sites as quickly as possible.”On the other hand, the Basic Policy on Decontamination also states: “Time is needed to secure andprepare disposal sites that require long-term management. Decontamination might not proceed quickly ifsuch disposal sites must be put in place first.” The Basic Policy on Decontamination stresses the needs of
temporary storage sites as: “It is realistic that such temporary storage site(s) is (are) to be located ineachmunicipality or community has its own individual temporary storage site(s) for the time being to keep soil
and wastes produced by decontamination.”
In response the MOE on October 29, 2011,presented its basic philosophy “Basic Philosophy on Interim
Storage and Other Facilities Required for the Handling of the Environmental Pollution from Radioactive
Materials Associated with the Accident at the Fukushima Daiichi Nuclear Power Station of Tokyo ElectricPower Company” (hereafter referred to as the “MOE Basic Philosophy on Interim Storage”),
The MOE Basic Philosophy on Interim Storage is summarized in Figures 3-1 to 3-3, and includes theflow schematics for treatment of wastes and the roadmap towards the installation of an interim storage
facility in Fukushima Prefecture, where significant amounts of removed soil and other wastes are
anticipated to be produced.
Flow Diagram for Treatment of Specified Waste(*)
and Decontaminated Soil,etc. based on the Act on Special Measures (Fukushima Pref.)(*)Waste within the Countermeasure Area or Designated Waste (the Act on Special Measures, article 20)

Specified Waste
Waste in the Countermeasure Area
(Former Restricted Area, Deliberate
Evacuation Area)

Designated Waste(over 8,000Bq/kg)

Recyclable
Waste

Soil and Waste Generated from
Decontamination Work

Incineration
Combustibles

Incineration

Combustibles

Incinerated ash,etc.

e.g. disaster waste, rubbish after
cleaning homes up, paddy straw,
etc.
RecycleTemporary Storage site

Less than or equal
100,000Bq/kg

Over 100,000Bq/kg
Volume Reduction,etc.

Existing Controlled Landfill Site
(Regarding Specified Waste, utilization of FUKUSHIMAECOTECH is in the process)Interim Storage Facilities

to Final Disposal
Note) Waste other than specified waste less than or equal
8,000Bq/kg is subject to the Waste Management and Public
Cleaning Act (Certain part is subject to the Act on Special
Measures)Note) At the discussion about the plan of the Interim Storage
Facilities, amount of soil and waste which is difficult toestimate at the present such as an amount generated
from follow-up decontamination is also taken into
consideration.

Figure 3-1 Treatment flow of specified and other wastes produced in decontamination(Fukushima Prefecture)80.
80Source: Ministry of the Environment (MOE), “Basic Philosophy on Interim Storage and Other Facilities

161

ForestFarmland

Building

Park,etc.

①Start of Full-fledged②Storage in Temporary Storage site

Earth moundSandbags

Secured by Local Government orcommunity respectively※ except in case of temporary storage on site

③Storage in Interim Storage Facility(less than 30 years)

Only in Fukushima Prefecture(No carry-on from the outside the prefecture)

Waiting for construction

Under construction

建設中

Receiving delivery

Delivery completed

After delivery

搬入中④Final Disposal :Disposal out of Fukushima

Figure 3-2

Treatment of soil and wastes produced in decontamination (Fukushima
Prefecture).

Required for the Handling of the Environmental Pollution from Radioactive Materials Associated with theAccident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company” (October 29,2011). Figure 3-3 and Figure 3-3 are generated from the same source.

162Specified Waste
Designated Waste(over 8,000Bq/kg)

Stored at generated site (water
treatment plant, incineration
plant, farm house, etc.)

Soil and Waste Generated from
Decontamination Work
Incineration

Combustibles

Volume Reduction(Incineration, etc.)

Incinerated ash,etc.

Incinerated ash,etc.(*)

e.g. Sewage sludge, ricestraw, compost, etc.

Temporary
Storage Facilities(On-site Storage)

Soil

Waste(*)

5 prefectures: Miyagi, Ibaraki,
Tochigi, Gunma, Chiba

Note) For 5 prefectures(Miyagi, Ibaraki, Tochigi,
Gunma, Chiba)where designated waste
storage is pressing, the government hasplanned to newly establish treatment
facility in each

Combustibles

Other than 5 prefectures of
Miyagi, Ibaraki, Tochigi,
Gunma, Chiba

Disposal Facility (Isolated Type)

Disposal Standard
Pending(*)Decontamination waste inradioactive cesium concentration
exceeding 8,000Bq/kg will be
designated and treated as
designated waste.

Existing Disposal Site

Note) The national government will conduct monitoring after the
disposal of designated waste

Figure 3-3

Treatment flow of specified and other wastes produced in decontamination(areas outside Fukushima Prefecture).

3.1.2. Configurations of Temporary Storage Sites
Facility configurations, their management, and other conditions necessary for temporary storage sites toquickly begin decontamination work are specified in the “Guidelines Pertaining to the Storage of Removed
Soil” as shown in Chapter 2.4 of this Decontamination Report (the “report” in this document).
However, most of the descriptions in the Guidelines are relevant to the prevention of effects fromradioactive materials on human health and the living environment. In the installation of a temporary site,
there are other conditions required, too, such as fire prevention measures.
Basic configurations of temporary storage sites are shown below in more detail, using the classifications
for the wastes to be stored in the temporary storage sites.

（1） Storage of combustibles
Combustibles such as naturally fallen leaves and branches, and intentionally cut branches, etc. generategases by their decomposition and when accumulated, that might lead to a fire. Therefore, they should becovered with gas- and air-permeable waterproof sheets or the like and gas venting pipes should be provided.
Storage conditions of wastes should be checked regularly, and if white smoke or steam, etc. is noticed,
appropriate management measures should be taken by, for instance, measuring the interior temperatures of
the accumulated wastes (Figure 3-4).

（2） Storage of non-combustibles like soil
Non-combustibles like removed soil may be stored after being covered with waterproof (seepage control)
sheets, since they do not generate gases during storage (Figure 3-5).

163

Basic Structure

Thermometer
Breathable Waterproof Sheet
Sandbags for shielding
Degassing pipe (mountain sand, etc.)

Large sandbags for shielding(mountain sand, etc.)

Fence, etc.

Flexible container, Large
sandbag, etc.(Removed
waste : around 1m3)

enough distance
Sandbags, etc.

enough distance
Sandbags, etc. Fence, etc.

Rainwater
Drainage

Drainageslope

Hole for Monitoring
Groundwater

Drain pipe forcollected water

Drainage slope dependingon site condition

Rainwater
Drainage

Drainageslope

Seepagecontrol sheet

Protective layer(supplemental water
Leveling of collection layer)
groundWater Collecting
Tank(as needed)

Groundwater

Figure 3-4 Basic configuration of a temporary storage site above ground for combustibles removed in decontamination work81.

Basic Structure

Breathable Waterproof Sheet

Large sandbags for shielding(mountain sand, etc.)

Fence, etc.

Sandbags for shielding(mountain sand, etc.)

Flexible container, Large
sandbag, etc.(Removed
waste : around 1m3)

enough distance
Sandbags, etc.

enough distance
Sandbags, etc. Fence, etc.

Drainageslope

Rainwater
Drainage
Hole for Monitoring
Groundwater

Drainageslope

Seepagecontrol sheet
Drain pipe forcollected water

Drainage slope dependingon site condition

Protective layer(supplemental water
Leveling of collection layer)
groundRainwater
Drainage
Water Collecting
Tank(as needed)

Groundwater

Figure 3-5 Basic configuration of a temporary storage site above ground for non-combustibles removed in decontamination work.

81Source: Decontamination Information Site (http://josen.env.go.jp/soil/temporary_place.html). Figure 3-5 has the same source.

1643.1.3. Examples of Temporary Storage Sites
Some examples of temporary storage sites cited from the “Temporary Storage Site Installation
Casebook" (August, 2013), which was compiled by the Division of Fukushima Prefecture Decontamination
Measures, are presented here.
As given in Table 3-1, the above-mentioned document gives ten examples of temporary storage sites,
two examples of air dose rate measurements, and an example of a field observation tour to a temporarystorage site.
Figures 3-6 to 3-10 show examples of temporary storage sites located in a swimming pool, a forest, an
abandoned quarry, the vicinity of a condominium, and a dry field.
Table 3-1 Examples collected in the “Temporary Storage Sites Casebook"82
Content

ExampleExamples of installationi) Public facility (Pool) (Koori town)ii) Paddy field (Yugawa village)iii) Plowed field (Kawamata town, Ten-ei village)iv) Forest (Miharu town, Tamakawa village)v) Residents area neighborhood (Koori town, Date city)vi) Land adjacent to paddy field and orchard (Date city)vii) Utilization of mountain sand collection place ruins (Date city)

Measurement of air dosei) Housing development neighborhood (Koori town)

rateii) Plowed field (Kawamata town)

Field inspection party of

Field inspection party of temporary storage site for Ono town inhabitants

temporary storage site

(Kawamata town)

82 Source:

Division of Fukushima Prefecture Decontamination Measures, “Temporary Storage Site
Installation Examples" (August, 2013). (Figure 3-6 to Figure 3-10 are generated from the same source.)165

（1） A temporary storage site using a swimming pool
【 Before installation 】【 After installation 】

Area, etc.
Waste to bedelivered
Form of facility
Storage Capacity

Approx. 2,500m2 (municipal ownership place)
Removed soil and vegetation generated by decontamination of
educational facilities
Semi-underground facility
Approx. 1,100m3 (using weather resistance large sandbags)

Status ofmanagement○Air dose rate (measuring daily (week day))[before delivery] 0.47μSv/h(2012.5)[after delivery] 0.28μSv/h(2013.7)○Radioactivity concentration of the groundwater (measuring
weekly)[Before delivery] N.D.(2012.5)[After delivery] N.D.(2013.7)○Radioactivity concentration of the leachate(measuring when the leachate is discovered)
The facility has been installed with the public pool which was
not used in an earthquake disaster.
It is approx. 30 meters to the most recent residential house.

Location of
installation

Prefecturalroad

Temporarystorage site
(Former swimming pool)

Figure3-6 A temporary storage site using a swimming pool.

（2） A temporary storage site in a forest【 Before installation 】【 After installation 】

Area, etc.

4,683m2 (national forest)

Wastes to bedeliveredRemoved soil and fallen leaves generated by decontaminationof school and school route, etc.

Form of Facility
Storage Capacity

Above ground facility
Approx. 1,788m3 (using flexible container)

Status ofmanagement○Air dose rate (measuring weekly)[Before delivery] 0.26μSv/h(2012.11)[After delivery] 0.14μSv/h(2013.5)○Radioactivity concentration of the groundwater (measuringmonthly)[Before delivery] N.D.(2013.5)[After delivery] N.D.(2013.6)○Radioactivity concentration of the leachate(measuring when the leachate is discovered)

Location of
installation

Temporary storage site

The national forest has been developed for the installation of
temporary storage site. A swamp flows near. (approx. 10 meters
to the swamp )It is approximately 500 meters to the most recent residential
house.

Figure 3-7 A temporary storage site in a forest.

166

Shrine（3） A temporary storage site in an abandoned place digging out sand in a mountain【 Before installation 】【 After installation 】【 Temporary storage site inside 】

Area, etc.

9,894m2 (private land)

Wastes to bedeliveredRemoved soil and vegetation generated by decontamination ofresidential houses and roads

Form of Facility
Storage Capacity

Above ground facility
3,303m3
Breakdown : Combustibles:552m3 Incombustibles:2,751m3(using
flexible container)(city ordering)○Air dose rate (measuring weekly)[Before delivery] 0.33μSv/h(2013.1)[After delivery] 0.57μSv/h(2013.8)○Radioactivity concentration of on-site pond water (measuringmonthly)[Before delivery] N.D.(2012.12)[After delivery] N.D.(2013.8)○Radioactivity concentration of the leachate(measuring when the leachate is discovered)

Status ofmanagement

Figure 3-8 A temporary storage site in an abandoned place digging out sand in a mountain.

167

（4） A temporary storage site near a residential area⑤-1 Residents Area Neighborhood (Koori town)[After installation][Before installation]

Approx. 900m2 (Municipal ownership place)
Removed soil and vegetation generated bydecontamination of residential house
Semi-underground facility
750m3 (using flexible container)○Air dose rate (measuring daily (week day))[Before delivery] 0.62μSv/h(2012.11)[After delivery] 0.26μSv/h(2013.6)○Radioactivity concentration of the groundwater(measuring monthly)[Before delivery] N.D.(2012.11)[After delivery] N.D.(2013.6)○Radioactivity concentration of the leachate(measuring when the leachate is discovered)

Location of
installation

The temporary storage site has been installed using
Green belt between residential area andrailway(Tohoku Main Line) .
It is approximately 10 meters to the most recent
residential house.

The JR Shinkansen

JR Toholu
Main Line

Temporary storage site

Air dose rate (μSv/h)Area, etc.
Wastes to bedelivered
Form of Facility
Storage Capacity
Status ofmanagement

Air dose rate (μSv/h)

Figure 3-9 A temporary storage site in the vicinity of a condominium.

168

（5） A temporary storage site in a dry field[Before installation]

Area, etc.
Wastes to bedelivered
Form of Facility
Storage
Capacity

Status ofmanagement

20,331m2 (private land)
Removed soil,etc. generated by decontamination of residential
house and road,etc.
Above ground facility
Approx. 5,350m3 (using weather resistance large sandbags)○Air dose rate (measuring weekly)[Before delivered] 0.33μSv/h(2012.10)[After delivered] 0.25μSv/h(2013.6)○Radioactivity concentration of the swamp water (measuringmonthly)[After delivered] N.D.(2013.6)* Because water level under the ground is low and specimen
can not be gathered, the swamp water is measured.
○Radioactivity concentration of the leachate(measuring when the leachate is discovered)Mulberry field has been developed for the installation of
temporary storage site.
It is approximately 200 meters to the most recent residential
house.

Ukanizawa

Ootsunaki

Temporary storage site

Air dose rate (μSv/h)

Location of
installation[After installation]

Air dose rate (μSv/h)* Measuring air dose rate at the plural points in the temporary storage site
* Reason why the air dose rate decreased during January to March is considered to be the effectof shielding by snow.

Figure 3-10 A temporary storage site in a dry field.

169

3.2. Wastewater Treatment
3.2.1. Notes of Caution for Wastewater Treatment
Water is used in high-pressure water cleaning of roofs, roads and the like for decontamination as well as
possibly in the cleaning of tools used for decontamination.
Wastewater used in these tasks must be treated appropriately, as it might have been contaminated byradioactive materials. However, most radioactive cesium is in a form that is strongly adsorbed on soil
particles, and hardly any of it will dissolve into the wastewater. Therefore, the central element ofwastewater treatment is to remove fine soil particles contained in the wastewater.

（1） Necessity of wastewater collection and treatment
The “Guidelines Pertaining to Decontamination and Other Measures,“ mentioned in Chapter 2.2 of thisreport specifies that no wastewater treatment is essentially needed in cases where soil sediments are
removed in the decontamination work in decontamination areas (areas subject to the decontamination plansestablished by relevant municipalities).
However, in principle, wastewater should be treated in situations where the wastewater is highly turbidor the wastewater has been collected from high-pressure water washing with vacuum collection of water.

（2） Notes of caution for decontamination of water used for washing
When decontaminating using water, the sequence of decontamination should be determined as shown
below with consideration of water transfer (Chapter 2.2). The wastewater discharge channels should bechecked, the wastewater flow should be dammed up using sandbags and the like as needed to allow finesoil particles contained in it to settle and be collected. Then the supernatant liquid may be discharged(Figure 3-11). Actual scenes and methods of wastewater treatment are shown in Figure 3-12 and Figure3-13. Figure 3-14 shows an example of high-pressure water cleaning equipment with vacuum collection ofwater.
In Fukushima City and other municipalities, there have been examples of formulating decontaminationplans, as seen in Figure 3-15, in consideration of local rainwater and surface water flows, when planningthe decontamination works..

Figure 3-11

Treatment of wastewater used in washing (including sedimentation alreadypresent in the street drains)83.

83Source: Ministry of the Environment (MOE) “Guidelines pertaining to decontamination and othermeasures“ (2nd Edition (amended in December 2014)),
http://josen.env.go.jp/material/pdf/josen-gl02_ver2_supplement1412.pdf),

170

Figure 3-12 Treatment of wastewater used in washing (Kawauchi Village)84

8. Treatment of wastewater from cleaning
Cleaning is essential in the house decontamination, but it is difficult to recover all the wastewater. The
measures such as follows are taken on the site.
①Minimizing use of water with water for the last finish, in advance removing moss, soil, and the like withradioactive materials by hand which deposit on roof, rainwater guttering, etc., then absolutely decreasing
migration of radioactive materials into cleaning water.
(The past 19 times measurement results of wastewater from cleaning: approx. 36Bq/l on average)②Reducing a outflow of radioactive materials to lower basin by installing “filtering device” using zeolite instreet drains to which wastewater is channeled. However, this method requires the establishment of storage
area like temporary storage site, etc. for sedimented soil and spent zeolite.
(The past 19 times measurement results of wastewater from cleaning: approx. 10Bq/l on average after
filtration, resulting in average reduction rate of 73%)
<Example of “Filtering Device” using street drains>
・Because radioactive cesium is almost adhered to soil, “Filtering Device” as shown in the rough sketch below
shall be installed so that muddy water in wastewater does not flow out to lower basin, sedimented soil.
・Very small amount of radioactive cesium contained in supernatant liquid shall be adsorbed to zeolite, etc.
upstream

upstream

downstream

Street drains

Sandbag Sedimented soils, etc.
adsorbing cesium, etc.
Zeolite, etc.
Sandbag

downstream

Example of construction

Figure 3-13 Treatment of wastewater used in washing (Fukushima Prefecture)85.

84Source: Kawauchi Village (October 1, 2013), Decontamination and dose control for villagers to return fromfull evacuation
85Source: Fukushima City (January 2013), Decontamination status in Fukushima City, Fukushima City
(January 2013)

171

Work Summary:Using a unique cleaning effect of the high pressure warm water and thecapture effect of the polyionized water, radiological scattering isprevented and decontamination water is recovered with a suction unit at
the same time.
Work Flow:
Cleaning water is transferred to the cavitation vehicle from the water
truck, polyionized, and then transferred to the cleaner.
High pressure cleaning with the polyionized water from a nozzle (twoplaces) in the cleaner is implemented. Cleaning work is performed
without discharging decontamination water into the neighborhood bysucking it from the outer periphery of the cleaner with the suction unit of
the vacuum suction vehicle at the same time. The recovered
decontamination water has radioactive materials removed bycoagulating sedimentation.

Guide
Water Truck

Cavitation Vehicle

Vacuum Suction
VehicleSucking decontaminationwater from the outer
periphery of the cleaner

WorkerCleaner

Guide

Cleaning is done by jetting polyionizedwater at high pressure from two places
while turning a nozzle.

Figure 3-14

Decontamination of roads by high-pressure washing with vacuum collection of
the water used (Kawauchi Village)86.

Oyama Decontamination Plan

Western District Division and Sequence

Eastern
DistrictFigure 3-15

Decontamination plan taking water channels into account (Arrows indicate
water flow lines)87.

86Source: Kawauchi Village (October 1, 2013), Decontamination and dose control for villagers to return fromfull evacuation

87Source: Fukushima City (January 2013), Decontamination status in Fukushima City

172

3.3. Volume Reduction
3.3.1. Necessity of Volume Reduction
Wastes contaminated with radioactive materials and secondary wastes from decontamination works areproduced in large quantities. Therefore, volume reduction is essential in the process of treatment anddisposal of those wastes, in order to reduce the total amount of waste produced and to secure the storagesites. Combustible wastes contaminated with radioactive materials need to be stabilized to prevent theirdecomposition and emission of unpleasant odors. Intermediate treatment by incineration and other means
can reduce the disposal volume to around one-twentieth to one-fifth of the original volume.

3.3.2. Volume Reduction Methods
There are many volume reduction methods from physical processes such as simple compression andcrushing to chemical processes such as incineration and melting. Characteristics of each method aresummarized in Table 3.2.
Table 3-2 Comparison of volume reduction methods88
MethodVolumeDecontamination
reduction
Workability
effecteffectVolumereduction
rate (%)

Measures

Secondary
waste

Effluent gas

much

Effluent gas

much

Effluent gas

littleMelting

○

○

△

～99

High
Temperature
Incineration
Low
Temperature
Incineration

○

○

△

～90

Drying

△

×

○

5～30

---

none

Cleaning

△

△

○

5～10

Wastewater

much

Classification

〇

△

△

10～90

Wastewater

littleCompression

△

×

○

20～50

---

none

Shredding

△

×

△

～50

Dust

little

○

△

○

50～80

Each method of volume reduction is outlined below, being cited from the “Report on the surveys ofoff-site emergency responses associated with the accident at the Fukushima Daiichi Nuclear Power Stationand the environmental restoration activities88.”（1） Melting method
The melting method reduces the volume of solid wastes by elevating their temperatures by means ofplasma heating and other means up to super high temperatures (above 1,200 °C) and produces stable
molten slag, while achieving a high decontamination effect by volatilizing most of the cesium including
radioactive cesium(hereinafter referred to as ”cesium”) present. But, while the melting method volatilizes
even silicic acids and other substances, treatment of a large quantity of secondary gaseous wastes becomes
88Source: Atomic Energy Society of Japan (December 2, 2013), Report on the surveys of off-site emergency

responses associated with the accident at the Fukushima Daiichi Nuclear Power Station and theenvironmental restoration activities. (Table 3-3 has the same source.)

173

necessary. It is not practical to apply this method to the treatment of large quantities of contaminated wastes,in view of the work conditions at super high temperatures and the cost of fuel to melt the wastes.

（2） High temperature incineration
The high temperature incineration method reduces the volume of contaminated wastes by burning them(using heavy oil and other fuel) at temperatures up to around 1,000 °C in the air, volatilizing containedwater and volatile oxides. Cesium volatilization is limited, but some cesium could be scattered andcontaminate the upper part of incinerator or other parts depending on combustion temperatures andconditions. This method is well established and is able to treat massive wastes.

（3） Low temperature incineration
The low temperature incineration method burns wood and other materials in a reducing atmosphere of
600 to 800 °C, and then carbonizes the cinders for volume reduction. By volatizing carbon and hydrogencontents in the wastes, the volume reduction rate reaches around 90%, and no secondary wastes areproduced because cesium volatilization is restrained. But, on the other hand, the cesium concentration in
the residue becomes higher. This makes it necessary to give special consideration to the handling andstorage methods depending on the concentrations of radioactive materials when radioactivity exceeds 8,000
Bq/kg, although the volume of wastes to be handled is decreased.

（4） Drying
Drying is carried out by heating wastes at the ambient temperature or below 100 °C. Big weight andvolume reductions are achieved in the case of watery sludge. Trees and vegetation materials can be reducedin volume by drying to some extent, and no further secondary treatment is needed regarding decompositionand other undesirable changes.

（5） Washing
The washing method aims at reducing the volume of contaminated wastes by: dissolving the soluble
materials by high-pressure water washing or immersing into water; separating fine particles from larger
solids by suspending the fine particles in the water; and collecting the solids by solid/liquid separation suchas filtration or other means. In this method radioactive cesium is dissolved into water and fine particles
with adsorbed cesium are separated. The target objects can be decontaminated, but the water content of thewaste collected is high and a secondary treatment is needed for volume reduction by drying and othermeans. Furthermore, the liquid collected contains a high concentration of cesium and also needs asecondary treatment for sorption and separation of the cesium.

（6） Classification
Classification is a method to separate and fractionate fine particles such as clay, to which cesium adheres,by sieves, and to reduce the volume of contaminated soil. There are two types of classification methods: thewet method uses a difference in sedimentation order in the water and the dry method uses sieving. The wetmethod gives effective separation, but the amount of secondary waste such as contaminated water increases.
In contrast, the dry method is advantageous in producing no secondary waste, although it is a roughseparation process. If a predetermined radioactivity decontamination effect is obtained in the separation by
the particle size, the dry method is effective as a pretreatment method.

（7） Compression
The compression method is a method to reduce the volume by compressing contaminated wastes having
174low bulk densities with a press machine and other means. Because none of the radioactive materials aretransferred, after being processed the wastes contain a higher density of radioactivity per unit volume.
Therefore, it becomes necessary to give consideration to the handling and storage methods. This method iseffective for application to contaminated wastes such as wood, trees and plant materials.

（8） Crushing
The crushing method is applied to contaminated wastes having shapes of a rectangle, circle or the like.
The size of such contaminated wastes is reduced by crushing and densification, and thus the space forwaste storage is reduced. No decontamination effect is obtained, since radioactive materials are nottransferred by the crushing method. It is necessary to be careful not to disperse fine particles whencrushing.
It should be noted that there are diverse wastes produced by radioactive contamination, and bydecontamination, too. Therefore, suitability of individual methods of volume reduction depends on thetarget wastes for application. As shown in Table 3-3, there are cases in which sufficient effects cannot be
obtained in volume reduction.
Table 3-3 Applicability of volume reduction methods for selected target items
ObjectVolumeWeight loss
CesiumRadioactivity
Volumereduction
movement
reduction
methodeffectSoil
Meltingyes
yes
decrease
large

Wood

Grass,
straw

Rice

Concrete
SludgeIncineration

yes

no

increaselarge

Cleaning

yes

yes

decreasesmallClassification

yes

yes

decrease

mediumIncineration

yes

no

increaselarge

Low Temp.
Incineration
Cleaning

yesnoincrease

mediumyes

yesdecrease

small

Compressionnonoalmost same

mediumIncineration

yes

no

increaselarge

Low Temp.
Combustion
Cleaning

yesnoincrease

mediumyes

yesdecrease

small

Compressionnonoincrease

large

Compressionnonoalmost same

small

Shreddingnonoalmost same

mediumDryingyesnoincrease

mediumCleaning

yes

yes

decrease

small

3.3.3. Examples of Volume Reduction
A few examples of ongoing volume reduction activities of wastes are shown below.

（1） Crushing
Cut branches produced from the forest decontamination are bulky and need much space if they are
packed as they are and they produce many waste containers. Therefore, a crushing facility can be used to175crush cut branches for more effective packing in flexible containers. An example is practiced in Katsurao
Village and other municipalities.

Nogawa district

Figure 3-16 Branches cut down (left) in forest decontamination and a crushing facility(right)89.

Flexible container filling
Shredding

Injection

Accumulation of combustibles

Figure 3-17

Interior views of a crushing facility: collection (left), putting in and crushing(center), and packing into flexible containers (right).

（2） Chipping
The volume of contaminated wastes produced from decontamination work, such as branches and leaves,
can be reduced by crushing into chips. Then, they can be stored more effectively in the temporary storagesite of limited space. This method is being practiced in Date City and other municipalities.

89Source: Okumura-gumi Corporation (Figure 3-17 has the same source.)

176

Figure 3-18 Before (left) and after (right) chipping90.

Figure 3-19 Chipping machine.

（3） Compression / Packaging
Examples (1) and (2) above are intended to reduce the volume of wastes by crushing so that the materials
become more tightly packed. There is another example of volume reduction by suction compression asshown below.
In this example, the volume is reduced by suction compression using compression storage bags. If
ordinary packing bags are used, the suction openings tend to become clogged with leaves or the bags
become torn by branches, but these difficulties can be overcome by using a special nozzle and a special
compression storage bag, enabling the volume to be reduced to 1/3 to 1/2 of the original volume for
combustibles such as fallen leaves, branches with leaves, grasses, etc.
The compression storage bags have an added odor killing function that controls odors from the
combustibles arising around the temporary storage sites.

90Source: Division of Fukushima Prefecture Decontamination Measures (May 17, 2013), Decontamination

Good Practices Casebook (Figure 3-19 has the same source.)

177

Figure 3-20 Before (left) and after (right) compression91.

91Source: Taisei Corporation homepage(http://www.taisei.co.jp/about_us/release/2013/1353289519671.html)

178

4． Management of decontamination projects
4.1. Flow of the Decontamination Process
The basic flow of the decontamination process is shown in Figure 4-1.
Targets for decontamination extend over a wide range, including soil, houses, roads, fields
and forests (only within living spaces). Decontamination was first focused on buildings andresidential areas necessary for the protection of human health. Therefore, the first thing to do
was to investigate ownership of land plots and buildings.
The next things to do were to measure radiation dose and to survey the state of buildings
and other structures in advance of the decontamination work, because the attachment
conditions of radioactive substances differ depending on the material to which they areattached. Based on the investigation results, decontamination plans were prepared for eachland plot and building that would ensure the most effective methods would be used.
The decontamination work was moved forward by getting the understanding of land andbuilding owners for field surveys, their confirmation of decontamination methods, and finally
their consent for conducting the decontamination work. More specifically, their consent toenter the land was obtained, the decontamination plans were explained (to obtain the consent
to conduct the decontamination work and to report on commencement), and the results of thedecontamination work and other related things were reported.
After the completion of the decontamination work, the effectiveness of the decontamination
was checked, and this monitoring was continued to check that the radiation dose has been
sufficiently reduced allowing the residents to return.

Flow of decontamination process
Survey of land and buildings(consent of landowners, etc.>)

Interaction
with client
Consent of accessto the site

Pre-project radiation monitoring andsurvey of state of buildings etc.
Creation of decontamination plans for eachland/building

Decontamination work

Opinions on
decontamination,
notice ofcommencement

Post-project radiation monitoring
Report of results
Completion, ongoing monitoring

Figure 4-1 Flow of decontamination process92.

92Source: Decontamination Information(http://josen.env.go.jp/about/method_necessity/method_area.html)

179

4.2. Contents of Decontamination Work
This section describes the specific contents actually implemented by the Ministry of theEnvironment (MOE) and decontamination business operators for decontamination andrelated works in the Special Decontamination Areas as ordered by the MOE.
(1) Knowing the air dose rates by detailed monitoring(2) Issuing of decontamination work orders and related matters by the ordering party(MOE)(3) Implementing decontamination work by decontamination business operators(4) Securing necessary resources by decontamination business operators

4.2.1. Knowing the Air Dose Rates by Detailed Monitoring
The MOE carried out extensive monitoring between November 2011 and April 2012 in orderto produce detailed air dose rate distribution charts and to prepare for formulating
decontamination plans focusing on residential areas in the area that were subject todecontamination work by the national government (Special Decontamination Areas) underthe Act on Special Measures Concerning the Handling of Environmental Pollution byRadioactive Materials Discharged by the Nuclear Power Station Accident Associated with the
Tohoku District Off the Pacific Ocean Earthquake That Occurred on 11 March, 2011 (“Act on
Special Measures” in this report).

（1） Summary of implementation
The monitoring program was implemented under the direction and supervision of the MOE.
The monitoring was carried out by the Japan Atomic Energy Agency (JAEA) mobile
monitoring vehicles and drone helicopters, and by Tokyo Electric Power Co., Inc. (TEPCO)
employees making hand-carry measurements over a 100 m grid as well as using mobile
monitoring vehicles (TEPCO cooperated at the request of the MOE on these extensive
monitoring activities), in the restricted area and the deliberate evacuation area where the air
dose rates were 20 mSv and 50 mSv per year, respectively, as well as areas where the air dose
rates were lower (1 mSv, 5 mSv and 10 mSv per year).
More specifically, based on the monitoring data in the restricted area and deliberate
evacuation areas published by the Cabinet Office and the Ministry of Education, Culture,
Sports, Science and Technology (MEXT), the areas for detailed monitoring were selected on a
2 km x 2 km grid in each area corresponding to respective radiation dose ranges.
Consideration was given to the distribution of residential areas in determining the extent ofareas for detailed monitoring. Each section of 2 km x 2 km was then in principle zoned in a
100 m meshed grid, in order to gain a more extensive understanding of the air dose rate
distribution.
Eleven municipalities were monitored: Tamura City, Minamisoma City, Kawamata Town,
Naraha Town, Tomioka Town, Kawauchi Village, Okuma Town, Futaba City, Namie Town,
Katsurao Village and Iitate Village.

180

Area

Table 4-1 Summary of detailed monitoring93
Implementation period

MethodNeighboring regionof 50mSv per year

Dec. 15, 2011 to Dec. 21
Jan. 6, 2012 to Jan. 16

Monitoring by monitoring car
and measuring personnel

Neighboring regionof 20mSv per year

Nov. 7, 2011 to Nov. 24

Monitoring by monitoring car
and monitoring personnel

Neighboring regionof 10mSv per year

Feb. 17, 2012 to Feb. 28
Apr. 6, 2012 to Apr. 12

Monitoring by monitoring car
and monitoring personnel

Neighboring regionof 5mSv per year
Neighboring regionof 1mSv per year

Jan. 6, 2012 to Mar. 3

Monitoringbyunmannedhelicopter
Monitoring by monitoring car

Feb. 17, 2012 to Feb. 28（2） Measurement methods
In order to efficiently understand the radiation data at each point of the 100 m mesh grid,
while using existing data, additional data were collected by monitoring vehicles(measurement instruments were mounted on cars), aerial monitoring (measurement
instruments were mounted on drone helicopters) and persons walking through areas withhand-carry instruments.
The basic policy followed in selecting monitoring methods was to use mobile monitoringvehicles for the urban and residential areas and suburban roads, and to use drone helicoptersor rely on persons walking for schools, parks and fields with no roads.

（3） Results of detailed monitoring
Detailed monitoring clarified the distributions of air dose rates, mainly in residential areas,
and they were classified into three ranges: below 20 mSv per year (3.8 μSv/h), between 20 and
50 mSv per year (9.5 μSv/h), and above 50mSv per year.

93Source: Decontamination Information(http://josen.env.go.jp/about/method_necessity/method_area_monitoring.html )181

Figure 4-2 General map of the detailed monitoring results94.

94Source: Decontamination Information (http://josen.env.go.jp/area/pdf/monitaring_zentai_final.pdf)

1824.2.2. Decontamination Work Ordered by the Ordering Party (MOE)
Decontamination and related works in the Special Decontamination Areas ordered by the
MOE followed the government procurement procedures, as in ordinary public works projects:
relevant public notices were issued for procurement based on the specifications,decontamination business operators were selected and the orders were issued. Since many of
the individual activities of decontamination work were similar to those in ordinary public
works projects, the ordering framework for ordinary public works was applied with
supplementary additions of matters specific to decontamination work.
The MOE presented common specifications for decontamination and related works for theSpecial Decontamination Areas (hereafter “Common Specifications”), and formulated common
decontamination work specifications to ensure that the details of work agreements and design
documents were interpreted and implemented in a uniform manner, and that, by setting out
other necessary matters, the agreements were properly executed. In addition, special
specifications setting out specific technical requirements (hereafter “Special Specifications”)
were formulated on an individual project basis for the actual conditions of the area or site
subject to decontamination, and individual decontamination projects were carried out basedon these Common Specifications and Special Specifications.
It would have taken a long time to commence decontamination projects upon acquisition ofconsent to the decontamination works and the decontamination methods for each object to be
decontaminated from the stakeholders such as land owners, as is practiced in ordinary public
works projects. Therefore, the MOE placed an order for decontamination and related works in
the Special Decontamination Areas before fixing everything. By using the prior survey results,
the order was made based on the estimated decontamination area sizes and number ofdecontamination target buildings for each type of target object and decontamination method.
The quotes could be fixed after the decontamination methods for each target object were fixed
and the decontamination area sizes as well as the number of buildings to decontaminate were
fixed in the actual project operation. The MOE and decontamination business operatorsconcluded an agreement to adopt a method of calculating payments based on work unit prices
and the actual volume of work completed. For the actual operation, the MOE formulated
provisional estimation standards of decontamination and related works in the Special
Decontamination Areas (hereafter “Provisional Estimation Standards”), in which the unit
prices for the work are defined in advance.
The following shows the Common Specifications, Special Specifications, Provisional
Estimation Standards, and ordering system and procedures for decontamination and related
works in the Special Decontamination Areas as ordered by the MOE.

1）Common Specifications
The Common Specifications describe general parts of technical requirements and work
contents which are needed in implementing the work such as the work sequence, qualities ofmaterials to be used, quantities, finished qualities, work methods, etc.
The MOE developed the Common Specifications by incorporating new decontamination
work methods based on work experiences and the latest version of the Common Specifications(7th Edition) was issued in April 2014.
Tables 4-2 to 4-6 list the contents of Chapters 1 to 5 of the Common Specifications (7thEdition).

183

Table 4-2 Contents of “Chapter 1 General Provisions” in the Common Specifications (7thEdition)95
SectionParagraph
1-1-1 Application
Section 1 General Items
1-1-2 Definition of terms
1-1-3 Works on Special Decontamination Areas
1-1-4 Radiation work leader, operation leader
1-1-5 Check with design document
1-1-6 Breakdown of contract
1-1-7 Schedule
1-1-8 Implementing plan
1-1-9 Registelation of work performance information
1-1-10 Supervision personnel
1-1-11 Commissioned supervisor
1-1-12 Usage of work land, etc.
1-1-13 Start of work
1-1-14 Subcontract of work
1-1-15 Ledger of working structure
1-1-16 Cooperation of mutual contractor
1-1-17 Cooperation for investigation and test
1-1-18 Temporary halt of work
1-1-19 Revision of schedule
1-1-20 Examination committee for design change
1-1-21 Supplied material and lent itams
1-1-22 List of decontamination worker and identification card
1-1-23 Provision of allowance
1-1-24 Entrance into land and building
1-1-25 Generated materials at construction site
1-1-26 Investigation (including confirmation) and witness bysupervision staff
1-1-27 Investigation of work completion
1-1-28 Investigations of previously finished portion
1-1-29 Technical investigation
1-1-30 Execution management
1-1-31 Performance report
1-1-32 Management of decontamination workers
1-1-33 Security during work
1-1-34 Security measurement for ionizing radiation
1-1-35 Cleanup
1-1-36 Accident report
1-1-37 Environment measurement
1-1-38 Coordination with peripheral residents
1-1-39 Care for cultural property
1-1-40 Management of traffic safety
1-1-41 Compliance for laws and regulations

Source: Decontamination Project Common Specifications (7th Edition)(http://tohoku.env.go.jp/fukushima/to_2014/data/0410ba.pdf) (Table 4-3 to Table 4-6 have the same source.)
95

184

Section

Paragraph
1-1-42 Procedures to public office
1-1-43 Revision of work duration and work time
1-1-44 Submitted document
1-1-45 Damage by inevitable force
1-1-46 Patent, etc.
1-1-47 Insurance and compensation for accident
1-1-48 Measure for specific case
1-1-49 Confidentiality obligation
1-1-50 Handling of individual information
1-1-51 Securement of information security

Table 4-3 Contents of “Chapter 2 Work materials” in the Common Specifications (7th Edition)
SectionParagraph
Section 1 Application－
Section 2 Quality and test of work material (including －confirmation)
Section 3 Work material
2-3-1 Large sandbag, etc.

Table 4-4 Contents of “Chapter 3 Decontamination” in the Common Specifications (7thEdition)SectionParagraph
Section 1 Common items
3-1-1 Test of construction
1. Residents, etc.
Section 2 Explanation of decontamination
2. School
method
3. Park (small)
4. Park (large)
5. Large facility
6. Road
7. Slope
8. Farmland
9. Grass field, Lawn
10. Orchard
11. Forest
12. Deleted
13. Temporary storage area, etc.
14. Deleted
15. Effluent processing

185

Table 4-5 Contents of “Chapter 4 Work management” in the Common Specifications (7thEdition)SectionParagraph
4-1-1 Common items
4-1-2 Radiation measurement at
measures for decontamination work
4-1-3 Security, management and transfer
of temporary storage area, etc.
4-2-1 Management of storage area after
completion of storage

Section 1 Measurement of radiation dose

Section 2 Management of temporary storage
area, etc.
Section 3 Confirmation of construction result
Section 4 Confirmation investigation

Section 5 Handling of removed soil, etc.

4-3-1 Confirmation of construction resultwith decontamination measures on
residential district
4-4-1 General rule
4-4-2 Decision of management value
4-4-3 Implementation of confirmation
investigation
4-5-1 Discretion
4-5-2 Dose measurement
4-5-3 Grant of identification number andtag, etc.
4-5-4 Development of storage ledger

Table 4-6 Contents of “Chapter 5 Reporting” in the Common Specifications (7th Edition)
SectionParagraph
5-1-1 Submittal document
Section 1 Report and submittal document
5-1-2 decontamination management
information
5-1-3 Report of decontamination result on
residential district, etc.
5-2-1 Report of decontamination result on
Section 2 Report of decontamination result toresidential district, etc. to related persons
related persos（2） Special Specifications
The Special Specifications supplement the Common Specifications and specify details or
specific technical requirements in individual decontamination tasks, considering the actual
situations of the area or site to be decontaminated. The Special Specifications were presented
as a supplement to the Common Specifications with specific notes in the procurement forindividual decontamination tasks.

（3） Provisional Estimation Standards
The Provisional Estimation Standards was developed for estimating costs fordecontamination and related works in the Special Decontamination Areas ordered by the
MOE. The Provisional Estimation Standards may be excluded from application, when theirapplication is extremely inadequate or difficult because of diverse conditions of the site or thenatural environment.
186

Estimation

The Provisional Estimation Standards specify materials and equipment needed, workload,
unit prices of machinery, workforces, expenses, etc. required for implementing thedecontamination and related works. The construction cost can be calculated based on these
specifications.
The first edition was developed in May 2012. Thereafter the Provisional Estimation
Standards were revised to match the actual site situations based on experiences indecontamination projects, e.g., incorporating new work methods. In April 2014, the 7th Edition
was put into effect (Provisional Estimation Standards (7th Edition)).

Site investigation

Investigation of geography, geology, meteorology, water quality, powered
water supply, traffic condition, circumstances, existing structure(underground buried object), site material at construction site

Development ofdesign drawing

Development of basic design drawing and various structure drawing, such asplan chart, cross section drawing, lateral profile, and standard scale drawing

Quantity calculation

Calculation of soil volume, calculation of material, etc. calculation of
structure

Development ofconstruction plan

Selection of construction method, setting of construction term, selection of
construction machinery type, standard and machine combination, selection of
temporary work and machine

Development ofspecial note
specification

Especially necessary items which are not written in Common Specifications
and necessary items on contract which cannot be described on drawing

Decision of various
unit priceDecision of material unit price, labor unit price, and machinery depreciation,
etc.

Estimation of direct
construction cost

Decision of days per unit work, development of unit price list and breakdown
document estimation of direct construction cost

Development ofschedule

Decision of work sequence, estimation of working days from work amountper day, adding rainy weather, Sunday, holiday consideration, develop
schedule with network or bar-chart

Estimation ofcommon temporary
cost

Estimation of transportation cost, preparation cost, cost to prevent project loss,
safety cost, service cost, technical management cost, and maintenance cost

Estimation of site management cost
Estimation of general management cost, etc.
Audit of design
document

Comprehensive check of design document

Summary of design
document

Summary of design document, design drawing, and specification, etc.

Decision of
estimated cost

Contract officer shall decide estimated cost.

Figure 4-3 Construction cost estimation flow96.
The Provisional Estimation Standards specify workload needed for each object to be
decontaminated and the decontamination method in terms of workforce, quantities generated
for removal, and materials and equipment required per unit area for decontamination tasks.
An example of workload is shown below for the work of removing sediments from residential
area roofs and the like (other than concrete roofs). It specifies 0.50 work supervisor and 3.20
decontamination workers are required per 1,300m2 area to be decontaminated.
The workload developed in the Special Specifications by the MOE was based on two types ofresults: the results of the “decontamination model projects” performed by the JAEA
96Source: Decontamination Construction Project Management Standards in the Special Decontamination

Areas (7th Edition) (http://tohoku.env.go.jp/fukushima/to_2014/data/0410aa.pdf) (Figure 4-4 has the same
source.)187

Fukushima Technology Headquarters in JFY 2011 under consignment by the Cabinet Officefor verifying decontamination techniques required for effective decontamination in high-doseareas; and the results of independent decontamination projects performed by municipalities
in Fukushima Prefecture.
Title

Standard

Unit

QuantityWork supervisor

Person0.50

Decontamination worker

Person3.20

Summary●Labor cost●Material cost
Large sandbag

Bag

Later

●Miscellaneous cost
Miscellaneous cost%

1.0

1% of labor cost

Total
Miscellaneous cost include pitchfork, etc. and added above percentage to labor cost.

Figure 4-4 Example of workload.
(Sediment removal from a roof in a residential area (roof material other than concrete))
It is difficult to show simply the cost of decontamination work, since it is affected by various
factors such as: the size/extent of houses/land; materials of roofs and walls; extent andconditions of gardens (presence of garden trees, and others); availability of aerial lift (bucket
crane) work vehicles; necessity to install temporary scaffolds; necessity to replace gravel;necessity to decontaminate surrounding forests; transfer of removed soil and the like to thetemporary storage site, etc.
For ordinary residences, the workload per house is estimated at approximately 50
worker-days (about 10 workers working for five days)97.

（4） Ordering of decontamination and related works
For the ordering of decontamination and related works in the Special Decontamination
Areas, the MOE issued, in accordance with the government procurement procedures, a publicannouncement and notice of Common Specifications, Special Specifications, Provisional
Estimation Standards and other relevant documents and publicly advertised for technicalproposals. After reviewing the technical proposal documents, the MOE invited public bids andopened them. The decontamination business operators were selected by comprehensive
evaluation of cost points and technical evaluation points.
For the public announcement and notice, the MOE coordinated estimation unit prices todecide its estimated price as the ordering party. The unit prices were estimated based on thepast examples of public works and the results of decontamination model projects asmentioned in (3) above.
For the Intensive Contamination Survey Areas, the municipal governments developed
decontamination work plans, as mentioned in Chapter 1.1.7, and they placed an order fordecontamination and related works using the special grant for emergency work of radiation
reduction measures of the National Government as the financial resource which was provided
based on the decontamination work plans. The special grants cover decontamination methods
to be used in relatively high dose areas and in relatively low dose areas. For example: for the

97Source: “On-site explanation of decontamination plan and request for understanding of implementation fordecontamination works” (http://www.katsurao.org/uploaded/attachment/6.pdf )188

work to decontaminate a stand-alone house in a relatively high dose area, such work methods
are added as: (i) removing surface soil, covering with fresh soil, and consolidating for restoring
the gardens and the like to the original state; (ii) upturning, (iii) removing contaminated soil,
and covering with fresh soil from excavation for field storage development；or (iv) coveringwith uncontaminated soil.98

4.2.3. Decontamination Work by Decontamination Business Operators
The following is an overview of the decontamination and related works performed bydecontamination business operators for an order from the MOE to carry out decontaminationin the Special Decontamination Areas.

（1） Development of work plans
Prior to the commencement of decontamination work, decontamination business operatorsdevelop a comprehensive work plan including all necessary steps and methods to complete theproject, and submit it to the MOE supervisor.
It should be noted that this comprehensive work plan describes an overview of the work, theoverall schedule, site organizational chart, work methods (including test work methods andevaluation methods), work management plan, safety management plan (including mattersrelated to radiation protection, and methods to prevent the spread of contamination), andemergency systems and responses, etc.

（2） Development of organizational structure for implementation
1）Designation of the radiation control officer and work leaders
Decontamination business operators are required to designate a person to direct andsupervise the radiation management of decontamination workers (radiation control officer),and a person in each work unit (work group) to lead the group’s activities (work leader).
The radiation control officer is in charge of the following activities.
Conducting special education for decontamination workers based on Article 19 of the
Ionizing Radiation Ordinance for Decontamination
Instructing decontamination workers thoroughly in proper wearing of protective
clothes and equipment according to the work contents
Instructing decontamination workers in thoroughly practicing proper operation ofmachines and equipment necessary to control ionizing radiation
Inspecting in advance machines, equipment and the like which are necessary to control
ionizing radiation, and securing necessary functions and quantities
Inspecting in advance protective clothes, equipment and the like, and securing
necessary functions and quantities
Controling access of persons not engaged in the work to the site
Supervising decontamination workers in using radiation measuring instruments
Understanding the work sequence, work contents, and working environment such as
the average air dose rate at the working location, and assisting the acting site manager
and similar responsible person(s) at meeting(s) for work procedures before starting thework
Administrating properly the decontamination workers’ roster and their radiation
passbooks
Administrating the records of radiation exposure dose measurements of
98Source: Ministry of the Environment (MOE), "Radiation reduction measures special urgent projectsubsidyhandling instructions" (tentative translation)

189decontamination workers2）Preparation of rosters of decontamination workers and their identification cards
Decontamination business operators are required to prepare a roster of decontamination
workers in which a record is made for each worker before they begin the designateddecontamination work, their name, age, job title, and radiation passbook registration number.
When the decontamination workers terminate their engagement in the designated work, thedecontamination business operators remove them from the roster. Decontamination business
operators are required to check decontamination workers have or do not have their radiation
passbooks at the time they start the decontamination work. If workers have radiation
passbooks, the decontamination business operator record the registration numbers in theroster; workers who do not have the radiation passbook are required to get it by the time theyleave the designated work.
In addition, decontamination business operators are required to submit requests to the
MOE supervisor for personal identification cards for each decontamination worker, and uponreceiving the issued cards, ensure that decontamination workers always carry these cards
with them while working.

（3） Test work
Test work is carried out for the purpose of choosing the most effective decontamination
methods from candidate methods for particular target objects to be decontaminated, which
are designated by the MOE supervisor, before commencing the actual decontamination andrelated works. Once no further significant reductions can be observed in radiation dose rates,
even with repeated decontamination processes, the decontamination business operators
report this to the MOE supervisor and proceed at his/her direction.
This is due to the reality that, unless test work is carried out in actual site conditions, theoptimum parameters in decontamination work cannot be determined, for example, thenumber of steps for wiping work, the depth and speed of deep ploughing work, the water jetpressure and moving speed of high-pressure road surface cleaners, etc. Specifically, forexample, the surface dose rate can be further reduced with two wiping steps than with only
one, and further with three than with only two, but after a certain number of steps the rate ofsurface dose reduction declines. Increase of wiping steps has a disadvantage, too. A new paper
towel or rag cleaning face is used in each step of wiping. Consequently, an increase in thenumber of steps of wiping causes not only increased work time but also an increase ofmaterials and waste. In deep plowing work, the standard plowing depth is 30 cm for a gooddecontamination effect, but when the soil base is shallow, stones may be turned up in thesurface layer or water leaks from rice fields may be caused. Coordination becomes necessary
for setting the best parameter for a particular decontamination target. Also in deep plowing
work, higher moving speeds of the machinery (tilling tractors) may shorten the work time, but
this may not stir the soil enough to achieve a sufficient decontamination effect.
Test work should be implemented considering the following items.
(i) Decontamination business operators are required to prepare the test work plan andsubmit the document to the MOE supervisor; the document describes thedecontamination flow, test locations, number of test points, measurement methods(including measuring equipment), number of tests, etc. for the decontamination objects
and decontamination methods as designated by the MOE supervisor.
(ii) The decontamination flow should include several cases in which parameters possibly
affecting the decontamination rates (e.g., work time per unit area, number of tests, test
location, water pressure for high-pressure washing, and distance between the jet nozzle
and ground, etc.) are changed.
(iii) Test locations and points for the target objects to be decontaminated and methods
thereof designated by the MOE supervisor should be chosen with a good balance that190

considers the situation in the area where the decontamination measures are to be
implemented.

（4） Implementation of decontamination projects
The Common Specifications specify decontamination methods for each target object to be
decontaminated. Prior to commencing the work, decontamination business operators prepare
the comprehensive work (or construction) plans, including procedures, methods and all othernecessary items required for completion of the project, and submit them to the MOE
supervisor.
The decontamination work covers not only decontamination for reducing air dose rates in anarrow sense, but also the methods for pre-decontamination works and post-decontamination
works for restoration. For example “cleaning by road sweepers” (6.1.2.6) has the purpose ofbeing a prior preparation to decontamination work or the purpose of maintenance.
“Restoration of soil fertility” (8.1.2.7-(1) and others) for farmland can be regarded as a
post-process work (restoration to the state before contamination). On the other hand, there
are such methods as “sediment removal” (1.1.1.1 and others), which, depending on actual site
conditions, can be regarded as methods for reducing the air dose rate in a narrow sense of
decontamination, or can be also regarded as a preparatory process before “wiping” (1.1.1.2
and others) or “brush cleaning” (1.1.1.3 and others).
Table 4-7 Decontamination methods for each decontamination target 99
TargetDecontamination methods
1. Residential 1.1 Roofs,
1.1.1 Roofs (all1.1.1.1 Sediment removal
areas, etc.
rooftops
materials except 1.1.1.2 Wiping
concrete)
1.1.1.3 Brush cleaning
1.1.2 Roofs
1.1.2.1 Sediment removal(concrete)
1.1.2.2 Wiping
1.1.2.3 Brush cleaning
1.2 Walls,
1.2.1 Except
1.2.1.1 Wiping
Fencesearthen walls
1.2.1.2 Brush cleaning
1.2.2 Earthen
1.2.2.1 Wiping
walls
1.3 Gutters
1.3.1 Eave
1.3.1.1 Sediment removal
gutters
1.3.1.2 Wiping
1.3.1.3High-pressure
washing
1.3.2
1.3.2.1 High-pressure
Downspouts
washing
1.4 Gardens, 1.4.1 Unpaved
1.4.1.1 Sediment removal
etc.
surfaces
1.4.1.2 Weeding, mowing
1.4.1.3 Close mowing of
lawns
1.4.1.4 Peeling off grass andlawn top layer
1.4.1.5 Sodding
1.4.1.6 High-pressure
washing of gravel andcrushed stone
Source: Decontamination Project Common Specifications (7th Edition)(http://tohoku.env.go.jp/fukushima/to_2014/data/0410ba.pdf)
99

191

Target1.4.2 Paved
surfaces

Schoolbuildings

2.1 Roofs,
roof tops－

2.2 Walls,
fences

－2.3 Gutters2.3.1 Eave
gutters

2.4 Groundsurfaces, etc.

2.3.2
Downspouts
2.4.1 Sediment2.4.2 Grassareas, Lawns

2.4.3 Gravel,crushed stone

2.4.4 Soil

192

Decontamination methods
1.4.1.7 Removal of gravel
and crushed stone
1.4.1.8 Covering of gravel
and crushed stone
1.4.1.9 Peeling off topsoil
1.4.1.10 Covering the
ground surface
1.4.1.11 Topsoil removal intree root vicinity etc.
1.4.1.12 Pruning of garden
trees
1.4.1.13 Trimming of garden
trees
1.4.1.14 (Deleted)
1.4.1.15 Upturning soil
1.4.2.1 Sediment removal
1.4.2.2 Brush cleaning
1.4.2.3 High-pressure
washing
1.4.2.4 Peeling1.4.2.5 Abrasive material
blasting
2.1.1.1 Sediment removal
2.1.1.2 Wiping
2.1.1.3 Brush cleaning
2.1.1.4 High-pressure
washing
2.2.1.1 Wiping
2.2.1.2 Brush cleaning
2.2.1.3 High-pressure
flushing
2.3.1.1 Sediment removal
2.3.1.2 Wiping
2.3.1.3 High-pressure
washing
2.3.2.1 High-pressure
washing
2.4.1.1 Sediment removal
2.4.2.1 Weeding, Mowing
2.4.2.2 Close mowing of
lawns
2.4.2.3 Peeling off grass andlawn top layer
2.4.2.4 Sodding
2.4.3.1 High-pressure
washing of gravel andcrushed stone
2.4.3.2 Removal of gravel
and crushed stone
2.4.3.3 Covering of gravel
and crushed stone
2.4.4.1 Topsoil removal
around drain outlets, eave

Target2.4.5 Plantings

2.4.6 Paved
surfaces

3. Parks(small)2.5 Playequipment,
etc.
3.1 Roofs,
rooftops

2.5.1 Playequipment, etc.

3.2 Walls,
Fences

3.2.1 Walls,
Fences

3.3 Gutters3.3.1 Eave
gutters

3.4 Grounds,
etc.

－

3.3.2
Downspouts
3.4.1 Sediment3.4.2 Grassareas, Lawns

3.4.3 Gravel,
Crushed stone

193

Decontamination methods
gutter outlets
2.4.4.2 Peeling off topsoil
2.4.4.3 Covering of groundsurface
2.4.4.4 Upturning
2.4.5.1 Topsoil removal intree root vicinity etc.
2.4.5.2 Pruning of plantings
2.4.5.3 Trimming of trees
2.4.6.1 Sediment removal
2.4.6.2 Brush cleaning
2.4.6.3 High-pressure
washing
2.4.6.4(1)、2.4.6.4(2)Scraping
2.4.6.5 Abrasive material
blasting
2.4.6.6 Superhigh pressure
flushing
2.4.6.7 Resurfacing
2.5.1.1 Wiping, Brushcleaning, Scraping
3.1.1.1 Sediment removal
3.1.1.2 Wiping
3.1.1.3 Brush cleaning
3.1.1.4 High-pressure
washing
3.2.1.1 Wiping
3.2.1.2 Brush cleaning
3.2.1.3 High-pressure
washing
3.3.1.1 Wiping
3.3.1.2 Brush cleaning
3.3.1.3
High-pressurewashing
3.3.2.1 High-pressure
washing
3.4.1.1 Sediment removal
3.4.2.1 Weeding, mowing
3.4.2.2 Close mowing of
lawns
3.4.2.3 Peeling off grass andlawn top layer
3.4.2.4 Sodding
3.4.3.1 High-pressure
washing of gravel andcrushed stone
3.4.3.2 Removal of gravel
and crushed stone
3.4.3.3 Covering of gravel
and crushed stoneTarget3.4.4 Soil

3.4.5 Plantings

3.4.6 Paved
surfaces

3. Parks (big)

3.5 Playequipment,
etc.
4.1 Roofs,
Rooftops

3.5.1 Playequipment, etc.

4.2 Walls,
Fences

4.2.1 Walls,
Fences

4.3 Gutters4.3.1 Eave
gutters

4.4 Groundsurfaces, etc.

－

4.3.2
Downspouts
4.4.1 Sediment4.4.2 Grassareas, Lawns

4.4.3 Gravel,
Crushed stone

4.4.4 Soil

194

Decontamination methods
3.4.4.1 Peeling off topsoil
3.4.4.2 Covering of groundsurface
3.4.4.3 Upturning
3.4.5.1 Topsoil removal intree root vicinity etc.
3.4.5.2 Pruning of plantings
3.4.5.3 Trimming of trees
3.4.6.1 Sediment removal
3.4.6.2 Brush cleaning
3.4.6.3 High-pressure
washing
3.4.6.4 Peeling3.4.6.5 Abrasive material
blasting
3.5.1.1 Wiping, Brushcleaning, Peeling4.1.1.1 Sediment removal
4.1.1.2 Wiping
4.1.1.3 Brush cleaning
4.1.1.4 High-pressure
washing
4.2.1.1 Wiping
4.2.1.2 Brush cleaning
4.2.1.3 High-pressure
washing
4.3.1.1 Sediment removal
4.3.1.2 Wiping
4.3.1.3 High-pressure
washing
4.3.2.1 High-pressure
washing
4.4.1.1 Sediment removal
4.4.2.1 Weeding, mowing
4.4.2.2 Close mowing of
lawns
4.4.2.3 Peeling off grass andlawn top layer
4.4.2.4 Sodding
4.4.3.1 High-pressure
washing of gravel andcrushed stone
4.4.3.2 Removal of gravel
and crushed stone
4.4.3.3 Covering of gravel
and crushed stone
4.4.4.1 Topsoil removal
around drain outlets, Eave
gutter outlets
4.4.4.2 Peeling off topsoil
4.4.4.3 Covering of groundsurfaceTarget4.4.5 Plantings

4.4.6 Paved
surfaces

5. Large
facilities

4.5 Playequipment,
etc.
5.1 Roofs,
Rooftops

4.5.1 Playequipment, etc.

5.2 Walls,
Fences

5.2.1 Walls,
Fences

5.3 Gutters5.3.1 Eave
gutters

5.4 Groundsurfaces, etc.

5.4.1 Sediment5.4.2 Grassareas, Lawns

5.1.1 Roofs,
Rooftops

5.4.3 Gravel,crushed stone

5.4.4 Soil

5.4.5 Plantings

195

Decontamination methods
4.4.4.4 Upturning
4.4.5.1 Topsoil removal intree root vicinity etc.
4.4.5.2 Pruning of plantings
4.4.5.3 Trimming of trees
4.4.6.1 Sediment removal
4.4.6.2 Brush cleaning
4.4.6.3 High-pressure
washing
4.4.6.4 Peeling4.4.6.5 Abrasive material
blasting
4.4.6.6 Super-high-pressure
washing
4.4.6.7 Repaving
4.5.1.1 Swabbing, cleaning,
peeling
5.1.1.1 Sediment removal
5.1.1.2 Wiping
5.1.1.3 Brush cleaning
5.1.1.4 High-pressure
washing
5.2.1.1 Wiping
5.2.1.2 Brush cleaning
5.2.1.3 High-pressure
washing
5.3.1.1 Sediment removal
5.3.1.2 Wiping
5.3.1.3 High-pressure
washing
5.4.1.1 Sediment removal
5.4.2.1 Weeding, mowing
5.4.2.2 Close mowing of
lawns
5.4.2.3 Peeling off grass andlawn top layer
5.4.2.4 Sodding
5.4.3.1 High-pressure flushof gravel and crushed stone
5.4.3.2 Removal of gravel
and crushed stone
5.4.3.3 Covering of gravel
and crushed stone
5.4.4.1 Topsoil removal
around drain outlets, Eave
gutter outlets
5.4.4.2 Peeling off topsoil
5.4.4.3 Covering of groundsurface
5.4.4.4 Upturning
5.4.5.1 Topsoil removal intree root vicinity etc.

Target5.4.6 Parking
lots (concrete,asphalt)

6. Road

5.5 Playequipment,
etc.
6.1 Pavedroad

5.5.1 Playequipment, etc.

6.2 Unpaved
roads

6.2.1 Road
surfaces (soil)

6.1.1 Sediment6.1.2 Road,
Sidewalk

6.2.2 Road
surfaces (gravel,crushed stoneroads)

6.3
Guardrails

6.3.1 Guardrails

6.4 Side
ditches , etc.
6.5
Pedestrian
bridges

6.4.1 Side
ditches , etc.
6.5.1 Pedestrian
bridges

196

Decontamination methods
5.4.5.2 Pruning of plantings
5.4.5.3 Trimming of trees
5.4.6.1 Sediment removal
5.4.6.2 Brush cleaning
5.4.6.3 High-pressure
washing
5.4.6.4 Peeling
5.4.6.5 Abrasive material
blasting
5.4.6.6 Super-high-pressure
washing
5.4.6.7 Repaving
5.5.1.1 Wiping, Brushcleaning, Peeling6.1.1.1 Sediment removal
6.1.2.1 High-pressure
washing
6.1.2.2 Peeling6.1.2.3 Abrasive material
blasting
6.1.2.4 Super-high-pressure
washing
6.1.2.5 Repaving
6.1.2.6 Cleaning with roadsweepers
6.2.1.1-(1) Weeding
6.2.1.1-(2) Sedimentremoval6.2.1.2 Side ditches, etc.
6.2.1.3 Covering of groundsurface
6.2.1.4 Upturning
6.2.2.1-(1) Weeding
6.2.2.1-(2) Sedimentremoval6.2.2.2 High-pressure
washing of gravel andcrushed stone
6.2.2.3 Removal of gravel
and crushed stone
6.2.2.4 Covering of gravel
and crushed stone
6.3.1.1 Brush cleaning
6.3.1.2 High-pressure
washing
6.3.1.3 Wiping
6.4.1.1 Bottom sedimentremoval, etc.
6.5.1.1 Sediment removal
6.5.1.2 High-pressure
washing
6.5.1.3 Wiping

Target6.6 Roadsidetrees

6.6.1 Sediment6.6.2 Grass
6.6.3 Roadsidetrees

7. Slopes

7.1 Slopes

8. Farmland

8.1 Rice
paddies

7.1.1 Sediments(grass, fallen
leaves, etc.)
8.1.1 Grass

Decontamination methods
6.5.1.4 Brush cleaning
6.6.1.1 Sediment removal
6.6.2.1 Weeding, mowing
6.6.3.1 Soil removal aroundroot area of roadside trees
6.6.3.2 Debranching ofroadside trees

8.1.2 Soil

197

7.1.1.1 Sediment removal
8.1.1.1-(1) Manual weeding
8.1.1.1-(2) Machine weeding
8.1.1.1-(3) Buildup of
weeding material
8.1.1.1-(4) Packing
8.1.1.1-(5) Small transfer insite
8.1.2.1-(1) Bump leveling
8.1.2.1-(2) Surface fixationmaterial dispersion
8.1.2.2-(1)-①、
8.1.2.2-(1)-②Peeling off
surface soil (standardtransportation method)
8.1.2.2-(1)-③ Packing(standard transportation
method)8.1.2.2-(1)-④ Smalltransport vehicles(standard transportation
method)8.1.2.2-(2)-① Peeling off
surface soil (suction
method)8.1.2.2-(2)-② Packing(suction method)
8.1.2.2-(2)-③ Smalltransport vehicles (suction
method)8.1.2.3 Deleted
8.1.2.4-(1) Reverse
cultivation (plowing 30cm)
8.1.2.4-(2) Reverse
cultivation (plowing 45cm)
8.1.2.4-(3) Base land
preparation
8.1.2.4-(4) Turn plowing
8.1.2.5 Deep plowing
8.1.2.6 Adding soil
8.1.2.7-(1) Restoration ofsoil fertility (soil
improvement agent

Target8.2 Fields

8.2.1 Grass
8.2.2 Soil

8.3 Meadows

8.3.1 Grass

8.3.2 Soil

9. Grass areas,
lawns
10. Orchards

8.4 Water
channels

8.4.1 Water
channels

8.5 Ridge
fronts

8.5.1 Ridge
fronts

9.1 Shrubs(dense)9.2 Shrubs(coarse)10.1
Orchards

9.1.1 Shrubs(dense)9.2.1 Shrubs(coarse)10.1.1 Sediment10.1.2 Grass
10.1.3 Orchard
198

Decontamination methods
dispersal)
8.1.2.7-(2) Restoration ofsoil fertility (zeolite
dispersal)
8.1.2.8 Upturning
8.2.1.1 Weeding
8.2.2.1 Surface fixationmaterial dispersion
8.2.2.2-(1) Peeling off topsoil(standard transportation
method)8.2.2.2-(2) Peeling off
surface soil (suction
method)8.2.2.3 Deleted
8.2.2.4 Reverse cultivation
8.2.2.5 Deep plowing
8.2.2.6 Adding soil
8.2.2.7 Land power recovery
8.2.2.8 Upturning
8.3.1.1 Weeding
8.3.1.2 Deleted
8.3.1.3-(1) Seeding(dispersion)
8.3.1.3-(2) Seeding(suppression)
8.3.2.1 Peeling off surface
soil
8.3.2.2 Reverse cultivation
8.3.2.3 Deep plowing
8.3.2.4 Adding soil
8.3.2.5 Land nutrient
recovery
8.4.1.1-(1) Bottom
sediments removal, etc.
(earth and sand removal)
8.4.1.1-(2) Bottom
sediments removal, etc.
(packing)
8.5.1.1-(1) Sedimentremoval8.5.1.1-(2) Weeding
8.5.1.2-(1) Peeling off
surface soil
8.5.1.2-(2) Packing
8.5.1.3 Ridge front recovery
9.1.1.1 Trimming
9.2.1.1 Trimming
10.1.1.1 Sediment removal
10.1.2.1 Weeding
10.1.3.1 Peeling off coarse

Targettree

10.1.4 Soil
11. Forests

11.1
Evergreen
needle-leavedtrees

11.1.1 Organic
sediments

11.1.2 Soil11.1.3 Timber

11.2
Deciduous
broadleaf
trees

11.1.4 Roughcutting
11.1.5 Removalof residualorganic
sediments
11.2.1 Organic
sediments

11.2.2 Soil11.3 Bushes

11.2.3 Timber
11.2.4 Roughcutting
11.2.5 Removalof residualorganic
sediments
11.3.1 Organic
sediments

199

Decontamination methods
bark
10.1.3.2 High-pressure
washing of tree bark10.1.3.3 Pruning of orchard
trees
10.1.3.4 Trimming oforchard trees
10.1.4.1 Peeling off surface
soil
10.1.4.2 Adding soil
11.1.1.1-(1)、11.1.1.1-(2)、11.1.1.1-(3) Removal oforganic sediments
11.1.1.1-(4) Removal oforganic sediments(non-management zone)
11.1.1.1-(5) Arrangement of
cutoff chips
11.1.2.1 Prevention ofre-spreading (soil loading)
11.1.2.2 Prevention ofre-spreading (board rack)
11.1.3.1-(1)、11.1.3.1-(2)、11.1.3.1-(3) Pruning of
needle leaf trees, collectionof branches
11.1.4.1 Pruning
underbrush, shrubs
11.1.5.1 Removal of residualorganic sediments
11.2.1.1 Removal of organic
sediments
11.2.1.2 Removal of organic
sediments(non-management zone)
11.2.2.1 Prevention ofre-spreading (soil loading)
11.2.2.2 Prevention ofre-spreading (board rack)
11.2.3.1 Fascine bonding
11.2.4.1 Pruning
underbrush, shrubs
11.2.5.1 Removal of residualorganic sediments
11.3.1.1 Removal of organic
sediments
11.3.1.2 Removal of organic
sediments(non-management zone)

Target11.3.2 Soil

12. (Deleted)
13. Temporary
installations,
etc.

－
－

11.3.3 Timber
11.3.4 Roughcutting
11.3.5 Removalof residualorganic
sediments－－

200

Decontamination methods
11.3.2.1 Prevention ofre-spreading (soil loading)
11.3.2.2 Prevention ofre-spreading (board rack)
11.3.3.1 Fascine bonding
11.3.4.1 Pruning
underbrush, shrubs
11.3.5.1 Removal of residualorganic sediments－
13.1.1.1 Groundwater
investigation for storage
area
13.1.1.2 Weeding
13.1.1.3 Trimming of shrubs(thick)13.1.1.4 Trimming of shrubs(coarse)13.1.1.5-(1) Logging, root
removing (logging work)
13.1.1.5-(2) Logging, root
removing (root removing
work)
13.1.1.5-(3) Logging, root
removing (accumulation
work)
13.1.1.6 Leveling13.1.1.7 Cutting earth,
Filling earth
13.1.1.8 Covering of gravel ,crushed stone
13.1.1.9-(1) Installation ofbottom sheets (water
blocking sheet)
13.1.1.9-(2) Installation ofprotection layers
13.1.1.9-(3) Installation of
upper sheets (breathable
waterproof sheets andwater blocking sheets)
13.1.1.10 Leachatecollection channels,
Leachate collection pipe
facilities
13.1.1.11 Installation ofleachate collection facilities
13.1.1.12 Installation of
surface water collection
facilities
13.1.1.13 Deleted
13.1.1.14 Storage carry-in,Target14. Deleted
15. Effluent
treatment－
15.1 Effluent
treatment－
15.1.1 Effluent
treatment

Decontamination methods
installation
13.1.1.15 Lateral shielding
13.1.1.16 Upper shielding
13.1.1.17 End treatment
13.1.1.18 Ancillary facilities
13.1.1.19 Installation ofradiation tubes (gas-ventpipes), gas-vent outlets
13.1.1.20 Installation ofthermometers－15.1.1.1 Treatment ofdischarged water(precipitation treatment)
15.1.1.2 Sludge treatment
15.1.1.3-(1) Installation of
turbid water treatment
facilities
15.1.1.3-(2) Water
treatment facilities forremoval of turbidity（5） Project management
The Common Specifications (7th Edition) specify the project management methods forradiation dose measurements, administration of temporary storage sites, and confirmation of
the work results.

1）Radiation dose measurements
Decontamination business operators are required to select appropriate measuring
instruments which have sufficient performance for measurements, taking into account theenvironment, use conditions, and other matters. Decontamination business operators also
ensure that appropriate numbers of instruments are available and calibrated in advance.
Decontamination business operators report to the MOE supervisor the name, serial number,date of calibration, term of validity and error values (the variance in measurements at thesame measuring point) of the instruments, and conduct daily inspections of them.
When measuring air dose rates, radiation survey meters which meet JIS Z 4333
specifications and the following performance and requirements should be used.
Type of radiation to measure: gamma rays, X-rays
Reference radiation source for calibration: cesium-137
Display unit: μSv/h
Relative standard errors100: below ±15%
Energy characteristics: energy range 60 keV to 1.5 MeV, sensitivity 0.85 to 1.15
Directional characteristics: below ±25% (angular range of ±90°)
Response time or time constant: to be specified
The relative standard error is the deviation of readings of the instrument from the reference radiationdose, expressed in percent. (Some instruments use the terms “reading accuracy” or “relative readings error”
with the same meaning)
100

201

Service temperature range: covers -10 to +40 deg C
On the other hand, when measuring surface contamination densities, surface
contamination survey meters which meet performance and other requirements specified in
JIS Z 4329 should be used, and the results should be recorded as count rates (counts per
minute, cpm).
The measurement of radiation dose rate should be done in principle under dry conditions(to avoid shielding influence of moisture), and should follow the specific sequence below.
Set and fix the time constant at 10 s when measuring radiation.
Read and record the readings 30 s after fixing the probe (detectors) of the measuring
instrument at the measuring point.
Keep the probe parallel to the ground surface, while facing east and holding the probe
as far away from the body as possible for the measurement.
Take the average of the readings as the measured value.
For those who are not specialists in using radiation measuring instruments, information isprovided in the “Performance check-sheet of radiation measuring instruments” (Performance
Check-sheet Committee, Japan Electric Measuring Instruments Manufacturers' Association,
April 2013) to select the proper instruments.

2）Administration of temporary storage sites
Once all the removed soil and the like have been received, and shielding work above themhas been completed, the decontamination business operators are required to commence
administration of each temporary storage site and to continue this administration as
appropriate in accordance with the direction of the MOE supervisor, until the responsibility ofmanagement of temporary storage sites is handed over to the MOE or other operators
designated by the MOE.

3）Confirmation of project results
Upon implementation of decontamination and other measures in residential areas and thelike, decontamination business operators are required to: compile a report on the work resultsof these measures; allow the responsible person (foreman or manager) of the operator to check
whether the measures have been appropriately implemented in each residential area and thelike based on the report; and submit the results to the MOE supervisor.

（6） Check surveys
The goal of decontamination work is to reduce radiation levels, and given that this cannot
be confirmed visually, quality management methods are important. For example, it is difficult
to judge visually the finished quality of wiping and cleaning after decontamination work.
Therefore, MOE personnel randomly choose some part of the surfaces after decontamination,
have the decontamination business operators perform their decontamination work again
using the same method, and check if there is no further reduction in surface dose rates after
this additional decontamination.
In the case of wiping and cleaning, the number of wiping steps and the cleaning speed are
set from the test decontamination results as those values which can achieve no further
significant radiation dose reduction. Therefore, where wiping and cleaning are finished, nofurther significant reduction will be anticipated, even if the work is repeated. To the contrary,
if the radiation dose is found to have fallen in the check below the control value (the standard
deviation of the dose reduction rate before and after the additional check of thedecontamination measure), the decontamination measures should be repeated under the
direction of the MOE supervisor.
The radiation dose measurements in the check surveys should be carried out before andafter the decontamination work using lead blocks in order to shield measurement
202

instruments from radiation emitted by the surroundings. The same measurement
instruments should be used before and after the decontamination work to measure the air
dose rates at a distance of 1 cm from the surface being checked.

（7） Project management standards
The Decontamination Work Project Control Standards presented in the Common
Specifications specify the schedule and progress control, finished quality control, material
quality control and photo control.

1）Schedule and progress control
Decontamination business operators are required to perform appropriate schedule controls
using maps, networks, bar charts, etc., and to prepare daily work reports from the day of workcommencement until the day of its completion. The daily reports should include the weather,
workplaces, work contents, list of workers on duty, quantities of finished work, machinery
used, radiation dose rates in the work areas, etc. as well as the items instructed, approved,
consulted about, etc., and should be accompanied by attachments such as work photos inaccordance with the Photo Control Standards, the checklists of the results of decontamination
related works.

2）Finished quality control
Decontamination business operators are required to measure the items as specified in the
Finished Quality Control Standards for each type of work designated in the Common
Specifications, and to prepare and control the Finished Quality Control Sheets which record
the compared results of the measured values with the work plan values.

203

Finished work quality measuring control

Work
Residential
area

Regulated Remark
value
(mm)

Measuring criterion

Items

Removalof gravelandcrushedstone(1.4.1.7)

・1 place per work area 1000m2( 1place per work site for equal and lessthan work area 1000m2,
・Reference height is defined as the height above sea level lower than theheight before work by regulated height (5cm) for the relevant place foreach measuring point
・Direct measurement on the basis of the height above sea level for the
ground surface after work

Referenceheight±10

Removalof gravel,andcrushedstone(1.4.1.8)

・1 place per work area 1000m2( 1place per work site for equal and less than work
area 1000m2,
・Reference height is defined as the height above sea level before work of “removalof gravel and crushed stone (1.4.1.7)”for the relevant place for each measuring
point・Direct measurement on the basis of the height above sea level for the groundsurface after work

Referenceheight±10

Scraping of
surface soil
(1.4.1.9)

・1 place per work area 1000m2( 1place per work site for equal and less than work
area 1000m2,
・Reference height is defined as the height above sea level lower than the height
before work by regulated height (5cm) for the relevant place for each measuring
point・Direct measurement on the basis of the height above sea level for the groundsurface after work

Referenceheight±10

Covering
overgroundsurface(1.4.1.10)

・1 place per work area 1000m2( 1place per work site for equal and less than work
area 1000m2,
・Reference height is defined as the height above sea level before work of “scrapingof surface soil(1.4.1.9) “for the relevant place for each measuring point
・Direct measurement on the basis of the height above sea level for the groundsurface after work

Referenceheight±10

Upturn(1.4.1.15)

・1 place per work area 1000m2( 1place per work site for equal and less than work
area 1000m2). The following item①should be measured.
Referenceheight±10①
・Reference elevation is defined as the elevation lower than that (V0) before the workby the standard value (10cm).
・Direct measurement on the basis of the height above sea level for the groundsurface after scraping of surface soil

V0
h1

V1

Figure 4-5 Finished Quality Control Standards (Excerpt)101.

3）Material quality control
Decontamination business operators are required to ensure appropriately that the qualityof materials used in decontamination and related works meet the Material Quality Control
Standards.

101Source: Decontamination Construction Project Management Standards in the Special Decontamination

Areas (7th Edition) (http://tohoku.env.go.jp/fukushima/to_2014/data/0410aa.pdf) (Figure 4-6 to Figure 4-7
have the same source.)

204

Type
Residentialarea, School,
Park, Large
facility,
Farm landClass

Category

Residential Mandatory
area, school,park, large
facility, farm
land

Test item

Test method

Measurement Gamma- rayof radioactive spectrometry
CesiumdensityStandard value

Test standard

Remarks

Sum of Cesium Once for each
134 and Cesium product district
137 shall be
before carry-in
under 400 Bq/kg

Other quality control is based on “civil engineering work control criteria and its regulated value”(Ministry of Land, Infrastructure, Transport and Tourism).

Figure 4-6 Material Quality Control Standards.

4）Photo management
As a means of managing the construction work, decontamination business operators are
required to take photographs, in accordance with the Photo Control Standards, at eachconstruction stage, of the following items: the state of areas that cannot be visually confirmed
after the completion of construction work; finished work measurements; material quality
control conditions, and accidents during construction. Further, these photos are to beappropriately controlled, stored and submitted at the completion of construction work.
Pictures before start and completion(including previously completed portion)
Picture of construction status
Picture of safety control
Picture of material used for work

Construction photographs

Picture of quality control
Picture of finished work control
Picture of disaster
Picture of accident
Others (pollution, circumstance, and compensation)

Figure 4-7 Classification of work photos (excerpt) in the Photo Control Standards.

4.2.4. Securing of Necessary Resources by Decontamination Business Operators
There were a number of issues faced by decontamination business operators in securingresources needed in the decontamination and related works ordered by the MOE in theSpecial Decontamination Areas. These issues and the methods for solving them aresummarized below.

（1） Issues concerning radiation measurements1）Procurement and operation of exposure dose measurement apparatuses for workers
External exposure dose of workers can be controlled based on measurements obtained using
personal dosimeters (cumulative-type dosimeters or electronic dosimeters). Somedecontamination business operators used an access management system and other systems
related to the air dose distribution in the workplaces for exposure dose control. Measurements
using whole-body counters (WBCs) were used for internal exposure dose control.
205

Decontamination business operators instructed each worker to wear personal
cumulative-type dosimeters and to read the indications before and after the work day formeasurement of the exposure dose for that day. The measured data were processed together
with the information stored in the data base and used for personal exposure dose control.
On the other hand, individual workers are required to receive medical checks for ionizing
radiation in decontamination and related works at the time of employment by thedecontamination business operator or at the time of relocation, and periodically after thatonce in every six months. Internal exposure dose is measured by using WBCs or bioassays, orby evaluating measurement of the air-borne radioactive material concentrations. The WBCs
installed in hospitals were used for the evaluations of community residents, too. Since theWBCs are costly, the MOE opened two WBC Inspection Offices, one in Minami-soma City andanother in Naraha Town (this has since been moved to Tomioka Town).
The issues for decontamination business operators were the requirements: (i) to manage
exposure dose control effectively for a huge number of workers, several thousand (1,000 to
6,000 people) per site; (ii) to manage screening processes of those workers which wereconcentrated exclusively at limited time spans of the day (lunch time, end of the day, etc.); and(iii) to handle a concentration of new workers and leaving workers at limited times of the year
(for example, at the end of the fiscal year).
To cope with these issues, some decontamination business operators adopted a more
efficient dose control system by mechanizing the screening equipment such as hand-footmonitors or the like by using IT tools. There was also a case in which one decontamination
business operator donated a WBC to the local hospital and allowed it to be used for evaluationof local residents when not being used to evaluate the business operator’s workers. Anotherdecontamination business operator applied fingerprint authentication devices for its
radiation control system (Fig.4-8).
Issues, however, remain in balancing cost and efficiency improvement by mechanization
and automation in small-sized or short-term decontamination projects.

Figure 4-8 Example of radiation control using a fingerprint authentication device102.

2）Measurement of air dose rates and other quantities
Scintillation survey meters were mainly used to measure air dose rates of gamma-rays andsurface dose rates. GM survey meters were used to measure beta-rays emitted from theobjects to be decontaminated in order to find the degree of the contamination of the surfaces
and also to check the decontamination effects after decontamination.
Collimators were used in many cases in order to avoid the influence of backgroundradiation from the surroundings, when using scintillation survey meters to measure the102Source: Kajima Corporation (Figure 4-9 has the same source.)

206

degree of the contamination or to check the decontamination effects, and using GM survey
meters to measure the surface contamination densities. For cases in which measurements
were implemented without using collimators, these were for unstable places such as on walls
or roofs where it was not possible to attach the collimators or there were risks of damage tothe targets. Regarding the collimators, if they were used in the measurements before
decontamination they had to be used in the measurements after it and vice versa.
The measurement positions must be known geographically which presents some issues.
The conventional position measuring GNSS (global navigational satellite system;
using a fixed type position checking apparatus) has good accuracy, but is bulky andso heavy that it requires two persons to carry it. On the other hand, thetablet-embedded global positioning system (GPS) is light and easy to handle, but it
has poor accuracy and needs much time to locate the measurement points, especiallyfor inaccurate data.
One person reads the measurements while a second person records the data on paper
or a tablet device. Such work flow is inefficient and has the risk of reading errors
depending upon how proficient the persons are.
To cope with these issues, a wearable GNSS system was used by one decontamination
business operator in measuring the air dose rates. The system had several advantages: (i) one
worker instead of two was needed for measuring and recording data because the equipment
weight was reduced to 1/5 that of the conventional apparatus and measured data were sent by
a wireless transmitter to a recording unit; (ii) work efficiency was improved more thanten-fold by having a high-speed navigation system like that of a car-navigation system; and(iii) the progress of decontamination work can be visualized using the measured results andthe geographic information system (GIS) (Fig.4-9).

Figure 4-9 Example photos showing use of GNSS-based air dose rate measurement system.

（2） Materials and equipment for use in decontamination work
The “Decontamination Guidelines” requires tools be prepared that are necessary fordecontamination and related works and for collection of removed soil and other wastes,
depending on the decontamination target objects or work circumstances. Examples ofdecontamination tools for the work on structures like buildings are shown in Figure 4-10.
207

Restoration and reconstruction work from the damage by the Great East Japan Earthquakeand ensuing tsunami (hereafter simply the “earthquake and tsunami”) has been ongoing on
the Pacific coast in parallel with the decontamination work. This situation sometimes caused
problems to secure necessary quantities of special equipment to use in the decontamination
work. Specifically, it became necessary to improve efficiency and to make a comparative study
between the cost and effectiveness of special equipment, which is generally expensive. Second,equipment leasing companies showed reluctance to enter into lease contracts, being
concerned about contamination of equipment by radionuclides, especially in the early days ofthe decontamination work.
One decontamination business operator was able to over these problems by using materials
and equipment for ordinary general civil engineering work and to use agricultural machinery
owned by local farmers; for the latter the decontamination business operator employed thefarmers under a contract and used their agricultural machines for decontamination work.
Example ofgeneralequipment

Examples ofequipment forcleaning withwater
Examples ofequipment forcleaning metal
surfaces
Examples ofequipment forcleaning wood
surfaces
Examples ofequipment forwork in highplacesExamples ofequipment for
scraping away
Examples ofequipment forcovering the
ground surface

Mower, hand shovel, grass sickle, broom, bamboo rake,
dustpan, tongs, shovel, small shovel, metal rake, compact heavymachinery for scraping away topsoil, garbage bags (bags forburnable matter, burlap sacks for soil and sand (sandbags)),
vehicles for transporting collected removed soil, etc. to theon-site storage location (truck, two-wheeled cart, etc.),ladder
Hose, shower nozzle, high pressure water cleaner, brushes(scrub brush, brush for cleaning vehicles, brush for cleaninghigh places), scrubbing brushes (circular scrubber, steel wool
brush, etc.), wire brushes, tools for pushing away water (broom,
scraper, etc.), bucket, detergent, dustcloth, sponges, paper
towelsBrush, sandpaper, cloth, removing agents

Brush, sandpaper, power sander, cloth, steam cleaner, waterhigh pressure washer, tools for pushing away water (broom,
scraper, etc.)

Scaffold, mobile lift, aerial vehicle

Grinding machine, equipment for scraping away, equipment
needed to prevent dispersion (dust collector, curing mat)
Self-propelled surface compaction roller, plywood for surface
compaction, sprinkling equipment

Figure 4-10 Examples of decontamination tools for work on structures like buildings103.

103Source: Decontamination Guidelines (2nd Edition)(http://josen.env.go.jp/material/pdf/josen-gl-full_ver2_supplement1412.pdf) (Figure 4-11 has the same source.)208

（3） Protective clothing, equipment and other items
The minimum suitable protective clothing, equipment and other items were used according
to the Ionizing Radiation Ordinance for Decontamination and Guidelines of Ionizing
Radiation Ordinance for Decontamination. By doing so, the amount of waste was limited by
avoiding the excessive use of protective clothing, equipment and the like.
The Ionizing Radiation Ordinance for Decontamination and Guidelines of Ionizing
Radiation Ordinance for Decontamination require that protective clothing, equipment andothers be used depending on the radioactivity densities of the contaminated soil and the like,and the dust conditions (Table 4-8).

High density
dust work(exceeding
10mg/m3)

Other than theabove

Table 4-8 Protective clothing, equipment and others104
High contamination soil, etc.
Other than high contamination soil,(exceeding 500 thousands Bq/kg)
etc. (less than 500 thousands
Bq/kg)
Entire body chemical protective
Long-sleeved clothing, cotton
suit over long-sleeved clothing
gloves, rubber boots, dust
(Tyvec etc.), rubber gloves (together protective mask with trappingwith cotton gloves), rubber boots,
efficiency above 80%
dust protective mask with trapping
efficiency above 95%
Long-sleeved clothing, rubberLong-sleeved clothing, cotton
gloves (together with cotton gloves), gloves, rubber boots, dust
rubber boots, dust protective mask protective mask with trappingwith trapping efficiency above 80% efficiency above 80%* Surgical masks, non-woven fabric masks and other practical masks also may be used when handlingvegetation and leaf mold.

（4） Storage containers for removed soil and other wastes
Flexible containers and large sandbags of about 1m3 capacity (dimensions: about 1.1 m indiameter by about 1.1 m in height) (hereinafter referred to as “flecon bags”) were mainly usedas storage containers in the decontamination and related works in the Special
Decontamination Areas ordered from the MOE. Durable materials were used for long-term
storage (a few years) and for storing removed soil containing much water. Selection ofcontainers was based on characteristics, weight, storage duration, etc. of the removed soil andother wastes. Examples of flecon bags include cloth-type containers (for one-time use) with aweather-resistant inner bag, running-type containers (for repeated use), and large
weather-resistant sandbags with an inner bag (Figure 4-11).
Currently used are, as specified in the Common Specifications (7th Edition), those products
which meet the specifications of “Flexible Containers Based on the Decontamination
Guidleines” by the Japan Flexible Container Industries Association, the “Layer Stack Method
Design and Construction Manual for Weather-resistant Large Sandbags” by the Public Works
Research Center, and are certified by official test organizations, as meeting the performancestandards required for materials and container bags.

104Source: Ionizing Radiation Ordinance for Decontamination and Guideline on Ionizing Radiation Ordinancefor Decontamination (http://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000029897.html )209

Figure 4-11 Examples of flecon bags and large sandbags.
The Common Specifications stipulate that removed soil and other wastes generated in thedecontamination work in the Special Decontamination Areas are to be stored in either of thefollowing nine groups (i) to (ix).
Combustibles:(i) Vegetation (pruned branches, fallen leaves, lawn grass, moss, weeds, litter layers,
trimmed trees, roots, etc. Attached soil should be removed to the extent possible).
(ii) Other combustible wastes (Tyvek coveralls, disposable work clothing, masks,
filters, rubber gloves, paper, etc.)
Incombustibles, mixtures:(iii) Soil and others (soil, gravel, small stones, etc. Vegetation should be removed tothe extent possible.)(iv) Concrete and other materials (tiles, bricks, blocks, rocks, etc.)(v) Mixtures with asphalt(vi) Other incombustibles and mixtures (except dangerous objects, hazardous
materials)
Dangerous objects, hazardous materials(vii) Architectural material including asbestos(viii) Plaster boards(ix) Other dangerous objects, hazardous materials
The Common Specifications require that the tags attached to flexible containers and othersimilar containers be made of materials with corrosion resistance, weather resistance, good
durability and not hazardous and the required information about contents, etc., should bemachined into the tag surface so that it is legible for at least three years under the combined
conditions of decontamination work, and transfer to and storage at temporary storage sites;
finally the tags should be identified by color according to the individual contents.

210

A
B
C
D
E
F

Table 4-9 Correspondence between contents and tag colors105.
Color Content
White Soils, etc. (earth, small stone, gravel, etc.)
Green Corruptive combustible material (pruning branch, fallen leaves, lawn, moss, weed,
litter layer, trimmed tree, uprooting, etc.)
Yellow Combustible material (Tyvec, waste clothe, mask, filter, rubber gloves, paper, etc.)
Blue
Incombustible (concrete, etc. (tile, bricks, block, rock, etc.), mixture with asphalt,
sludge, etc.)
Black Incinerated ash
RedDangerous article (Material including asbestos, soils polluted hazardous material)

There was a case in which one decontamination business operator developed a Quick
Register (QR) code system and applied it for efficiently processing the information below as
the decontamination work progressed:
Read selectively necessary items and input dose data with a handy type input machine;
Transfer the information to a small printer and issue the QR code; andExport the data to the decontamination information system in the format of a delivery.

Development of “QR code issuing system”
・Handy-type input machine which can selectnecessary items and dose・Transfer of data and issuing QR code
・Data are able to be assembled into personal
computer with product-format todecontamination information system
Tag（QR code）

一時保管場でのタグ取付状況

Printer

Handy-type input machine

Making label

Figure 4-12 Examples of QR code issuing system106.

（5） Issues associated with supervisors, skilled workers (with qualifications), anddecontamination workers
Decontamination experts were quite limited among managers and employees (foremen andworkers) of decontamination business operators. Also persons who were knowledgeable about
radiation were limited. Quite a few workers had no field experience in civil engineering or
construction work and they lacked knowledge about industrial health and safety practices,which was quite fundamental at such workplaces. The issue then was to provide education
about basic work safety practices.
Some decontamination business operators had their own personnel educate the workers
while the personnel themselves were learning about the topics, or the operators had the105Source: Decontamination Project Common Specifications (7th Edition)(http://tohoku.env.go.jp/fukushima/to_2014/data/0410ba.pdf)
106Source: Kajima Corporation (Figure 4-14 has the same source.)211

workers learn by actually doing the decontamination work.
To secure necessary numbers of decontamination workers with suitable qualifications, therising market wage was an issue, too. This is because of the ongoing restoration andreconstruction work in parallel with the decontamination work on the Pacific coast from thedamage by the earthquake and tsunami. In particular, the issue regarding decontamination
workers was not only the big workforce required, but also the changing demand of workforce
with the progress of decontamination work as illustrated in Figure 4-13. Somedecontamination business operators, while emphasizing recruitment of local workers, triedalso to acquire workers from prefectures outside Fukushima.

numbers of decontamination workers(persons)trend on numbers of decontamination workers

Accumulative numbers as of December 299,000

Figure 4-13 Monthly change of workforce (Example)107.

107Source: Okumura Corporation (Figure 4-15 has the same source)212

（6） Accommodation facilities for workers
The issue for a large number of the decontamination workers was to secure daily
commuting means (limited available routes and subsequently, traffic jams) from outside theSpecial Decontamination Areas, since all the residents had been evacuated and all existingaccommodation facilities and the like were not in service. Overnight stays are generally notallowed in the areas to which evacuation orders are being prepared to be lifted, but they were
exceptionally allowed if needed for reconstruction. There was a case, in which accommodation
facilities for workers were exceptionally built in the Special Decontamination Areasthroughcoordination with the local municipality and the Nuclear Emergency Response Local
Headquarters.
Some difficulties faced were as given below.
Need to increase the capacity of accommodation facilities for increased number ofworkers subject to the work progress.
Concerns of local residents about workers coming from outside and possible worseningof public morals (expressed as opposition to building the accommodation facilities).
Opposition from the local residents when building an accommodation facility for thoseworkers who were decontaminating a site different from their own municipality. Timeloss by commuting over a long distance was another difficulty in this case.
Traffic congestion along the route between the accommodation facility and the worksite during commuting times.
To cope with these difficulties, the following measures were taken by some decontamination
business operators.
Making school buildings and public facilities, etc. the earliest decontamination targets
so that they could be used as accommodation facilities close to the work site.
Having local municipalities provide a piece of land in their possession todecontamination business operators for the purpose of building an accommodation
facility for workers.
Prioritizing contracts with local workers who can commute from their own residences.
Implementing institutionalized patrols of accommodation facilities.
Taking measures to mitigate the commuting burden by providing commuter buses,
operating them on a time-shifted schedule (time-shifted duty hours of workers) andother means.

[Planning] workers approximately 500 persons
Within Fukushima Prefecture (commuter) 300persons
Outside Fukushima Prefecture (lodging) 200persons
・Setting accommodation facility for workers at
playground in Miyakoji middle school(approximately 200 persons)
Increase of workers
・Renting “Boy Scouts lodge for Nakano District inTokyo”(approximately 150 persons)■Distribution of accommodation facility for workers
・Within Fukushima Prefecture 60%(within Tamura city 22%, others 38%)
・ Outside Fukushima Prefecture 40%

Figure 4-14 Example to secure accommodation facilities for workers (plan and result).
213

Figure 4-15 Example of an accommodation facility for about 350 workers.

（7） Processing of household wastes, foods, water, etc.
Special Decontamination Areas include the places damaged by the earthquake and tsunami.
In such places, some of the infrastructures are still not available, including roads, watersupply and sewerage systems, general waste treatment facilities, etc. and business activities
such as retailing have been halted since the residents were evacuated.
In the usual situation, each business operator is responsible for disposing wastes produced
by workers (lunch boxes and other garbage). However, general waste treatment facilities,
industrial waste treatment facilities and sewage treatment facilities were out of service,having been damaged by the earthquake and tsunami and not restored. Neighboring
treatment facilities had to bear the load instead, but their treatment capacities were exceeded.
Consequently, the decontamination business operators were asked in the early stage to treat
the garbage and sewage by themselves. In a later stage, the government, the ordering party,
exchanged information with local treatment facilities, in which the amount of sewage andwastes was predicted together. Measures were jointly taken to coordinate the balance sheet ofthe volume to come from the decontamination work plan and the processing capacities oftreatment facilities in order to avoid adverse impacts from the activity.
Regarding meals and water, an independent rest house was set near the working site ofdecontamination activities from the viewpoint of radiation protection. Workers were strongly
instructed to stay inside the rest house while eating meals and drinking water, not outside on
the decontamination site. If a rest house was not available, they were instructed to eat anddrink inside a vehicle.

214

4.3. Acquisition of Residents’ Consent
This section describes the efforts made in advance surveys, acquiring consent, andafter-action reporting, and presents the challenges identified through these processes by theordering party (MOE) and business operators for decontamination work in the Special
Decontamination Areas.

4.3.1. Efforts Made by the Ordering Party (MOE)
In implementing decontamination and other related works, the MOE tried to acquire priorconsent of stakeholders such as residential land owners (people who have the right to claim
the authority to prevent the decontamination and other related works from being taken for
the target objects to be decontaminated such as land, structures on it, or standing trees orother fixtures rooted on it) with regard to the details of said works.
In Tamura City, advance surveys and consent acquisition activities could start ahead ofother municipalities. The MOE personnel involved themselves in the advance survey andconsent acquiring initiatives. The knowledge and experience they obtained were applied andreflected in activities in other municipalities. Since the MOE personnel who could be allocated
was limited, the advance surveys and consent acquisition were commissioned to private
operators for cities other than Tamura City. The MOE personnel took the role to confirm theresults of the commissioned work.

（1） Advance surveys
After collecting and organizing the relevant information on land, houses, etc., advancesurveys of properties (field surveys) were performed prior to conducting the decontamination
work.

1）Collecting and ordering information on land and houses
Stakeholders were identified, using such sources of information as real estate registers,
land and house records, house drawings and land lot maps, and the relevant information wascollected about land and houses by marking residential boundaries (on a land owner basis)and buildings onto maps and aerial photographs.
A great deal of effort was needed in solving the following issues for confirmation with thecooperation of local municipal personnel, local district officers, land planning unions, etc., inorganizing the relevant information on land, houses, etc.
Some house drawings were very old or did not exist.
A particular stakeholder could have more than one piece of land and more than one
house. It took time to consolidate registered owners to one name for identifying what
properties were actually owned by that particular stakeholder.
There were diverse cases with complicated relationship of rights, possibly because ofinheritance: more than one owner had the right to one piece of land; registeredinformation had not been revised after the death of stakeholder(s); a person or persons
different from the registered owner(s) used and managed a piece of farmland for
agricultural activities. In particular, it took much time to identify stakeholders andacquire their consent in a situation in which the stakeholders were not living at thesite.
2）Property surveys prior to decontamination work
It was necessary to identify in the document of consent the target objects to be
decontaminated by photos, drawings and other means. Therefore, decontamination business215

operators conducted radiation monitoring surveys and damage surveys of buildings as part oftheir advance property surveys (field surveys) ahead of the drafting of the document ofconsent prior to decontamination work.
Decontamination methods to choose depend on the target object to be decontaminated and,the materials and state of the object’s surfaces. As part of the radiation monitoring survey,
measurements were made at selected points which could represent each target object to be
decontaminated in the survey area.
It was necessary to confirm with the stakeholders the status quo of buildings and otherproperties prior to conducting the decontamination work. Given that they might have been
completely or partially destroyed, or partially damaged due to the earthquake and tsunami,
the state of damage to each building was visually inspected by qualified architects or
emergency risk assessment officers, and photo records were prepared for each building
subject to decontamination.
Prior consent was needed to enter the private land for advance property surveys (fieldsurveys) ahead of decontamination work and the surveys could be conducted only where it
had been granted.

（2） Drafting the document of consent
Personnel of the MOE or a private business commissioned for acquisition of consent
prepared the “Building Current Condition Diagram,” which used photos to explain to eachstakeholder the appearance of buildings and damage conditions, and the “Decontamination
Plan,” which showed the buildings and the scope of land subject to decontamination and thedecontamination methods to be used.

Figure 4-16 Example Decontamination Plan108.

（3） Arranging special considerations, visiting the site
Upon drafting the document of consent, the stakeholder(s) was (were) invited to the site,

108Source: "On-site explanation of the Decontamination Plan and request for understanding of

implementation for decontamination work" (http://www.katsurao.org/uploaded/attachment/6.pdf ) (Figure
4-17 to Figure 4-18 have the same source.)216

where the drafted document of consent was explained and the scope of the decontamination
work was checked against the actual property. The stakeholder(s) was (were) then consulted
on any special conditions for decontamination, the items that they wanted to include in theliving spaces for decontamination (e.g., shrines built by ancestors on a nearby hill, mountainstreams, access paths thereto, etc.) and the items that they did not want to decontaminate(gardens with garden trees and moss that had important personal meanings to thestakeholder(s)). Once all these were arranged, they were appended as special conditions in thedraft document of consent (if necessary, the contents in the draft document of consent wererevised).

（4） Acquisition of consent
When the stakeholder(s) could confirm the contents of the “Building Current Condition
Diagram” based on its explanation using photos, the appearance of the buildings and thedamage conditions, they were asked to sign and affix their personal seal to the “Current
Conditions Report” (Figure 4-17). Further, when the consent was obtained to implement
decontamination work in line with the scope of the target buildings and land and thedecontamination methods thereof set out in the “Decontamination Plan” (including special
considerations), stakeholders were asked to sign and affix their personal seal to the“Decontamination Implementation Consent Form” (Figure 4-18).
Stakeholders were asked to sign and affix their personal seal to the consent forms at thesite, but in some cases follow-ups were needed when they wished to consult with their familyor neighbors. There were also cases, in which their consent could not be obtained due todissatisfaction with decontamination methods or other reasons.

217

Figure 4-17 Example of Current Conditions
Report.

Figure 4-18 Example of Decontamination
Implementation Consent Form.

（5） Post-work reports
Upon completion of the decontamination work, a post-work report was made on the work
results based on the decontamination implementation plan. Post-work radiation monitoring
was carried out immediately after the work completion in order to prepare for checking
afterward whether the decontamination effect was maintained. With this, thedecontamination work was considered to have been completed, but radiation monitoring was
carried out thereafter on an ongoing basis.
In the meantime, sometimes difficulties arose with stakeholders originating from gaps
between their expectations and the realities of decontamination work. Basically, these gaps inunderstanding should be solved through resident briefings and the decontamination consent
acquisition processes, but actually there were cases which could not be solved; radioactive
cesium could not be completely removed due to the conditions of the land in use and thelimitations of decontamination methods used, or complete recovery was not possible after
topsoil removal of agricultural land or the felling of ornamental garden plants. The following
are some typical examples of issues raised by stakeholders from these gaps in understanding.
There were locations where radiation doses did not decrease even after thedecontamination work had been done.
Some areas were not decontaminated, which included steep slopes and the like.
No decontamination work was done if radiation doses were low before the work.
Trees and branches were not cut down.
Tiles were not replaced with new ones.
Decontamination work did not recover the land to the condition suitable for commercial
agriculture use.
Unwanted household goods were not removed as trash.
Houses damaged by the earthquake and tsunami were left as they were being218

contaminated by radioactive materials. They should have been dismantled andremoved, since they could not be used.
If decontamination work were to be done beyond pre-defined standards at the request ofparticular stakeholders, such exceptional service could impact the implementation of theentire decontamination project in terms of the relationships with other stakeholders. Steps
were taken for work supervisors themselves, not the decontamination workers, to listen to
the stakeholders’ claims, consult with MOE supervisors on decisions and leave a record of
the decisions, in order to ensure consistent and rational decisions concerning the project asa whole.

219

4.3.2. Efforts Made by Decontamination Business Operators
Tamura City could undertake advance surveys and consent acquisition activities ahead ofother municipalities, as described before. The MOE personnel involved themselves in these
activities, and the knowledge and experience they obtained were then used and reflected in
the work in other municipalities. In some other cases, private entities commissioned by the
MOE carried out advance surveys, field surveys and consent acquisition activities prior to thedecontamination work ordered by the MOE.

（1） Advance surveys
In some cases, private entities (e.g. entities having measurement technologies or IT/dataprocessing technologies) carried out advance surveys upon consignment by the MOE, before
decontamination work in the Special Decontamination Areas was started upon order of the
MOE. In one example, the data relevant to land and houses were processed, using GIS
technologies in the procedures shown below. By creating a database, the next steps of fieldsurveys and preparation and distribution of the document of consent were carried out more
efficiently.
Creating ortho-images for the target area, with roads, coverings, vegetation, land andhouse outlines in a scale of 1/1,000.
Assigning building management numbers for each building on housing maps.
Creating residential boundaries (in units by land ownership) using ortho-images andlot number maps.
Extracting the lot numbers of buildings from existing lot number maps, and matchingthem with housing tax master maps to compile building data and attribute data109（2） Field (site) surveys
In some cases, private entities (e.g. entities having GIS technologies) implemented field(site) surveys, upon consignment by the MOE, before decontamination work in the Special
Decontamination Areas was started upon order from the MOE .
Some entities used PDAs (personal digital assistants) equipped with GPS and input map
information in advance into the PDAs so that on-site the survey workers could more
efficiently input any additional information obtained as they conducted their field surveys109.

（3） Consent acquisition activities
There were also cases where the MOE commissioned private businesses (for example,
environment consulting companies) to conduct consent acquisition activities in parallel withthe decontamination work ordered by the MOE110.
Specifically, private business firms commissioned by the MOE conducted the following
activities under the guidance and supervision of the MOE Fukushima Office forEnvironmental Restoration.
Notifying stakeholders of the results of advance survey activities.
Investigating views on methods for local briefings and other procedures in relation toconsent acquisition.
Arranging schedules for local briefings.
Acquiring consent from stakeholders for decontamination work.
109Source: Asia Air Survey website "Environmental Rehabilitation Assistance Efforts"(https://www.ajiko.co.jp/dl/pdf_tf2014/p12-15.pdf)
110Source: Namie Town "Request for Cooperation in Acquiring Consent for Kitatanashio Administrative
District Decontamination Work" (http://www.town.namie.fukushima.jp/site/shinsai/20140501-01.html )220

4.4. Communication with Local Residents and Local Municipalities
This section presents an overview of challenges, means for solving them, measures taken,
etc. with regard to communication between the MOE, decontamination business operators,
local residents, local governments, etc. in relation to the decontamination work ordered in theSpecial Decontamination Areas by the MOE.

4.4.1. Securing Temporary Storage Sites
Securing temporary storage sites involved a number of challenges and much time to settle,
as it required the understanding of landowners and local residents in order to proceed. This
was the same in Intensive Contamination Survey Areas as it was in Special Decontamination
Areas. The following challenges were encountered in securing temporary storage sites.
Questions over why TEPCO or the National Government did not receive soil and otherthings removed.
Concerns over the safety of temporary storage sites.
Concerns about the possibility that the temporary storage sites would end up being
used as disposal sites without such an agreement having been finalized.
Doubts that even if a temporary storage site was necessary, it would be used for storingsoil removed from other areas, too.
The MOE investigated the feasibility and coordinated the use of state-owned land for
temporary storage sites, and there were cases in which national forests were used as
temporary storage sites. But in many cases, that was not practical. Many state-owned forests
are designated by the Forest Act as forest reserves for conservation. In order to use this land
as a temporary storage site, relevant documents describing the state of trees and the current
state of the forest would have to be examined and necessary procedures would have to betaken to remove the land from designated forest reserves for conservation. Such procedures
needed a great deal of time and cooperation between relevant organizations. Furthermore,since the state-owned forests are generally mountainous, construction work was needed toflatten the land and new access roads needed to be developed and improved in some cases. It
took a very long time to prepare for use of a state-owned forest as a temporary storage site.
Furthermore, much of the secured land was sloped, resulting in less area available for storage.
In other cases, no sufficient place other than the constructed temporary storage site wasavailable for treating trees felled during construction and cut vegetation. Thus, the available
area for storing was reduced.

4.4.2. Launching of the “Decontamination Dial 110 (Hotline)” to Receive Information about
Questionable Decontamination WorkA contact point has been established to receive information by telephone or online fromlocal residents upon witnessing decontamination work that they suspected to beinappropriate (hereafter refferd to as the “Decontamination Dial 110 (Hotline)”).
The MOE checks the information received, issues cautions to decontamination business
operators if the information is correct, and provides explanation on handling of the matter on
its homepage.

4.4.3. Efforts Made by Decontamination Business Operators
The following issues were encountered in communication between decontamination
business operators and local residents or local governments in conducting decontamination
221

work in the Special Decontamination Areas ordered by the MOE.
It was important not only to reduce air dose rates in the living spaces bydecontamination work, but also to mitigate or remove the concerns of residents throughsincere risk communication.
There were many occasions where it was impossible to move forward unless thecooperation of local residents and local governments was available.
People could not be sure how much radiation dose rates would drop under the MOE
decontamination specifications, because there were no specific target values(standards) for radiation dose rates after decontamination.
There were requests not related to decontamination made at the time of site visits prior
to the decontamination start.
Residents could not be present on the decontamination site when the decontamination
work was ongoing. It was thus important for decontamination business operators to betrusted to carry out the items properly as agreed in advance at the time of site visits (noimproper decontamination work).
Reluctance of owners to let construction companies from outside of the area conductdecontamination work.
Indefinite terms for operating the temporary storage sites under unclear site
conditions.
Mass media and other news sources did not necessarily convey a complete picture ofdecontamination activities, or the detailed considerations of decontamination business
operators when dealing with the local community.
In response, efforts as described below have been taken by decontamination business
operators (Figures 4-19 to 4-28).
Pursuing residents’ understanding of the decontamination specifications through site
visits prior to the decontamination work start. MOE personnel joined the advance site
visits, and sincerely explained to them what could be done and what could not be done.
Presenting relevant information on homepages and in town papers jointly published incooperation with the town staff, as part of information disclosure on work status andprogress; these presentations were done with the consent of the ordering party.
Supporting local checks by residents (e.g., decontamination workers carried elderly
residents to site checks).
Opening resident consultation windows and call centers for decontamination work
matters, and sincerely responding to requests and questions from residents.
Arranging site visit tours of decontamination work in each district of a town where all
townspeople had evacuated.
Providing a “common room (chatting room)” and ”public restroom for townspeople”who
returned home on a temporary basis to the evacuation area.
Responding sincerely to residents who came to observe the work upon request andpermission.
Eliminating anxieties of residents by making the staff visible and accessible.
Communicating on a regular basis, building a relationship of trust through a build-up
from small things.
Volunteering to remove snow for home-bound elderly people in areas with heavy
snowfalls.
Holding social gatherings such as rice cake making or golf tournaments for residents
living in temporary housing.
Participating in, supporting and sponsoring events held in the area.
Conducting “blue light” (voluntary) security patrols.
Conducting patrols with safety patrol vehicles (including checks of litter), andpatrolling villages and residences.
Installing traffic safety banners at dangerous curves and narrow roads as traffic safetymeasures.
222

Decorating fences enclosing temporary storage sites with photos or having high school
students draw pictures in order to improve the image of the temporary storage sites.
Installing banners on roads in the decontamination work area, indicating that thedecontamination work was being carried out.

Figure 4-19 Removing concerns by face-to-face communication with responsible staff111.

Figure 4-20 Goodwill exchange with local
residents (example) 112.

Figure 4-21 Call center (example)113.

Figure 4-22 A town paper jointly publishedwith the town staff (example).

Figure 4-23 Homepage (example).

111Source: Taisei Corporation
112Source: Obayashi-Gumi Corporation

113Source: Maeda Corporation (Figure 4-22 to Figure 4-24 have the same source.)

223

・Institutionalizing a dedicated safety management system and patrol activities
・Institutionalizing a dedicated safety management system with executive classmembers of 3 JVs for proper safety and decontamination works
・Daily patrols by the system members
・Regular patrols by the personnel of head office and branch offices【Flow of safety patrols by the system members】
Safety patrols by thesystem members

Confirmationof ex-standardwork

On-site modification
after work
interruption

Special education
Re-confirmation ofwork procedure

Restart of work

Figure 4-24 Dedicated safety management system (example).

Security patrol by the personnel including former Fukushima
Prefectural Police Department personnel as key members(Appreciation prize awarded on December 28, 2012 andDecember 27, 2013)

A“Blue light”
security patrol car

Departure for security
patrolFigure 4-25 “Blue light” (voluntary) security patrol (example)114.

In-village patrol
Area to patrol: Katsurao village(crushing facilities and others)
Frequency: Sunday, all day long
Residence patrol
Dormitory for decontamination workers to patrol: 4placesFrequency: Monday to Sunday, unscheduled patrol
twice a day, from evening to mid-night at dormitories

Monthly security patrol (1st and 3rd Friday)
Area to patrol: Prefectural and national highways,
wide area agricultural roads

Security patrol car

Litter checks

Patrol route in a village

Figure 4-26 Safety patrol (example)115.

114Source: Taisei Corporation and Maeda Corporation

115Source: Okumura-Gumi Corporation (Figure 4-27 has the same source)

224

Security monitoring at adormitory fordecontamination workers

A banner for safe driving (in Katsurao village)
・21 banners at 9 places on 3 nearby highways
・30 banners at 14 locations on village roads/forest roads

Traffic safety banners inpoor-sighted curves(Shikiihata district)

Traffic safety moral-up campaign: Monday to Wednesdayof the first week every month
Traffic safety campaign week: attendance at the patrol
departure of the Tamura Police Station (September 20)
Traffic safety flyer (September 27)

Traffic safety moral-up
campaign

Traffic safety banners innarrow roads (Oozasa
district)

Traffic safety campaign
week: patrol departure

Figure 4-27 Traffic safety banners and activities to encourage good driving manners(example).
Paintings on loading and unloading places for the temporary storage site
Paintings on the fences for the sandbags working place for volume
reduction as part of decoration

Figure 4-28 Decorating fences surrounding temporary storage sites with colorful photos anddrawings (example)116.

4.4.4. Provision of Wide-ranging Information to Local Residents, and related activities
In moving forward with decontamination projects in the Intensive Contamination Survey
Areas, in addition to the Special Decontamination Areas, it was absolutely necessary to
respond to all kinds of concerns and frustrations of local residents about the decontamination
methods and work, and concerns about safety and other issues with regard to establishingtemporary storage sites. The MOE cooperated with Fukushima Prefecture and set up the“Decontamination Information Plaza” in January 2012, near Fukushima Station, in order todisseminate relevant information on decontamination and radiation and to provide anoperation base for experts to carry out informational activities. The Decontamination
Information Plaza has been promoting communication with local communities by providing
various exhibits and pamphlets, arranging workshops or opinion exchange meetings,
dispatching registered experts to local governments or communities upon request, or
responding to consultations from the local residents. The MOE has also made efforts tofacilitate people’s understanding through its website (Decontamination Information Site (inJapanese): http://osen.env.go.jp ) and a call center, and through information dissemination via
the mass media.
In JFY2014, the MOE joined in an advertisement project “Thanks, Helmet” arranged by the“ONE Fukushima” program by eight local mass media entities (newspapers, TVs and radio
broadcasting) in Fukushima Prefectre. This project was planned in order to eliminate
116Source: Maeda Corporation225

negative image toward the decontamination work and decontamination workers, and to
facilitate the understanding of local residents toward decontamination. In the project,“Thanks messages” being addressed to decontamination workers were solicited, mainly from
evacuees of Futaba District (Gun) and school pupils in Koriyama City (elementary schools
and junior high schools). The messasges expressed and conveyed their feelings of thanks andsupport to the decontamination workers. Those messages were distributed to thedecontamination workers in a form of stickers to be attached to their helmets (more than
1,000 messages were collected and more than 3,000 decontamination workers received them).
Many decontamination workers expressed their willingness to return their messages. They
responded in the form of sending large poetry cards with their return thanks messages,
donating planters, volunteer service of paining playing equipment, etc. to the schools. The
activities were widely disseminated through mass media in the prefecture. The project could
facilitate motivating the decontamination workers and raising their morales throughheart-warming communication with local residents and children.

4.5. Project Management Executed by Decontamination Business Operators
Decontamination business operators encountered various issues in implementing
decontamination and related works in the Special Decontamination Areas, upon orders being
placed by the MOE. The problem solving approaches taken by the decontamination business
operators and the ideas behind them are outlined below.

4.5.1. Schedule Control
There are snowbound areas in winter season in the Special Decontamination Areas. In suchareas, no decontamination works is scheduled during snowbound months because there are
special difficulties as listed below.
Big uncertainties cannot be avoided in air dose and surface dose density measurements
in snow-covered environment.
The quality of decontamination work may drop due to difficulty in confirming theeffectiveness of the work results in a snow environment.
The efficiency of surface soil removal work, weeding or other tasks drops because weeds
are knocked down by the snow.
Snow may attach to the soil and other things removed, and the added moisture causes
an increase in weight and volume.
Snow and ice melt when the temperature increases in temporary storage sites and thewater content oozes out and accumulates in the sites. Volume changes of the filled bags
at the sites will occur and may damage the cover sheets and other things.
Transportation by trucks on the slopes to the temporary storage sites in mountainousor hilly locations becomes impossible, and removed materials, which should betransferred to the temporary storage sites, must be left in the work areas.
Also when it rains more than a preset amount, the decontamination work is halted, because
rainfall causes uncertainties in air dose and surface dose density measurements; removed
materials may be carried away or swell and increase in weight; water contents ooze out andaccumulate in the temporary storage sites; rainwater accumulates in the temporary storagesites once the temporary cover sheets are removed for bringing in new waste materials, etc.
The project schedule had to be managed in consideration of those days when
decontamination work could not be done due to adverse weather conditions. Beside weather
conditions, following issues arose for schedule control.
Decontamination work should be completed the soonest in the living spaces.
There would be delays in obtaining residents’ consent and securing temporary storagesites.
226

Responses would need to be made to requests to complete decontamination of shrinesand graveyards before mid-August for O-bon.
Examples of measures to meet these conditions by one decontamination business operator
were:Intensive deployment of large workforce.
Workforce control depending on the decontamination work progress.
Schedule control subject to the request of the local communities.
large facilities
RemarkPreparatory works
Residential areas andthe like, large facilities
Farmland

Schedule overview

Decontamination
works halted due tosnowfalls
Phase

Preparatory
works

Forests, grassland,
lawns, etc.
Roads and the like
Temporary storage
facilities

Post-decontamination
work

Workers(people)Preparatory
decontamination ofgraveyards and shrines

More than 1,200
workers at
maximum

Planning
Results

Decontamination works

Graveyards,
shrinesAmount

Unit

1

set

Test trial

1

set

Fact-finding
survey171,100 piece

Preparation for
construction,planning

Decontaminationof forests andslopes
Decontaminationof residential
areas and the like
Decontaminationof roads
Decontaminationof farmland
Temporarystorage facility

673.5

ha

480 Cases
(80)

ha

(426)

ha

1

set

2013
3

4

5

6

7

2014
8

9

10

11

12

1

2

3

Radiation monitoring before and after decontamination works
Pruning – Sediments removal – Crushing (for volume reduction)
Preparatory decontamination ofstate roads and prefectural roads

Preparatory decontamination ofvillage roads and forest roads

Preparatory decontaminationof farmland
Construction of waterways – Sheet settings – Bringing in andsetting of materials and equipment for custody

Figure 4-29 Example of decontamination schedule117.

4.5.2. Operational Framework for Decontamination WorkAs was mentioned briefly in Chapter 4.2.4 (5), the issues encountered in thedecontamination operation include:
Large workforce of thousands (1,000 to 6,000) needed at one work site118.
Workforce management depended strongly upon the schedule and progress of
decontamination works.
Rapid turnover of workers.
Qualities of workers.
Obtaining the radiation exposure history and health conditions of workers upon
recruiting them.
For instance, there was a case in which the daily maximum number of workers needed was
1,200, far above the planned workforce at the beginning as shown in Figure 4-31, in thedecontamination work for an area with about 120 houses in a residential area, about
1,300,000m2 of farmland, about 1,900,000m2 of forests and about 96 km of roads. In suchcircumstances, the decontamination business operator took such measures as follows.
Promoting recruitment of local workers.
Employing local farmers (utilizing agricultural machinery already in their possession).
Recruiting workers nationwide.
Providing periodic and continuing education of new workers for the field work.
Providing full medical check-ups at designated hospitals with costs paid by the primarycontractor.

117Source: Kajima Corporation and Okumura-gumi Corporation (Table 4-30 has the same source.)
118 Examples:

About 2,700 workers were needed at the peak in a site of about 17,000,000 m2 fordecontamination work (about 470 houses as well as farmland, roads and other items were included), while
about 3,000 workers were needed in a site of about 14,000,000 m2 (including about 1,270 houses) or about
2,200 workers in a site of about 8,300,000 m2 (including about 1,180 houses).

227

Operational organization

Site Representative (Site Manager)

Integrated Office(43persons)

Deputy Site Manager

Section Head
( Otakizawa)

Section Head
(Chimijyou)

Section Head
(Baba)

Section Head
(Aiko)

Section Head
(Ogita)JV Staff

JV Staff

JV Staff

JV Staff

JV Staff

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

The area to decontaminate was divided into five (5) sections

Con
tract
ors

Section Head

Section Head（Roads, temporarystorage facilities）(Radiation related
matters)

JV Staff

JV Staff

Con
tract
ors

Con
tract
ors

Con
tract
ors

Con
tract
ors

＊One section was managed by 5 to 6 JV staff.
＊Total of 43 staff managed each office,including those for safety, engineering andadministration.

1work zone
(21persons)
Forest2work zone
(21persons)resident

3work zone
(21persons)
Forest4work zone
(17persons)resident

Kaminogawa

Kaminogawa

Kamikazurao

Kamikazurao

NogawaNogawaNatsuyu

Ochiai

Shimokazurao

Shimokazurao

IwakadoKouyachiDaihouOozasaNatsuyu

5work zone
(21persons)
Forest6work zone
(4persons)Temporarystorage

OchiaiJizousawa

KouyachiOozasaIwakadoDaihouFigure 4-30 Example of operational framework for decontamination work.

[Planned] total workforce: about 70,000
The site divided into five (5) sections.
About 100 workers per each of five sections,
totaling about 500 workers at daily maximum
・Difference in workload is outstanding inforests and others
・Small transfer to vehicles for transport(hand carry, by machines)
・To keep the goal of “completing
decontamination by the yearend”[Record] total workforce: about 120,000
The site divided into five (5) sections.
Daily maximum of 1,200 workers deployed for the site.
Figure 4-31 Example of recruiting and deploying workers (plan and result)119.

The prime contractor signed an employment contract with local farmers
for decontaminating their own farmland as decontamination workers
Time was needed to sign
the employment contract,
because of difficulty inreaching an agreement
in wages or conditions of
employment, or in
obtaining theirunderstanding of social
insurance or taxes.

Figure 4-32 Example of employing local farmers120.

119Source: Kajima Corporation

120Source: Obayashi Corporation

2284.5.3. Sharing of Information and Safety Precautions
One issue was how the relevant information and safety precautions could be sharedcompletely between many contractors and the large number of workers involved, not onlywith the primary contractors (some of which were Joint Ventures (JVs)) and their personnel.
The complete sharing of relevant information between relevant organizations was also achallenging issue. An example to solve such issues can be found in the following case for one
decontamination business operator.
Information sharing meetings were periodically held with relevant organizations
concerning the decontamination work, its progress and other relevant information.
Participating organizations were: the MOE Fukushima Office for Environmental
Restoration, local municipalities, the Labour Standards Inspection Office, police andfire stations, and the primary contractors (JVs).
Plenary or separate morning assemblies and daytime assemblies were regularly held
for thorough dissemination and sharing of information at different levels between the
primary contractors (JVs), subcontractors and individual work sections.

Progress review meetings
The project progress was regularly checked and relevant information wasshared between the Fukushima Office for Environmental Restoration, Naraha
Town, the Tomioka Labour Standards Inspection Office, Futaba Police
Station, and the relevant decontamination business operators.

Figure 4-33 Photo taken at a project review meeting121.

121Source: Maeda Corporation229

13:00Daytime
昼 Assembly
礼

11:30

Decontamination
作業間
Work Coordination
連絡調整会議Meeting
JV & First
Subcontractors
JV・一次協力会社

各工区で実施To be held at individual（JV・全協力会社）
sections (JV & all contractors)

Decontamination
除染作業
workers
従事者

17:30

JV
assembly
JV打合せ
8:00

Site
Manager, Deputy Site
所長・副所長Manager,
・各工区長Section Heads

Morning
朝 礼
Assembly
To be held at各工区で実施
individual
sections (JV （JV・全協力会社）& all contractors)

各工区毎の
Meetings
at
打合せ
individual
sections

Section Heads, JV Staff,
各工区長・JV職員
First
Subcontractor
・一次会社職長
ForemenFigure 4-34 Example flowchart of dissemination and sharing of information and safety
precautions122.
Some decontamination business operators prepared specific work procedures fordecontamination workers to refer to during actual work. These work procedures elaborated
on the decontamination methods presented in the Decontamination Guidelines, technicalspecifications and other relevant documents. The work procedures also provided
information concerning, not only the decontamination skills, but also the supervising
responsibilities of decontamination business operators, application methods of materials
and equipment of decontamination work, safety checks and precautions to be taken, andresponses to be taken in an emergency or unusual situations, etc.
These work procedures are updated based on experience and knowhow obtained from theactual decontamination work. When updated, actions are taken to disseminate the new
information to the decontamination workers on the job (for instance, holding a meeting fordisseminating and sharing the information).

Periodic education
By reviewing the updated work proceduresat the periodic education opportunities, theworkers’ understanding of work contents shallbe facilitated.

Upon noticing a flaw
while on duty,
updating of work
procedures shall beprompted

Work procedures update
JV OfficeRule formulation for updating work proceduresWork flows shall be clearly defined for
updating the work procedures, thus preventing
irrelevant work not included in the work
proceduresWork procedures updating flow
Standard dissemination flow ofwork procedures

Information dissemination
to JV staff for each section

Work halted

Contractors’ workers
ReportingContactors’ work leadersWork sites

Work procedures dissemination meetings
Whenever the work procedures are updated,a dissemination meeting shall be held witheverybody present
At the dissemination meetings, the work
procedures (Vol. 1, Vol. 2 and Common) shallbe used.

Information dissemination
to work leaders

ReportingUpdating work
procedures
Information dissemination todecontamination workers

Reporting・Consultation/coordination

Deputy Site Director andTechnical Supervisor

JV staff & Section HeadApproval
ReportingApproval

Holding a work
procedures
dissemination meeting

CustomerWork resumed

Figure 4-35 Example flowchart of information dissemination and sharing of updated work
procedures123.

122Source: Kajima Corporation
123Source: Maeda Corporation

230

4.5.4. Hiring and Separation Management of Workers
In the hiring and separation management (upon recruitment and upon separation) ofworkers, the decontamination workers are required by law, as mentioned earlier, to receive
internal exposure measurement for radiation protection and exposure control before and after
the employment by the decontamination business operators. For the internal exposure
measurement, the whole body counters (WBCs) installed by the MOE were available at nocharge to the workers and decontamination business operators.
Newly employed workers are to receive basic and special education upon beginning thedecontamination work, including:
To recieve internal exposure measurements by a WBC.
To receive eduction about decontamination and related works by using educationalslides, DVDs and the like.
To receive education on and learn the matters concerning safety principles, safety rules
and the like through lectures given by JV safety personnel at the site office.
To learn specific work procedures through attending the work procedures
dissemination meetings held at the site office, assembly halls, or the like.

Radiation education, WBC

Education: at Kajima Hirono Office,
WBC: Hirono Town, Naraha Town

Educational slides, Safety andsanitation educational DVD“Safety and sanitation manual fordecontamination work,” Special
education movie fordecontamination works, etc.

Education for fresh workers

at site office

Education by JV safety staff, Site safety
policyWorking procedures
dissemination meetings,
safety education

at site offices, assembly
halls, etc.

Working procedures dissemination meetings bycontractors’ foremen and JV personnel,
Dissemination of information on accidents relevant
to decontamination work, Education of safety rules

Figure 4-36 Example flowchart of education flow for decontamination workers124.

4.5.5. Protection from wildlife
Concerns about protecting from wildlife also existed. There were cases in which
decontamination business operators removed beehives and had to prepare protective
equipment and medications in advance, or they consulted with the municipal offices for how
to deal with livestock such as cows that had been abandoned by owners when evacuation
orders were given.

124Source: Kajima Corporation

2314.6. Radiation Protection Measures
4.6.1. Ionizing Radiation Ordinance for Decontamination
As mentioned earlier, the Ministry of Health, Labour and Welfare (MHLW) issued the“Guidelines on Prevention of Radiation Hazards to Workers Engaged in Decontamination and
Related Works” on December 22, 2011, as the measures required to ensure the safety ofworkers, in combination with the Ionizing Radiation Ordinance for Decontamination (TheGuidelines were partly amended on June 15, 2012.). The Guidelines specify the following:
personnel subject to exposure dose control; methods of control administration of exposure
dose measured; measures to decrease exposure dose; measures to prevent contamination fromspreading; measures to prevent internal exposures; education for workers; measures toensure health; and safety and sanitation management system.125
In the decontamination work, radiation protection measures are provided to thedecontamination workers pursuant to the Ionizing Radiation Ordinance for Decontamination.
The MOE arranged the following measures in order to ensure that decontamination workers
and operators observed those measures set in the Ionizing Radiation Ordinance for
Decontamination.
Holding workshops for potential decontamination workers.
Stipulating in the decontamination order contract the condition that thedecontamination business operators must observe the Ionizing Radiation Ordinance for
Decontamination.
Preparing methods to estimate necessary expenditures and reserve budgets fornecessary equipment for radiation protection.
Requiring decontamination business operators to include relevant descriptions
concerning technological concepts of workers’ radiation protection in thedecontamination plan documents when applying for National Government work under
direct jurisdiction of the MOE.
In the meantime, the decontamination business operators took the following measures forradiation protection.
When designating a new decontamination work area, the air dose was measured before
workers engaged in the decontamination work. If micro hot spots were recognized, they
were clearly so indicated by markings or setting fences, or the access to the hot spots
was controlled.
Where the air dose rate exceeded the level to cause 50 mSv/y, the workers were
instructed to wear full-face masks, protective clothing and other items in order toprevent dust containing radioactive materials from attaching to the workers.
In work areas, where the air dose rate was below the level to cause 50 mSv/y, too,
workers were instructed to wear half-face masks.

4.6.2. Surface Contamination Inspection (Screening)
The Ionizing Radiation Ordinance for Decontamination obligates decontamination business
operators to conduct surface contamination inspections (screening) in order to prevent
contaminants containing radioactive nuclides from being brought out from the work areas.
The difficulty in the actual screening operation was to conduct the screening inspections fora large number of workers, particularly at some specific time periods (lunch time, at the endof the day, etc.). There was a case in which the screening process was automated for better
efficiency and worker-power saving at the times for breaks, lunch or the end of the day.
In measuring the surface contamination densities, as mentioned in 4.1.3 (5) 1), it isrequired to use surface radiation contamination survey meters which meet the performance
125Source: Ministry of Health, Labour and Welfare (MHLW), Guidelines for Prevention of Radiation Hazards

for Workers Engaged in Decontamination and Other Radiation Works (June 15, 2012)232

requirements and other conditions specified in JIS Z 4329 and the measured data by such
survey meters are to be recorded as the counting rate (cpm). In reality, however, the data
varied among measurement devices depending on their respective measurement efficiencies
and areas of measurement.

Screening facility at the
Tomioka Town gymnasium(place for recess)Finger print
authentication device

Figure 4-37 Photos of workers undergoing automatic screening126.

4.7. Education and Health Care for Decontamination Workers
4.7.1. Education of Workers
Decontamination work does not usually require ordinary workers to be highly experienced
or have special skills; although it is true that only certified workers with particularqualifications or skills may be engaged in operating heavy machinery for carrying heavy
objects or scraping soil off, transferring wastes, etc., or for tasks done at high places using
aerial lifting equipment, such as needed in washing and wiping processes for roofs and others.
But even ordinary workers are required to understand the basics of decontamination andfollow the pre-determined working procedures. Otherwise, the expected decontamination
effects may not be obtained, the decontamination effects may even drop, the amount ofmaterials to remove may increase or even trouble may take place with the local residents.
Furthermore, it was foreseen that most of these ordinary workers had no prior experience indecontamination and lacked knowledge or experience in radiation protection.
Before the Great East Japan Earthquake, ordinary citizens in Japan did not usually haveknowledge of radiation nor were they familiar with decontamination. It was impossible tosecure a large workforce consisting of workers who had had experience and knowledge about
radiation and decontamination.
Certain qualities are also required of decontamination workers, not only their availability
in large numbers. Education was the only way to foster knowledge about decontaminationand promote the necessary qualities among the workers. Before commencing decontamination
works, the decontamination business operators provided new workers with basic and special
education pursuant to the Ionizing Radiation Ordinance for Decontamination. In addition,
workshops, training and other activities were periodically held about safety as well as daily
morning activities on risk potential prediction and mutual checks of protective equipment
before commencing the day’s work. Other activities included collection of success stories andfailures in order to develop the workers in broad areas. The decontamination business
operators promoted special education smoothly and easily using educational movies on theYouTube produced by the MHLW for decontamination and related works. Workshops on
126Source: Kajima Corporation

233

decontamination work arranged by the Fukushima Prefectural Government and MOE for theworkers and work leaders also facilitated the education activities done by thedecontamination business operators.
Education activities should be repeated. Decontamination methods and knowhow of site
works are improved day by day. Successful experiences as well as failures, near-miss casesand other experiences from work sites were used for ensuring safety through periodic
education opportunities after decontamination work was started by new workers. A system
was developed that allowed supervisory personnel to check on-site that each worker took
notes when attending the education activities, submitted reports after workshops andrecorded their attendance at the educational programs on their worker ID cards.
The following are examples of educational programs conducted for decontamination
workers127.

127Source: Maeda Corporation (Figure 4-38 to Figure 4-44 have the same source.)234

（1） Educational programs upon beginning the jobs
1）Safety education for newly employed workers
Safety education for newly employed workers included: explanation of the jobs to do using
flowcharts, safety policies at the work place; basic rules of safety and sanitation; activities
relevant to safety and sanitation; safety rules when on duty; instruction to be checked using
the WBC; and items to consider with respect to residents.
Program

Key contents

1

Confirmation of employment
contract

Confirmation of the company to belong to, minimum wages, special
duty allowance, medical checks

2

Outline of the jobs

Explanation of an outline of jobs to do

Safety policies at the working
place

Explanation of safety policies at the working place
Prevention of falling down
Prevention of minor collision between men and heavy machinery
Prevention of minor collision between men and mowers
Radiation and health cares
Other related topics

4

Basic rules of safety andsanitation

Explanation of basic rules of safety and sanitation
Consideration to give to local residents
Dose measurements and contamination inspections
Safety equipment
Practice to carry Identification Card and armband
Information on work plans and work procedures
Smoking, eating and drinking
Responses to take when injured
Traffic rules

5

Activities relevant to safety andsanitation

Explanation of activities relevant to safety and sanitation

6

Tidiness and order

Explanation of the rules to keep working places tidy and in order

7

Risk potential prediction “KY”

Explanation of the process to predict risk potential for sharing
KY: an acronym of “Risk potential prediction” in Japanese)

8

Harmonization with thecommunity

Explanation of consideration to give to local residents

9

Safety rules on duty

Explanation of “22 musts in safety rules” which assembled the cases
experienced and the results found during patrol for each of selected
cases

10

Instruction to receive WBC
checksInstruction of receiving the WBC check and considerations to give.

3

Figure 4-38 Example program of safety education for newly employed workers.

2352）Safety and work education
Safety and work education is conducted by: (i) clarifying concrete work procedures and key
items to ensure safety at the workplace; and (ii) providing a safety manual, which collectedcases of experience and results found during patrols and compiling the information into
“mandatory workplace safety rules.”2. Working policy at workplace
Provide sufficient qualities to meet expectations of the customer and local communities in reliability, credibility andsatisfaction by the work with due consideration to the environment. The work is based on the concept of “Quality first”
and “Customer first” with the fundamental philosophy of “Grasp the customer’s credit by the work in good quality.”
Achieve zero disaster over the whole period of work by upgrading motivation of the personnel and workers toward
safety.
Key execution items for safety at the workplace
1. Prevention of falling down
・To secure the safe working floor and to wear a safety belt and fall arresting devices/equipment fora fixed rope (Brand name Rolip, for instance) when working at an elevated place.
・To fix the ladder and to prohibit a stepladder
2. Prevention of minor collision between men and heavy machinery・To designate the “Keep out” zone around the machine operation area before commencing the work
・To arrange a traffic controller and a guard
3. Prevention of minor collision between men and mowers
・To keep out of the dangerous zone (5m from the mower, 15m between mowers)
・Mutual calls of attention
4. Radiation control and health care・To wear dust masks
・To practice gargling, hand washing・To practice routine conditioning of body rhythm
5. Not to give any concerns to the local people

Figure 4-39 Example chart of work policy posted at a workplace.

Safety rules for decontamination①Rules for drags for cart wheels⑪Rules for scaffold elevators (1)②Rules for construction vehicles (1)⑫Rules for scaffold elevators (2)③Rules for construction vehicles (2)⑬Rules for using stepladders④Rules for working with heavy machinery⑭Rules for using roof Rolip and fixed ropes (1)(note) Rolip (a brand name of fall arresting
device/system for a fixed rope)⑤Rules for access to heavy machinery⑮Rules for using roof Rolip and fixed ropes (2)⑥Rules for the temporary storage facility and others⑯Rules for water supply⑦Rules for unifying wireless (voiced) call signs⑰Rules for the temporary storage facility⑧Rules for working shoes⑱Rules for garbage trucks⑨Rules for using knives⑲Rules for seat belts when using construction
machinery of vehicle type

⑩Rules for using mowers⑳Rules for iron plate floors for cranes⑰Rules for the temporary storage facility (3)1) Fix a rope at 1m from the end of sandbags when stacked in three layers or more.
2) Use a tensioner to fix a rope with a strong bracing cableby implantation single
tubes or the like3) Set a fulcrum point at the middle on the longitudinal direction
4) Set stepping structures/steps on the aisle side and inside5) Workers on duty wear safety belts and connect them to the fixed rope whenworking near the end (to) of sandbags stacked.

⑳Rules for iron plate floors for cranes
Use iron plate floors of 5x10 (1.500mmx3,000mm)
or bigger below outriggers for the cranes ofsuspension weight of 50t or more.
Iron plate floors of
1,200mmx1,200mm orbigger are exceptionallyacceptable only when to set
the cranes on the horizontal
and hard places covered
with crushed stones.

Figure 4-40 Example chart of safety rules for decontamination work.

3）Dissemination of information on work plans and work proceduresWork procedures are based on manuals for individual tasks and disseminated at meetings
for that purpose.

2364）Proper decontamination education
Education for items to note in proper decontamination is conducted at the start of a new job
as well as at the time of regular safety education.

5）On-site education
For better understanding by workers, practical training is implemented on-site.

Figure 4-41 Photo of workers getting practical training at a work site.

6）Other related matters
Special education for decontamination work, which is legally compulsory, is conductedbased on the “Materials for Special Education on Decontamination and Related Works”(Compiled by the Health Measures Office for Ionizing Radiation Workers, MHLW), separate
from the education for newly employed workers. Theoretically, respective contractors should
provide such education to their workers, but the primary contractors (JVs) directly provided it
to all workers as their responsibility.
Newly employed workers wear a special band on their helmets for the first week of work foreasier identification; and responsible personnel and work leaders promote continuous
education and training.

Figure 4-42 Photo showing a newly employed worker wearing the special helmet band foreasier identification.

237

（2） Periodic safety education program
Through providing periodic safety education opportunities, workers are reminded
repeatedly about safety-related items and a safety mindset is strengthened by repeating theitems to note, checking seasonal concerns (e.g., freezing in winter) and exchanging opinions
on safety among workers.

Safety Education (January)① Hazard cases of other companies, other locations, etc.
② “Let’s find risk potential I”(Text by the Head Office, Maeda Corporation)③ Safety DVD “Six legal obligations which nobody can overlook”④ “Let’s find risk potential II”(Text by the Head Office, Maeda Corporation)⑤ Coffee break⑥ Reminding the safety rules at the working place⑦ About proper decontamination⑧ Wages are received appropriately?
⑨ Let’s drive safely this month⑩Prevention of radiation hazards
Maeda & Kounoike JV(Additional responses to decontamination and related works)(12:00 to 16:00 on January 23 and 24)

Figure 4-43 Example of a periodic safety education program.
Issues in providing education for workers included the following.
Among managers and other employees on practical level (foremen, workers) of thedecontamination business operators, there were few decontamination experts who
could be instructors. There were also few persons who were knowledgeable about
radiation and could be instructors.
Quite a few workers had no field experience in civil engineering or construction work.
Education on basic safety management, which is quite common at such work places,
was also needed.
Safety education of workers was especially important, because the work environment
could not be simplified or made uniform due to the size and diversity of the work areas,
for instance, house roofs, forests, slopes, roadside embankments, etc.
A large number of workers had to be educated.
To cope with such difficulties, the following efforts were made by decontamination business
operators.
The decontamination business operators’ personnel were engaged in educating workers
while learning themselves.
Education was conducted every day to a group of about 100 workers.
Engagement of the decontamination business operators’ personnel themselves indecontamination work functioned as an effective education system.
Merit awards were given to conscientious workers.
Video films or other illustrated materials were used for facilitating easy learning.
Group leader training was practiced as the best model group. This training facilitateddecreased quality differences among groups and improved skills of the leaders.
Periodic meetings were organized to exchange opinions between group leaders.
Periodic study meetings were organized for workers.
Patrols and inspections were made by the quality manager and model group leaders.

238

Periodic education program
Continuous education shown in the flow below.
Education was conducted every day to a group of about 100 workers
Education flow of workers
Month 0Month 1Month 2Month nSafety education for
fresh workers

Periodic safety
education

Periodic safety
education

Periodic safety
education
Education on safety andwork rules

Special education on
decontamination

Education on safety andwork rules

Education on safety andwork rules

Education on safety andwork rules

Elaboration on work
procedures

Elaboration on work
procedures

Elaboration on work
procedures

Elaboration on work
procedures

Education on proper
decontamination

Education on proper
decontamination

Education on proper
decontamination

Continued education ofwork leaders

Continued education ofwork leaders

Continued education ofwork leaders

Education on proper
decontamination
Site training

Figure 4-44 Example flowcharts of educational programs for decontamination workers.
Education by using video films and illustrations for easy learning
Education is provided to all workers whenever fresh workers join, or work
contents or working areas are changed, by using video films or illustrations
which elaborate on work procedures in an easily understandable manner.
Decontamination procedures are well disseminated to the workers because
the materials are compiled in an easily understandable manner.

Figure 4-45 Example of an education session for decontamination workers by using video
films or drawings128.

Figure 4-46 Example scenes of safety activities129.

128Source: Shimizu Corporation
129Source: Maeda Corporation

239

4.7.2. Morale and Conscientiousness of Workers
Decontamination work is more or less similar to cleaning work, being different fromordinary civil engineering or construction work to build structures. Decontamination workers
cannot easily get the pleasure of achievement obtained by producing something or completing
construction of something. It is a concern that decontamination workers may be demoralizedin conducting huge numbers of boring tasks while paying attention to radiation protection.
Such factors may cause deterioration in the quality of the decontamination work.
On the other hand, decontamination workers were encouraged by the responses of local
residents to the outcome of decontamination work such as weeding, soil scraping or soil
replacement. In such decontamination work, the apparent changes led to the people’s positive
responses: “Fields looked nicer after decontamination”; or “Fields helped me recover hope toreturn home, when weeds fully covering the fields were removed and the surfaces of rice fields
and dry fields became visible after decontamination.
In the earlier stage of MOE decontamination works in the Special Decontamination Areas,
the needs of the decontamination workforce were limited and a significant portion of
decontamination workers were local residents under contract. They had high morale and wereconscientious with clear aims to decontaminate their own land. It can be said that theybrought about good tension in the work groups.
One decontamination business operator placed importance on sharing empathy with thelocal residents and developing teamwork spirit among decontamination workers. The
operator took the following measures in order to upgrade the quality of decontamination workby clearly identifying the objective of the work as recovering environmental conditions for the
residents to return home.
Expressing strong hopes toward restoration by placing banners in public places.
Reading slogans about the decontamination work out loud, with all workers responding,at daily morning assemblies.
Encouraging mixing with other work group members at safety campaign events.
Facilitating understanding of the construction workers (primary contractor’s personnel,
secondary contractors’ personnel and other workers) toward restoration by having
them live in the area to be decontaminated and arranging for them to mix with thelocal people.

Figure 4-47 Banners expressing hope and progress toward restoration of the area130.

130Source: Taisei Corporation

240

Figure 4-48 Photos showing daily morning assemblies with reading of a slogan and responseby all workers131.

4.7.3. Personal Exposure Dose Management for Workers
For external exposure dose management, some decontamination business operators used,besides personal dosimeters, the access management system and other systems connected tothe air dose measurement in the workplaces. Specifically, individual workers wore personal
dosimeters, and read the indication before and after the day’s work for measurement of the
exposure dose for that day. The measured data were processed together with the information
stored in the database and used for personal exposure dose management.
For internal exposure dose management, WBCs were used. Decontamination workers are
required to receive periodical medical checks for ionizing radiation when engaged indecontamination and related works as well as the WBC measurement for internal exposure
management. Decontamination workers are also required to receive such checks upon
employment, upon transfer to different work locations and every six months. The measured
data were processed together with the information stored in the data base and used for
personal internal exposure dose management.
Figure 4-49 illustrates the results of personal cumulative exposure dose of decontamination
workers in decontamination model projects in the Difficult-to-return Area (the area where itis expected that the residents have difficulties in returning for a long time). The
decontamination model projects in the Difficult-to-return Area were conducted in Futaba
Town and Namie Town where the air dose rate before decontamination had been as high as
the level to cause about 50 to 100 mSv per year. Protective measures were taken such as not
to have particular individuals work in high dose areas for a long time. Consequently, themaximum average personal exposure was 71.5 μSv/d over the work period of September 1,
2013 to February 22, 2014. This shows that, even if the person continues to work undersimilar conditions for 240 days (the average work days per year), the cumulative personal
exposure dose would be 17.2 mSv, not exceeding the legally set annual dose limit of “100 mSv
per five years AND 50 mSv per year.”

131Source: Shimizu Corporation, Maeda Corporation

241

Total number of workers

An open public spacein Futaba Town
Futaba Kosei General
Hospital

number of workers

Futaba Kindergarten
Ide District
Oobori District
Akougi Districtday

Figure 4-49 Example graph showing personal cumulative exposure dose of decontamination
workers(From the decontamination model projects in the areas where it is expected that theresidents have difficulties in returning for a long time)132.

4.7.4. Medical Checks for Ionizing Radiation and Use of Whole Body Counters
The MOE opened two WBC Inspection Offices, one in Minami-soma City and the other in
Naraha Town (having been moved to Tomioka Town) in order to make sure that workers of thedecontamination business operators received WBC measurements before and after
employment.

132Source: Ministry of the Environment (MOE), Results of decontamination model projects in areas where it isexpected that the residents have difficulties in returning for a long time (June 10, 2014)(https://josen.env.go.jp/area/model2.html ) (in Japanese)242

5． Effects of Decontamination
5.1. Evaluation Pertaining to the Goals of the Basic Policy
The Basic Policy based on the Act on Special Measures Concerning the Handling ofEnvironmental Pollution by Radioactive Materials Discharged by the Nuclear Power Station
Accident Associated with the Tohoku District Off the Pacific Ocean Earthquake That
Occurred on 11 March (hereafter refer to "Act on Special Measures") sets the goals for themeasures for decontamination (Figure 5-1) and the Ministry of Environment (MOE)published the "Evaluation of the Goals of Basic Policy" in December 2013.
Basic Policy Based on the Act on Special Measures (excerpt)(2) The following goals are set for the region with an additional exposure dose of less than 20
mSv/y.
a. The additional exposure dose of 1mSv/y or less shall be targeted as the long-term goal.
b. By the end of August 2013, the annual additional exposure dose of the general public shallbe decreased by about 50% as compared with the value at the end of August 2011, by physicalattenuation of radioactive materials and other effects also being taken into account.
c. It is important to restore the environment for children’s life with peace of mind.
Decontamination of children's living environments such as schools and parks shall be
implemented with high priority, and by the end of August 2013, the annual additional
exposure dose of children shall be decreased by about 60% as compared with the value at theend of August 2011, considering physical attenuation of radioactive materials and othereffects.
Figure 5-1 Basic Policy based on the Act on Special Measures133 .

5.1.1. Facilities Subject to Evaluation
The evaluation was implemented covering about 33,000 facilities (about 12,000 facilities inSpecial Decontamination Areas; about 21,000 facilities in Intensive Contamination Survey
Areas) and at about 330,000 measurement points (about 100,000 points in Special
Decontamination Areas; about 230,000 points in Intensive Contamination Survey Areas),
where the decontamination work had been carried out by the end of August 2013.
SchoolSpecial Decontamination Area
Facility no.

Measurement points no.

Measurement points no.

Housing

Otherfacility

24

123

4,645

Intensive Contamination
Survey Area

2,229

1,980

12,513456

Special Decontamination Area

494

949

61,9801,785

Intensive Contamination
Survey Area

36,136
Road

Facility no.

Park, Square

41,286
Forest153

121,741

4,268

Farmland

Pasture
land

Total

Special Decontamination Area

1,792

2,319

3,204

111

12,371

Intensive Contamination
Survey Area

1,220

940

1,633

97

21,068Special Decontamination Area

18,274

9,541

10,764513

104,300

Intensive Contamination
Survey Area

8,496

2,678

10,404

2,919

227,928＊ Special Decontamination Area･･･Tamura City, Kawamata Town, Kawauchi Village, Naraha Town, Okuma Town,
Katsurao Village, Iitate Village ( However, the measurement result of the data more than 3.8 μSv/h have been excluded)

Figure 5-2 Numbers of facilities and measurement points to be evaluated concerning the
reduction of additional exposure dose134 .
133Source: Ministry of the Environment (MOE), Basic Policy Based on the Act on Special Measures

Concerning the Handling of Radioactive Pollution, December 2011
134Source: Ministry of the Environment (MOE), "Evaluation concerning the goals of basic policy," December

2435.1.2. Basic Approach of Evaluation Methods
The air dose rate at the end of August 2011 was estimated from the air dose rate measured
before decontamination and the air dose rate at the end of August 2013 was estimated fromthe air dose rate measured after decontamination. The evaluation for each classification offacilities was done by integrating the air dose reduction rate by decontamination and the
reduction rate by physical attenuation of radioactive materials and other effects.
It should be noted that the Basic Policy set its goal on the reduction of additional exposure
dose. However, the additional exposure dose cannot be directly measured. The evaluation was
done instead, on the assumption that the exposure dose was proportional to the air dose rate
(Figure 5-3).

Figure 5-3 Basic concept of evaluation methods.

5.1.3. Evaluation Methods and Results（1） Annual additional exposure dose of the general public
1）Evaluation methods
The average additional radiation exposure dose was calculated for each facility
classification* by estimating the air dose rate at the end of August 2011, using themeasured values on a day before decontamination.
The average additional radiation exposure dose was calculated for each facility
classification* by estimating the air dose rate at the end of August 2013, using themeasured values on a day after decontamination.
The additional annual exposure dose was estimated as the total of the dose rate
multiplied by a coefficient defined for each classified facility subject to life patterns.
* Concerning roads or forests, each unit divided by facility numbers in the investigation
was dealt with as one facility. Evaluation of additional annual exposure dose of children
was done in the same way.

2013 (Figure 5-3 to Figure 5-7 have the same source.)2442）Evaluation results
The goal of reducing the additional annual exposure dose was evaluated as having beenachieved, as seen in the overall reduction rate of about 64% over the two year period (Figure
5-4).

Additional exposure
dose (%)
Goal
SpecialDecontamination
Areas
Intensive
Contamination
Survey Areas
Overall

Contribution ofphysical attenuation
effect (%)

about 50
about 67

Contribution of
decontamination effect (%)
about 10
about 27

about 40

about 62

about 22

about 64
about 24
Figure 5-4 Evaluation results of reduction rate over 2 years(Annual exposure dose of the general public)（2） Annual additional exposure dose of children1）Evaluation methods
The average additional radiation exposure dose was calculated for each facility
classification* by estimating the air dose rate at the end of August 2011, using themeasured values on a day before decontamination.
The average additional radiation exposure dose was calculated for each facility
classification* by estimating the air dose rate at the end of August 2013, using themeasured values on a day after decontamination.
The additional annual exposure dose was estimated as the total of the dose rate
multiplied by a coefficient defined for each classified facility subject to life patterns.
2）Evaluation results
The goal of reducing the additional annual exposure dose was evaluated as having beenachieved, as can be seen in the overall reduction rate of about 65% over the two year period(Figure 5-5).

Goal
SpecialDecontamination
Areas
Intensive
Contamination
Survey Areas
Overall

Reduction of
additional exposure
dose (%)
about 60
about 66

Contribution ofphysical attenuation
effect (%)

Contribution of
decontamination effect(%)
about 20
about 26

about 40

about 64
about 65

about 24
about 25

Figure 5-5 Evaluation results of reduction rate over 2 years(Annual additional exposure dose of children)245

（3） Reduction rate of additional exposure dose for air dose rate range
Reduction rates of the additional exposure dose were evaluated for each air dose rate range
before decontamination. Higher reduction rates of the additional exposure dose tend to beachieved in areas of higher air dose rate before decontamination. Higher reduction rates ofchildren’s additional exposure dose are higher than those of the general public for all air dose
rate ranges.

0.99 or higher

Reduction of
additional
exposure dose (%)
about 73

0.80 to below 0.99

about 64

0.61 to below 0.80

about 63

0.42 to below 0.61

about 60

about 20

0.23 to below 0.42

about 55

about 15

Air dose rate
(μSv/h)Contribution ofphysical attenuation(%)

Contribution of
decontamination effect (%)
about 33
about 24

about 40

about 23

Figure 5-6 Reduction rate of additional exposure dose for each air dose range (the generalpublic).

0.99 or higher

Reduction of
additional
exposure dose (%)
about 74

0.80 to below 0.99

about 67

0.61 to below 0.80

about 67

0.42 to below 0.61

about 63

about 23

0.23 to below 0.42

about 58

about 18

Air dose rate
(μSv/h)Contribution ofphysical attenuation(%)

Contribution of
decontamination effect (%)
about 34
about 27

about 40

about 27

Figure 5-7 Reduction rate of additional exposure dose for each air dose rate range (children).

5.2. Overview on the Decontamination Effects
The “Decontamination effects (air dose rate) in the decontamination work implemented by
the National Government and local municipalities” (prepared by the MOE, Decontamination
Team, December 2013) reviewed the decontamination effects (air dose rate) in thedecontamination work to date, focusing on to what extent the air dose rate (at the height of 1m) could be reduced by decontamination, from the viewpoint of evaluating the exposure doseto the general public.

246

5.2.1. Data for Evaluation
The report reviewed about 250,000 data (two measured values before and after
decontamination per one measurement point) of the air dose rate (measured at the heights of
1 m and 50 cm; unit, μSv/h), roughly between March 2012 and October 2013 in thedecontamination work implemented in JFY 2012 onward (in 10 municipalities under the
National Government jurisdiction and in 90 municipalities in 8 prefectures under local
jurisdiction).
The evaluation was limited to the data collected at the time of evaluation. Decontamination
methods and decontamination target places include various types depending on the situations.
In residential areas, for example, the evaluation of air dose rate was based on the results fromvarious complex effects of gardens with soil, paved surfaces, roofs, walls, etc. The following
data were excluded from the evaluation.
The air dose rate data below 0.23μSv/h before decontamination.
Top 1% and bottom 1% of the reduction rate data (Outlier data, unsuitable for grasping
the overall trend).

Classification work

National Government

Land- use Classification

Air dose rate(1m)Air dose rate(0.5m)

Public facilities *2

approx. 12,000-

Residential area

approx. 54,000

Road

approx. 28,000-

Farm land

approx. 11,000-

Forestapprox. 10,000-

Sum

Local municipalities

approx.116,000-

Public facilities *2

approx. 36,000-

Residential area

approx. 37,000

-

Road

approx. 6,000-

Farm land

approx. 10,000-

approx. 3,000--

approx.40,000

approx.92,000

approx.40,000

approx.208,000

approx.40,000

ForestChildren’s living environment

*3

Sum
Total

Note: There is a case in which the total does not match due to rounding off the fractional.
＊1：Less than 0.23μSv/h of decontamination data before, data of upper reduction rate 1% and lower reduction rate
1% are excluded and calculated.
＊2：Public facilities include school, park or large facility.
＊3：Children’s living environment include elementary school, kindergarten and park.

Figure 5-8 Data for evaluation135 .

5.2.2. Summary of the Results
In terms of typical distribution ranges of air dose rate (the range here refers to rates
between the 25th percentile value and the 75th percentile value), the air dose rate before
decontamination was 0.36 to 0.93 μSv/h, and it was reduced to 0.25 to 0.57 μSv/h after
135Source: Ministry of the Environment (MOE), Decontamination Team, “Decontamination effects (air doserate) implemented by the National Government and local municipalities,” December 2013 (Figure 5-9 to
Figure 5-14 have the same source.)247

decontamination. As a whole, the air dose rate was reduced and at the same time, its
distribution range became narrower after decontamination. This indicates the
reduction rate of air dose rate by decontamination in the higher air dose rate areas islarger and the reduction rate in lower air dose rate areas is smaller.
The air dose rate was reduced by decontamination by about 30 to 50% on average in all
dose rate ranges (below 1μSv/h, 1 to 3.8μSv/h and above 3.8μSv/h, respectively, before
decontamination). This indicates the higher the dose rates before decontamination, thelarger the decontamination effects and the air dose rate reduction.
In the current review, the evaluation was done by air dose rates (μSv/h) from theviewpoint of evaluating exposure dose of the general public. Regarding the difference of
decontamination effects (reduction rates) depending on the target place and thedecontamination methods, the evaluation results by surface contamination densities(cpm) were made public in January 2013, in which the decontamination effect byremoving radiocesium from the decontamination targets had been confirmed.
The air dose rate reduction features varied subject to influences from the surroundingarea, depending on the characteristics of decontamination site, type of land-use andothers.
Concerning the relation between the type of land-use and decontamination effects, thedecontamination effects were relatively high in the residential areas and relatively low
in the forests. It should be noted that the data for forests do not directly indicate theeffects on the neighboring living environment such as residential areas because thedata for forests included a considerable number of data collected inside the forests.
(Note) The forests were decontaminated by removing accumulated leaf litter and woody
materials. The decontamination guidelines were revised based on the new knowledge
obtained for more effective decontamination, by, for example, adding the removed
accumulated organic materials to targets for the decontamination methods, and also byconsidering the migration of radiocesium over time.
Regarding the living environment for children such as schools, parks, etc., there weresome data measured at different heights. Therefore, the data were reviewed separately
in individual cases. As the result, the reduction rate was roughly 50% to 80%, tending
to be higher compared with that of the whole area (air dose rate at 1 m in height).

Air dose rate *1,2
(measurement
hight 1m)
Reduction rate of
air dose rate
(average) *2,3
ex) Reduction rateof surface
contamination
density *4

Before decontamination : 0.36 to 0.93μSv/h
After decontamination : 0.25 to 0.57μSv/h
Before decontamination
ｌess than 1μSv/h

Before decontamination
1~3.8μSv/h

Before decontamination
3.8μSv/h or more

43%

51%

32%

Asphalt pavement of parking lot: washing is aprox.50 to 70%
High-pressure washing is approx.30 to 70%
Soil ground: stripping of surface soil is approx..80 to 90%＊1.Band of value of 25 percentile and 75 percentile of air dose rate.
＊2.Data at measurement height 0.5m is not included in the data of living environment for children on school etc..
＊3.Average data of reduction rate of air dose rate at each decontamination classification before.
( reduction rate(%) =(1-air dose rate before decontamination/ air dose rate before decontamination)×100)＊4.Announcement “effect of decontamination method in the work by National Government and local municipalities" has been Press
released on 18.Jan.2013.

Figure 5-9 Decontamination effects in the decontamination work implemented by the
National Government and local municipalities (main results).

248

5.3. Decontamination Effects in Five Areas: Public Facilities, Residential Areas,
Roads, Farmland and Forests
The “Decontamination effects (air dose rate) in the decontamination work implemented by
the National Government and local municipalities” (prepared by the MOE, Decontamination
Team, December 2013) reviewed the decontamination effects also by land-use classification(five categories consisting of: public facilities and the like; residential areas; roads; farmland;
and forests) in addition to the review as a whole.

5.3.1. Public Facilities
The data of public facilities and the like included various data such as those of groundsurfaces of bare soil, asphalt paved surfaces, gravel, etc.
About 70% of the data were from the facilities with the air dose rate below 1 μSv/h
before decontamination and the average reduction rate for all public facilities was
about 34%.
In the areas with the air dose rate was below 1 μSv/h before decontamination, theaverage reduction rate was about 29% and the air dose rate after decontamination was
0.38μSv/h or less at half of the measurement points. The reduction rate was higher in
the areas with higher air dose rate before decontamination and the average air dose
rate at the points of 1 μSv/h before decontamination was about 0.6 μSv/h (a reduction
rate of about 40%).
In the areas with the air dose rate ranges of 1 to 3.8 μSv/h and 3.8 μSv/h or higher
before decontamination, the reduction rates were higher in the areas with higher air
dose rate as compared with those in the areas with the rate of less than 1 μSv/h, andthe average reduction rate in the areas with the rate of more than 3.8 μSv/h before
decontamination was about 53%.
Most of the data with high air dose rate were data obtained by decontamination of apublic facility as a single target. For this reason, the air dose rate of public facilities
after decontamination tended to be higher when compared with the air dose rate ofresidences which were decontaminated zone-wise including the surroundings. However,
the air dose rate of public facilities is expected to be reduced through decontaminationof their surroundings.

249

Figure 5-10 Air dose rate (at 1m) in the National Government work (public facilities).

5.3.2. Residential Areas
The number of data measured in residential areas was about 50,000, about half of thedata were from the work by the National Government, which included a wide variety ofdata such as bare soil, gardens, grass fields, gravel, concrete paved surfaces, etc.
About 70% of the data were from the zones with the air dose rate below 1 μSv/h before
decontamination and the average reduction rate for all residential areas was about
43%, which was relatively higher than for all decontamination work.
In the zones with the air dose rate below 1 μSv/h before decontamination, the average
reduction rate was about 40% and the air dose rate after decontamination was
0.33μSv/h or less at half of the measurement points. The reduction rate was higher inthe zones with higher air dose rate before decontamination and the average air dose
rate at the points of 1 μSv/h before decontamination was about 0.5 μSv/h after
decontamination (a reduction rate of about 50%).
In the zones with the air dose rate ranges of 1 to 3.8 μSv/h and 3.8 μSv/h or higher
before decontamination, the reduction rates were higher in the areas with higher air
dose rate as compared with those in the zones with the air dose rate of less than 1
μSv/h, and the average reduction rate in the zones with the air dose rate of more than
3.8 μSv/h before decontamination was about 57%.

250

Figure 5-11 Air dose rate (at 1 m) in the National Government work (residential areas).

5.3.3. Roads
The data for roads included those of paved roads, gravel and crushed stone roads, etc.
About 70% of the data were from the roads with the air dose rate below 1 μSv/h before
decontamination and the average reduction rate for all roads was about 33%.
On the roads with the air dose rate below 1 μSv/h before decontamination, the average
reduction rate was about 29% and the air dose rate after decontamination was
0.40μSv/h or less at half of the measurement points. The reduction rate was higher on
the roads with higher air dose rate before decontamination and the average air dose
rate at the points of 1 μSv/h before decontamination was about 0.6 μSv/h after
decontamination (a reduction rate of about 40%).
On roads with the air dose rate ranges of 1 to 3.8 μSv/h and 3.8 μSv/h or higher before
decontamination, the reduction rates were higher on roads with higher air dose rate ascompared with that on the roads with the air dose rate of less than 1 μSv/h, and theaverage reduction rate on the roads with the air dose rate of more than 3.8 μSv/h before
decontamination was about 53%.

251

Figure 5-12 Air dose rate (at 1m) in the National Government work (roads).

5.3.4. Farmland
The data on farmland included those on orchards and pasture land, but most of themwere data on plowed land (deep plowing, top soil scraping). Most of the data on
farmland with the air dose rates exceeding about 2μSv/h before decontamination wereobtained from the farmland where decontamination was done by topsoil scraping.
About 70% of the data were from farmland with the air dose rate below 1 μSv/h before
decontamination and the average reduction rate for all farmland was about 34%.
On farmland with the air dose rate below 1μSv/h before decontamination, the average
reduction rate was about 28% and the air dose rate after decontamination was
0.44μSv/h or less at half of the measurement points. The reduction rate was higher on
the farmland with the higher air dose rate before decontamination and the average air
dose rate at the points of 1 μSv/h before decontamination was about 0.6 μSv/h (areduction rate about 40%).
On farmland with the air dose rate ranges of 1 to 3.8 μSv/h and 3.8 μSv/h or higher
before decontamination, the reduction rates were higher on farmland with higher air
252dose rate as compared with those on farmland with the air dose rate of less than 1
μSv/h. On farmland with the air dose rate exceeding about 2 μSv/h before
decontamination, the air dose rate was reduced to about 1 μSv/h, regardless of the air
dose rate before decontamination, because the decontamination was mostly by topsoil
scraping.

Figure 5-13 Air dose rate (at 1m) in the National Government work (farmland).

5.3.5. Forests
Most data of forests were those obtained by removing organic matter such as fallen
leaves and woody materials.
About 60% of the data were from forests with the air dose rate of below 1 μSv/h before
decontamination, lower in proportion of the data than in other land-use categories. The
average reduction rate for all forests was about 22%, lower than for all
decontamination work.
For forests with the air dose rate below 1 μSv/h before decontamination, the average
reduction rate was about 18% and the air dose rate after decontamination was
0.57μSv/h or less at half of the measurement points. The reduction rate was higher forforests with the higher air dose rate before decontamination and the average air dose253

rate at the points of 1 μSv/h before decontamination was about 0.75 μSv/h (a reduction
rate of about 25%).
For forests with the air dose rate of 1 μSv/h or higher before decontamination, thereduction rate was slightly higher than that for the forests with the air dose rate of lessthan 1 μSv/h before decontamination, and the average reduction rate for the forests
with the air dose rate of 1 to 3.8 μSv/h before decontamination was about 27%.
It should be noted that the data for forests do not directly indicate the effects on theneighboring living environments such as residential areas because the data for forests
included a considerable number of data collected inside the forests.

Figure 5-14 Air dose rate (at 1m) in the National Government work (forest).

5.4. Effects at Each Target Decontamination Place
The “Effectiveness of decontamination methods in the decontamination work implemented
to date by the National Government and local municipalities” (prepared by the MOE,
Decontamination Team, January 2013) reviewed the results of decontamination work in theearly stage (mainly in JFY 2011) implemented by the National Government and local254municipalities mostly in the area with comparatively high dose areas in Fukushima
Prefecture, focusing on to what extent the radioactive materials could have been reduced bydecontamination work.

5.4.1. Outline
The data collected mainly in the neighboring areas of residential areas such asbuildings and structures, roads, etc. were reviewed, which had been obtained in thedecontamination work at the first stage. (Data one plowed land and forests were
excluded from the review because the numbers of data points were insufficient.)
The effectiveness of decontamination methods was evaluated in terms of reduction
rates of surface contamination densities because the review purpose was to evaluate
the effectiveness of each decontamination method.
The data to be reviewed were limited to those with surface contamination densities
before decontamination of higher than 2,000 cpm, in order to reduce data deviations
due to the influences from objects other than the target object.
ObjectNumber of Data
(2,000cpm or more)

Number of Data
(whole data)

Decontamination method for analysis

Rainwater gutter

343

772

High-pressure washing, Swabbing after removal of
sediments

Rainwater basin

85

214

High-pressure washing after removal of sediments

Side ditch

132

306

Removal of sediments, High-pressure washing after
removal of sediments

Roof

464

751

Wiping, Washing, High-pressure washingOuter wall

64

997

Wiping, Washing, High-pressure washing

Garden ground

446

628

Grass mowing, Stripping of top soil, Soil replacement,
Peeling off of lawn

Pavement surface of parking lots

601

781

Washing, High-pressure washing, Scraping off

Ground (soil)
271of additional exposure
343
Strippingof toppublic)
soil
Fig.5-6 Reduction rate
dose
(generalRoad (surface of asphalt pavement)

506

539

Total

2,912

5,331

Washing, Pressure washing, Scraping off

Figure 5-15 Target objects of decontamination, numbers of data and decontamination
methods136 .

136Source: Ministry of the Environment (MOE), Decontamination Team, “Effectiveness of decontamination

methods in the decontamination work implemented to date by the national government and local
municipalities", January 2013 (Figure 5-16 to Figure 5-29 have the same source.)255

5.4.2. Effectiveness of Decontamination Methods for Each Target Decontamination Place（1） Buildings and structures
1）Rainwater gutters and street drainsa.) Rainwater gutters
The reduction rate of surface contamination densities was around 60 to 80% by wiping
after sediment removal and around 40 to 80% by high-pressure water washing after
sediment removal. Higher reduction rate by wiping after sediment removal wasachieved than by high-pressure water cleaning.
Substantial amounts of radioactive materials were accumulated in the sediments inrainwater gutters. It should be noted that sediment removal is an effective approachfor decontamination.

Figure 5-16 Decontamination effect for a target decontamination place (rainwater gutters).

256b.) Rainwater cisterns
The reduction rate of surface contamination densities was around 60 to 90% by
high-pressure water washing after sediment removal.
The effect by sediment removal was considered large, too.
It should be noted in data interpretation that radioactive materials sunk into seams orcracks in high concentrations from rainfall in the early stage after the nuclear power
plant accident and lowered the reduction rate.
It is a point of careful attention in decontamination that soil and other objects in thesurrounding area might be contaminated in case the rainwater cisterns are damaged
and leaking.

Figure 5-17 Decontamination effect for a target decontamination place (rainwater cisterns).

257c.) Street drains
The reduction rate of surface contamination densities was around 70 to 90% bysediment removal and around 60 to 90% by high-pressure water washing after
sediment removal.
Substantial amounts of radioactive materials were accumulated in street drains. It is apoint of careful attention in decontamination that simple removal of sediments can beeffective enough and that the possibility should be considered for contamination of thesoil and other objects in the surrounding area in case the street drains are damaged
and leaking.

Figure 5-18 Decontamination effect for a target decontamination place (street drains).

2582）Roofs and other house structures
The reduction rate of surface contamination density on the roofs was around 0 to 20%(*) by wiping, around 20 to 60% by water washing, and 40 to 80% by high-pressure
water washing. (* The reduction rate was improved to 20 to 50% using a better way of
wiping in the decontamination of roofs of private houses implemented in the autumn of2012.)The reduction rate for rooftops was around 60 to 90% by high-pressure water washing.
The rooftop shapes are generally not very complicated and therefore the high-pressure
water washing is effective.
The reduction rate for verandas and similar structures was around 20 to 50% by
high-pressure water washing. But the available data were limited. If the high-pressure
water washing was done after the sediments were removed, the reduction rate reachedaround 60 to 90%.
Points of attention in data interpretation are:Data for roofs had deviations depending on their shapes or surface materials.
Data deviations occurred in high-pressure water washing, since contaminatedwastewater was left.
Low reduction rates were experienced in some cases of water washing and wipingof roofs even with high surface contamination densities before decontamination.
These cases were for cement tiles, unglazed clay tiles and painted steel plates. The
cause of the low reduction rate is considered to have come from the influence ofrust or the roof materials themselves.
Points of attention in decontamination are:Measures should be taken to prevent wastewater from spreading when
decontaminating using water.
If rust is present, it should be removed by wiping and other means before
high-pressure water washing, because its presence lowers the effect.
A possibility should be considered in high-pressure water washing of damaging thestructures, for instance, peeling off their surface materials.

259

Figure 5-19 Decontamination effect for a target decontamination place (roofs and others).

2603）Exterior wallsa.) Concrete walls
The reduction rates of surface contamination densities were around 10 to 30% by
wiping and around 20 to 80% by high-pressure water washing. However, the data of
wiping were limited.
Many data were available for low surface contamination densities (less than 2,000 cpm)
before decontamination. This is likely because the amount of radioactive materials
attached was small or the radioactive materials had been washed away to some extent
by rainfall.
It is a point of attention in data interpretation that contamination of exterior walls was
generally low, since rain, dust and other things were less likely to be attached on thewalls than on the roofs, rainwater gutters, etc.
Points of attention in decontamination are:
The need for decontamination should be assessed by comparing the backgroundradiation levels and the contaminated situation of the objects.
A possibility should be considered in high-pressure water washing of damaging thestructures, for instance, peeling off wall surface materials.

Figure 5-20 Decontamination effect for a target decontamination place (concrete).

261b.) Metal walls, windows, doors and shutters, etc.
Few data were available for metal walls, windows, doors and shutters, etc.
For metal walls, the reduction rate was around 40 to 70% by cleaning and around 40 to
90% by high-pressure water washing.
For windows, doors and shutters, the reduction rate was around 70 to 80% by wiping,around 20 to 70% by water washing, and around 50 to 90% by high-pressure water
washing.
Many data were available for low surface contamination densities (less than 2,000 cpm)
before decontamination. This is likely because the amount of radioactive materials
attached was small or radioactive materials had been washed away by rainfall.
It is a point of attention in data interpretation that the contamination of windows,
doors and shutters is generally low, since rain, dust and other things are less likely to
be attached on these surfaces than on the roofs, rainwater gutters, etc.
It is a point of attention for decontamination that the need should be assessed bycomparing the background radiation levels and the contaminated situation of theobjects.

Figure 5-21 Decontamination effect for a target decontamination place (metal walls, windows,
doors and shutters, etc.).

262

c.) Tiles and sidings
The reduction rate of surface contamination densities was around 60 to 70% by
high-pressure water washing. But the data were limited.
The reduction rate by high-pressure water washing of tiles and sidings was higher thanthat of concrete walls.
Many data were available for low surface contamination densities (less than 2,000 cpm)
before decontamination. This is likely because the amount of radioactive materials
attached was small or the radioactive materials had been washed away by rainfall.
It is a point of attention in data interpretation that the contamination of tiles andsidings is generally low, since rain, dust and other things are less likely to be attachedon the tiles and sidings than on the roofs, rainwater gutters, etc.
It is a point of attention for decontamination that the need should be assessed bycomparing the background radiation levels and the contaminated situation of theobjects.

Figure 5-22 Decontamination effect for a target decontamination place (tiles and sidings).

2634）Ground surfaces such as gardensa.) Bare soil and grassland
The reduction rate of surface contamination densities was around 0 to 60% by grass
mowing, around 40 to 80% by topsoil scraping, and around 70 to 100% by soil
replacement.
Soil replacement was applied in cases where the surface contamination density was
relatively high before decontamination.
The points of attention in data interpretation are:Topsoil scraping of gardens may lower the certainties of decontamination work
because of the presence of vegetation or more unevenness than on other types ofground surfaces.
The effect of decontamination by grass mowing may possibly change because theattachment of radioactive materials to the grass changes with time and also as
grass grows uptake of radioactive materials may occur.
In some cases, the reduction rate becomes lower due to decrease of shielding effectsof beta rays by grass as a result of mowing.

Figure 5-23 Decontamination effect for a target decontamination place (bare soil, grassland)264b.) Lawns
The reduction rate of surface contamination densities was high; 70 to 90% by peelingoff of lawns and about 90% by soil replacement (coverage with crushed stones after
removal of lawns).
It is a point of attention in decontamination that it is necessary to consider “closemowing combined with topsoil removal(*),” for which a certain effect of dose reduction
has been confirmed, from the viewpoint of controlling the amount of removed soil
generated as well as regeneration of the lawns.
(*) Close mowing combined with topsoil removal: a method to remove the topsoil
including the root layer of dead lawns and other grasses depending on the situation ofradioactive materials.

Figure 5-24 Decontamination effect for a target decontamination place (lawns).

2655）Paved surfaces such as parking lotsa.) Asphalt paved surfaces
The reduction rate of surface contamination densities was around 50 to 70% bycleaning, around 30 to 70% by high-pressure water washing, and around 70 to 90% by
surface scraping.
In high-pressure water washing, the reduction rate had large deviations irrespective of
surface contamination densities before decontamination.
A point of attention in data interpretation is that the decontamination effects may havelarge deviations because of variations in decontamination conditions of high-pressure
water washing at each decontamination place (nozzle elevations above ground surface,work time per unit area, and other conditions) and the size of the area to be
decontaminated like parking lots or the different conditions of paved surfaces(permeability or drainage capability).
Points of attention in decontamination are:Measures should be taken to prevent wastewater from spreading when
decontaminating using water.
The possibility that radioactive materials may have deposited into cracks should
be considered.

Figure 5-25 Decontamination effect for a target decontamination place (asphalt paved
surfaces).

266b.) Concrete paved surfaces
The reduction rate of surface contamination densities was around 40 to 70% by
high-pressure water washing and around 60 to 90% by surface scraping.
The reduction rate varies depending on the work method of surface scraping.
A point of attention in data interpretation is that the decontamination effects may havelarge deviations because of variations in decontamination conditions of high-pressure
water washing at each decontamination place (nozzle elevations above ground surface,work time per unit area, and other conditions) and the size of the area to be
decontaminated like parking lots or the different conditions of paved surfaces(permeability or drainage capability).
Points of attention in decontamination are:
Relatively high reduction rates are obtained on the concrete surfaces because ofless unevenness, but contamination tends to be concentrated around moss-covered
spots.
Measures should be taken to prevent wastewater from spreading when
decontaminating using water.

Figure 5-26 Decontamination effect for a target decontamination place (concrete paved
surfaces).

267c.) Interlocking block surfaces
The reduction rate of surface contamination densities was around 50 to 80% by
high-pressure water washing and around 40 to 70% by scraping.
Points of attention in data interpretation are:
The reduction rate can be lowered in scraping if scraped chips and radioactive
materials are left in the gaps between the interlocking blocks.
The reduction rate by scraping (abrasive material blasting and concrete surface
planing) of interlocking blocks is lower than that by scraping of asphalt paved or
concrete paved surfaces. The scraped chips left in the gaps of interlocking are
likely one reason for this.

Figure 5-27 Decontamination effect for a target decontamination place (interlocking blocks).

2686）Ground surfaces and the like (soil)High reduction rates of around 80 to 90% were achieved by topsoil scraping.
Stable reduction rates seem to have been obtained, since the grounds have limited
unevenness.
It is a point of attention in decontamination that it is necessary to check the depth ofcontamination from the surface layer in advance and determine the optimum thicknessof scraping.

Figure 5-28 Decontamination effect for a target decontamination place (ground surfaces andthe like (soil)).

269

（2） Roads (asphalt paved surfaces)
Most data are from decontamination by cleaning and the reduction rate was around 0
to 50%. Large deviations were seen in the reduction rate because most data wereobtained from decontamination by special cleaning vehicles that restore permeable
pavement.
The reduction rate by high-pressure water washing was around 10 to 50%. However,the data were limited.
The reduction rate by scraping was around 10 to 70% (* the reduction rate is currently
being improved by better collection of scraped chips.)
The reduction rates of the asphalt-paved roads by any decontamination methods ofcleaning, high-pressure water washing, or scraping were in many cases lower thanthose of asphalt-paved surfaces in parking lots of structures such as buildings.
Points of attention in data interpretation are:
The decontamination effect may have large deviations because of deviations indecontamination conditions of high-pressure water washing at eachdecontamination place (nozzle elevations above ground surface, work time length
per unit area and other conditions) and the size of the area to be decontaminatedlike parking lots or the different conditions of paved surfaces (permeability or
drainage capability).
The reduction rate tends to be low when vehicles to restore permeable pavements
are used with low water pressure and recirculated wastewater. Also, the cleaning
and wastewater collection performance are downgraded on the road surfaces
distorted or damaged by the earthquake and other reasons.
Measures should be taken to prevent wastewater from spreading, when decontaminating
using water.

Figure 5-29 Decontamination effect for a target decontamination place (asphalt paved
surfaces).

2706． Outline of decontamination methods, applications and conditions thereof, andexamination of the effects
Chapter 6.1 outlines the decontamination methods and their applications and conditions
for the decontamination works in the Special Decontamination Area as directed by the
Ministry of Environment (MOE). Chapter 6.2 shows some of the verification results ofdecontamination effects in the decontamination works executed.
The methods to apply and their conditions and the decontamination effects depend on
various environmental conditions such as site situations, material properties and surface
conditions of the objects subject to decontamination, and their aging variation with time.
Therefore, the best decontamination methods and conditions are not easy to specify
beforehand, even for a particular item to be decontaminated.
For example, the decontamination methods for the decontamination works have beenchanging with time after the accident. In the early stage, high-pressure water cleaning was
effective in decontaminating paved road surfaces. But after some time, radioactive cesium
has migrated from the surface deep into the materials so that scraping of the paved roadsurfaces by shot-blasting became a practical and effective approach, instead of simply
washing the surfaces.
Meanwhile, weeds have grown in house gardens and on unpaved road surfaces as time
elapsed after the accident. Also underbrush and shrubs have grown in farmland. Weedremoval and underbrush/shrubs cutting are currently being added to the decontamination
work, which had not been practiced in the early stage.

6.1. Outline of Decontamination Methods and Their Applications and Conditions
Outlines of decontamination methods, and their applications and conditions used in thedecontamination works in the Special Decontamination Areas as directed by the MOE aregiven below.
Decontamination methods are specified in the Common Specifications of Decontamination
Works (“Common Specifications” in this report) (7th Edition), and this report summarizes thedecontamination methods for each decontamination object shown in Table 6-1. As mentioned
in Chapter 4.1.3 (4), the Common Specifications (7th Edition) deals with not only (i)decontamination methods for reducing air dose rates, but also (ii) the methods forpre-decontamination works and post-decontamination works for restoration.
It should be noted that the amount of materials removed such as soil is not given in Chapter
6.1. It can be estimated, for instance, the reference soil thickness of about 5 cm set when
scraping farmland (rice fields, dry fields, grassland) is multiplied by the size of thedecontamination area (if the area of 100 m2 is decontaminated by surface scraping, the soil toremove is estimated as 5 m3). In actual cases, it is not possible to scrape the surface land
uniformly. Uncertainties to some degree cannot be avoided. (See the case given later in
Chapter 6.2.1-(4) 2) i).)271

Table 6-1 Methods of decontamination for individual objects subject to decontamination
Classificationofdecontamination
Residential areas,
schools, parks,
large facilities,
roads, etc.

objectssubjecttosediments
Roofs/ rooftops, exterior
walls/outside
walls,
paved
surfaces(concrete, asphalt) andthe like of structures
Weeds, lawns
Gravel, crushed stones
Soil

Garden trees, planted
vegetation and roadside
trees

OthersSlopesRice fields, dry
fields,grassland,
etc.

Weeds

Soil

Waterways
OthersGrassland, lawns

272

Classification of decontamination methods
sediment removal
wipingbrush cleaning
high-pressure water cleaning
shot-blasting
Superhigh pressure water cleaning
Cleaning by road sweepers
Weeding, lawn mowing
deep pruning of lawns
Removal of gravel, crushed stones
Surface soil removal from rainwater
guttering drains, and under-eaves
Scraping of surface soil
Soil surface covering
Deep plowing
Surface soil removal from the bases oftrees
Delimbing of garden trees, planted
vegetation, roadside trees
Logging of garden trees, planted
vegetation
Wiping, cleaning, scraping of playgroundequipment
Removal of bottom sediments and the likein the street drains along the roads
Removal of weeds, fallen leaves, andsediments from the slopes
Weeding the rice fields and dry fields byhands
Weeding the rice fields and dry fields bymachinery
Collection of weeds removed from rice
fields and dry fields
Weeding the grassland
Leveling of unevenness
Spreadingofsurfacesolidificationmaterials
Scraping of surface soil (standard transfer
method)Dual plowing
Deep tillage
Soil replacement
Restoration of soil fertility
Removal of bottom sediments (soil sucking)Removal of bottom sediments (packing into
bags)
Packing into bags (standard transfer
method)Petit transfer on site (standard transfer
method)Weeding (dense shrubs)
Weeding (sparse shrubs)

Forests

Common items to theforests with mixed treesof coniferous evergreen
trees,
deciduous
broad-leaf
trees andothersConiferous
trees

evergreen

273

Removal of deposited organic sediments
Removal of deposited organic sediments(uncontrolled areas)
Prevention of soil secondary dispersion(lining up of sandbags)
Weeding underbrush and shrubs
Removal of organic sediment residues
Pruning of coniferous trees, collection ofslips6.1.1. Residential Areas, Schools, Parks, Large Facilities, Roads, etc.
（1） Sediment
1）Sediment removal
Locations to be
decontaminated137“1.1.1. Roofs (other than concrete)” of “1.1 Roofs/rooftops” in “1.
Residential areas and the like”“1.1.2. Roofs (concrete)” of “1.1 Roofs/rooftops” in “1. Residential areas
and the like”“1.3.1. Roof gutters” of “1.3 Rainwater gutters” in “1. Residential areas
and the like”“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like.”“1.4.2. Paved surfaces” of “1.4. Gardens and the like.” in “1. Residential
areas and the like.”“2.1. Roofs/rooftops” at “2. Schools”“2.3.1. Roof gutters” of “2.3. Rainwater gutters” at “2. Schools”“2.4.1. Sediment” of “2.4. School grounds and the like” at “2. Schools”“2.4.6. Paved surfaces” of “2.4. School grounds and the like” at “2.
Schools”“3.1. Roofs/rooftops” in “3. Parks (small)”“3.3.1. Roof gutters” of “3.3. Rainwater gutters” in “3. Parks (small)”“3.4.1.Sediment” of “3.4. Playgrounds and the like” in “3. Parks (small)”“3.4.6.Paved surfaces” of “3.4. Playgrounds and the like” in “3. Parks(small)”“4.1. Roofs/rooftops” in 4. Parks (large)”“4.3.1. Roof gutters” of “4.3. Rainwater gutters” in “4. Parks (large)”“4.4.1.Sediment” of “4.4. Playgrounds and the like” in “4. Parks (large)”“4.4.6.Paved surfaces” of “4.4. Playgrounds and the like” in “4. Parks(large)”“5.1.1. Roofs/rooftops” of “5.1. Roofs/rooftops” of “5. Large facilities”“5.3.1. Roof gutters” of “5.3. Rainwater gutters” of “5. Large facilities”“5.4.1.Sediment” of “5.4. Playgrounds and the like” of “5. Large
facilities”“5.4.6. Parking lots (concrete, asphalt)” of “5.4. Playgrounds and thelike” of “5. Large facilities”“6.1.1. Sediment” of “6.1. Paved roads” of “6. Roads”“6.2.1. Road surfaces (soil)” of “6.2. Unpaved roads” of “6. Roads”“6.2.2. Road surfaces (gravel, crushed stone)” of “6.2. Unpaved roads” of“6. Roads”“6.5.1. Pedestrian overpasses” of “6.5. Pedestrian overpasses” “6. Roads”“6.6.1. Sediment” of “6.6. Roadside trees” of “6. Roads”

Decontamination

Sediment removal

methods

137

Residential areas and the like,” “1.1 Roofs/rooftops,” “1.1.1. Roofs (other than concrete),” etc. in the“Locations to be decontaminated,” “Outline,” and “Required equipment and materials” correspond to theobjects subject to decontamination shown in Table 4-7 of the Common Specifications (7th Edition). The
same source applies hereafter.

274

Outline

Sediment shall be removed in the following
procedures(i) Removing fallen leaves, moss, mud, etc.
(ii) Packing the removed materials
from roofs/rooftops, roof gutters, gardens,
grounds, parking lots (concrete, asphalt),
roads/sidewalks, pedestrian overpasses, roadsidetrees, etc. in residential areas, schools, parks,
large facilities, roads, etc.

Decontamination processes■ When working on
roofs/rooftops, gardens, etc. of residences,schools, parks (small), parks (large) or large
facilities (1.1.1, 1.1.2, 1.4.1, 1.4.2, 2.1.1, 3.1.1,
4.1.1, 5.1.1);
grounds, paved surfaces, etc. of schools, parks(small), and parks (large) (2.4.1, 2.4.6, 3.4.1,
3.4.6, 4.4.1, 4.4.6); andgrounds of large facilities, parking lots
(concrete, asphalt) (5.4.1, 5.4.6), paved andunpaved roads (6.1.1, 6.2.1, 6.2.2), as well as
pedestrian overpasses (6.5.1) or roadside trees(6.6.1),
Sediment such as fallen leaves, moss andmud shall be collected using rubber hand
gloves, shovels, rakes, etc. and packed intolarge sandbags; andSediment on easily broken roofs shall be
removed with mops or the like, without
getting directly on the roofs, by using aerial
lift work vehicles and the like.
■ When working on roof gutters of residences,schools, parks (small), parks (large) or large
facilities (1.3.1, 2.3.1, 3.3.1, 4.3.1, 5.3.1),
Fallen leaves, moss, mud, etc. shall be
removed using rubber hand gloves, brooms,
brushes, etc. and packed into large
sandbags.

Tools, equipment and the like fordecontamination work

When working on
roofs/rooftops, gardens, etc. of residences,schools, parks (small), parks (large) or large
facilities (1.1.1, 1.1.2, 1.4.1, 1.4.2, 2.1.1,
3.1.1, 4.1.1, 5.1.1);
grounds of parks (small), paved surfaces,
etc. (3.4.1, 3.4.6); andpedestrian overpasses (6.5.1), roadside trees(6.6.1),Tools, equipment to use
Quantity
Rubber gloves, shovels, rakes,－
etc.
Large sandbags－*For the work at an elevated place, aerial lift
work vehicles or scaffolds shall be used.
275

When working on roof gutters of residences,schools, parks (small), parks (large) or large
facilities (1.3.1, 2.3.1, 3.3.1, 4.3.1, 5.3.1),
Tools, equipment to use
Quantity
Rubber gloves, brooms, brushes,－
etc.
Large sandbags－
When working on
grounds, paved surface, etc. of schools, parks(large) or large facilities (2.4.1,2.4.6, 4.4.1,
4.4.6);
grounds, parking lots (concrete, asphalt) oflarge facilities (5.4.1, 5.4.5), andpaved and unpaved roads (6.1.1, 6.2.1,
6.2.2),(per 1,300m2)
Tools, equipment to use
Quantity
Rubber gloves, shovels, rakes,－
etc.
Dump trucks
0.43
service days
Light oil
9.7L
Large sandbags－
Workforce needed■When working on

roofs/rooftops, gardens, etc. of residences,schools, parks (small), parks (large) or large
facilities (1.1.1, 1.1.2, 1.4.1, 1.4.2, 2.1.1, 3.1.1,
4.1.1, 5.1.1);
grounds of parks (small), paved surfaces, etc.
(3.4.1, 3.4.6); andpedestrian overpasses (6.5.1), roadside trees(6.6.1),(per 1,300m2)
Workforce needed
Quantity
Operation leaders
0.5
worker-days
Decontamination workers
3.2
worker-days
When working on roof gutters of residences,schools, parks (small), parks (large) or large
facilities (1.3.1, 2.3.1, 3.3.1, 4.3.1, 5.3.1),(per 1,300m2)
Workforce needed
Quantity
Operation leaders
0.5
worker-days
Decontamination workers
3.2
worker-days276

When working on
grounds, paved surface, etc. of schools, parks(large) or large facilities (2.4.1,2.4.6, 4.4.1,
4.4.6);
grounds, parking lots (concrete, asphalt) oflarge facilities (5.4.1, 5.4.5), andpaved and unpaved roads (6.1.1, 6.2.1,
6.2.2),(per 1,300m2)
Workforce needed
Quantity
Operation leaders
0.5
worker-days
Decontamination workers
3.2
worker-days
Drivers (ordinary
0.37
decontamination)
worker-days
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites
andconstraints regarding
objects and locations
to be decontaminated

In order to prevent contamination fromspreading due to decontamination work, theorder of tasks shall be considered. For
instance, when decontaminating residential
areas and the like, the decontamination
work shall be done starting with roofs
followed by rainwater gutters and thengardens and the like.
When decontaminating for the first timeafter the accident at a certain place,sediment shall be checked as to whether thefallen leaves and the like are from after theaccident or they were there at around thetime of the accident.

Radiation
exposureprotection of workers

Rubber gloves shall be worn.
The removed objects shall be immediately
packed to avoid unwanted exposure bycontact.

General labor safety ofworkers

For work at an elevated place, aerial lift
work vehicles or scaffolds shall be used.
For the work on roads, barricades and traffic
controllers shall be arranged.

Measures to prevent－

secondary wastes
Others－277

（2） Roofs/rooftops, exterior walls, outside walls, paved surfaces (concrete, asphalt), etc. of
structures

1）Wiping
Locations to be
decontaminated“1.1.1. Roofs (other than concrete)” of “1.1 Roofs/rooftops” in “1.
“Residential areas and the like”“1.1.2. Roofs (concrete)” of “1.1 Roofs/rooftops” in “1. Residential areas
and the like”“1.2.1. Other than earthen walls” of “1.2. Exterior walls/outside walls”
in “1. Residential areas and the like”“1.2.2. Earthen walls” of “1.2. Exterior walls/outside walls” in “1.
Residential areas and the like”“1.3.1. Roof gutters” of “1.3 Rainwater gutters” in “1. Residential areas
and the like”“2.1. Roofs/rooftops” at “2. Schools”“2.2. Exterior walls/outside walls” at “2. Schools”“2.3.1. Roof gutters” of “2.3. Rainwater gutters” at “2. Schools”“3.1. Roofs/rooftops” in “3. Parks (small)”“3.2.1. Exterior walls/outside walls” of “3.2. Exterior walls/outside
walls” in “3. Parks (small)”“3.3.1. Roof gutters” of “3.3. Rainwater gutters” in “3. Parks (small)”“4.1. Roofs/rooftops” in “4. Parks (large)”“4.2.1. Exterior walls/outside walls” of “4.2. Exterior walls/outside
walls” in “4. Parks (large)”“4.3.1. Roof gutters” of “4.3. Rainwater gutters” in “4. Parks (large)”“5.1.1. Roofs/rooftops” of “5.1. Roofs/rooftops” of “5. Large facilities”“5.2.1. Exterior walls/outside walls” of “5.2. Exterior walls/outside
walls” of “5. Large facilities”“5.3.1. Roof gutters” of “5.3. Rainwater gutters” of “5. Large facilities”“6.3.1. Guardrails” of “6.3.Guardrails” of “6. Roads”“6.5.1. Pedestrian overpasses” of “6.5. Pedestrian overpasses” of “6.
Roads”

Decontamination

Wipingmethods
OutlineDecontamination processes

Roofs/rooftops, exterior walls/outside walls, roof
gutters, guardrails, pedestrian overpasses, etc. inresidential areas, schools, parks, large facilities,
etc. shall be decontaminated through wiping.
The objects to be decontaminated shall becarefully wiped by using cleaning cloths andthe like moistened with water or the like(including neutral detergents or vinegar). In
wiping, their folded clean faces shall be useduntil repeated wiping gives hardly any
further
reductioninthesurfacecontamination density.

Tools, equipment and the like for278decontamination work

Tools, equipment to use
Quantity
Cleaning cloths and the like－
Brushes (including deck brushes,－
car washing brushes)* For the work at elevated places, adequate safetymeasures shall be taken for scaffolds, aerial lift
work vehicles and fall arresting devices/systems
using fixed ropes/safety belts, etc.

Workforce needed

When working on roofs/rooftops (1.1.1, 1.1.2,
2.1.1, 3.1.1, 4.1.1, 5.1.1) of residential areas,
schools, parks (small), parks (large), large
facilities, etc. and pedestrian overpasses(6.5.1),(per 130m2)
Workforce needed
Quantity
Operation leaders
0.3
worker-days
Decontamination workers
2.2
worker-days
When working on exterior walls/outside walls(1.2.1, 1.2.2, 2.2.1, 3.2.1, 4.2.1, 5.2.1) ofresidential areas, schools, parks (small),parks (large), large facilities, etc.,(per 1,300m2)
Workforce needed
Quantity
Operation leaders
2.6
worker-days
Decontamination workers
17.2
worker-days
When working on roof gutters（1.3.1, 2.3.1,
3.3.1, 4.3.1, 5.3.1 ） of residential areas,
schools, parks (small), parks (large), large
facilities, etc.,(per 130m)
Workforce needed
Quantity
Operation leaders
0.2
worker-days
Decontamination workers
1.1
worker-days
When working on guard rails (6.3.1),(per 100m)
Workforce needed
Quantity
Operation leaders
0.1
worker-days
Decontamination workers
0.8
worker-days

Idea
development,
lessons,

Prerequisites
andconstraints regarding
objects and locations

In order to prevent contamination fromspreading due to decontamination work,
wiping shall be done from top to bottom, for279

points
tokeepinmind, etc.

to be decontaminatedinstance, when wiping residential areas andthe like, starting with roofs first followed by
rainwater gutters and the like.
Surfaces with attached materials like moss or
mud which are difficult to remove by wiping,or clearly visible dirty surfaces shall bedecontaminated by carefully removing theattached dirt using brushes with dry
conditions without damaging the objects.
Folded clean faces of the cleaning cloths shallbe used for each wiping step, in order toprevent contaminants being reattached to thesurfaces.
When decontaminating earthen walls,
brushes and the like shall be used, notcleaning cloths and the like, to remove dirtwith dry conditions without damaging theobjects.
When decontaminating exterior walls/outside
walls other than earthen walls, or when
decontaminating
guardrails,
brushes(including car washing brushes, deckbrushes) and the like shall be used to remove
dirt with dry conditions without damaging
the objects. Surfaces with attached materials
like moss or mud which are difficult toremove, or clearly visible dirty surfaces shallbe decontaminated by carefully removing theattached dirt using metal brushes or brushes
moistened with water or the like without
damaging the objects.
Whendecontaminatingpedestrian
overpasses, their handrails shall bedecontaminated through wiping.
When rust is present, the rust itself shall be
removed through wiping and other means.

Radiation
exposureprotection of workers

Hand gloves and the like shall be worn.
Cleaning cloths and the like shall not bedirectly touched, because they might becontaminated by radiocesium.

General labor safety ofworkers

For the work at elevated places, adequate
safety measures shall be taken for scaffolds,
aerial lift work vehicles and fall arresting
devices/systems using fixed ropes/safety belts
and the like.
For the work on roads, barricades and traffic
controllers shall be arranged.

Measures to prevent－

secondary wastes
Others－2802）Brush cleaning
Locations to be
decontaminated“1.1.1. Roofs (other than concrete)” of “1.1 Roofs/rooftops” in “1.
Residential areas and the like”“1.1.2. Roofs (concrete)” of “1.1 Roofs/rooftops” in “1. Residential areas
and the like”“1.2.1. Other than earthen walls” of “1.2. Exterior walls/outside walls”
in “1. Residential areas and the like”“1.4.2. Paved surfaces” of “1.4. Gardens and the like” in “1. Residential
areas and the like”“2.1. Roofs/rooftops” at “2. Schools”“2.2. Exterior walls/outside walls” at “2. Schools”“2.4.6 Paved surfaces” of “2.4. Grounds and the like” at “2. Schools”“3.1. Roofs/rooftops” in “3. Parks (small)”“3.2.1. Exterior walls/outside walls” of “3.2. Exterior walls/outside
walls” in “3. Parks (small)”“3.4.6. Paved surfaces” of “3.4. Grounds and the like” in “3. Parks(small)”“4.1. Roofs/rooftops” in “4. Parks (large)”“4.2.1. Exterior walls/outside walls” of “4.2. Exterior walls/outside
walls” in “4. Parks (large)”“4.4.6. Paved surfaces” of “4.4. Grounds and the like” in “4. Parks(large)”“5.1.1. Roofs/rooftops” of “5.1. Roofs/rooftops” of “5. Large facilities”“5.2.1. Exterior walls/outside walls” of “5.2. Exterior walls/outside
walls” of “5. Large facilities”“5.4.6. Parking lots (concrete, asphalt)” of “5.4. Grounds and the like” of“5. Large facilities”“6.3.1. Guardrails” of “6.3.Guardrails” of “6. Roads”“6.5.1. Pedestrian overpasses” of “6.5. Pedestrian overpasses” of “6.
Roads”

Decontamination

Brush cleaning

methods
OutlineDecontamination processes

Roofs/rooftops and exterior walls/ outside walls
in residential areas, schools, parks and large
facilities, paved surfaces of gardens, grounds andthe like, parking lots (concrete, asphalt),
guardrails, pedestrian overpasses, etc. shall becleaned using brushes in the following
procedures(i) Cleaning using brushes(ii) Collecting used water
Cleaning by deck brushes or scrubbing
brushes shall be repeated carefully until
there is hardly any further reduction in thesurface contamination densities.
About 4L/m2 of water shall be poured on
surfaces before brushing and also after281

brushing for washing.
The cleaning water discharge lines shall becleaned beforehand for smooth discharge.
The discharge shall be collected in rainwater
cisterns and the like. After collection, it shallbe transferred to on-site or nearby
wastewater treatment facilities.
Tools, equipment and the like fordecontamination work

When working on
roofs/rooftops of residences, schools, parks(small), parks (large) or large facilities(1.1.1, 1.1.2, 2.1.1, 3.1.1, 4.1.1, 5.1.1),(per 130m2)
Tools, equipment to use
QuantityDeckbrushes,scrubbing－brushes, etc.
Sprinkler
trucks(tank
0.6 service
capacity 3,800L)
days
Light oil
9.9L
Water
0.5m3
Temporary systems and the－like for wastewater collection* For the work at elevated places, adequate
safety measures shall be taken for scaffolds,
aerial lift work vehicles and fall arresting
devices/systems using fixed ropes/safety belts,
etc.
When working on exterior walls/outside
walls other than earthen walls of residences
and the like (1,2,1), exterior walls/outside
walls of schools, parks (small), parks (large),
large facilities, etc. (2.2.1, 3.2.1, 4.2.1, 5.2.1),
paved surfaces of grounds and the like, ofresidences and the like, schools, parks(small) and parks (large), parking lots
(concrete, asphalt) of large facilities (5.4.6)
and pedestrian overpasses (6.5.1),(per 1,300m2)
Tools, equipment to use
Quantity
Deck brushes, scrubbing brushes,
－
etc.
Water
5m3
Temporary systems and the like－for wastewater collection* For the work at elevated places, aerial lift work
vehicles and scaffolds shall be used.
When working on guardrails (6.3.1),(per 1,900m)
Tools, equipment to use
Quantity
Deck brushes, scrubbing brushes,
－
etc.

282

WaterTemporary systems and the likefor wastewater collection
Workforce needed

5m3－

When working on
roofs/rooftops of residences, schools, parks(small), parks (large) or large facilities(1.1.1, 1.1.2, 2.1.1, 3.1.1, 4.1.1, 5.1.1),(per 130 m2)
Workforce needed
Quantity
Operation leaders
0.6
worker-days
Decontamination workers
3.6
worker-days
Drivers (ordinary
0.4
decontamination)
worker-days■When working on

exterior walls/outside walls other thanearthen walls of residences and the like
(1,2,1), exterior walls/outside walls ofschools, parks (small), parks (large), large
facilities, etc. (2.2.1, 3.2.1, 4.2.1, 5.2.1),
paved surfaces of grounds and the like, ofresidences and the like, schools, parks(small) and parks (large) (1.4.2, 2.4.6, 3.4.6,
4.4.6), parking lots (concrete, asphalt) oflarge facilities (5.4.6) and pedestrian
overpasses,(per 1,300m2)
Workforce needed
Quantity
Operation leaders
4.2
worker-days
Decontamination workers
28.1
worker-days
When working on guardrails (6.3.1),(per 1,900m)
Workforce needed
Quantity
Operation leaders
4.2
worker-days
Decontamination workers
28.1
worker-days
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedBrush cleaning shall be done from top tobottom in order to prevent contaminationfrom spreading due to decontamination
work,
for
instance,when
cleaning
residential areas and the like, starting withroofs first followed by exterior walls,
gardens, etc.
Cleaning shall be done from above in order
to avoid water being scattered.

283

Rotary brushes shall not be used when
decontaminating thatched roofs or tiled
roofs, as they are not suitable for suchmaterials.
Whendecontaminatingpedestrian
overpasses, their handrails shall be cleaned
with brushes.
Radiation

exposure

Rubber hand gloves, dust masks and otherprotection of workers

protective gear shall be worn.

General labor safety ofworkers

For the work at elevated places, adequate
safety measures shall be taken for scaffolds,
aerial lift work vehicles and fall arresting
devices/systems using fixed ropes/safety
belts, etc.
For the work on roads, barricades and traffic
controllers shall be arranged.

Measures to prevent－

secondary wastes
Others－2843）High-pressure water cleaning
Locations to be
decontaminated“1.3.1. Roof gutters” of “1.3 Rainwater gutters” in “1. Residential areas
and the like”“1.3.2. Rainwater pipes” of “1.3 Rainwater gutters” in “1. Residential
areas and the like”“1.4.2. Paved surfaces” of “1.4. Gardens and the like” in “1. Residential
areas and the like”“2.1. Roofs/rooftops” at “2. Schools”“2.2. Exterior walls/outside walls” at “2. Schools”“2.3.1. Roof gutters” of “2.3. Rainwater gutters” at “2. Schools”“2.3.2 Rainwater pipes” of “2.3. Rainwater gutters” at “2. Schools”“2.4.6. Paved surfaces” of “2.4. Grounds and the like” at “2. Schools”“3.1. Roofs/rooftops” in “3. Parks (small)”“3.2.1 Exterior walls/outside walls” of “3.2. Exterior walls/outside walls”
in “3. Parks (small)”“3.3.1. Roof gutters” of “3.3. Rainwater gutters” in “3. Parks (small)”“3.3.2. Rainwater pipes” of “3.3. Rainwater gutters” in “3. Parks (small)”“3.4.6.Paved surfaces” of “3.4. Playgrounds and the like” in “3. Parks(small)”“4.1. Roofs/rooftops” in “4. Parks (large)”“4.2.1 Exterior walls/outside walls” of “4.2. Exterior walls/outside walls”
in “4. Parks (large)”“4.3.1. Roof gutters” of “4.3. Rainwater gutters” in “4. Parks (large)”“4.3.2. Rainwater pipes” of “4.3. Rainwater gutters” in “4. Parks (large)”“4.4.6.Paved surfaces” of “4.4. Playgrounds and the like” in “4. Parks(large)”“5.1.1. Roofs/rooftops” of “5.1. Roofs/rooftops” of “5. Large facilities”“5.2.1 Exterior walls/outside walls” of “5.2. Exterior walls/outside walls”
of “5. Large facilities”“5.3.1.” of “5.3. Rainwater gutters” of “5. Large facilities”“5.3.2. Rainwater pipes” of “5.3. Rainwater gutters” of “5. Large
facilities”“5.4.6. Parking lots (concrete, asphalt)” of “5.4. Playgrounds and thelike” of “5. Large facilities”“6.1.2. Roads/Sidewalks” of “6.1. Paved roads” of “6. Roads”“6.3.1. Guardrails” of “6.3. Guardrails” of “6. Roads”“6.5.1. Pedestrian overpasses” of “6.5. Pedestrian overpasses” of “6.
Roads”

Decontamination

High-pressure water cleaning

methods
OutlineRoofs/rooftops, exterior walls/ outside walls,
rainwater gutters (roof gutters, rainwater pipes）
in the residential areas, schools, parks and large
facilities; grounds and the like (paved surfaces);parking lots (concrete, asphalt); and paved
roads/sidewalks, guardrails, and pedestrian
overpasses
shallbecleanedbyusing
high-pressure water cleaning in the following
procedures
285

(i) Cleaning by using high-pressurecleaners(ii) Collecting waste water
Decontamination processes

water■When working on roof gutters of residences andthe like, schools, parks (small), parks (large) andlarge facilities (1.3.1, 2.3.1, 3.3.1, 4.3.1, 5.3.1)
The cleaning water discharge lines shall becleaned beforehand for smooth discharge. The
discharge shall be collected in rainwater
cisterns or the like. After collection, it shall betransferred to on-site or nearby wastewater
treatment facilities.
High-pressure water cleaning shall beapplied mainly where, for instance, it is too
narrow for a hand to reach for wiping.
High-pressure water of about 2 L/min below 5
MPa in principle shall be sprayed by using
high-pressure water cleaners, with attention
to avoid damaging rainwater gutters.
The spray nozzle shall be brought near theobjects to be cleaned (about 20 cm) at an
appropriate moving speed for achieving thecleaning effect.
The water cleaning shall be done from theupper stream to the lower stream ofgradients to avoid water scattering to thesurroundings.
■When working on rainwater pipes of residences
and the like, schools, parks (small), parks (large)
and large facilities (1.3.2, 2.3.2, 3.3.2, 4.3.2, 5.3.2),
Sediment, if any, shall be removed before thecleaning.
The cleaning water discharge lines shall becleaned beforehand for smooth discharge. The
discharge shall be collected in rainwater
cisterns and the like. After collection, it shallbe transferred to on-site or nearby
wastewater treatment facilities.
High-pressure water of about 2 L/min below 5
MPa in principle shall be sprayed by using
high-pressure water cleaners, with attention
to avoid damaging rainwater gutters.
■When working on paved surfaces in the gardens
and the like of residences and the like, grounds
and the like of parks (small), and pedestrian
overpasses (1.4.2, 3.4.6, 6.5.1); paved surfaces of
the grounds and the like at schools and parks(large), parking lots (concrete, asphalt) of large
facilities, and paved roads/sidewalks (2.4.6, 4.4.6,
5.4.6, 6.1.2),
High-pressure water of about 20 MPa in
286

principle shall be sprayed in about 20 L/m2 byusing suction-type high-pressure watercleaners.
The cleaning water collected shall betransferred to on-site or nearby wastewater
treatment facilities.
The water cleaning shall be done fromperipheries to inner sides and from the upperstream to the lower stream of gradients toavoid water scattering to the surrounding.
The cleaning shall be done in a shieldedenvironment in order to avoid water
scattering when buildings stand closely next
to each other.
■ When working on roofs/rooftops of schools,
parks (small), parks (large) and large facilities(2.1.1, 3.1.1, 4.1.1, 5.1.1),
The cleaning water discharge lines shall becleaned beforehand for smooth discharge. The
discharge shall be collected in rainwater
cisterns and the like. After collection, it shallbe transferred to on-site or nearby
wastewater treatment facilities.
High-pressure water of about 15 MPa in
principle shall be sprayed in about 20 L/m2
using high-pressure water cleaners.
The spray nozzle shall be brought near theobjects to be cleaned (about 20cm) at an
appropriate moving speed for achieving thecleaning effect.
The water cleaning shall be done fromperipheries to inner sides and from the upperstream to the lower stream of gradients toavoid water scattering to the surrounding.
The cleaning shall be done in a shieldedenvironment by using sheets or the like inorder to avoid water scattering.
Attention shall be paid to protect water-proof
paints or water-proof sheets from damage.
■When working on exterior walls/outside wallsof schools, parks (small), parks (large) and large
facilities (2.2.1, 3.2.1, 4.2.1, 5.2.1), or guardrails ofroads (6.3.1),
The cleaning water discharge lines shall becleaned beforehand for smooth discharge. The
discharge shall be collected in rainwater
cisterns and the like. After collection, it shallbe transferred to on-site or nearby
wastewater treatment facilities.
High-pressure water of about 15 MPa in
principle shall be sprayed in about 20 L/m2
using high-pressure water cleaners.
287

The spray nozzle shall be brought near theobjects to be cleaned (about 20 cm) at an
appropriate moving speed for achieving thecleaning effect.
The water cleaning shall be done fromperipheries to inner sides and from the upperstream to the lower stream of gradients toavoid water scattering to the surrounding.
Tools, equipment and the like fordecontamination work

■When working on roof gutters of residences andthe like, schools, parks (small), parks (large) andlarge facilities (1.3.1, 2.3.1, 3.3.1, 4.3.1, 5.3.1)(per 130m)
Tools, equipment to use
Quantity
Sprinkler
trucks(Tank
0.6 service
days
capacity 3,800L）
High-pressurecleaners
1.9 service
days(Motor-driven, Output 3.7kw）
Enginegenerators(rated1.9
17/20kvA,
exhaustgas service days
suppression type (primaryside))
Light oil
36.4 LWater
0.3 m3
Temporary systems and the－like for wastewater collection■When working on rainwater pipes of residences

and the like, schools, parks (small), parks (large)
and large facilities (1.3.2, 2.3.2, 3.3.2, 4.3.2, 5.3.2),(per 130m)
Tools, equipment to use
Quantity
Sprinkler
trucks(Tank
1.7 service
days
capacity 3,800 L）
High-pressurecleaners
1.4 service
days(Motor-driven, Output 3.7 kw）
Engine generators (rated 17/20
1.4 service
kvA, exhaust gas suppression
days
type (primary side))
Light oil46.1 LWater
0.3 m3
Temporary systems and the－like for wastewater collection■When working on paved surfaces in the gardens

and the like of residences and the like and parks(small), pedestrian overpasses (1.4.2, 3.4.6, 6.5.1),(per 300 m2)
Tools, equipment to use
Quantity
Suction-typehigh-pressure 1 service day
cleaners (discharge pressure
20.5MPa, vacuum pump）

288

Rotary-type water
vehicles (φ300)

collecting

1 service day

Sprinkler trucks (tank capacity
3,800L)
Crane trucks (load capacity 2 t,suspension weight 2.9 t)
Sewage filters (200 L)
Sewagetank(1m3
polyethylene)
Feedwater
tank
(1
m3
polyethylene)
Light oilWater

1 service day
1 service day
1 service day
6 service days
1 service day
53.3 L
6 m3■ When working on roofs/rooftops of schools,

parks (small), parks (large) and large facilities(2.1.1, 3.1.1, 4.1.1, 5.1.1),(per 1,300 m2)
Tools, equipment to use
Quantity
High-pressurecleaners
4.2(Engine-driven, output 18 kw)
service days
Streetdraincleaner4(Blower-type, hopper capacity service days
3.1m3, air-flow 20m3/min)
Sprinkler trucks (tank capacity
4.9
3,800 L)
service days
Engine-generators(Rated
4.2
17/20
kvA,
exhaustgas service days
suppression
type(primaryside))
Submersible motor pumps for
4.2
construction work (50 mm service days
caliber, total head 20 m)
Water tanks (for general
4.2
construction work, 3 m3)
service days
Light oil
196.2 LWater
27 m3
Temporary systems and the－like for wastewater collection■When working on exterior walls/outside wallsof schools, parks (small), parks (large) and large
facilities (2.2.1, 3.2.1, 4.2.1, 5.2.1),(per 1,300 m2)
Tools, equipment to use
Quantity
High-pressurecleaners
4.2(Engine-driven, output 18kw)
service days
Streetdraincleaners
4(Blower-type, hopper capacity service days
3.1 m3, air-flow 20 m3/min)289

Sprinkler trucks (tank capacity
3,800 L)
Light oil
Water
Temporary systems and thelike for wastewater collection

4.9
service days
183.9 L
27 m3－

■When working on paved surfaces in the school

grounds and the like and parks (large), parking
lots (concrete, asphalt) of large facilities, andpaved roads/sidewalks (2.4.6, 4.4.6, 5.4.6, 6.1.2),(per 350 m2)
Tools, equipment to use
Quantity
Suction-typehigh-pressure1
water
cleaners(discharge service day
pressure 20.5 MPa, vacuum
pump）
Rotary-type water collecting
1
serviceday
vehicles (φ450)
Sprinkler trucks (tank capacity
3,800L)
Crane trucks (load capacity 2t,
suspension weight 2.9t)
Sewage filters (200 L)
Sewage tank (1 m3 polyethylene)
Feedwatertankpolyethylene)
Light oil
Water

(1

m3

1
service day
1service day
1service day
7
service days
1
service day
53.3 L
7 m3■When working on road guardrails (6.3.1),

Tools, equipment to use
High-pressurecleaners(Engine-driven, output 18 kw)
Streetdraincleaners(Blower-type, hopper capacity
3.1 m3, air-flow 20 m3/min)
Sprinkler trucks (tank capacity
3,800 L)
Light oil
Water
Temporary systems and the likefor wastewater collection

Workforce needed(per 1,900 m)
Quantity
4.2
service days
4
service days
4.9
service days
183.1 L
27 m3－

■When working on roof gutters of residences andthe like, schools, parks (small), parks (large) and290

large facilities (1.3.1, 2.3.1, 3.3.1, 4.3.1, 5.3.1)(per 130 m)
Workforce needed
Quantity
Operation leaders
0.4
worker-days
Decontamination workers
2.1
worker-days
Drivers (ordinary
0.4
decontamination)
worker-days■When working on rainwater pipes of residences

and the like, schools, parks (small), parks (large)
and large facilities (1.3.2, 2.3.2, 3.3.2, 4.3.2, 5.3.2)(per 130 m)
Workforce needed
Quantity
Operation leaders
0.5
worker-days
Decontamination workers
2.2
worker-days
Drivers (ordinary
1.1
decontamination)
worker-days■When working on paved surfaces in the gardens
and the like of residences and the like and parks(small), pedestrian overpasses (1.4.2, 3.4.6, 6.5.1),(per 300 m2)
Workforce needed
Quantity
Operation leaders
1.0
worker-day
Specialized decontamination
1.0
workers
worker-day
Decontamination workers
3.0
worker-days
Drivers (ordinary
1.0
decontamination)
worker-day■ When working on roofs/rooftops of schools,
parks (small), parks (large) and large facilities(2.1.1, 3.1.1, 4.1.1, 5.1.1), exterior walls/outside
walls of schools, parks (small), parks (large) andlarge facilities (2.2.1, 3.2.1, 4.2.1, 5.2.1),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
2.1
worker-days
Decontamination workers
7.9
worker-days
Drivers (ordinary
6.2
decontamination)
worker-days■When working on paved surfaces in the school
grounds and the like and parks (large), parking
lots (concrete, asphalt) of large facilities, and291

paved roads/sidewalks (2.4.6, 4.4.6, 5.4.6, 6.1.2),(per 350 m2)
Workforce needed
Quantity
Operation leaders
1.0
worker-day
Specialized decontamination
1.0
workers
worker-day
Decontamination workers
3.0
worker-days
Drivers (ordinary
1.0
decontamination)
worker-day■When working on road guardrails (6.3.1),(per 1,900 m)
Workforce needed
Quantity
Operation leaders
2.1
worker-days
Decontamination workers
7.9
worker-days
Drivers (ordinary
6.2
decontamination)
worker-days
Idea
development,
lessons,
points to
keep inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

In order to prevent contamination fromspreading due to decontamination work, theorder of works shall be considered. For
instance, when decontaminating residential
areas and the like, the decontamination work
shall be done starting with roofs followed by
rainwater gutters and then gardens and thelike. If residences and the like stand closely
next to each other, the cleaning shall be donein a shielded environment by using sheets
and the like in order to avoid water scatteringover surrounding residences and the like.
No risk of damaging the objects by
high-pressure water cleaning shall bechecked beforehand. Attention shall be paid
to the possibility of damaging objects bystripping off the surface.
Soil shall be cleaned at low pressures first inorder to prevent soil dispersion. The pressure
shall be increased gradually by confirming
the cleaning water flows and dispersion
conditions.
Special attention shall be paid when cleaning
the overlapping sections of roofs, places
where the metal is corroded, and around thedrains for rooftops. At these places large
amounts of sediment are attached.
Paved surfaces shall not be cleaned whenfrozen or snow covered.
Suction-type high-pressure water cleaners
shall be used when cleaning paved surfaces ofgardens and the like of residences and the292like, grounds and the like, of parks (small),pedestrian overpasses (1.4.2, 3.4.6, 6.5.1),
those of school grounds and the like, parks(large), parking lots (concrete, asphalt) oflarge facilities, or paved roads/sidewalks(2.4.6, 4.4.6, 5.4.6, 6.1.2). When cleaningother objects, the discharge water shall becollected in the rainwater cisterns and thelike.
Cleaning conditions for decontaminating
respective objects shall be as follows in
principle.
Objects to be
decontaminatedRoofgutters(1.3.1,
2.3.1, 3.3.1, 4.3.1, 5.3.1)
and rainwater pipes(1.3.2, 2.3.2, 3.3.2, 4.3.2,
5.3.2) of residences andthe like, schools, parks(small), parks (large)
and large facilities
Roofs/rooftops(2.1.1,
3.1.1, 4.1.1, 5.1.1) andexterior
walls/outside
walls (2.2.1, 3.2.1, 4.2.1,
5.2.1) of schools, parks(small), parks (large),
and large facilities, androad guardrails (6.3.1)
Paved
surfacesofgardens and the like ofresidences and the like,groundsofparks(small), and pedestrian
overpasses (1.4.2, 3.4.6,
6.5.1), those of school
grounds and the like,parks (large), parking
lots (concrete, asphalt)of large facilities, andpaved roads/sidewalks(2.4.6, 4.4.6, 5.4.6, 6.1.2)
Radiation

exposure

Conditions(principle)
Cleaning with highpressure water ofabout 5 MPa in
about 2 L/m2, inprinciple, by using ahigh-pressure watercleaner
Cleaning with highpressure water ofabout 15 MPa in
about 20 L/m2, inprinciple, by using ahigh-pressure watercleaner
Cleaning with highpressure water ofabout 20 MPa in
about 20 L/m2, inprinciple, by using asuction-typehigh-pressure watercleaner

Safety glasses, dust masks, hand gloves, etc.

protection of workers

shall be worn

General labor safety ofworkers

For the work at elevated places, adequate
safety measures shall be taken for scaffolds,
aerial lift work vehicles and fall arresting
devices/systems using fixed ropes/safety
belts, etc.
For the work on roads, barricades and traffic
293controllers shall be arranged.
Measures to prevent－

secondary wastes
Others－2944）Shot-blasting
Locations to be
decontaminated“1.4.2. Paved surfaces” of “1.4. Gardens and the like” in “1. Residential
areas and the like”“2.4.6. Paved surfaces” of “2.4. Grounds and the like” at “2. Schools”“3.4.6.Paved surfaces” of “3.4. Grounds and the like” in “3. Parks(small)”“4.4.6.Paved surfaces” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.6. Parking lots (concrete, asphalt)” of “5.4. Grounds and the like” of“5. Large facilities”“6.1.2. Roads/Sidewalks” of “6.1. Paved roads” of “6. Roads”

Decontamination

Shot-blasting

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Paved surfaces of gardens/grounds in theresidential areas, schools, parks and large
facilities, etc.,, parking lots (concrete, asphalt),
and paved roads/sidewalks shall be cleaned by
shot-blasting in the following procedures(i) Scraping off object
surfaces withshot-blasters(ii) Packing scrapped materials
Scraping shall be done in a fairly wide paved
place.
Abrasive materials such as steel shot shallbe shot on the surface with a shot-blaster for
scraping away the said surface uniformly.
Scrapped materials, asphalt and the like,shall be collected by a dust collector
connected to the shot-blaster.
Collected scrapped materials shall bepacked in large sandbags.
Fine particles generated shall be prevented
from dispersion to the surroundings bycovers and shall be collected.
A small amount of abrasive materials left
behind on the surfaces shall be collected by amanual magnet car and cleaning.
■When working on paved surfaces of gardens

and the like, of residences and the like (1.4.2),(per 350 m2)
Tools, equipment to use
Quantity
Shot-blasters(scraping/
6.5
suction width 700 mm)
service hours
Engine-generators(Rated1.09
100/125 kvA, exhaust gas service days
suppression type (primaryside))

295

Dust collectors (suction width
700/1000 mm, wind velocity
75 m3)
Crane trucks (load capacity 4t, suspension weight 2.9 t)
Trucks (load capacity 4 t)
Light oil
Large sandbags

6.5
service hours
1.23
service days
1.13
service days
192 L-

■ When working on paved surfaces in the

grounds of schools, parks (small), and parks(large) (2.4.6, 3.4.6, 4.4.6,), parking lots
(concrete, asphalt) of large facilities (5.4.6), andpaved roads/sidewalks (6.1.2),(per 500 m2)
Tools, equipment to use
Quantity
Shot-blasters(scraping/
6.5
suction width 1,000 mm)
service hours
Engine-generators(Rated1.03
125/150 kvA, exhaust gas service days
suppression type (primaryside))
Dust collectors (suction width
6.5
700/1000 mm, wind velocity service hours
75 m3)
Crane trucks (load capacity 8
1.23t, suspension weight 2.9 t)
service days
Trucks (load capacity 8 t)
1.13
service days
Light oil
255 L
Large sandbags-

Workforce needed■When working on paved surfaces of gardens

and the like, of residences and the like (1.4.2),(per 350 m2)
Workforce needed
Quantity
Operation leader
1.0
worker-day
Decontamination worker
2.0
worker-days
Driver (special
2.0
decontamination)
worker-days
Driver (ordinary
1.0
decontamination)
worker-day■ When working on paved surfaces in the
grounds of schools, parks (small), and parks(large) (2.4.6, 3.4.6, 4.4.6,), parking lots296

(concrete, asphalt) of large facilities (5.4.6), andpaved roads/sidewalks (6.1.2),(per 500 m2)
Workforce needed
Quantity
Operation leader
1.0
worker-day
Decontamination worker
2.0
worker-days
Driver (special
2.0
decontamination)
worker-days
Driver (ordinary
1.0
decontamination)
worker-day
Idea
development,
lessons,
points to
keep inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

Paved surfaces shall not be cleaned whenfrozen or snow covered.
Work shall be halted when raining or roads
are wet because working and collecting ofscrapped materials is difficult.
It should be noted that the decontamination
effect by scraping is lowered when ruts or
cracks are present on the paved surfaces
relative to smooth surfaces.
This cleaning method is not effective when
the road unevenness or crack depths exceed
5 mm.
At the edges of blasted area, 5 – 10 cm
overlapping is needed for removing surface
irregularity.
High-pressure water cleaning and the likeshall be used in place of the shot-blasting
method at the edges of paved surfaces 15 –30 cm from adjacent buildings or otherstructures.

Radiation

Safety glasses, dust masks, hand gloves, etc.

exposureprotection of workers

shall be worn.

General labor safety ofworkers

For the work on roads, barricades and traffic
controllers shall be arranged.

Measures to prevent－

secondary wastes
OthersFor the work in narrow spaces of less thanabout 10 m2 of paved surfaces in residential
areas, unit space of 350 m2 shall be read as
50 m2 (tools, equipment, workforce needed).

2975）Superhigh pressure water cleaning
Locations to be
decontaminated“2.4.6. Paved surfaces” of “2.4. Grounds and the like” at “2. Schools”“4.4.6.Paved surfaces” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.6. Parking lots (concrete, asphalt)” of “5.4. Grounds and the like” of“5. Large facilities”“6.1.2. Roads/Sidewalks” of “6.1. Paved roads” of “6. Roads”

Decontamination

Superhigh pressure water cleaning

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Paved surfaces of schools, parks (large) and large
facilities, parking lots (concrete, asphalt), andpaved roads/sidewalks shall be cleaned bysuperhigh pressure water in the following
procedures(i) Scraping off object surfaces with superhigh-pressure water cleaners(ii) Collecting wastewater from decontamination
Paved surfaces shall be scraped off by about
5mm with superhigh pressure watercleaners (cleaning water recovery-type) of
150 MPa or higher.
Wastewater collected shall be separated toscrapings (sludge) and water by the
coagulating sedimentation process, or othermeans.
Tools, equipment to use
Shovels , brooms and the likeSuperhigh pressure watercleaners (240MPa maximum
pressure (including powerful
vacuum trucks)
Streetdraincleaners(Capacity 5.1 m3)
Engine-generators (Rated 3
kvA, Low-noise type)Air
compressor(Portable,
Exhaust gas suppression type(Primary side) 3.5-3.7 m3/min)
Sprinkler
trucks(Tank
capacity 3,800 L)
Light oil
Gasoline
Large sandbags

298(per 1,300 m2)
Quantity
3.7
service days
3.5
service days
2.9
service days
4.7
service days
4.3
service days
1,207.2 L
9.5 L-

Workforce needed
Workforce needed
Operation leaders
Specialized decontamination
workers
Decontamination workers
Drivers (special
decontamination)
Drivers (ordinary
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 1,300 m2)
Quantity
2.8
worker-days
5.8
worker-days
4.8
worker-days
2.7
worker-days
5.4
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

Paved surfaces shall not be cleaned whenfrozen or snow covered.
Superhigh pressure water cleaners may be
not appropriate for scraping near curbs.
Handy-type/edge-scraping type cleaners or
high-pressure water cleaners can be usedinstead (costs of handy-type cleaners shallbe reviewed). When non-water-recovery-type
cleaners are used, the work shall be done
under covers to prevent water dispersion
and the cleaning water shall be collectedfrom street drains.
Radiation dose after decontamination shallbe measured after the road surfaces are
dried.

Radiation exposure
protection of workers

Rainwear, safety glasses, dust masks, hand

General labor safety ofworkers

For the work on roads, barricades and traffic
controllers shall be arranged.

Measures to prevent
secondary wastes

Scrapings (sludge) collected by coagulating
sedimentation
shallbethoroughly
dehydrated and packed in large sandbags.

Othersgloves, etc. shall be worn.

－

2996）Cleaning by road sweepers
Locations to be“6.1.2 Roads/sidewalks” of “6.1 Paved roads” of “6. Roads”

decontaminatedDecontamination

Cleaning by road sweepers

methods
OutlineDecontamination processes

Tools, equipment for decontamination
work

Paved roads/sidewalks shall be cleaned by roadsweepers
Paved roads/sidewalks shall be cleaned byroad sweepers in preparation for the work bydecontamination workers or for maintenance.
Trash collected shall be packed in flexible
containers.
(per 1 km)
Quantity*3(service hours)

Tools, equipment to use
Shovels, brooms, brushes, etc.
Road sweepers (Brush-type,
Hoppercapacity
3.1m3,
4-wheeled)
Light oil
12 x *3 (L)Note) The estimate shall be changed, if sprinkler
trucks are needed.

Workforce needed
Workforce needed
Operation leaders
Decontamination workers
Drivers (ordinary
decontamination)
Assistants todecontamination workers*1: 0.8×T1/T×1/L*2: 1.2×T1/T×1/L*3: T1/L(per 1 km)
Quantity*1( worker-hours)*2(worker-hours)*3 x 0.14(worker-hours)*3 x 0.13(worker-hours)

T1=L/V1＋ℓ/V2
T1= Time required for work (h)L= Cleaning distance (km)V1= Cleaning speed (km/h)= 6.0 km/h (time forcarrying away trash included)ℓ= Distance of journey (km) =ℓ1＋ℓ2＋ℓ3＋ℓ4ℓ1= Distance between the workplace and surplus
soil repository (km)ℓ2= Distance between the workplace and water300

supply point (km)ℓ3= Distance between the workplace to the next
workplace (km) (assuming no need to clean in thesection and the section is longer thanℓ4= Distance between the workplace and the base(km)
In calculating the distance of journey (ℓ) above,following factors shall be considered.
Δ L= Cleaning distance per hopper of street
sweepers (km) = hopper capacity x hopper
coefficient/amountoftrash=(3.10×0.61)/0.1=18.91(km)V2= Driving speed (km/h) =30.0 km/h
T= Road sweeper operation time per day =7.6
h/day
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

Paved surfaces shall not be cleaned whenfrozen or snow covered.
Packing work of the contaminated materials
removed and collected into flexible containers
shall be done under covers to prevent dust
from dispersion.

Radiation exposure
protection of workers

Safety glasses, dust masks, rubber gloves,etc. shall be worn when working outdoors.

General labor safety ofworkers

Barricades and traffic controllers shall bearranged, as the work is done on the roads.

Measures to prevent－

secondary wastes
Others－301

（3） Weeds/lawns
1）Weeding, lawn mowing
Locations to be
decontaminated“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like.”“2.4.2. Weeds/lawns” of “2.4. Grounds and the like” at “2. Schools”“3.4.2. Weeds/lawns” of “3.4. Grounds and the like” in “3. Parks (small)”“4.4.2.Paved surfaces” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.2. Weeds/lawns” of “5.4. Grounds and the like” of “5. Large
facilities”“6.6.2. Weeds” of “6.6. Roadside trees” of “6. Roads”

Decontamination

Weeding, lawn mowing

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Weeds/lawns of residences, schools, parks, large
facilities, and roadside trees, etc. shall be mowed in
the following procedures(i) Weeding and mowing by mowers and the like((ii) Collecting/transferring mowed weeds/grass)(iii) Packing of mowed weeds/grass
Prior to removing sediment and surface soil,
weeds that may hinder the work shall be
removed or weeded by shoulder-type mowers
or by hand.
Packing of weeds/grass removed in large
sandbags■When working on unpaved surfaces of gardens
and the like of residences and the like (1.4.1) andgrounds and the like of parks (small) (3.4.2),(per 1,300 m2)
Tools, equipment to use
Quantity
Mowers (shoulder-type, cutter
18.9
edge 255mm)
service days
Gasoline
46.2 L
Large sandbags■ When working on grounds and the like, of
schools, parks (large) and large facilities, etc.
(2.4.2, 4.4.2, 5.4.2),(per 1,300 m2)
Tools, equipment to use
Quantity
Dump trucks (load capacity 2t)
0.1(2t)
service days
Mowers (shoulder-type, cutter
19.0
edge 255mm)
service days
Light oil
2.6 L

302

Gasoline
Large sandbags

46.2 L-■When weeding roadside trees (6.6.2),(per 1,300 m2)
Tools, equipment to use
Quantity
Mowers (shoulder-type, cutter
6.0
edge 255mm)
service days
Light oil
3.8 L
Gasoline
14.5 L
Large sandbags
Workforce needed■When working on unpaved surfaces of gardens
and the like of residences and the like (1.4.1) andgrounds and the like of parks (small) (3.4.2),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
1.8
worker-days
Specialized decontamination
10.2
workers
worker-days
Decontamination workers
1.5
worker-days■ When working on grounds and the like, of
schools, parks (large) and large facilities, etc.
(2.4.2, 4.4.2, 5.4.2),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
1.8
worker-days
Specialized decontamination
10.2
workers
worker-days
Decontamination workers
1.5
worker-days
Drivers (ordinary
0.1
decontamination)
worker-days■When working on roadside trees (6.6.2),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
1.3
worker-days
Specialized decontamination
3.2
workers
worker-days
Decontamination workers
5.5
worker-days
Drivers (special
0.1
decontamination)
worker-days

Idea
development,
lessons,

Prerequisites
andconstraints regarding
objects and locations

Decontamination work shall be halted when
the weeds/lawns to be decontaminated arefrozen or snow covered.
303

points
tokeepinmind, etc.

to be decontaminatedRadiation exposure
protection of workers

Safety glasses, masks, gloves, etc. shall be

General labor safety ofworkers

For the work on road shoulders, barricades
and traffic controllers shall be arranged.
Mowers are simple machines, but it is easy for
operators to be hurt. Measures shall be taken
to prevent minor collisions with machines.
<Major safety measures>
・ Availability of protective covers shall bechecked.
・ Proper mounting of protective covers shallbe checked.
・ Knife-proof gloves shall be worn.
・ A no-access area shall be set around theweed cutter (5 m).
・ Distance shall be reserved between weed
cutters (15 m).

Measures to prevent
secondary wastes

Cut weeds/grass shall be collected quickly inorder to prevent scattering by wind and rain.

Others

worn.

－

304

2）Deep mowing of lawns
Locations to be
decontaminated“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like.”“2.4.2. Weeds/lawns” of “2.4. Grounds and the like” at “2. Schools”“3.4.2. Weeds/lawns” of “3.4. Grounds and the like” in “3. Parks (small)”“4.4.2.Paved surfaces” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.2. Weeds/lawns” of “5.4. Grounds and the like” of “5. Large
facilities”

Decontamination

Sod cutting

methods
OutlineWeeds and lawns of unpaved surfaces of gardens
and the like of residences and the like, andgrounds of schools, parks, large facilities shall be
removed by sod cutting in the following
procedures(i) Lifting of lawns by sod cutters and the like((ii) Collecting mowed weeds/grass, roots and soil(iii) Packing of removed materials

Decontamination processes■ When working on weeds/lawns of unpaved
surfaces of gardens and the like of residences andthe like (1.4.1) and grounds and the like of parks(small) (3.4.2),
Lawns shall be removed (reproducible
shallow scraping of about 3 cm depth) using
manually-guided sod cutters and the likeafter mowing. Root mat layers shall bepreserved.
Removed materials shall be packed in large
sandbags.
Bumps shall be covered with soil, and soil of 3
– 6 mm depth shall be scattered over them.
■When working on weeds/lawns of grounds andthe like of schools, parks (large) and large
facilities and the like (2.4.2, 4.4.2, 5.4.2),
Large sod cutters, where possible, shall cut
deeply (reproducible shallow scraping ofabout 3 cm depth).
Where large sod cutters cannot gain access,manually-guided sod cutters and the likeshall cut deeply (about 3 cm).
Root mat layers shall be preserved.
Removed materials shall be packed in large
sandbags.
Bumps shall be covered with soil, and soil of 3
– 6mm depth shall be scattered over them.

305

Tools, equipment and the like fordecontamination work

■ When working on weeds/lawns of unpaved
surfaces of gardens and the like of residences andthe like (1.4.1), and grounds and the like of parks(small) (3.4.2),(per 1,300 m2)
Tools, equipment to use
Quantity
Manually-guided sod cutters18.8(cutting path 55 – 65 cm)
service days
Gasoline
63.0 LFresh soil for scattering over
6.5 m3lawns
Large sandbags■When working on weeds/lawns of grounds andthe like of schools, parks (large) and large
facilities, etc. (2.4.2, 4.4.2, 5.4.2),(per 1,300 m2)
Tools, equipment to use
Quantity
Backhoes (Excavators) (Crawler
2.1
type, Exhaust gas suppression service days
type
(secondary),
Standard
bucket capacity 0.28 m3 whenheaped (0.2 m3 when flatly
filled))Dump trucks (load capacity 2 t)
0.7
service day
Manually-guided sod cutters1.1(cutting path 55 – 65 cm)
service days
Light oil
73.5 L
Gasoline
3.7 L
Fresh soil for scattering over
6.5 m3lawns
Large sandbags-

Workforce needed■ When working on weeds/lawns of unpaved
surfaces of gardens and the like of residences andthe like (1.4.1), and grounds and the like of parks(small) (3.4.2),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
3.8
worker-days
Specialized decontamination
10.0
workers
worker-days
Decontamination workers
15.0
worker-days■When working on weeds/lawns of grounds andthe like of schools, parks (large) and large
facilities, etc. (2.4.2, 4.4.2, 5.4.2),

306

Workforce needed
Operation leaders
Specialized decontamination
workers
Decontamination workers
Drivers
decontamination)
Drivers (ordinary
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(special(per 1,300 m2)
Quantity
0.6
worker-days
0.6
worker-days
1.3
worker-days
1.3
worker-days
0.6
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedDecontamination work shall be halted when
the weeds/lawns to be decontaminated arefrozen or snow covered.

Radiation exposure
protection of workers

Safety glasses, masks and gloves shall be

General labor safety ofworkers(When mowers, sod cutters and heavy machinery
are used,)
Setting of color cones or cone bars is
recommended to designate working areas
in order to prevent minor accidents byworker-machine collisions or being caught
in a machine (Driver is in charge). (Whenmowers are used,)
Mowers are simple machines, but it iseasy for operators to be hurt. Measures
shall be taken to prevent accidents due tominor collisions.
<Major safety measures>
・ Availability of protective covers shall bechecked・ Proper mounting of protective covers
shall be checked.
・ Knife-proof gloves shall be worn.
・ A no-access area shall be set around theweed cutter (5 m).
・ Distance shall be reserved between weed
cutters (15 m).

Measures to prevent

－

worn.

secondary wastes
Others－307

（4） Gravel, crushed stones
1）Removal of gravel, crushed stones
Locations to be
decontaminated“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like.”“2.4.3. Gravel, crushed stone” of “2.4. Grounds and the like” at “2.
Schools”“3.4.3 Gravel, crushed stone” of “3.4. Grounds and the like” in “3. Parks(small)”“4.4.3. Gravel, crushed stone” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.3. Gravel, crushed stone” of “5.4. Grounds and the like” of “5. Large
facilities”“6.2.2. Road surfaces (roads of gravel, crushed stone)” of “6.2. Unpaved
roads” of “6. Roads”

Decontamination

Removal of gravel, crushed stone

methods
OutlineGravel, and crushed stone of unpaved surfaces ofgardens and the like of residences and the like, ofgrounds of schools, parks, large facilities, andunpaved road surfaces (roads of gravel or crushedstones) shall be removed in the following
procedures(i) Removing gravel and crushed stone(ii) Packing removed gravel and crushed stone

Decontamination processes■When working on gravel and crushed stone ofunpaved surfaces of gardens and the like ofresidences and the like (1.4.1), and of grounds andthe like of parks (3.4.3),
Gravel and crushed stone shall be uniformly
removed (to about 5 cm depth) with shovels
and the like, and packed in large sandbags.
When the existing gravel or crushed stone isless than 5 cm deep, the top layer about 5 cm
deep and including the soil underneath shallbe uniformly removed and be packed in large
sandbags.
■ When working on gravel and crushed stone
from grounds and the like of schools, parks(large), large facilities, etc. (2.4.3, 4.4.3, 5.4.3),
Gravel and crushed stone shall be uniformly
removed (to about 5 cm depth) with backhoes
and the like, and packed in large sandbags.
When the existing gravel or crushed stone isless than 5 cm deep, the top layer about 5 cm
deep and including the soil underneath shallbe uniformly removed and be packed in large308

sandbags.
■When working on gravel and crushed stone ofunpaved road surfaces (roads of gravel andcrushed stone) (6.2.2),
The top surface layer shall be scraped away
in a uniform thicknesses (about 5 cm from thetop) by backhoes and the like, and packed inlarge sandbags.
Tools, equipment and the like fordecontamination work

■When working on gravel and crushed stone ofunpaved surfaces of gardens and the like ofresidences and the like (1.4.1), and of grounds andthe like of parks (3.4.3),(per 1,300 m2)
Tools, equipment to use
Quantity
Shovels and the like
Large sandbags■ When working on gravel and crushed stone
from grounds and the like of schools, parks(large), large facilities, etc. (2.4.3, 4.4.3, 5.4.3),(per 1,000 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes(Crawler
type,
1.4
Exhaust gas suppression type service days
(secondary), Bucket capacity
0.45 m3 when heaped (0.35 m3
when flatly filled))
Backhoes(Crawler
type,
3.9
Exhaust gas suppression type service days
(secondary), Bucket capacity
0.28 m3 when heaped (0.2 m3
when flatly filled))
Backhoes(Crawler
type,
2.8
Exhaust gas suppression type service days
(secondary), Bucket capacity
0.13 m3 when heaped (0.10 m3
when flatly filled))
Light oil360.1 L
Large sandbags■When working on gravel and crushed stone ofunpaved road surfaces (roads of gravel andcrushed stones) (6.2.2),(per 1,300 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes(Crawler
type,
11.2
Exhaust gas suppression type service days
(secondary), Bucket capacity309

0.28m3 when heaped (0.20 m3
when flatly filled))
Vibratory rollers (Combined
type, 3.0 – 4.0 t weight)
Light oil
Large sandbags
Workforce needed

5.6
service days
565.2 L-

■When working on gravel and crushed stone ofunpaved surfaces of gardens and the like ofresidences and the like (1.4.1), and of grounds andthe like of parks (3.4.3),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
7.7
worker-days
Decontamination workers
51.4
worker-days■ When working on gravel and crushed stone
from grounds, and the like, of schools, parks(large), large facilities, etc. (2.4.3, 4.4.3, 5.4.3),(per 1,000m2)
Workforce needed
Quantity
Operation leaders
1.7
worker-days
Decontamination workers
11.1
worker-days
Drivers (special
8.1
decontamination)
worker-days■When working on gravel and crushed stone ofunpaved road surfaces (roads of gravel andcrushed stones) (6.2.2),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
2.7
worker-days
Decontamination workers
17.9
worker-days
Drivers (special
16.8
decontamination)
worker-days

Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedHeavy machinery (small backhoes and thelike) are preferable to the extent possible forbetter construction efficiency.

Radiation exposure
protection of workers

Masks, gloves and the like shall be worn
when working with shovels and the like.

310

General labor safety ofworkers

Setting of color cones or cone bars is
recommended to designate working areas inorder to prevent minor accidents byworker-machine collisions or being caught ina machine (Driver is in charge).
For the work on roads, barricades and traffic
controllers shall be arranged.

Measures to prevent

Attention is needed to prevent excessive
digging by machinery. Digging depth
indicators shall be set for construction.

secondary wastes
Others－311

（5） Soil
1）Surface soil removal from rainwater gutter drains, under-eaves, etc.
Locations to be
decontaminated■Surface soil removal from rainwater gutter drains, under-eaves, etc.
“2.4.4. Soil” of “2.4. Grounds and the like” at “2. Schools”“4.4.4. Soil” of “4.4. Grounds and the like” in “4. Parks (large)”“5.4.4. Soil” of “5.4. Grounds and the like” of “5. Large facilities”■Surface soil removal from the bases of trees such as roadside trees
and the like
“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like”“2.4.5. Planted vegetation” of “2.4. Grounds and the like” at “2. Schools”“3.4.5 Planted vegetation” of “3.4. Grounds and the like” in “3. Parks(small)”“4.4.5. Planted vegetation” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.5. Planted vegetation” of “5.4. Grounds and the like” of “5. Large
facilities”“6.6.3. Roadside trees” of “6.6. Roadside trees” of “6. Roads”

Decontamination
methods

Soil sediment removal from rainwater gutter drains, under-eaves, etc.
Surface soil removal near the bases of trees and roadside trees

OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Soil sediment of rainwater gutter drains,
under-eaves, etc. of schools, parks, large facilities,
etc. shall be removed in the following procedures.
Similarly, surface soil of gardens and the like ofresidences and the like, and grounds of schools,
parks, large facilities, etc., and soil near the basesof planted vegetation on the roads, trees, roadsidetrees, etc. shall be removed in the following
procedures,(i) Removing surface soil(ii) Packing removed soil
Fallen leaves and soil sediment shall becollected using a shovel or rake, etc. andpacked in large sandbags.
Tools, equipment to use
Shovels, rakes, etc.
Large sandbags

Workforce needed
Workforce needed
Operation leaders
Decontamination workers

312

Quantity(per 1,300 m2)
Quantity
2.0
worker-days
13.3
worker-daysIdea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

The work site could be a high dose level place(hereafter hot spot) depending on the rainfall
conditions. The work flow to designate a hot
spot and monitoring threshold criteria shallbe prescribed in advance in consultation withthe supervisory personnel by referring to theradiation levels around the hot spot.

Radiation
exposureprotection of workers

Masks and gloves shall be worn under dust
handling conditions
Protective gear shall be considered and ahalf-face mask and hand gloves (cotton,
rubber) shall be worn if the radiocesium
concentration is high in the soil to handle,
and if the work corresponds to the work
under high dust concentrations as designatedin relevant guidelines of the Ministry of
Health, Labour and Welfare(MHLW).
If the work site is a hot spot, color cones andthe like shall be arranged, as appropriate, forindicating the hot spot in order to facilitate
reducing the long-term exposure of workers.

General labor safety ofworkers

Safety measures shall be taken for the workwith heavy machinery (proper arrangement
for preventing minor collisions of adjacently
working heavy machinery, and adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)

Measures to prevent－

secondary wastes
Others－313

2）Scraping of surface soil
Locations to be
decontaminated“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like”“2.4.4. Soil” of “2.4. Grounds and the like” at “2. Schools”“3.4.4. Soil” of “3.4. Grounds and the like” in “3. Parks (small)”“4.4.4. Soil” of “4.4. Grounds and the like” in “4. Parks (large)”“5.4.4. Soil” of “5.4. Grounds and the like” of “5. Large facilities”“6.2.1. Road surfaces (soil)” of “6.2. Unpaved roads” of “6. Roads”

Decontamination

Scraping of surface soil

methods
OutlineSoil of unpaved gardens and the like of residences
and the like, of grounds and the like of schools,
parks, large facilities, etc. and the unpaved roadsurface (soil) shall be scraped off in the following
procedures,(i) Scraping off surface soil(ii) Packing scraped soil

Decontamination processes■ When working on the unpaved surfaces ofgardens and the like of residences and the like
(1.4.1), and of grounds and the like of parks(3.4.4),
The garden topsoil shall be uniformly scraped
away (about 5 cm deep) by using bamboo
rakes or similar instruments, and packed inlarge sandbags.
Work breakdown shall be standardized andworkers shall be instructed prior to the workin order to avoid non-uniformity of scraping
thicknesses among workers.
■When working on the soil of grounds and thelike of schools, parks (large), large facilities, etc.
(2.4.4, 4.4.4, 5.4.4),
The surface soil shall be uniformly scraped(about 5 cm deep) with backhoes and the like,and packed in large sandbags.
■ When working on the soil of unpaved roadsurfaces (6.2.1),
The surface soil shall be uniformly scraped(about 5 cm deep) with backhoes and the like,and packed in large sandbags.

Tools, equipment and the like fordecontamination work

■ When working on the unpaved surfaces ofgardens and the like of residences and the like
(1.4.1), and of grounds and the like of parks(3.4.4),314

Tools, equipment to use
Bamboo rakes and the like
Large sandbags

Quantity-■When working on the soil of grounds and thelike of schools, parks (large), large facilities, etc.
(2.4.4, 4.4.4, 5.4.4),(per 1,000 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoe (Crawler type, Exhaust
2.7
gas
suppression
type service days
(secondary), Bucket capacity
0.45 m3 when heaped (0.35 m3
when flatly filled))
Backhoe (Crawler type, Exhaust
2.0
gas
suppression
type service days
(secondary), Bucket capacity
0.28 m3 when heaped (0.20 m3
when flatly filled))
Backhoes(Crawler
type,
0.2
Exhaust gas suppression type service days
(secondary), Bucket capacity
0.13 m3 when heaped (0.10 m3
when flatly filled))
Light oil360.1 L
Large sandbags■ When working on the soil of unpaved roadsurfaces (6.2.1),(per 1,300 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes(Crawler
type,
8.0
Exhaust gas suppression type service days
(secondary), Bucket capacity
0.28 m3 when heaped (0.2 m3
when flatly filled))
Light oil
362.9 L
Large sandbags
Workforce needed■ When working on the unpaved surfaces ofgardens and the like of residences and the like
(1.4.1), and of grounds and the like of parks(3.4.4),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
5.0
worker-days
Decontamination workers
33.4
worker-days■When working on the soil of grounds and the315like of schools, parks (large), large facilities, etc.
(2.4.4, 4.4.4, 5.4.4),(per 1,000 m2)
Workforce needed
Quantity
Operation leaders
1.0
worker-days
Decontamination workers
6.5
worker-days
Drivers (special
4.9
decontamination)
worker-days■ When working on the soil of unpaved roadsurfaces (soil) (6.2.1),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
1.8
worker-days
Decontamination workers
11.8
worker-days
Drivers (special
8.0
decontamination)
worker-days
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

The scraping thickness shall be set before thework. During the work, the scraping
thickness shall be properly confirmed for suredose reduction.

Radiation exposure
protection of workers

Masks and hand gloves shall be worn.

General labor safety ofworkers

Safety measures shall be taken for the workwith heavy machinery (proper arrangement
for preventing minor collisions of adjacently
working heavy machinery, and adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)

Measures to prevent－

secondary wastes
Others－3163）Soil surface covering
Locations to be
decontaminated“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like”“2.4.4. Soil” of “2.4. Grounds and the like” at “2. Schools”“3.4.4. Soil” of “3.4. Grounds and the like” in “3. Parks (small)”“4.4.4. Soil” of “4.4. Grounds and the like” in “4. Parks (large)”“5.4.4. Soil” of “5.4. Grounds and the like” of “5. Large facilities”“6.2.1. Road surfaces (soil)” of “6.2. Unpaved roads” of “6. Roads”

Decontamination

Soil surface covering

methods
OutlineSoil of unpaved gardens and the like of residences
and the like, of grounds and the like of schools,
parks, large facilities, etc. and the unpaved roadsurface (soil) shall be covered in the following
procedures,(i) Covering of surface soil uniformly with fresh
uncontaminated soil,((ii) Short distance transfer of fresh soil to small
places for spreading)(iii) Compacting

Decontamination processes■ When working on the unpaved surfaces ofgardens and the like of residences and the like
(1.4.1), and of grounds and the like of parks(3.4.4),The surface, if its topsoil is scraped away,
shall be covered by fresh soil of similar
quality as before to a similar height.
The new topsoil shall be spread, leveled andcompacted back to the original height andsimilar porosity.
■When working on the grounds and the like ofschools, parks (large), large facilities, etc. (2.4.4,
4.4.4, 5.4.4),
The surface, if its topsoil is scraped away,
shall be covered by fresh soil of similar
quality as before to a similar height by using
backhoes and the like.
The new topsoil shall be spread, leveled andcompacted back to the original height andsimilar porosities.
■When working on the unpaved road surfaces(soil) (6.2.1),
The surface, if its topsoil is scraped away,
shall be covered by fresh soil of similar
quality as before to a similar height using
backhoes and the like.
317

The new topsoil shall be spread, leveled andcompacted back to the original maximum
height and similar porosity.
Tools, equipment and the like fordecontamination work

■ When working on the unpaved surfaces ofgardens and the like of residences and the like
(1.4.1), and of grounds and the like of parks(3.4.4),(per 1,300 m2)
Tools, equipment to use
Quantity
Shovels and the like.
Vibratory rollers (hand guide
15.8
type, 0.8 – 1.1 t weight)
service days
Light oil
56 L
Fresh soil for covering
72.2 m3■When working on the grounds and the like ofschools, parks (large), large facilities, etc. (2.4.4,
4.4.4, 5.4.4),(per 1,000 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes(Crawler
type,
1.1
Exhaust gas suppression type service days
(secondary), Bucket capacity
0.28 m3 when heaped (0.20 m3
when flatly filled))
Vibratory roller (Exhaust gas
1.5
suppression type (primary), service days
Combined type, 3 – 4 t)
Vibratory rollers (Exhaust gas
0.4
suppression
type, service days
manually-guided type, 0.5 – 0.6t)Dump trucks (load capacity 2 t)
1.8
service days
Light oil106.6 LFresh soil for covering
55.5 m3■When working on the unpaved road surfaces(soil) (6.2.1),(per 1,300 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes(Crawler
type,
19.0
Exhaust gas suppression type service hours(secondary), 0.28 m3 whenheaped (0.20 m3 when flat))Vibratory rollers (Exhaust gas
2.0
suppression type (primary),rollers per
Combined type, 3 – 4 t)
day

318

Light oil
Fresh soil for covering
Workforce needed

156.0 L72.2 m3■ When working on the unpaved surfaces ofgardens and the like, of residences and the like
(1.4.1) and of grounds and the like of parks (3.4.4),(per 1,300m2)
Workforce needed
Quantity
Operation leaders
3.3
worker-days
Specialized decontamination
11.5
workers
worker-days
Decontamination workers
10.7
worker-days■When working on the grounds and the like ofschools, parks (large), large facilities, etc. (2.4.4,
4.4.4, 5.4.4),(per 1,000 m2)
Workforce needed
Quantity
Operation leaders
0.7
worker-days
Specialized decontamination
0.4
workers
worker-days
Decontamination workers
4.7
worker-days
Drivers (special
2.6
decontamination)
worker-days
Drivers (ordinary
1.5
decontamination)
worker-days■When working on the unpaved road surfaces(soil) (6.2.1),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
3.5
worker-days
Specialized decontamination
6.9
workers
worker-days
Decontamination workers
1.4
worker-days
Drivers (special
3.0
decontamination)
worker-days

Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedIt was hard to secure similar soil/stones as
the original ones for the gardens of private
residences. Occasionally, it was difficult toobtain their consent to the materials evenwhen similar ones were offered.

Radiation
exposureprotection of workers

The work is often done combined withscraping work. Protective gear such as masks
shall be worn even though the dose decreases

319once fresh soil is spread.
General labor safety ofworkers

Measures to prevent

Safety measures shall be taken for the workwith heavy machinery (proper arrangement
for preventing minor collisions of adjacently
working heavy machinery, and adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)－

secondary wastes
Others－3204）Deep plowing
Locations to be
decontaminated“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like”“2.4.4. Soil” of “2.4. Grounds and the like” at “2. Schools”“3.4.4. Soil” of “3.4. Grounds and the like” in “3. Parks (small)”“4.4.4. Soil” of “4.4. Grounds and the like” in “4. Parks (large)”“5.4.4. Soil” of “5.4. Grounds and the like” of “5. Large facilities”“6.2.1. Road surfaces (soil)” of “6.2. Unpaved roads” of “6. Roads”

Decontamination

Deep plowing

methods
OutlineSoil of unpaved gardens and the like of residences
and the like, of grounds and the like of schools, parks,
large facilities, etc. and the unpaved road surface(soil) shall be plowed deeply in the following
procedures,(i) Excavating surface soil for temporary storage,(ii) Excavating sub-surface soil for temporary storage,(iii) Spreading and compacting of surface soil (in the
sub-surface layer)(iv) Spreading and compacting of sub-surface soil (inthe surface layer)(v) Leveling the top surface

Decontamination processes■When working on the unpaved surfaces of gardens
and the like of residences and the like (1.4.1), and ofgrounds and the like of parks (3.4.4),
The surface soil to about 10 cm depth shall be
uniformly scraped away by hand using shovels
and the like and be placed temporarily on plastic
sheets and the like.
The sub-surface soil to about 20 cm depth shallbe uniformly scraped away and be placed
temporarily apart from the surface soil storage.
The surface soil shall be spread in the
sub-surface layer using shovels. The sub-surface
soil shall be spread over it, leveled andcompacted to the original level with similar
porosity.
■ When working on the grounds and the like ofschools, parks (large), large facilities, etc. (2.4.4,
4.4.4, 5.4.4), and the unpaved road surfaces (soil)(6.2.1),The surface soil to about 10 cm depth shall be
uniformly scraped away by using backhoes andbe placed temporarily on plastic sheets and thelike.
The sub-surface soil to about 20 cm depth shallbe uniformly scraped away and be placed321temporarily apart from the surface soil storage.
The surface soil shall be spread with shovels byhand or using backhoes. The sub-surface soil
shall be spread over it, leveled and compacted tothe original level with similar porosity
Tools, equipment and the like fordecontamination work

■When working on the unpaved surfaces of gardens
and the like of residences and the like (1.4.1), and ofgrounds and the like of parks (3.4.4),
Tools, equipment to use
Quantity
Shovels and the like
Compactors (Dumpers)
Plastic sheets■ When working on the grounds and the like ofschools, parks (large), large facilities, etc. (2.4.4,
4.4.4, 5.4.4), and the unpaved road surfaces (soil)(6.2.1),(per 1,300 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes (Crawler type, Exhaust
7.9
gas suppression type (secondary), service days
Bucket capacity 0.28 m3 whenheaped (0.20 m3 when flat))
Backhoes (Crawler type, Exhaust
6.1
gas suppression type (secondary), service days
Bucket capacity 0.45 m3 whenheaped (0.35 m3 when flat))Vibratory rollers (Exhaust gas
7.9
suppression
type(primary), service days
combined type, 3 – 4 t)
Light oil
549.9 L
Plastic sheet-

Workforce needed■When working on the unpaved surfaces of gardens
and the like of residences and the like (1.4.1), and ofgrounds and the like of parks (3.4.4),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders26.0 worker-days
Decontamination workers
173.0
worker-days■ When working on the grounds and the like ofschools, parks (large), large facilities, etc. (2.4.4,
4.4.4, 5.4.4), and the unpaved road surfaces (soil)(6.2.1),

322

Workforce needed
Operation leaders
Specialized decontamination
workers
Decontamination workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 1,300 m2)
Quantity
1.3 worker-days
6.2 worker-days
8.5 worker-days

Prerequisites andconstraints
regarding objects
and locations to be
decontaminatedIn many cases, especially in residential areas,
this method is often not accepted because thecontaminated soil is not removed.

Radiation exposure
protectionofworkers

Dust masks and rubber gloves shall be worn
when working by hands using shovels and thelike.
Contaminated surface soil collected and piled up
forms temporary hot spots. Early backfill isdesirable before the radiation dose becomes high.

General labor safetyof workers

Safety measures shall be taken for the work withheavy machinery (proper arrangement for
preventing minor collisions of adjacently working
heavy machinery, and adequate instructions andsupervision, as well as thorough control for
preventing access to the machinery)

Measures to prevent－

secondary wastes
Others－323

（6） Garden trees, planted vegetation, roadside trees1）Surface soil removal from bases of trees and the like
The same as the soil sediment removal from rainwater gutter drains, under-eaves, etc. in
the residential areas, schools, parks, large facilities, roads, etc. explained in (5) 1).

2）Delimbing of garden trees, planted vegetation and roadside trees
Locations to be
decontaminated■Delimbing of garden trees“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like”■Delimbing of planted vegetation“2.4.5. Planted vegetation” of “2.4. Grounds and the like” at “2. Schools”“3.4.5. Planted vegetation” of “3.4. Grounds and the like” in “3. Parks(small)”“4.4.5. Planted vegetation” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.5. Soil Planted vegetation” of “5.4. Grounds and the like” of “5.
Large facilities”■Delimbing of roadside trees“6.6.3. Roadside trees” of “6.6. Roadside trees” of “6. Roads”

Decontamination

Delimbing of garden trees, planted vegetation and roadside trees

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Garden trees of residences and the like, planted
vegetation of the grounds of schools, parks, large
facilities, etc., and roadside trees shall bedelimbed in the following procedures.
(i) Delimbing of garden trees, hedges, planted
vegetation((ii) Collecting fallen leaves and the like and small
amount transfer of collected materials)(iii) Packing collected materials
Garden trees, hedges, planted vegetation androadside trees shall be delimbed or pruned byusing pruners and branch cutters, to an
extent that does not cause significant harm totheir growth according to the tree species andtheir delimbing period.
Branches trimmed off shall be packed inlarge sandbags. Too long branches for large
sandbags shall be chopped into short lengths
for packing■When working on garden trees of unpaved
surfaces of gardens and the like of residences andthe like (1.4.1), planted vegetation of the grounds
324and the like of schools, parks, large facilities, etc.
‘2.4.5, 3.4.5, 4.4.5, 5.4.5),
Tools, equipment to use
Rakes and the like
Chain saws (Edge length 350
mm, exhaust 34 cc))
Gasoline
Large sandbags

Quantity
6.5
service days
7.0 L-

■When working on roadside trees (6.6.3),(per 1,300 m2)
Tools, equipment to use
Quantity
Bamboo rakes and the like
Aeriallift
work
vehicles
11.2(Lift-mounted truck, beam-type, service days
work floor elevation 9.7 m)
Chain saws
20.0
(Edge length 350 mm, exhaust service days
34 cc))
Crane trucks (Load capacity 4 t,
3.3
Suspension weight 2.9 t)
service days
Light oil259.9 L
Gasoline
21.6 L
Large sandbags
Workforce needed■When working on garden trees of unpaved
surfaces of gardens and the like of residences andthe like (1.4.1), planted vegetation of the grounds
and the like of schools, parks, large facilities, etc.
‘2.4.5, 3.4.5, 4.4.5, 5.4.5),(per 1,300 m2)
Workforce needed
Quantity
Operation leaders
2.1
worker-daysPlant decontamination
11.5
workers
worker-days■When working on roadside trees (6.6.3),(per 1,300m2)
Workforce needed
Quantity
Operation leaders
4.2
worker-days
Specialized decontamination
9.0
workers
worker-days
Decontamination workers
8.0
worker-days
Drivers (special
10.7
decontamination)
worker-days

Idea
development,
lessons,

Prerequisites
andconstraints regarding
objects and locations

Subject to the heights of garden trees,
planted vegetation and roadside trees thedelimbing work becomes the same as the325points
tokeepinmind, etc.

to be decontaminatedpruning work of coniferous trees (11.1.3.1).
Some municipalities set rules to unify thepruning heights. Such cases shall be checkedin advance, and preparatory consultation
shall be carried out as needed.

Radiation

Safety glasses, dust masks, hand gloves, etc.

exposureprotection of workers

shall be worn.

General labor safety ofworkers

Workers shall wear safety glasses, whendelimbing and pruning, to prevent chips/dust
from getting into their eyes.
Work areas shall be clearly indicated and ano-access area shall be set.
Pruning with chain saws shall be done in astanding and stable posture.
When carrying a chain saw in the hands, theengine shall be switched off, braked, andcarried using both hands.
Allowable time for use shall be indicated oneach chain saw on a sticky tape and the like(to prevent vibration hazard)
For delimbing higher branches by using
branch-cutters and the like, working
positions shall be appropriately chosen toprevent the cut branches from hitting theworkers.

Measures to prevent－

secondary wastes
OthersRequests from some municipalities shall beconsidered to shake down twigs and leaves
stuck on the branches around the pruning
area.

326

3）Cutting of garden trees and planted vegetation
Locations to be
decontaminated■Cutting of garden trees“1.4.1. Unpaved surfaces” of “1.4. Gardens and the like” in “1.
Residential areas and the like”■Cutting of planted vegetation“2.4.5. Planted vegetation” of “2.4. Grounds and the like” at “2. Schools”“3.4.5. Planted vegetation” of “3.4. Grounds and the like” in “3. Parks(small)”“4.4.5. Planted vegetation” of “4.4. Grounds and the like” in “4. Parks(large)”“5.4.5. Soil Planted vegetation” of “5.4. Grounds and the like” of “5.
Large facilities”

Decontamination

Cutting of garden trees and planted vegetation

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Garden trees of residences and the like andplanted vegetation of the grounds of schools,
parks, large facilities, etc. shall be cut in thefollowing procedures.
(i) Cutting garden trees and hedges(ii) Pruning and cross-cutting(iii) Packing collected materials
Garden trees, hedges and planted vegetation
shall be cut using chain saws and the like.
Branches pruned and the like shall be packed
in large sandbags. Too long branches for large
sandbags shall be chopped into short lengths
for packing.
(per 13 trees)
Tools, equipment to use
Quantity
Chain saws
2.5
(Edge length 350 mm, exhaust service days
34 cc)
Gasoline
2.7 L
Large sandbags*Applicable when the diameter at the chest levelexceeds 6 cm.
*Rough terrain cranes, if needed, shall be selectedwhich meet the codes for field conditions.

Workforce needed
Workforce needed
Operation leaders
Plant decontamination
workers

327(per 13 pieces)
Quantity
0.9
worker-days
1.0
worker-day

Decontamination workers

4.9
worker-days*Applicable when the diameter at the chest levelexceeds 6 cm.
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

Trees to be cut shall be confirmed withstakeholders in presence and duly marked forpreventing possible trouble.

Radiation exposure
protection of workers

Safety glasses, masks, rubber gloves, etc.

General labor safety ofworkers

Workers shall wear safety glasses, whendelimbing and pruning, to prevent chips/dust
from getting into their eyes.
Work areas shall be clearly indicated and ano-access area shall be set.
Commencement of the cutting work shall besignaled to nearby workers in the
pre-arranged method.
Chain saws shall be operated in a stableposture.
When carrying a chain saw in the hands, theengine shall be switched off, braked andcarried using both hands.
Allowable time for use shall be indicated oneach chain saw on a sticky tape and the like(to prevent vibration hazard).

Measures to prevent

shall be worn.

－

secondary wastes
Others－328

（7） Other objects to be decontaminated
1）Wiping, cleaning and scraping of playground equipment
Locations to be
decontaminatedDecontamination“2.5.1. Playground equipment and the like”
equipment and the like” at “2. Schools”“3.5.1. Playground equipment and the like”
equipment and the like” in “3. Parks (small)”“4.5.1. Playground equipment and the like”
equipment and the like” in “4. Parks (large)”“5.5.1. Playground equipment and the like”
equipment and the like” of “5. Large facilities”

of “2.5. Playgroundof “3.5. Playgroundof “4.5. Playgroundof “5.5. Playground

Wiping, cleaning and scraping of playground equipment and the likemethods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Workforce needed

Playground equipment and the like of schools,
parks, large facilities, etc. shall be wiped, cleaned
or scraped.
Surfaces of playground equipment shall becleaned with water by using brushes,
cleaning cloths and the like. Neutral
detergents, vinegar (diluted acetic acid), etc.
shall be used as needed.
In wiping, cleaning cloths and the likemoistened with water and the like (including
neutral detergents, vinegar) shall be usedwith each face of the folded cloths used until
repeated wiping gives hardly any further
reduction in the surface contamination
density.
Tools, equipment to use
Cleaning cloths and the like
High-pressure water cleaners
Sand paper, grinders, etc.
Brushes, sand paper, electric
tools, etc.
Large sandbags

Quantity-(per piece of playground equipment)
Workforce needed
Quantity
Operation leaders
0.1
worker-days
Decontamination workers
0.4
worker-days* Applicable to two-seat swings (2.0 m high, 3.0 mwide), one way slides (2.0 m high, 40 cm wide x
4.0 m long slide face), etc.

329

Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

A fresh wiping face of the cloth shall be used
for each wiping step, in order to prevent
contaminants being reattached to theequipment.
Paper towels and the like shall be used forwiping of flat surfaces of painted equipment(horizontal bars, jungle gyms, etc.). Drybrushes shall be used on uneven surfaces
such as monuments at schools and the like.
Possibilities of paint stripping upon wiping
and brushing of playground equipment at
schools shall be discussed with theeducational committee in advance.

Radiation
exposureprotection of workers

Paper towels used for wiping shall not betouched with the bare hands, because they
may be contaminated with radiocesium.
The air dose rate in the working area shall beclearly indicated and the workers notified.
The dose rates in the decontamination
working area shall be measured in advanceand, if the dose rate is high, the area shall beclearly indicated by color cones, color conebars, etc.
Daily and accumulated exposure doses ofindividual workers shall be indicated in aneasily understandable way and kept undercontrol.
Unnecessary access to large packed sandbags
shall be restricted because of high dose rate
risk.
Protective equipment such as disposable
masks, rubber gloves, etc. shall be disposed ofat the pre-designated spots when the work isfinished.

General labor safety ofworkers

Protective equipment (masks, gloves, etc.)
shall be properly worn.
Stability and safety of work floors shall beensured for the work in high places such as 2m high swings.

Measures to prevent
secondary wastes

For volume reduction of secondary wastes,
paper towels and other disposable items usedin wiping work shall be pressed, or
suction-compressed by vacuum cleaners intosealed storage bags.

OthersWhenleavingtheworking
areas,
contamination on body surfaces shall bechecked as lower than 1,300 cpm
byscreening, which is stricter than theallowable limit of 13,000 cpm.

3302）Removal of bottom sediment from street drains and the like of roads
Locations to be
decontaminatedDecontamination“6.4.1. Street drains and the like” of “6.4. Street drains and the like” of“6. Roads”
Removal of bottom sediment from street drains and the like of roads

methods
OutlineBottom sediment of street drains and the like ofroads shall be removed in the following
procedures:(i) High-pressure water cleaning of bottom
sediment(ii) Suctioning up sediment(iii) Transfer of wastewater to a wastewater
treatment facility

Decontamination processes

Tools, equipment and the like fordecontamination work

High-pressure water of about 14 MPa fromdrainage pipe cleaners and the like shall be
used for cleaning in about 20 L/m3. The
wastewater shall be collected.
Sediment removed shall be packed in large
sandbags. The wastewater collected shall betransported to an on-site or nearby
wastewater treatment facility.
Tools, equipment to use
Shovels, brooms, etc.
Drainagepipecleaners(Floor-type, hopper capacity
10.3m3, air-flow 40m3/min)
Drainagepipecleaners(Floor-type, hopper capacity
3.1 m3, air-flow 40 m3/min)
Drainage pipe cleaner (Tank
capacity
2m3,
pressure
14MPa)
Light oil
Water

Workforce needed
Workforce needed
Operation leaders
Decontamination workers
Drivers (ordinary
decontamination)
Idea
development,

Prerequisites andconstraints regarding(per 1,300 m)
Quantity
4.0 service days
1.2 service days
5.3 service days
457.6 L
9.0 m3(per 1,300 m)
Quantity
4.1
worker-days
19.2
worker-days
8.1
worker-days

Sediment easily removable such as fallen
leaves, moss or mud shall be removed in331lessons,
pointstokeep
inmind, etc.

objects and locations
to be decontaminatedadvance by shovels and the like.
When the concrete joint gaps of street drains are
deep, a spatula or the like shall be used to remove
the sediment from the joint gaps.
The cleaning shall be done under covers to
avoid water scattering when buildings standclosely next to each other.
When cleaning covered street drains by using
high-pressure water, the cleaner shall beequipped with a spray nozzle forhigh-pressure water that is inserted in thestreet drains of the roads in order to clean thebottom, sides and top (backside of the cover)of the covered drains.
When a spray nozzle cannot be equipped on
the high-pressure water cleaner for covered
street drains, for instance when much sandhas flowed from mountains and slopes into
the street drains, the cover shall be removed
temporarily and cleaning shall be done byhand.
When removing sediment with hand by using
shovels and the like from street drains
without a cover, wheelbarrows shall be used
for transferring sediment removed to a
nearby spot for collection, as the road surface
is smooth.
Before commencing the high-pressure watercleaning of street drains, the wastewater
discharge lines shall be checked, and small
sandbags shall be lined up to dam the street
drains downstream. The wastewater shall becollected by a street drain cleaner. Small
sandbags containing zeolites shall be placeddownstream to prepare for possible overflow
incidents.

Radiation
exposureprotection of workers

The dose rates in the working area shall be
indicated clearly and the workers notified.
The dose rates in the decontamination
working area shall be measured in advanceand, if the dose rate is high, the area shall beclearly indicated by color cones, color conebars, etc.
Daily and accumulated exposure doses ofindividual workers shall be indicated in aneasily understandable way and kept undercontrol.
Unnecessary access to large packed sandbags
shall be restricted because of their high dose
rate risk.
Protective equipment such as disposable
masks, rubber gloves, etc. shall be disposed of332

at the pre-designated spots when the work isfinished.
General labor safety ofworkers

Measures to prevent

Protective equipment (masks, gloves, etc.)
shall be properly worn.
No one shall stand in the water jet zones at
the time of high-pressure water cleaning.
Attention shall be paid not to cut the fingers
when cleaning street drains by hand using
spatulas or the like.
－secondary wastes

OthersWhenleavingtheworkingarea,
contamination on body surfaces shall bechecked as lower than 1,300 cpm
byscreening, which is stricter than theallowable limit of 13,000 cpm.

333

6.1.2. Slopes
1）Removal of weeds, fallen leaves and sediment on slopes
Locations to be“7.1.1. Weeds, fallen leaves, sediment” of “7.1. Slopes” of “7. Slopes”

decontaminatedDecontamination

Removal of weeds, fallen leaves and sediment on slopes

methods
OutlineWeeds, fallen leaves and sediment on slopes shallbe removed in the following procedures:(i) Branches and leaves, shrubs, weeds, etc. which
can impede decontamination work shall be
removed (weeding, cutting) with shoulder-type
mowers, sickles, etc.
(ii) Weeds, fallen leaves and sediment shall be
removed.
(iii) Transferring removed materials(iv) Packing removed materials

Decontamination processes

Tools, equipment and the like fordecontamination work

Sediment such as fallen leaves, moss, mud,etc. shall be removed by rakes and other tools
and packed in large sandbags.
Tools, equipment to use
Mowers (shoulder-type, cutter
diameter 255 mm)
Light oil
Sand paper, grinder, etc.
Gasoline
Large sandbags

Workforce needed
Workforce needed
Operation leaders
Specialized decontamination
workers
Decontamination workers
Drivers (special
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated(per 1,300 m2)
Quantity
6.5
service days
0.2
service days
7.4 L
18.6 L(per 1,300 m2)
Quantity
1.8
worker-days
3.5
worker-days
8.2
worker-days
0.2
worker-days

Before sediment removal, weeds, which can
impede the work, shall be removed by using ashoulder-type mower or by hand.
The amount of sediment removal (depth to be
removed) shall be determined by test trials.
When decontaminating slopes with a cut

334surface, the conditions of any nets shall bechecked before the work.
When working on long and big slopes, thearea within about 20 m from the living spaceshall be covered with due attention to theusage status and other conditions ofsurrounding areas.
When the slopes need protective measures ofvegetation, appropriate construction methods
shall be chosen in accordance with the“Guidelines of road construction methods for
slope protection and stabilization (June 2009,
Japan Road Association)
Radiation exposure
protection of workers

Safety glasses, dust masks, gloves, etc. shall

General labor safety ofworkers

When working on steep slopes and badfooting slopes, slip prevention measures shallbe ensured by using fixed ropes, safety belts,
sliding devices on fixed ropes, etc.
For work on roadside slopes, barricades andtraffic controllers shall be arranged.

be worn.

Measures to prevent
secondary wastes－

Others

The following points shall be noted whencollecting contaminated objects on slopes:
Transfer methods of large sandbags
containing contaminated materials removed
on the slopes (especially transfer upward)
Crossing methods of rivers, brooks and thelikeNecessary consultations with supervisors onthese collection methods335

6.1.3. Rice Fields, Dry Fields, Pastures, etc.
（1） Weeds
1）Weeding by hand in rice fields and dry fields
Locations to be
decontaminated“8.1.1. Weeds” of “8.1. Rice fields” in “8. Farmland”“8.2.1. Weeds” of “8.2. Dry fields” in “8. Farmland”

Decontamination

Weed removal in rice fields and dry fields

methods
OutlineRice fields and dry fields shall be weeded using
shoulder-type mowers or the like

Decontamination processes

Weeds in rice fields and dry fields shall be
removed by using shoulder-type mowers or
the like

Tools, equipment and the like fordecontamination work

Tools, equipment to use
Mowers (Shoulder-type, cutter
diameter 255 mm)

Workforce needed
Workforce needed
Operation leaders
Specialized decontamination
workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

Quantity(per 100 m2)
Quantity
0.02
worker-days
0.23
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedWeeds in narrow places, slopes and the like
where large mechanized weeding equipment
is not applicable.

Radiation
exposureprotection of workers

Protective equipment such as dust masks
shall be properly worn to protect against dust
blown up by mowers.

作業員の一般労働安全対策

Non-associated personnel shall be kept fromthe working place, as accidents often occur
due to insufficient education on machinery
use or kickbacks by mowers.
To prepare for flying stones, protective
equipment shall be properly worn, forexample, wearing safety goggles and the like,or placing protective nets.

Measures to prevent－

secondary wastes
Others－3362）Weeding by machines in rice fields and dry fields
Locations to be
decontaminated“8.1.1. Weeds” of “8.1. Rice fields” in “8. Farmland”“8.2.1. Weeds” of “8.2. Dry fields” in “8. Farmland”

Decontamination

Weeding by machines in rice fields and dry fields

methods
OutlineWeeding by machines in rice fields and dry fields

Decontamination processes

Weeds in rice fields and dry fields shall be
removed using farm tractors or the like.

Tools, equipment and the like fordecontamination work(per 1,000 m2)
Tools, equipment to use
Quantity
Farm
tractors(110PS,
0.27
wheel-type)service hours
Off-set shredders
0.04(working width 200 cm)
service days
Light oil
3.0 L

Workforce needed
Workforce needed
Operation leaders
Drivers (special
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 1,000 m2)
Quantity
0.01
worker-days
0.05
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

The work shall be done in areas which exceed
a certain size (more than 1,000 m2) andwhere machinery has no risks of overturning.

Radiation
exposureprotection of workers

Protective equipment such as dust masks
shall be properly worn to protect against dust
blown up.

General labor safety ofworkers

Safety measures shall be taken for the workwith heavy machinery (proper arrangement
for preventing minor collisions of adjacently
working heavy machinery, and adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)

Measures to prevent－

secondary wastes
Others－3373）Collection of weeds removed from rice fields and dry fields
Locations to be
decontaminated“8.1.1. Weeds” of “8.1. Rice fields” in “8. Farmland”“8.2.1. Weeds” of “8.2. Dry fields” in “8. Farmland”

Decontamination
methods

Collection of contaminated weeds removed from rice fields and dryfieldsOutlineWeeds removed from rice fields and dry fields
shall be collected

Decontamination processes

Tools, equipment and the like fordecontamination work

Weeds removed shall be collected by using
hay collectors, packing machines for weeding,and other machines.
(per 1,000 m2)
Tools, equipment to use
Quantity
Hay collectors
0.63 service(Hand guided-type, 120cm)
days
Packing machines for weeding 0.59 service
days
(Hand
guided-type,φ
500x700))
Gasoline
21.3 L

Workforce needed
Workforce needed
Operation leaders
Drivers (special
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 1,000 m2)
Quantity
0.06
worker-days
1.16
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

The work shall be done in areas exceeding acertain size (more than 1,000 m2) and wheremachinery has no risks of overturning.

Radiation
exposureprotection of workers

Protective equipment such as dust masks
shall be properly worn to protect against dust
blown up.

General labor safety ofworkers

Safety measures shall be taken for work withheavy machinery (proper arrangement for
preventing minor collisions of adjacently
workingheavy
machinery,adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)

Measures to prevent－

secondary wastes
Others－3384）Weeding of grassland
Locations to be“8.3.1. Weeds” of “8.3. Grassland” in “8. Farmland”

decontaminatedDecontamination

Weeding of grassland

methods
OutlineWeeding of grassland

Decontamination processes

Weeds in grassland shall be removed by using
farm tractors or the like.
Weeds removed shall be formed in roll bales.

Tools, equipment and the like fordecontamination work

Tools, equipment to use
Farm tractors (Riding-type,wheel-type, four-wheel drive,
52 -59kw class (70 – 80PS))
Flail mowers (Direct mounttype) (1.5 m wide)
Roll balers (1.0 m wide, 1.0 m
tall)
Rake (3.6 m wide)
Beam sprayers (600 L, 12.3m
Wide)
Trucks (Load capacity 4.0 – 4.5
t)Light oil
Herbicide
Water

Workforce needed
Workforce needed
Operation leaders
Drivers (ordinary
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per ha)Quantity
5.3
service hours
0.5
service days
0.1
service days
0.1
service days
0.1
service days
0.3
service hours
39.7L
5.0L
0.6m3
(per ha)Quantity
0.17
worker-days
1.1
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

The work shall be done in areas exceeding acertain size (more than 1,000 m2) and wheremachinery has no risks of overturning.

Radiation
exposureprotection of workers

Protective equipment such as dust masks
shall be properly worn to protect against dust
blown up from weeding and roll discharging.

General labor safety ofworkers

Safety measures shall be taken for the workwith heavy machinery (proper arrangement
for preventing minor collisions of adjacently339

working heavy machinery, and adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)
Measures to prevent－

secondary wastes
Others－340

（2） Soil
1）Leveling of unevenness
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”

Decontamination

Leveling of unevenness in rice fields and dry fields

methods
OutlineUnevenness of soil in rice fields and dry fields
shall be leveled.

Decontamination processes

Unevenness of surface soil shall be leveled byusing vibratory rollers or the like.

Tools, equipment and the like fordecontamination work

Tools, equipment to use
Vibratory rollers (Riding-type
combined roller 3 t, Exhaustgas
suppression
type(primary))
Light oilWorkforce needed
Workforce needed
Operation leaders
Drivers (special
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 1,000 m2)
Quantity
1.25
service hours
3.8 L(per 1,000 m2)
Quantity
0.02
worker-days
0.29
worker-days

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedCombined rollers shall not be used in flooded
rice fields, because rollers sink in the fields
and lose mobility
Mobility of combined rollers shall be checkedin advance.
Basically no decontamination work shall bedone during rain storms or in pooled water
areas, because the surface layer of the arable
land will be kneaded.

Radiation

Dust masks, gloves, etc. shall be worn

exposureprotection of workers
General labor safety ofworkers

No one other than the operation leader andthe designated driver is allowed to enter thefields to level the unevenness with combinedrollers.
Existing access routes, if suitable, shall be
used for entering the field for leveling theunevenness.
If no access route is available, the combined341

roller shall enter the field slowly at a rightangle to the ridge along the field. This is to
avoid the roller overturning.
If the slope of the entry route crossing theridge along the field is too steep, a new entry
route shall be constructed in order to preventthe roller from overturning.
It shall be checked that no new big holes weremade by wild bores or the like after weeds
were removed and collected.
Measures to prevent－

secondary wastes
Others－3422）Spreading surface solidifiers
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”

Decontamination

Spreading surface solidifiers

methods
OutlineSurface solidifiers shall be spread on the soil of rice
fields and dry fields

Decontamination processes

Tools, equipment and the like fordecontamination work

Solidifier solution shall be spread on the soil
by using a seed scatterer or the like. The
surface soil shall be checked as firmly
solidified.
The following conditions are assumed forsurface soil solidification: the amount ofsolidifier 15 t/ha, the depth of solidification 2 –3 cm, solidification time required 7 days
(consecutive dry days).
The water to prepare the solidifier solution(solvent) shall be checked in advance that noradioactive materials can be detected in it.
(per 1,000 m2)
Tools, equipment to use
Quantity
Seeders (Riding-type , 1.0 m3)
2.14
service hours
Air compressors (25PS, 0.7 MPa,
0.36
3
2.5 m /min)service days
Crane truck (Load capacity 4 t,
3.25
suspension weight 2.9 t)
service hours
Sprinkler truck
1.11(Tank capacity 3,800 L)
service hours
Light oil
36.9 L
Surface solidifier (neutral)
1.5 t

Workforce needed
Workforce needed
Operation leaders
Specialized decontamination
workers
Decontamination workers
Drivers (special
decontamination)
Drivers (ordinary
decontamination)
Idea

Prerequisites and(per 1,000 m2)
Quantity
0.26
worker-days
0.62
worker-days
0.31
worker-days
0.56
worker-days
0.22
worker-days

No work shall be done in winter, as the343

development,
lessons,
pointstokeep
inmind, etc.

constraints regarding
objects and locations
to be decontaminatedsolidifier does not work.
Weather conditions affect the time required forsolidification.
No spreading of solidifier shall be allowed onwater retaining spots.

Radiation

Safety glasses, dust masks, etc. shall be worn.

exposureprotection of workers
General labor safety ofworkers

The worker controlling the nozzle and theassistant must wear safety glasses to prevent
solidifiers from entering the eyes.
The nozzle shall be firmly held so as not to bewhipped about by the hose pressure.
After the hose is firmly held, the signal shallbe given to start spreading of solidifiers.
The moving parts of the seed scatterer shall becovered to prevent the operator from beingcaught in them.

Measures to prevent

The solidifiers shall be procured in flexible

secondary wastes

containers.

Others－3443）Scraping the surface soil
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Scraping of surface soil (standard transfer method)

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Surface soil of rice fields, dry fields and grasslandshall be scraped away (standard transfer method)
The surface soil shall be scraped away byusing backhoes or the like (to about 5 cm
depth)
When scraping the surface soil in big areas of morethan 30a,(per 100 m2)
Tools, equipment to use
Quantity
Backhoes(Crawler-type,
0.48
exhaustgas
suppression service hours(primary), Bucket capacity 0.45
m3 when heaped (0.35 m3, when
flatly filled))
Light oil
5.3 L
*This applies when topography and field conditions
are relatively favorable and the area has about
30a in regular shape.
■When scraping the surface soil in small areas ofless than 30a,(per 100 m2)
Tools, equipment to use
Quantity
Backhoe (Crawler-type, exhaust
0.56
gas
suppression(primary), service hours
Bucket capacity 0.45 m3 whenheaped (0.35 m3, when flatly
filled))Light oil
6.2 L
*This applies when the field conditions are notfavorable, e.g., the field is not regular in shape.

Workforce needed■When scraping the surface soil in big areas ofmore than 30a,(per 100 m2)
Workforce needed
Quantity
Operation leaders
0.03
worker-days
Decontamination workers
0.18
worker-days345

Drivers (special
0.08
decontamination)
worker-days*This applies when topography and field conditions
are relatively favorable and the area is about 30ain regular shape.
■When scraping the surface soil in small areas ofless than 30a,(per 100 m2)
Workforce needed
Quantity
Operation leaders
0.09
worker-days
Decontamination workers
0.26
worker-days
Driver (special decontamination)
0.09
worker-days*This applies when the field conditions are notfavorable, e.g., the field is not regular in shape.
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedNo work shall be done in flooded rice fields.

Radiation

Masks, gloves, etc. shall be worn.

exposureprotection of workers
General labor safety ofworkers

Measures to prevent

The working areas shall be marked with color
cones, color cone bars, etc. for access control inorder to prevent minor collisions between
backhoes.
－secondary wastes
OthersBanners or the like shall indicate where aerial wires
run above farm roads or farmland, and a traffic
controller shall be arranged in order to prevent
damaging aerial wires when passing under them.

3464）Deep plowing
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Deep plowing

methods
OutlineSoil in rice fields and grassland shall be plowed
deeplyDecontamination processes

Tools, equipment and the like fordecontamination work

The base mat shall be flattened by double
plowing of surface soil by rotary tillers or the
like.
Tools, equipment to use
Farm tractors (Riding-type,wheel-type, four wheel driven
22kW-class (30PS)
Light oilWorkforce needed
Workforce needed
Drivers (ordinary
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 10,000 m2)
Quantity
26.0
service hours
67.6 L(per 10,000 m2)
Quantity
5.0
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedNo work shall be done in flooded rice fields
where the tractors may not be operable.
Mobility of wheel-type tractors shall bechecked in advance.

Radiation exposure
protection of workers

Masks, gloves, etc. shall be worn.

General labor safety ofworkers

No one other than the designated driver shallbe allowed to enter the fields to plow deeply.
Existing access routes, if suitable, shall be
used for entering the fields.
If no access route is available, the tractor shallenter the field slowly moving forward at aright angle to the ridge along the field. This is
to avoid the tractor overturning.
If the slope of the entry route crossing theridge along the field is too steep, a new entry
route shall be constructed in order to preventthe tractor from overturning.
It shall be checked that no new big holes weremade by wild bores or the like after weeds
347were removed and collected.
Counter weights shall be attached to thetractor with a mounted rotary tiller, as
appropriate, according to the instruction
manual of the tractor when it enters or leaves
the field (ascends or descends a ridge along thefield), because the center of gravity of the
tractor moves backward and the tractor issusceptible to overturning.
A rotary tiller shall be mounted or demounted
on a flat place such as a farm road with thetractor engine switched off.
When doing maintenance on the rotary tiller,
for example its cutting edges, not only theengine shall be switched off, but the rotary
shall be locked and held from below by a tableor the like to avoid its dropping suddenly.
Measures to prevent－

secondary wastes
Others－3485）Deep tillage
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Deep tillage

methods
OutlineSurface soil of rice fields, dry fields and grasslandshall be tilled deeply.

Decontamination processes

The fields shall be tilled twice (tillage depthof about 30 cm) by using a deep tilling rotary
tiller.

Tools, equipment and the like fordecontamination work(per 10,000 m2)
Tools, equipment to use
Quantity
Farm tractors (Riding-type,4.3
wheel-type four wheel driven 52 service days
- 59kw-class (70 - 80PS),
22kw-class (30PS)
Light oil
60.0 L

Workforce needed
Workforce needed
Drivers (ordinary
decontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 10,000 m2)
Quantity
4.0
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminated

The farmland where the soil was stirred byplowing after the accident shall be tilled inreverse or deeply.
Deep tillage may damage the roots inorchards, tea plantations and other farmland
where perennial produce is planted.
If the ground below the tilling depth isrudaceous, precautions shall be taken, forexample, to remove the gravel beforehand
because the gravel may come up in the tilling
layer by deep tillage.
The underground water level shall bemeasured, if required, so necessary
precautions may be taken in deep tilling.
When the surface soil is frozen due to lowtemperatures, small-size tractors may not be
sufficient for deep tilling.

Radiation

Safety glasses, dust masks, rubber gloves,

exposureprotection of workers

etc. shall be worn.

General labor safety ofworkers

No one other than the designated driver shallbe allowed to enter the fields to till deeply.

349

Existing access routes, if suitable, shall be
used for entering fields.
If no access route is available, the tractor
shall enter the field slowly moving forward at
a right angle to the ridge along the field. This
is to avoid the tractor overturning.
If the slope of the entry route crossing theridge along the field is too steep, a new entry
route shall be constructed in order to preventthe tractor from overturning.
It shall be checked that no new big holes weremade by wild bores or the like after weeds
were removed and collected.
Counter weights shall be attached to thetractor with a mounted rotary tiller, as
appropriate, according to the instruction
manual of the tractor when it enters or leaves
the field (ascends or descends a ridge along
the field), because the center of gravity of the
tractor moves backward and the tractor issusceptible to overturning.
A rotary tiller shall be mounted or demounted
on a flat place such as a farm road with thetractor engine switched off.
When doing maintenance on the rotary tiller,
for example its cutting edges, not only theengine shall be switched off, but the rotary
shall be locked and held from below by a tableor the like to avoid its dropping suddenly.
Measures to prevent－

secondary wastes
Others－3506）Soil replacement
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Soil replacement

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Surface soil of rice fields, dry fields and the likeshall be replaced with fresh soil in the following
procedures.
(i) Bringing in and spreading fresh soil(ii) Short transferring of fresh soil to narrowplaces and spreading.
(iii) Compacting
After scraping the soil off the surface, heavymachinery shall be used for replacing,spreading and leveling the fresh soil back to
the original elevation.
The MOE supervisory personnel shall be
consulted for determining the quality of
replacing fresh soil.
Results of soil tests including grain sizes andradioactive material concentration
measurement in the replacement fresh soil
shall be reviewed and approved before use by
the MOE supervisory personnel.

(per 1,000 m2)
Tools, equipment to use
Quantity
Shovels and the like
Backhoes(Crawler-type,1.1
exhaustgas
suppression service days
(secondary), Bucket capacity
0.28 m3 when heaped (0.20m3,
when flatly filled))
Vibratory rollers (Exhaust gas
1.5
suppression (primary), combined service days
type 3 – 4 t)
Vibratory rollers (Exhaust gas
0.4
suppression (primary), combined service day
type 3 – 4 t)
Dump trucks (Load capacity 2 t)
1.8
service days
Light oil106.6 LFresh soil
55.5 m3

351

Workforce needed

Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 1,000 m2)
Workforce needed
Quantity
Operation leaders
0.7
worker-days
Specialized
decontamination
0.4
workers
worker-days
Decontamination workers
4.7
worker-days
Drivers (special
2.6
decontamination)
worker-days
Drivers (ordinary
1.5
decontamination)
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedDifferences shall be noted between thesurface soil stirred by plowing and that notplowed after the accident. Even if theradioactive concentration is equal, the air
dose rate is higher above the unplowed soil
which keeps the surface as it was.
The soil replacement and other measuresneeded shall be implemented after
decontamination, soil analysis and diagnosis.

Radiation

Safety glasses, dust masks, rubber gloves,

exposureprotection of workers

etc. shall be worn.

General labor safety ofworkers

Existing access routes, if suitable, shall be
used for entering the fields.
If no access route is available, the heavymachinery shall enter the field slowly moving
forward at a right angle to the ridge along thefield. This is to avoid the heavy machinery
overturning.
If the slope of the entry route crossing theridge along the field is too steep, a new entry
route shall be constructed in order to preventthe heavy machinery from overturning.
It shall be checked that no new big holes weremade by wild bores or the like by which theheavy machinery might be overturned.

Measures to prevent－

secondary wastes
Others－3527）Restoration of soil fertility
Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Restoration of soil fertility

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Soil fertility of rice fields, dry fields and grasslandshall be restored by spreading soil conditioners or
zeolite.
Soil conditioners shall be sprayed by asprinkler mounted on a tractor.
Soil conditioners shall be those reported to
the Governor of Fukushima Prefecture as
special fertilizers pursuant to the Fertilizer
Control Law (Law No. 127, 1950) and thosewhich can increase soil fertility by integrated
improvement of physicochemical andbiological properties of the soil.
The soil conditioners shall be approved by thesupervisory MOE personnel in advancethrough test results.
Zeolite may be used in place of the soil
conditioners.
When spraying soil conditioners,(per 10,000 m2)
Tools, equipment to use
Quantity
Construction
tractors
1.1(Ordinary type, load capacity 9 service hourst)
Lime spreaders 138(Towing
1.1
capacity 800 L, spray span 3 m service hours
class)
Light oil
13.0 L
Soil
conditioner(calcium Depending oncarbonate)soil
properties
Soil conditioner (potassium
0.8 t
silicate)*Machinery for spraying soil conditioners
When spraying zeolite,
Tools, equipment to use
Farm tractor (Crawler-type,
40PS)

138

Machines for dispersion of fertilizer and soil improving agent

353(per 1,000 m2)
Quantity
0.56 service
hours

Lime spreaders (Spray span 1.8
m class)
Light oil
ZeoliteWorkforce needed

When spraying soil conditioners,(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
0.2
worker-days
Decontamination workers
0.77
worker-days
Drivers (special
0.17
decontamination)
worker-days
When spraying zeolite,
Workforce needed
Operation leaders
Specialized decontamination
workers

Idea
development,
lessons,
pointstokeep
inmind, etc.

0.1 service
days
4.3 L
0.5 t

(per 1,000 m2)
Quantity
0.15
worker-days
0.09
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedUpon completion of decontamination andanalysis, the amount of soil conditioners or
zeolite shall be determined.

Radiation

Safety glasses, dust masks, rubber gloves,

exposureprotection of workers

etc. shall be worn.

General labor safety ofworkers

Existing access routes, if suitable, shall be
used for entering the farmland.
If no access route is available, the heavymachinery shall enter the field slowly moving
forward at a right angle to the ridge along thefield.
If the slope of the entry route crossing theridge along the field is too steep, a new entry
route shall be constructed in order to preventthe heavy machinery from overturning.
It shall be checked that no new big holes weremade by wild bores or the like by which theheavy machinery might be overturned.

Measures to prevent－

secondary wastes
Others－354

（3） Waterways
1）Removal of bottom sediment (soil suctioning)
Locations to be“8.4.1. Waterways” of “8.4. Waterways” in “8. Farmland”

decontaminatedDecontamination

Removal of bottom sediment (soil suctioning ) from waterways inmethods

farmland

OutlineBottom sediment in waterways of farmland shallbe removed (soil suctioning)

Decontamination processes

Tools, equipment and the like fordecontamination work

Sediment easily removable such as fallen
leaves, moss, mud, etc. shall be removed byusing shovels and the like.
Tools, equipment to use
Shovels and the like

Workforce needed
Workforce needed
Operation leaders
Decontamination workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

Quantity(per 10 m３)
Quantity
0.21
worker-days
8.37
worker-days

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedMost work for removing bottom sediment inwaterways of farmland is done in narrow
spaces and shall be done by hand. The bottom
sediment collected shall be immediately
packed in small bags nearby and transferredby hand. The small bags shall be such that
hand-carry belts may be used for easytransfer in bad footing spaces (570×530×H550).
If the waterway has flow, the working zone
shall be dammed upstream and downstream
to
block
the
flow.
A
hand-carrywater-immersed
pump(2B, discharge
amount 0.1 – 0.12 m3/min) shall be used sothat the removal work can be done in no-flow
conditions.

Radiation
exposureprotection of workers

The air dose rate in working areas shall beclearly indicated to the workers.
The air dose rate in the working areas fordecontamination shall be measured inadvance, and if the dose rate is high, the area
shall be so indicated by using color cones,
color cone bars and the like.

355

Daily and accumulated exposure doses ofindividual workers shall be indicated in aneasily understandable way and kept undercontrol.
Unnecessary access to places with large
packed sandbags shall be restricted becauseof their high dose rate risk.
Protective equipment such as disposable
masks, rubber gloves, etc. shall be disposed ofat the pre-designated spots when the work isfinished.
General labor safety ofworkers

Measures to prevent

Protective equipment (masks, gloves and thelike) shall be appropriately worn.
Special attention shall be paid to footwear of
workers transferring packed bags and thelike, since the waterways in farmland are
muddy and there are slopes or ridges along
fields where workers may slip.
－

secondary wastes
OthersWhenleavingtheworking
areas,
contamination on body surfaces shall bechecked as lower than 1,300 cpm
byscreening, which is stricter than theallowable limit of 13,000 cpm.

3562）Removal and the like of bottom sediment (Packing)Locations to be“8.4.1. Waterways” of “8.4. Waterways” in “8. Farmland”

decontaminatedDecontamination

Removal of bottom sediment in waterways of farmland (Packing)methods
OutlineBottom sediment in waterways in farmland shallbe removed (and packed).

Decontamination processes
Tools, equipment and the like fordecontamination work

Workforce needed

Bottom sediment collected shall be packed inlarge sandbags by hand.
Tools, equipment to use
Large sandbags
Workforce needed
Operation leaders
Decontamination workers

Idea
development,
lessons,
pointstokeep
inmind, etc.

Quantity(per 10 bags)
Quantity
0.11
worker-days
1.68
worker-days

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedLarge sandbags may lose their shape, whenbeing packed with collected sediment, due todifficulty of uniform filling. For shapekeeping and easy packing, large sandbags
shall be filled on a dedicated table.
Bottom sediment has high water content. In
order to prevent contaminated water fromleaking, an inner bag shall be placed in thelarge sandbags, or water-proof flexible
containers shall be used.

Radiation
exposureprotection of workers

The air dose rate in working areas shall beclearly indicated to the workers.
The air dose rate in the area fordecontamination shall be measured inadvance, and if the dose rate is high, thearea shall be so indicated by using color
cones, color cone bars and the like.
Daily and accumulated exposure doses ofindividual workers shall be indicated in aneasily understandable way and kept undercontrol.
Whenever sand or the like is attached(deposited) on workers’ clothing or protective
equipment, sand or the like shall be wipedaway immediately in order to prevent
contamination from spreading.
Unnecessary access to places with large
357

packed sandbags shall be restricted becauseof their high dose rate risk.
Protective equipment such as disposable
masks, rubber gloves, etc. shall be disposedof at the pre-designated spots when thework is finished.
General labor safety ofworkers

Measures to prevent

Protective equipment (masks, gloves and thelike) shall be appropriately worn.
Special attention shall be paid to footwear of
workers transferring packed bags and thelike, since the waterways in farmland are
muddy and there are slopes or ridges along
fields where workers may slip.
Safety systems and equipment shall bechecked before commencing the day’s work.
When using backhoes for packing, access to
the rotating range shall be prohibited inorder to prevent minor collisions.
－secondary wastes
OthersWhenleavingtheworking
areas,
contamination on body surfaces shall bechecked as lower than 1,300 cpm
byscreening, which is stricter than theallowable limit of 13,000 cpm.

358

（4） Others
1）Packing (standard transfer process)Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Packing (standard transfer process)methods
OutlineSoil removed from rice fields, dry fields or
grassland in farmland shall be packed for transfer(standard transfer process)Decontamination processes

The soil removed shall be collected andpacked in large sandbags by using backhoesor the like.

Tools, equipment and the like fordecontamination work

Tools, equipment to use
Backhoes(Exhaust
gas
suppression (primary), crawler
type, Bucket capacity 0.45 m3
when heaped up, 0.35 m3 when
flatly filled)
Light oil
Large sandbags

Workforce needed
Workforce needed
Operation leaders
Specialized
decontamination
workers
Decontamination workers
Driverdecontamination)
Idea
development,
lessons,
pointstokeep
inmind, etc.

(special(per 10 bags)
Quantity
1.42
service hours

16.0 L(per 10 bags)
Quantity
0.06
worker-days
0.21
worker-days
0.24
worker-days
0.23
worker-days

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedSpecial attachments shall be fabricated for
packing into large sandbags.
Lined up heights of large sandbags after
being filled shall be leveled.

Radiation

Safety glasses, dust masks, gloves, etc. shall

exposureprotection of workers

be worn.

General labor safety ofworkers

The work proceeds next to heavy machinery.
The working range of the heavy machineryshall be clearly indicated and supervising
personnel shall be arranged.
359

Safety education shall be provided to theworkers on nearby parallel work with heavymachinery.
Measures to prevent
secondary wastes

OthersTwigs, protrusions or the like in the sedimentcollected shall be removed before being
packed in large sandbags to prevent bag
breaks.
－3602）Small transfer within the working fields (standard transfer process)Locations to be
decontaminated“8.1.2. Soil” of “8.1. Rice fields” in “8. Farmland”“8.2.2. Soil” of “8.2. Dry fields” in “8. Farmland”“8.3.2. Soil” of “8.3. Grassland” in “8. Farmland”

Decontamination

Small transfer (standard transfer process)methods
OutlineContaminated soil removed from farmland (ricefields, dry fields and grassland) shall betransferred short distances in small amounts(standard transfer process) within the working
fields.

Decontamination processes

Crane backhoes, rough terrain haulers or the
like shall be used for small and shorttransfers in the working fields (loading,unloading)Tools, equipment and the like fordecontamination work(per 10 bags)
Tools, equipment to use
Quantity
Crane backhoes (Exhaust gas
1.3
suppression (primary), crawler service hours
type, Bucket capacity 0.28 m3
when heaped up (0.25 m3 when
flatly filled))
Crane backhoes (Exhaust gas
0.28
suppression (primary), crawler service hours
type, Bucket capacity 0.45 m3
when heaped up (0.35 m3 when
flatly filled))Roughterrainhaulers
0.18(Exhaust
gas
suppression service days
(primary), crawler type, load
capacity 4 t)
Light oil
31.5 L* per short transfer distance L=100 m (round trip)

Workforce needed(per 10 Bags)
Workforce needed
Quantity
Operation leaders
0.06
worker-days
Specialized decontamination
0.23
workers
worker-days
Drivers(special
0.44
decontamination)
worker-days* per short transfer distance L=100 m (round trip)

Idea
development,

Prerequisites
andconstraints regarding

Transfer paths easily get muddy in rain. Iron
sheets or the like shall be needed to cover the361

lessons,
pointstokeep
inmind, etc.

objects and locations
to be decontaminatedmuddy paths used for transfer.

Radiation

Safety glasses, dust masks, gloves, etc. shall

exposureprotection of workers

be worn.

General labor safety ofworkers

Clear indication of transfer paths.
The work proceeds next to heavy machineryor vehicles. The working range of the heavymachinery shall be clearly indicated andsupervising personnel shall be arranged.
Safety education shall be provided to theworkers on nearby parallel work with heavymachinery and vehicles.

Measures to prevent－

secondary wastes
Others－362

6.1.4. Grassland, Lawns
1）Cutting down shrubs (dense)
Locations to be“9.1.1. Shrubs (dense)” of “9.1. Shrubs (dense)” in “9. Grassland, lawns”

decontaminatedDecontamination

Cutting down shrubs (dense)

methods
OutlineShrubs (dense) in grassland and lawns shall be
cut down in the following procedures.
(i) Cutting down shrubs(ii) Small amount and short distance transfer inthe working fields(iii) Packing of cut shrubs

Decontamination processes

Tools, equipment and the like fordecontamination work

Large weeds, shrubs and the like shall be cut
down by chainsaws and the like and be
packed in large sandbags.
Cut shrubs and the like too large to pack inlarge sandbags shall be chopped into
packable sizes, or cut in about 2 m long pieces
after removing leaves with a hatchet and tied
using strings or the like in about 30 cm
diameter bundles. The removed leaves shallbe packed in large sandbags.
Tools, equipment to use
Cutters (Chainsaw, edge 600
mm long (80 cc))
Gasoline
Large sandbags

Workforce needed
Workforce needed
Operation leaders
Specialized
decontamination
workers
Decontamination workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated(per 1,000 m2)
Quantity
13.3
service days
16.8 L(per 1,000 m2)
Quantity
3.6
worker-days
5.3
worker-days
16.7
worker-days

The geometry of grassland and lawns isdiverse. Depending on the work site
situation, the spot for packing into large
sandbags, transfer paths, loading stations,etc. shall be chosen and designated. Flat
spaces shall be chosen for packing andtemporary storage in order to ensure working
safety.
Worker safety shall be ensured before
363

starting cutting by designating safe working
and transfer paths.
Basically chainsaws shall be used for cutting
in dense shrub areas. Shrubs cut down shallbe pruned to carriable sizes and be carriedout for collection after removing branches.
When cutting down tall bamboo trees, the cut
bamboo may be impediments to working. The
cut bamboo trees shall be carried out as they
are and be pruned elsewhere.
When packing, branches or the like may
damage the large sandbags. To prevent
sandbags being damaged, shrubs shall be cut
so that no sharp cut ends are left.
Large sandbags may lose shape, when being
packed with collected cut materials, due todifficulty of uniform filling. For shapekeeping and easy packing, the large sandbags
shall be filled on a dedicated table.
Radiation exposure
protection of workers

The air dose rate in working areas shall beclearly indicated to the workers.
The air dose rate in the area fordecontamination shall be measured inadvance, and if the dose rate is high, the area
shall be indicated by using color cones, color
cone bars and the like.
Daily and accumulated exposure doses ofindividual workers shall be indicated in aneasily understandable way and kept undercontrol.
When collecting cut branches and leaves,rakes or the like shall be used in order toprevent direct handling to the extent
possible.
Unnecessary access to places with large
packed sandbags shall be restricted becauseof their high dose rate risk.
Protective equipment such as disposable
masks, rubber gloves, etc. shall be disposed ofat the pre-designated spots when the work isfinished.

General labor safety ofworkers

Protective equipment (masks, gloves and thelike) shall be appropriately worn.
Safety systems and equipment shall bechecked before commencing the day’s work.
When using backhoes for packing, the accessto the rotating range shall be prohibited inorder to prevent minor collisions.
Safety glasses shall be properly worn, whenpacking, to prevent branches from poking the
eyes.

364

When cutting, flying stones or rotating edges
may hurt nearby workers. To prevent the, theworking zones shall be set apart with aninterval of about 10 to 15 m, and the work
shall be done under a foreman’s supervision.
When working on vibratory machines such as
chain saws and weed cutters, a rest of morethan 5 min shall be taken each 30 min inorder to prevent vibration hazard.
When working with hatchets for cutting, a
suitable distance shall be kept fromneighboring workers.
Measures to prevent－

secondary wastes
OthersWhenleavingtheworking
areas,
contamination on body surfaces shall bechecked as lower than 1,300 cpm
byscreening, which is stricter than theallowable limit of 13,000 cpm.

3652）Cutting down shrubs (sparse)
Locations to be
decontaminatedDecontamination“9.2.1. Shrubs (sparse)” of “9.1. Shrubs (sparse)” in “9. Grassland,
lawns”
Cutting down shrubs (sparse) in grassland, lawns

methods
OutlineShrubs (sparse) in grassland and lawns shall be
cut in the following procedures.
(i) Cutting down shrubs(ii) Small amount and short distance transfer inthe working fields(iii) Packing cut shrubs

Decontamination processes

Tools, equipment and the like fordecontamination work

Weeds, shrubs and the like shall be cut downby shoulder-type mowers and the like and be
packed in large sandbags.
(per 1,000 m2)
Tools, equipment to use
Quantity
Mowers (Shoulder-type, cutter
2.0
255 mm, 1.3 kW class)service days
Gasoline
5.7L
Large sandbags-

Workforce needed
Workforce needed
Operation leaders
Specialized
decontamination
workers
Decontamination workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminated(per 1,000 m2)
Quantity
3.1
worker-days
1.1
worker-days
7.0
worker-days

The geometry of grassland and lawns isdiverse. Depending on the field situation, thespot for packing into large sandbags, transfer
paths, loading stations, etc. shall be chosen
and designated. Flat spaces shall be chosen
for packing and temporary storage in order toensure working safety.
Work safety shall be ensured before starting
cutting by designating safe working andtransfer paths.
Shoulder-type mowers shall be used for
cutting in sparse shrub areas. Too large
shrubs to cut by mowers shall be cut by
chainsaws.
When cutting down tall bamboo trees, the cut
bamboo may be impediments to working. The

366

cut bamboo trees shall be carried out as they
are and be pruned elsewhere.
When packing, branches or the like may
damage the large sandbags. To prevent this,shrubs shall be cut so that no sharp cut ends
are left.
Large sandbags may lose their shape, whenbeing packed with collected scrubs, due todifficulty of uniform filling. For shapekeeping and easy packing, the large sandbags
shall be filled on a dedicated table.
Radiation
exposureprotection of workers

The air dose rate in working areas shall beclearly indicated to the workers.
The air dose rate in the area fordecontamination shall be measured inadvance, and if the dose rate is high, theareas shall be so indicated by using color
cones, color cone bars and the like.
Daily and accumulated exposure doses ofindividual workers shall be indicated in aneasily understandable way and kept undercontrol.
When collecting cut branches and leaves,rakes or the like shall be used in order toprevent direct handling to the extent
possible.
Unnecessary access to places with large
packed sandbags shall be restricted becauseof their high dose rate risk.
Protective equipment such as disposable
masks, rubber gloves, etc. shall be disposed ofat the pre-designated spots when the work isfinished.

General labor safety ofworkers

Protective equipment (masks, gloves and thelike) shall be appropriately worn.
Safety systems and equipment shall bechecked before commencing the day’s work.
When using backhoes for packing, the accessto the rotating range shall be prohibited inorder to prevent minor collisions.
Safety glasses shall be properly worn, whenpacking, to prevent branches from poking theeyes.
When cutting, flying stones or rotating edges
may hurt nearby workers. To prevent this,the working zones shall be set apart with aninterval of about 10 to 15 m, and the work
shall be done under a foreman’s supervision.
When working on vibratory machines such as
mowers and weed cutters, a rest of more than
5 min shall be taken each 30 min in order toprevent vibration hazard.

367

When working with hatchets for cutting, a
suitable distance shall be kept fromneighboring workers.
Measures to prevent－

secondary wastes
OthersWhenleavingtheworking
areas,
contamination on body surfaces shall bechecked as lower than 1,300 cpm byscreening, which is stricter than theallowable limit of 13,000 cpm.

368

6.1.5. Forests（1） Items common to the forests with mixed trees of coniferous evergreen trees, deciduous
broad-leaf trees and others

1）Removal of sediment (organic materials)
Locations to be
decontaminated“11.1.1. Sediment (organic materials)” of “11.1. Coniferous evergreen
trees” in “11. Forests”“11.2.1. Sediment (organic materials)” of “11.2. Deciduous broad-leaf
trees” in “11. Forests”“11.3.1. Sediment (organic materials)” of “11.3. Forests with mixed
trees” in “11. Forests”

Decontamination

Removal of Sediment (organic materials)

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work
Workforce needed

Sediment(organic
materials)offorests(coniferous evergreen trees, deciduous broad-leaf
trees, other mixed trees, etc.) shall be removed in
the following procedures.
(i) Removing organic materials such as fallen
leaves(ii) Small and short transfer in working fields(iii) Packing removed organic materials
Fallen leaves, fallen branches and the like ina layer about 5 cm deep from the surface
shall be collected and carried by rakes or the
like to the bottom edge of slopes and be
packed in large sandbags. The removal
should not be as deep as to reach the mineralsoil layer.
Fallen branches or the like too big to pack inlarge sandbags as they are shall be chopped
into packable sizes, or cut into about 2 m longpieces and bundled using strings or the likein about 30 cm diameter bundles.
Tools, equipment to use
Rakes or the like
Large sandbags■ WhenQuantity-

working on cedar trees amongconiferous evergreen trees,(per 10,000 m2)
Workforce needed
Quantity
Operation leader
21.1
worker-days
Decontamination workers (for86.1
removing organic materials)
worker-days
Decontamination workers (small
31.6transfer)
worker-days369

Decontamination
workers(packing into large sandbags)

22.8
worker-days

When working on Japanese cypress amongconiferous evergreen trees(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
15.6
worker-days
Decontamination workers (for57.4
removing organic materials)
worker-days
Decontamination workers (small
31.6transfer)
worker-days
Decontamination
workers
15.2(packing into large sandbags)
worker-days
When working on Japanese red pine and thelike among coniferous evergreen trees, andother mixed trees,(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
20.5
worker-days
Decontamination workers (for83.2
removing organic materials)
worker-days
Decontamination workers (small
31.6transfer)
worker-days
Decontamination
workers
22.0(packing into large sandbags)
worker-days
When working on Japanese emperor oak andthe like among coniferous evergreen trees,(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
21.5
worker-days
Decontamination workers (for88.1
removing organic materials)
worker-days
Decontamination workers (small
31.6transfer)
worker-days
Decontamination
workers
23.3(packing into large sandbags)
worker-days
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedSafety measures are occasionally difficult totake on steep slopes and the like. In suchcases, decontamination work has been
implemented, upon consultation with theordering party, for individual working areas(for example, 2 m from the top of slopes or 2
m from the bottom of slopes).

Radiation

Safety glasses, masks and gloves shall be

exposureprotection of workers

worn.

370

General labor safety ofworkers

Measures to prevent

In case general safety measures are
insufficient to secure working safety, forexample, on steep slopes, safety measures
shall be strengthened depending on
individual working conditions.
Where risks of falling down or sliding down
are present, safety measures shall be needed,
for instance, installing fixed ropes and using
fall arresting devices.
If there are roads along the forest edge,
barricades and traffic controllers shall bearranged.
－secondary wastes
OthersAs a preparatory measure for small transfer,
workers shall be instructed to carry small
empty sandbags when collecting organic
materials.

3712）Removal of Sediment (organic materials) (non-control areas)
Locations to be
decontaminatedDecontamination“11.1.1. Sediment (organic materials)” of “11.1. Coniferous evergreen
trees” in “11. Forests”“11.2.1. Sediment (organic materials)” of “11.2. Deciduous broad-leaf
trees” in “11. Forests”“11.3.1. Sediment (organic materials)” of “11.3. Forests with mixed
trees” in “11. Forests”
Removal of Sediment (organic materials) (non-control areas)

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Workforce needed

Sediment (organic materials) of forests(coniferous evergreen trees, deciduous broad-leaf
trees, forests with mixed trees, etc.) in
non-control areas shall be removed in thefollowing procedures.
(i) Removing organic materials such as fallen
leaves(ii) Small amount and short-distance transfer inworking fields(iii) Packing removed organic materials
Fallen leaves, fallen branches and the like ina layer about 10 cm deep from the surface
shall be collected and carried using rakes or
the like to the bottom edge of slopes and be
packed in large sandbags. The removal
should not be so deep as to reach the mineralsoil layer.
Fallen branches or the like too large to packin large sandbags shall be chopped into
packable sizes, or cut in about 2 m longpieces and bundled using strings or the likein about 30 cm diameter bundles
Tools, equipment to use
Rakes or the like
Large sandbags

Quantity-(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
28.2
worker-days
Decontamination workers (for133.3
removing organic materials)
worker-days
Decontamination
workers
31.6(small transfer)
worker-days
Decontamination
workers
22.8(packing into large sandbags)
worker-days*This applies when the organic material layer372thickness exceeds 10 cm, irrespective of the tree
types.
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedSafety measures are occasionally difficult totake on steep slopes and the like. In suchcases, decontamination work has been
implemented, upon consultation with theordering party, for individual working areas(for example, 2 m from the top of slopes or 2
m from the bottom of slopes).

Radiation exposure
protection of workers

Safety glasses, masks and gloves shall be

General labor safety ofworkers

In case general safety measures are
insufficient to secure working safety, forexample, on steep slopes, safety measures
shall be strengthened depending on
individual working conditions.
Where risks of falling down or sliding down
are present, safety measures shall beneeded, for instance, installing fixed ropes
and using fall arresting devices.
If there are roads along the forest edge,
barricades and traffic controllers shall bearranged.

Measures to prevent

worn.

－

secondary wastes
OthersAs a preparatory measure for small transfer,
workers shall be instructed to carry small
empty sandbags when collecting sediment.

3733）Prevention of secondary dispersion of contaminated soil (lining up of sandbags)
Locations to be
decontaminated“11.1.2. Soil” of “11.1. Coniferous evergreen trees” in “11. Forests”“11.2.2. Soil” of “11.2. Deciduous broad-leaf trees” in “11. Forests”“11.3.2. Soil” of “11.3. Forests with mixed trees” in “11. Forests”

Decontamination

Prevention of secondary dispersion of contaminated soil (lining up of

methods

sandbags)

OutlineSecondary dispersion of contaminated soil inforests (coniferous evergreen trees, deciduous
broad-leaf trees, other mixed trees, etc.) shall be
prevented by lining up sandbags.

Decontamination processes

When removing fallen leaves from steep
slopes, sandbags shall be lined up at theforest edges in order to prevent soil frombeing eroded.
Sandbags shall be lined up with their small
tied end in front unless otherwise
instructed.
Sandbags of 48cm x 62cm (No. 2) shall be
used and when packed shall measureapproximately about 50cm x 40cm x 10cm.

Tools, equipment and the like fordecontamination work

Tools, equipment to use
Shovels and the like
Sandbags (jute, 48 x 62 cm)
mountain sandWorkforce needed
Workforce needed
Operation leaders
Decontamination workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 50 spots)
Quantity
200 bags
4.0 m3(per 50 spots)
Quantity
0.2
worker-days
1.5
worker-days

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedSandbags shall be lined up at the forest edgein order to prevent soil from eroding, whenorganic materials such as fallen leaves are
removed from steep slopes in forests, orwhen soil erosion by rainfall is possible after
the removal of sediment organic materials

Radiation

Dust masks, rubber gloves and the like shall

exposureprotection of workers

be worn.

General labor safety ofworkers

Protective measures shall be taken toprevent sliding down, such as fixed ropes,
safety belts and sliding devices on fixedropes.

374

Measures to prevent－

secondary wastes
Others－3754）Cutting down underbrush and shrubs
Locations to be
decontaminated“11.1.4. Underbrush cutting” of “11.1. Coniferous evergreen trees” in“11. Forests”“11.2.4. Underbrush cutting” of “11.2. Deciduous broad-leaf trees” in“11. Forests”“11.3.4. Underbrush cutting” of “11.3. Forests with mixed trees” in “11.
Forests”

Decontamination

Cutting down underbrush and shrubs

methods
OutlineDecontamination processes

Tools, equipment and the likefor decontamination work
Workforce needed

Underbrush and shrubs in forests (coniferous evergreen
trees, deciduous broad-leaf trees, other mixed trees, etc.)
shall be cut down.
Underbrush and shrubs shall be cut down by using
shoulder-type mowers and the like. The cut materials
shall be collected at the forest edge and packed inlarge sandbags.
Pieces too big to pack in large sandbags as they are
shall be chopped into packable sizes, or cut into lessthan 2 m long pieces and tied using strings or the likein about 30 cm diameter bundles. The bundles shall becollected and piled up at the forest edge forsubsequent processes (transfer to volume reduction
facilities or volume reduction by wood crushers).
Tools, equipment to use
Sandbags

Quantity-

When the objects to be cut down are sparsely
distributed, less than 17,000 pieces/ha (good visibility
in the forests and easy to walk around),(per 10,000 m2)
Quantity
Workforce
Slope
Slope
Slope
needed0 to 20°
21 to 30°
> 31°
Operation
leaders
Decontaminatio
n workers376

1.1
worker-days
7.1
worker-days

1.2
worker-days
7.7
worker-days

1.3
worker-days
8.6
worker-days

When the objects to be cut down are intermediate indistribution, between 17,000 and 28,000 pieces/ha,(per 10,000 m2)
Quantity
Workforce
Slope
Slope
Slope
needed0 to 20°
21to 30°> 31°
Operation
leaders
Decontamination
workers

1.5
1.6
1.6
worker-days worker-days worker-days
10.0
10.4
10.9
worker-days worker-days worker-days

When the objects to weed are densely distributed,
more than 28,000 pieces/ha (lots of underbrush, poor
visibility in the forests and hard to walk around),(per 10,000 m2)
Quantity
Workforce
Slope
Slope
Slope
needed0 to 20°
21 to 30°
> 31°
Operation
leaders
Decontamination
workers

Idea
development, lessons,points to
keep inmind, etc.

1.9
2.1
2.2
worker-days worker-days worker-days
12.9
13.7
14.5
worker-days worker-days worker-days

Prerequisites
and constraints
regardingobjects andlocations to be
decontaminatedThis work is to improve visibility at the bases of trees
in forests.

Radiation
exposureprotection
workers

Dust masks, rubber gloves and the like shall be worn.
The underbrush and shrubs are likely to have grownafter the accident. The spot to place the cut materials
collected shall be chosen carefully, because the air
dose rate may increase after the cutting work

Generalsafetyworkers
Measures

of

labor
of
to

The mower edge may be hidden in the underbrush
during cutting. Due attention shall be paid to the feetso as not to get cuts or injuries from the blade edges－

prevent
secondarywastesOthers－3775）Removal of residual sediment (organic material)
Locations to be
decontaminated“11.1.5. Removal of residual sediment (organic materials)” of “11.1.
Coniferous evergreen trees” in “11. Forests”“11.2.5. Removal of residual sediment (organic materials)” of “11.2.
Deciduous broad-leaf trees” in “11. Forests”“11.3.5. Removal of residual sediment (organic materials)” of “11.3.
Forests with mixed trees” in “11. Forests”

Decontamination

Removal of residual leaf litter and woody materials (organic materials)

methods
OutlineResidual sediment (organic materials) in forests(coniferous evergreen trees, deciduous broad-leaf
trees, other mixed trees, etc.) shall be removed.

Decontamination processes

Tools, equipment and the like fordecontamination work

Where residual organic materials are left
behind after removal work, they shall becollected by rakes or the like and be packed inlarge sandbags after being transferred to thebottom of the slope.
The removal of residual organic materials
should not be so deep as to reach the mineralsoil layer, the same as in removing theorganic materials originally.
Tools, equipment to use
Rakes or the like
Large sandbags

Workforce needed
Workforce needed
Operation leaders
Decontamination workers
Idea
development,
lessons,
pointstokeep
inmind, etc.

(per 10,000 m2)
Quantity(per 10,000 m2)
Quantity
3.6
worker-days
24.0
worker-days

Prerequisites
andconstraints regarding
objects and locations
to be decontaminatedExposed roots of trees and low areas on theslopes may induce surface water streams,
causing deterioration of forests. Prior tocommencing the work of removing organic
materials,
theforestmanagerandsupervisory personnel shall be closely
consulted on designating the area of work.

Radiation
exposureprotection of workers

Dust masks, rubber gloves and the like shallbe worn.
Precautions shall be taken to prevent
inhaling fine organic materials scatteredwhen the residue is being collected378

General labor safety ofworkers

Measures to prevent

Safety measures shall be taken for the workwith heavy machinery (proper arrangement
for preventing minor collisions of adjacently
working heavy machinery, and adequate
instructions and supervision, as well as
thorough control for preventing access to themachinery)－

secondary wastes
Others－379

（2） Coniferous evergreen trees
1）Pruning coniferous trees and collecting pruned branches
Locations to be“11.1.3. Trees” of “11.1. Coniferous evergreen trees” in “11. Forests”

decontaminatedDecontamination

Pruning coniferous trees and collecting pruned branches

methods
OutlineDecontamination processes

Tools, equipment and the like fordecontamination work

Workforce needed

Coniferous evergreen trees in the forests shall be
pruned and the pruned branches shall becollected in the following procedure.
(i) Pruning(ii) Collecting pruned branches
Branches of living coniferous evergreen
trees (cedar, Japanese cypress, and the like)of more than 3 year old class shall be cut off
using saws or the like up to the height ofabout 4 m from the ground, if they standwithin about 5 m from the forest edge (about
1 or 2 rows). But the tree canopies of morethan half of their original size shall be left. If
branches and leaves of living trees
considerably hang above buildings, theyshall be cut off using saws and the like.
Branches too long to pack in large sandbags
as they are shall be chopped into packablesizes, or cut into less than 2 m long pieces
and tied using strings or the like in about 30
cm diameter bundles. The bundles shall becollected and piled up at the forest edge forsubsequent processes (transfer to volume
reduction facilities or volume reduction bywood crushers).
Tools, equipment to use
Saws or the like
Large sandbags

Quantity-■When cutting cedars,(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
16.1
worker-days
Decontamination
workers
77.5(for pruning)
worker-days
Decontamination
workers
29.7(for bundling)
worker-days*In cases pruned branches and fallen leaves arebundled and transferred to the bottom of slopes.

380

When cutting Japanese cypress,(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
19.4
worker-days
Decontamination
workers
99.3(for pruning)
worker-days
Decontamination
workers
29.7(for bundling)
worker-days*In cases pruned branches and fallen leaves arebundled and transferred to the bottom of slopes.
When cutting Japanese red pine and thelike,(per 10,000 m2)
Workforce needed
Quantity
Operation leaders
16.9
worker-days
Decontamination
workers
99.3(for pruning)
worker-days
Decontamination
workers
13.2(for bundling)
worker-days*In cases pruned branches and fallen leaves arebundled and transferred to the bottom of slopes.
Idea
development,
lessons,
pointstokeep
inmind, etc.

Prerequisites andconstraints regarding
objects and locations
to be decontaminatedThis method may be applied to windbreaktrees around housing areas

Radiation
exposureprotection of workers

Dust masks, rubber gloves and the like shallbe worn.
At the top of untreated trees, radioactive
materials are likely to have attached.
Maximum attention shall be paid not totouch materials falling from above(branches, leaves, dust, etc.)

General labor safety of

Cautions shall be taken to prevent workers

workers

being hit with objects dropped during
pruning.

Measures to prevent－

secondary wastes
Others－381

6.2. Verification of Decontamination Effects
Chapter 6.2 shows some of the verification results of decontamination effects in thedecontamination works done under various test conditions in the Special Decontamination
Areas as arranged by the MOE.
It should be noted that the decontamination effects depend on various environmental
conditions such as material properties or surface conditions of the objects subject todecontamination, or their aging variation with time, and therefore, the same decontamination
effects cannot be necessarily expected even if the same decontamination methods for aparticular item are applied. There are also some cases which showed different results fromthose of model projects conducted by the Cabinet Office and Japan Atomic Energy Agency(JAEA) or those experienced in the first stage decontamination work in relatively high doseareas in Fukushima Prefecture (mainly in JFY 2011).
It should be also noted that the decontamination methods and application conditions cannot
be decided solely by the test decontamination results. The specific decontamination methods
and application conditions have been decided for individual communities upon the residents’consent with consideration to workability, preservation of functions of the item to be
decontaminated, and the like.
The verification results are shown below for individual decontamination methods tested in
two groups of Special Decontamination Areas, i.e., relatively low dose areas ofresiding-restricted areas (the areas in which residing is restricted) and the evacuation orderlifting preparation areas (the areas in which the evacuation orders are being prepared forlifting), and relatively high dose areas of difficult-to-return areas (the areas where it isexpected that the residents have difficulties in returning for a long time).
The decontamination effects are shown basically in terms of the changes in surface
contamination densities (cpm). But for farmland, where penetrated contamination is likely,
rather than surface contamination, the decontamination effects are expressed in terms of thechange in dose equivalent (μSv/h).

382

6.2.1. Residing-restricted Areas (Areas in Which Residing is Restricted) or Evacuation

Orders Lifting Preparation Areas (Areas in Which Evacuation Orders are Being
Prepared for Lifting)
The following are the results of decontamination effects under various test conditions
obtained from the decontamination work model projects authorized by the MOE in theresiding-restricted areas and the evacuation order lifting preparation areas.

（1） Residential areas and the like1）Roofs/rooftops
A) Wiping
After removing sediment on roofs when present, one to three wiping operations wereconducted using disposable paper wipes.
The test decontamination was conducted on roofs facing east, south, west and north. Roofs
facing east had mostly higher values of air dose rates and surface contamination densities
than the other roofs. This will be attributed to the wind direction and the source ofradioactive materials.
Higher surface contamination densities (3,000 to 5,000 cpm) have been experienced on
roofs with seams such as batten-seamed roofs and folded-plate roofs or metallic roofs withrust such as galvanized steel sheets, while lower densities have been experienced on roofs
with flat surface materials or fewer seams. This indicates that radioactive materials tend
to be attached and remained on roof surfaces with uneven configurations, while from flat
surface roofs radioactive materials may be washed away by rainfall even if attached once.
The air dose rate was reduced by about -13 to +28% (about 9 to 11% on the average) by
wiping the roofs after removing sediment, and the surface contamination densities werereduced by about -13 to +79% (average about 27 to 39%).
There were variations in the radiation reduction effects by wiping. Even 10 wiping
operations did not lower the dose to the lowest level. Once the contamination is reduced toseveral hundred [cpm], the data variation becomes big. The radiation reduction effects ata particular place remained almost unchanged even if wiping operations were repeated(once, twice, three times and ten times).

383

Table 6-2 Example results in residential areas, etc. of wiping roofs and rooftops
Air dose rate139 at 1
cm away from thesurface(μSv/h)Surfacecontamination
density(without
shielding cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom the surface(%)

Decontamination
rate of Surface
contamination
density(%)

Before wiping

1.2

1.32×103－－

After first wiping
AftersecondwipingAfter third wiping

1.0

6.00×102

11

33

1.1

5.57×102

9

36

1.0

5.00×10211

39

After tenth wiping

1.0

5.20×10210

27Work Schedule※ Dose equivalent rate, surface contamination density and reduction rate are the average of theirmeasurements.
※ Even if the reduction rate was negative at a measuring point, the reduction rate of the concerned point
was not considered to be zero, and was calculated using the raw value (negative value).
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method2）Exterior walls/outside walls
A) Wiping, brushing
Glass surfaces, siding walls, wooden walls, mortar walls, earthen walls, and galvanizedsteel sheet walls, corrugated sheet walls and metal walls were wiped or brushed once tothree times (both for mortar walls, but only brushing for earthen walls and only wiping forothers).
Whatever the material was, the surface contamination densities were confirmed to belower than those on the roofs or in the rainwater gutters.
The dose rate was basically low, and the dose rate change was minimal even when wiped
or brushed, irrespective of moss presence, the wall materials, and the numbers of wiping
and brushing operations.

3）Rainwater guttersA) Sediment removal, wiping
Sediment causes high dose rates. There is a case in which the maximum dose rate before
decontamination was 10 μSv/h and the surface contamination density was 17,000 cpm.
The reduction effects by removing sediment was about 3 to 78% (average 42%) for air dose
rates and about 20 to 59% (average 35%) for surface contamination densities. The effects
by wiping were about –11 to +18% (average about 7 to 11%) for air dose rates and about–30 to +52% (average about –1 to +11%) for surface contamination densities.
In decontaminating rainwater gutters, sediment removal is most effective. This is because
the sediment includes most of the radioactive contaminants.

139

Air dose rate measured 1 cm away from the ground or 1 cm away from the surface of target.

384

Table 6-3 Example results in residential areas, etc. of removing sediment from rainwater
gutters followed by wiping

Work Schedule

Air dose rate at 1
cm away fromsurface(μSv/h)Surfacecontamination
density(without
shielding cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom surface(%)

Decontamination
rate of Surface
contamination
density(%)

Before removing
5.2
1.03×104－－
sediments
After removing
2.0
5.87×103
42
35
sediments
After first wiping
1.9
6.07×1037(-1)
3
After second wiping
1.8
5.27×10911After third wiping
1.8
5.27×103
11
6※ The effect of decontamination depends on the various factor such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

3854）Street drains
A) Sediment removal
In street drains the maximum air dose rate of 2.4 μSv/h and surface contamination
density of 1,310 cpm were observed before decontamination.
The reduction in the surface contamination density reached as high as 47%. The concrete
covers of street drains lowered the surface contamination density to as low as 290 cpm.
Table 6-4 Example results in residential areas, etc. of removing sediment from side
ditchesWork Schedule

Air dose rate at 1
cm away fromsurface(μSv/h)Surfacecontamination
density(without shielding
cpm)

Decontamination
rate of Air dose rate
at 1 cm away fromsurface(%)

Decontamination
rate of surface
contamination
density(%)

With cover－－
1.4
4.10×102(before work)
Without cover－－
2.4
1.31×103(before work)
After removing
1.4
6.90×102
42
47
sediments
After cleaning
1.4
5.10×102
42
61
side ditches
With cover
1.1
2.90×102
54
78(after work)※ The reducing rate is the value after the cover was removed.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and etc.The results shown above are theresults which have been examined for the specific target to be decontaminated. Therefore, it does notassure that the equivalent effect can be attained by using the same decontamination method.

5）Outdoor equipment and the likeA) Wiping
Wiping operation was done one to three times.
The maximum air dose rate and surface contamination density of outdoor equipment andthe like have been measured as 0.80 μSv/h and 920 cpm, respectively.
The reduction rate of air dose rates was about -6 to +6% on the average and that of surface
contamination densities was about 44 to 85% on the average.
By repeating the wiping operation, the surface contamination densities decreased386

Table 6-5 Example results in residential areas, etc. by wiping outdoor equipment and thelikeWork Schedule

Air dose rate at 1
cm away fromsurface(μSv/h)Surfacecontamination
density(without shielding
cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom surface(%)

Decontamination
rate of surface
contamination
density(%)

Before wiping

8.0×10-1

9.20×102－－

8.5×10-1

5.20×102(-6)

44

7.5×10-1

2.10×102

6

77

7.5×10-1

1.40×1026

85

After first
wipingAfter second
wipingAfter third
wiping※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

387

（2） Schools1）Roofs of a swimming poolA) Wiping
The top part and the lower part of the roofs of a swimming pool were wiped.
The surface contamination density at the top was 340 to 440 cpm (average 400 cpm)
before decontamination. At the lower part it was 560 to 630 cpm (average 600 cpm). The
surface contamination density at the lower part was slightly higher than that at the top.
The reduction rate of air dose rates by wiping was –4 to +4% on the average, while that of
surface contamination densities was about 27% to 36% on the average.
Table 6-6 Example results in schools of wiping swimming pool roofs
Work Schedule

Upper

Lower

BeforewipingAfter wiping
BeforewipingAfter wiping

Air dose rate at 1
cm away fromsurface(μSv/h)Surfacecontamination
density(with shielding
cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom surface(%)

Decontamination
rate of surface
contamination
density(%)

1.2

4.00×102

－

－

1.2

2.60×102

4

36

1.8

6.00×102

－

－

1.9

4.30×102(-4)

27※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore、it does not assure that the equivalent effect can be attained by the same decontamination
method.

388

2）Pool sides
A) High-pressure water cleaning
High-pressure cleaning (vacuum collection 15 MPa, discharge flow rate of 12.7 L/min and
20 L/m2) were done one to three times.
The surface contamination density was 6,550 to 11,000 cpm, and the average was 9,330
cpm before decontamination. The pool side surface material was rubbery and black dirt
was recognized on the surface and roughness was locally observed in the area to be
decontaminated.
After the first high pressure cleaning, unevenness of the cleaning was visually observedon the pool side surfaces. After the second high pressure cleaning, hardly any cleaning
unevenness was visible on the surface. After the third high pressure cleaning, it was
visually confirmed that the dirt was almost uniformly removed from the surface.
As a result of implementing high-pressure water cleaning, the rate of reduction in the air
dose rate was approximately 76 to 79% on average, and the percent decrease in surface
contamination density was approximately 93 to 98% on average.

Table 6-7 Example results in schools for high-pressure water cleaning of swimming poolsides

Work Schedule

Before high pressurecleaning
After first cleaning
After second cleaning

Air dose rate at 1
cm away fromsurface(μSv/h)Surfacecontamination
density(with shielding
cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom surface(%)

Decontamination
rate of surface
contamination
density(%)

3.4

9.33×103－－

8.1×10-1

6.50×102

76

93

-1

2

79

97

6.9×102.70×10

7.0×10-1
1.90×102
79
98
After third cleaning※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

389

3）Exterior walls (with minor staining)A) Brushing (dry)The decontamination effect by brushing in dry conditions was checked on the test target
portion of the exterior wall surface with minor staining.
When shielding was used for more reliable measurement, the surface contamination
density was 100 to 110 cpm and the average was 100 cpm before decontamination.
The surface contamination density after dry brushing was 90 to 150 cpm and the average
was 130 cpm.
Little change was observed, since the contamination before decontamination was low
enough.
Table 6-8 Example results of (dry) brushing school external walls (with minor staining)Work Schedule

Air dose rate at
1 cm awayfrom surface(μSv/h)Surfacecontamination
density(without
shielding cpm)

Decontamination
rate of Air dose rate
at 1 cm away fromsurface(%)

Decontamination
rate of surface
contamination
density(%)

Before brushing

9.1×10-1

1.00×102－－

8.6×10-1
1.30×1026(-24)
After brushing※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore、it does not assure that the equivalent effect can be attained by the same decontamination
method.

4）Exterior Wall (with major staining)A) Brushing (wet)The decontamination effect by one-time brushing or twice brushing in wet conditions waschecked on the test target portion of the exterior wall surface with major staining.
When shielding was used for more reliable measurement, the surface contamination
density was 310 to 620 cpm and the average was 430 cpm before decontamination.
The surface contamination density after the first brushing was 180 to 430 cpm and theaverage was 280 cpm. The surface contamination rate after the second brushing was 230
to 420 cpm and the average was 320 cpm, slightly higher than those after the firstbrushing. It was interpreted that uncertainties were included in the data due to low
contamination. Because of the low values before decontamination for the wall, the average
reduction rate in the second brushing was 24 %.

390

Table 6-9 Example results of (wet) brushing school external walls (major staining)Work Schedule

Air dose rate at 1
cm away fromsurface(μSv/h)Surfacecontamination
density(with shielding
cpm)

Decontamination
rate of Air dose rate
at 1 cm away fromsurface(%)

Decontamination
rate of surface
contamination
density(%)

Before brushing

1.2

4.30×102－－

After first
1.1
2.80×102
6
35
brushing
After second
1.2
3.20×102(-5)
24
brushing※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and etc.The results shown above are theresults which have been examined for the specific target to be decontaminated. Therefore, it does notassure that the equivalent effect can be attained by using the same decontamination method.

391

5）Slopes in School PlaygroundA) Weeding and lawn scraping
Slopes in a school playground were weeded and the lawns were scraped away.
The surface contamination density was 1,490 to 1,970 cpm, and the average was 1,580
cpm before decontamination.
The surface contamination density was 1,920 to 2,710 cpm and the average was 2,380 cpm
after weeding, higher than that before weeding. After scraping lawns away by a backhoe,
the surface contamination density dropped to 170 to 280 cpm and the average to 230 cpm.
(The average reduction rate of surface contamination densities was about 85%).
Table 6-10

Example results of implementing weeding and lawn scraping on slopes in aschool playground

Work Schedule

Air dose rate
at 1 cm awayfrom surface(μSv/h)Air doserate at 1 m
away fromsurface(μSv/h)Surfacecontaminationdensity(withshieldingcpm)

Before weeding

4.8

3.2

1.58×103

Decontamination rate ofAir doserate at 1 cm
away fromsurface(%))

Decontamination rate ofAir doserate at 1 m
away fromsurface(%)

Decontaminationrate ofsurfacecontaminationdensity
(%)

－

－

－

4.5
2.8
2.38×1036
12(-53)
After weeding
After scrapping
1.4
2.1
2.30×102
72
35
85
lawn
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

6）Pavement (berm140 concrete)A) Abrasive vacuum blasting
The abrasive vacuum blasting effect for berm concrete was checked. The blasting speed
was set at 4 min/m2.
Berm concrete surfaces are often found under the eaves at schools or large size facilities.
Hot spots were frequently generated there caused by rain dripping from roofs.
The reduction rate of surface contamination densities by abrasive vacuum blasting wasabout 81% on the average.

140Berm concrete is an earthen-based concrete surface often found on the ground under eaves in order toprevent water intrusion into buildings.

392

Table 6-11 Example results of implementing abrasive vacuum blasting of pavement surfaces(berm concrete) in schools
Air doserate at 1 cm
Work Schedule away fromsurface(μSv/h)BeforeblastingAfterblasting

Surface
Air dose
Decontamination Decontamination Decontamination
contamination
rate at 1 mrate of Air dose rate of Air dose rate of surface
density
away fromrate at 1 cm away rate at 1 m away contamination(withsurfacefrom surface
from surface
densityshielding(μSv/h)
(%))
(%)
(%)
cpm)

－

－

2.00×103

－

－

－

－

－

3.80×102－－

81※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

393

（3） Roads
1）Paved surfaces
A) High-pressure water cleaning.
Test cleaning was executed on a paved road at three different flow rates of 10 L/m2, 15
L/m2 and 20 L/m2. The discharge pressure of high pressure water cleaning was set at 15
MPa.
The dose rates before decontamination were 1.0 to 1.1 μSv/h at 1 cm from the surface and1.1 to 1.2 μSv/h at 1m above the ground, and the surface contamination density was 310 to530 cpm.
The reduction rates of doses rate in all cases were 26 to 29% at 1cm from the surface and 9
to 11% at 1m above ground, and those of surface contamination densities were 55 to 66%.
The decontamination effect was evident. Concerning the effect of cleaning water flow
rates, no significant difference was observed.
Table 6-12

Example results of implementing high-pressure water cleaning of roadpavement surfaces

Water flow rate

10L/m2

15L/m2

20L/m2

Beforecleaning
Aftercleaning
Beforecleaning
Aftercleaning
Beforecleaning
Aftercleaning

Decontaminationrate of Air
dose rate
at 1 cmaway fromsurface(%))

Decontaminationrate of Air
dose rate
at 1 maway fromsurface(%)

Decontaminationrate ofsurfacecontaminationdensity(%)

Air doserate at 1 cm
away fromsurface(μSv/h)Air doserate at 1 m
away fromsurface(μSv/h)Surfacecontamination
density(withshielding
cpm)

1.1

1.1

1.18×103－－－

7.8×10-1

1.0

5.30×102

29

11

55

1.0

1.1

9.90×102－－－

7.2×10-1

9.8×10-1

4.50×102

29

9

55

1.0

1.2

9.10×102－－－

7.4×10-1

1.0

3.10×102

26

11

66

※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

394

2）Street drains
A) High-pressure cleaning
Decontamination effects of the air dose rate and surface contamination density were
measured at the two removable grating covers.
The reduction rates were about 64% for both of dose rates (at 1 cm from the surface) andsurface contamination densities, while the reduction rate for the dose rates at 1 m above
the ground was about 14%.
Table 6-13

Example results of implementing high-pressure water cleaning of road side
ditchesWork
Schedule

Air doserate at 1 cm
away fromthe surface(μSv/h)Air doserate at 1 m
away fromthe surface(μSv/h)Surfacecontamination
density(withshieldingcpm)

Decontamination rate ofAir doserate at 1 cm
away fromthe surface(%))

Decontamination rate ofAir doserate at 1 m
away fromthe surface(%)

Decontamination rate ofsurfacecontaminati
on density(%)

Before
－
－
－
1.7
1.0
5.30×102
cleaning(※)
After
6.1×10-1
9.0×10-1
1.90×10264
1464
cleaning(※)※ The measurement which was measured using a collimator.at one location.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

（4） Farmland
1）Rice fields
A) Leveling unevenness
The uneven topsoil was leveled by using a vibratory roller (combined roller). After levelingthe unevenness, irregularity of the test area was checked for the measurements.
The maximum difference in elevation of unevenness in rice fields was 40 to 60 mm before
leveling. In areas with many wild boars, it was confirmed that the difference had
increased to 95 to 110 mm.
It could be seen that the unevenness was reduced to 20 to 43 mm by leveling and theground surface looked generally smooth. In the rice fields of areas with many wild boars,
the unevenness was 57 to 97mm after leveling. It was visually confirmed that leveling byvibratory rollers could reduce the unevenness. The big unevenness caused by wild boars
could have been certainly reduced, but the change was minimal.
If the surface soil hardness was more than approximately 10 mm (by Yamanaka’
durometer), leveling work was possible. If there were many consecutive rainy days, thesoil hardness was less than 10 mm, and the leveling work was hard to do. The accessconditions (the access route, road widths or other conditions) of heavy machinery should
be checked in advance. Only roads with the gradient of 20 degrees or less were accessibleby heavy machinery.

3952）Dry fields
A) Off-scraping of topsoil
Topsoil was scraped off, after spraying surface solidifiers, by soil skimmers141.
The reduction rate of dose rates at 1 cm from the surface and at 1 m above the ground wasabout 36 to 37% and the reduction rate of surface contamination densities was about 47%.
The amount of soil carried out from dry fields by skimmers was 41 flexible container bags,
weighing 37.2 tons. When the area of 400 m2 was scraped uniformly to the depth of 5 cm,
the theoretical amount should have been 30 tons (specific gravity: 1.5). Actually, 7.2 tons(about 24%) more topsoil was scraped off than the planned amount.
Skimmers with rubber caterpillars could run smoothly for scraping. The surface finish
after scrapping topsoil was also good. The topsoil scraping approach by skimmers isappropriate for application in large flat fields.
Table 6-14

Work
Schedule

Example results of scraping topsoil in fields

Surface
Air dose
Air dose
Decontamination Decontamination Decontamination
contamination
rate at 1 cm rate at 1 mrate of Air dose rate of Air dose rate of surface
density
away from away fromrate at 1 cm away rate at 1 m away contamination(withsurfacesurfacefrom surface from surface
densityshielding(μSv/h)(μSv/h)
(%))
(%)
(%)
cpm)

Before
－
－
－
2.1
2.4
5.70×102
scrapping
After
1.3
1.5
2.70×10237
36
47
scrapping※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

141

Topsoil scrapping and recovering machine396

（5） Forests
A) Surface layer removal and topsoil scraping
The air dose rate was measured before weeding and surface layer (dry leaves) removal.
After weeding and removing dry leaves, the level obtained was defined as the reference
level (DL-0cm). The dose rate and the surface contamination density were measured at
1cm intervals in the depth direction from the reference level. The measurement was
terminated when hard soil layers appeared at the depth of DL-3cm to DL-4cm.
Measurements were implemented at three locations; on the southern slope of a forest of
deciduous trees, on the southern slope of a forest of evergreen trees, and on the western
slope of a forest of deciduous trees.
Occasionally the dose rate increased by weeding and dry leaf removal. The surface
contamination density decreased by removing the surface topsoil as seem in themeasurements made at 1cm intervals. By removing the surface topsoil by about DL-2 toDL-3cm from the reference level, the surface contamination density decreased to about
200 to 950 cpm. The reduction rate of surface contamination densities reached about 25 to
63% (about 36 to 53% on the average). The higher the initial surface contamination
density was, the higher the reduction rate was achieved.
It was understood that removing surface soil as deep as DL-2 to -3cm was appropriate forthe site conditions and the viewpoints of radiation reduction and soil erosion.
Table 6-15

Example results in a forest for surface layer removal and topsoil scraping

Work
Schedule

Air doserate at 1
cm away
from thesurface(μSv/h)Beforeremoving
surfacelayer
Afterremoving
surfacelayer
DL-1 cm

Surface
Air dose
Decontamination Decontamination
contamination
Decontamination
rate at 1 mrate of Air dose rate of Air dose
densityrate of surface
away fromrate at 1 cm
rate at 1 m away(with
contamination
the surface
away from the from the surface
shieldingdensity (%)(μSv/h)surface (%)
(%)
cpm)
－

－

2.5

2.3

9.2×102

2.5

2.0

9.7×102

(-1)

10

(-2)

2.4

2.0

9.9×102

5

12

(-5)

DL-2 cm

1.9

2.0

6.1×102

25

12

36

DL-3 cm
DL-4
cm(※)

1.5

1.9

4.4×102

39

14

53

1.8

2.9

4.0×102

53

26

68

－

※ DL-4cm was measured at one location.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which habe been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

397

6.2.2. Difficult-to-return Area (Areas Where It Is Expected That the Residents Have Difficulties
in Returning for a Long Time)The following are the results of decontamination effects under various test conditions
obtained from the decontamination work model projects authorized by the MOE in the
difficult-to-return area.
The surface contamination densities were always measured in terms of the radiation doseat 1cm from the surface. Beta rays from the surface contamination were measured as thedifference between the values with a collimator and the acrylic shielding plate and with only acollimator.

（1） Residential areas and the like1）RoofsA) Wiping
Test decontamination was executed for two types of roofing materials (ceramic tiles andgalvanized steel sheets) in District A and only ceramic tiles in District B.
In District A, the surface contamination densities showed big variation in data, probably
due to different surface configurations. The decontamination effect was evaluated interms of the dose equivalent rate.
The reduction rate of air dose rates (at 1cm from the surface, with a collimator) in District
A was 0 to 12%, showing no visible decontamination effects. Such results were also foundat other test cases. Significant reduction effects could not be confirmed even for different
wiping methods.
In District B, no significant reduction effects could be confirmed in evaluating the air dose
rates (at 1cm, with a collimator). On the other hand, in the evaluation of surface
contamination densities, some reduction effects could be confirmed by the first wiping, but
no further effects were confirmed by further wiping.
Wiping by disposable paper towels was chosen as the standard method, by which
improvement in decontamination workability could be expected.
In consideration of workability, wiping more than once, and finishing work by the second
wiping operation was chosen as the standard decontamination method for roofs.

398

Table 6-16 Example results of wiping roofs on residential land, etc. (District A residences,
ceramic tiles)

Work Schedule

BeforewipingAfterwipingBeforeWet paper wiping
towel
After
wipingDry paper
towel

Air dose rate at
1 cm away fromthe surface(μSv/h)Surfacecontamination
density (without
shielding cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom the surface(%)

Decontamination
rate of Surface
contamination
density (%)

7.7×10-1－－－

7.8×10-1

－

(-2)

－

7.5×10-1－－－

7.7×10-1

－

(-3)

－

※ The value shown in the table is the average of the value (s) measured at 3 locations.
※ The decontamination rate is the average value of decontamination rate at each measurement point.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

Table 6-17 Example results of wiping roofs on residential land, etc. (District A residences,
galvanized steel sheet plate roofs)

Work Schedule

Dry
paper
towelsWet
paper
towels

BeforewipingAfterwipingBeforewipingAfterwipingAir dose rate at 1
cm away fromthe surface(μSv/h)Surfacecontamination
density (without
shielding cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom the surface(%)

Decontamination
rate of Surface
contamination
density (%)

1.1

－

－

－

1.1

－

6

－

1.2

－

－

－

1.1

－

7

－

※ The value shown in the table is the average of the value (s) measured at 3 locations.
※ The decontamination rate is the average value of decontamination rate measured at each point.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been executed in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

399

Table 6-18

Example results of wiping roofs on residential land, etc. (District B, ceramic tiles)
Air dose rate at 1
cm away fromthe surface(μSv/h)Surfacecontamination
density (without
shielding cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom the surface(%)

Decontamination
rate of Surface
contamination
density (%)

Before wiping

1.1

1.41×103－－

After first wiping

1.2

1.25×103(-3)

11

After second wiping

1.1

1.23×1034

12After third wiping

1.1

1.20×1032

15Work Schedule※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

400B) Brushing
Test decontamination of cement tile roofs in District A was conducted by using a deckbrush.
Generally decontamination is believed to be ineffective on cement tiles.
The decontamination effect was checked by two ways of brushing, in one direction or
back-and-forth directions ten times. However, it was confirmed that the reduction rate ofsurface contamination densities was 0%, showing no decontamination effects.
The poor decontamination effect was understood to be due to rough surfaces of cement
tiles, on which fine grains containing radioactive materials were easily deposited into theporous structure of the surface layer.
It was found that brushing had no decontamination effects at all.
Table 6-19

Example results of brushing cement tile roofs on residential land, etc.

Work Schedule

One waybrushingRoundbrushing

Beforewiping
After
two
times
wiping
After
four
times
wipingBeforewipingAfter tentimes
wipingAir dose rate at 1
cm away from thesurface (μSv/h)

Surfacecontamination
density (without
shielding cpm)

Decontamination
rate of Air dose
rate at 1 cm awayfrom the surface(%)

Decontamination
rate of Surface
contamination
density (%)－

1.12×104－－－

1.12×1040－－

1.12×1040－－

1.00×104－－－

1.00×1040－※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

401

2）Exterior Walls
A) WipingFor exterior walls, wiping effects were tested on the wall materials such as soft
lysine-sprayed walls, pea gravel-washed walls and metallic siding. In many cases thedecontamination effect had little correlation with the wall materials.
Although no big difference was recognized depending on different wiping methods, wiping
by wet paper towels was chosen as the standard decontamination method for external
walls, in consideration of the test results on the roofs and workability.
The decontamination rate of the third wiping from the second wiping was -1% in District
C and +12% in District D. The improvement of decontamination in the third wiping was
not significant when compared with those of the first two wiping steps.
For the exterior wall decontamination, twice wiping (finishing work by the second wiping)
was chosen as the standard decontamination method.
Table 6-20

Example results of wiping external walls on residential land, etc.

Work Schedule

Ceramic
siding,wiping by
dry paper
towel
Metallic
siding,[wiping
by
wet
paper
towel

Before wiping
After
first
wipingAftersecondwipingAfter
thirdwipingBefore wiping
After first
wipingAftersecondwipingAfter
thirdwipingDecontamination
Decontamination
rate of Air dose
rate of Surface
rate at 1 cm away
contaminationfrom the surface
density (%)(%)

Air dose rate at 1
cm away from thesurface (withshielding, μSv/h)

Surfacecontamination
density (withshielding cpm)－

7.84×102－－－

6.43×102－18－

5.52×102－30

5.60×102

29

2.2

－

－

－

1.8

－

18

－

1.7

－

25

1.5

35

※ For metallic siding, many discrepancies due to impact to be considered that surface shape affected on
surface contamination density were confirmed. Therefore, the effect was evaluated by dose equivalentrate.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

402

3）GuttersA) Sediment removal and wiping
Test decontamination of gutters were done by wiping, the standard method, changing thenumber of wiping operations under two conditions of wet wiping and dry wiping.
Collimators could not be used for the air dose rate measurements due to narrow gutter
openings.
For the surface contamination density, the first wiping after removing sediment gave ahigh decontamination rate. No further big decrease could be observed even if wiping was
repeated. Wet wiping gave a higher decontamination rate than dry wiping.
A combination of wiping by wet paper towels and wiping once or more after removing
sediment was chosen as the standard decontamination method for gutters.
Table 6-21

Example results in residential areas of removing sediment from roof gutters
followed by wiping

Work ScheduleDrywiping(wiping
by
dry
paper
towel)

Wet
wiping(wiping
by
wet
paper
towel)

Before wiping
Afterremoving
sediments
After
first
wipingAfter second
wipingAfter
thirdwipingAfter fourth
wipingAfter
fifthwipingAfter
sixthwipingBefore wiping
Afterremoving
sediments
After
first
wipingAfter second
wipingAfter
thirdwipingAfter fourth
wipingAfter
fifthwipingAfter
sixthwiping.

Decontamination
Decontamination
rate of Air dose
rate of Surface
rate at 1 cm
contamination
away from thedensity (%)
surface (%)

Air dose rate at 1
cm away fromthe surface (withshielding, μSv/h)

Surfacecontamination
density (withshielding cpm)

3.0×10－－－1.2×102.25×104

61

－

9.2

2.31×104

69

(-3)

8.7

1.74×104

71

23

9.0

1.26×104

70

44

8.9

1.55×104

70

31

8.8

1.35×104

71

40

8.8

1.35×10471

40

3.0×10－－－1.2×102.25×10461－

1.0×109.75×103

66

56

1.0×107.30×103

66

67

1.0×105.60×103

66

74

1.0×107.20×103

66

67

1.0×107.00×103

66

68

1.0×107.00×103

66

68

403

※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

4044）Paved surfaces
A) High-pressure water cleaning and shot-blasting
Test decontamination of paved surfaces were executed by the following three methods; i)high-pressure water cleaning with vacuum collection of water (water pressure of 20 MPa,
2 times cleaning), ii) shot-blasting (discharge pressure of steel shot, 5M Pa by thestandard decontamination method in accordance with the decontamination guidelines)
and iii) shot-blasting (discharge pressure of steel shot, 7M Pa). The decontamination
rates were compared, the damaged condition of paved surfaces was checked and theapplicable scope of each decontamination method was verified.
The highest decontamination rate was obtained by the standard method of shot-blasting(discharge pressure of steel shot 7 MPa), but shot-blasting marks remained on the paved
surface and the road surface markings were even erased.
The high-pressure water cleaning with vacuum collection of water was appropriate toapply in narrow gaps and on the paved surfaces where damage should be avoided. The
shot-blasting at 7 MPa could basically be applied to flat places over a certain distance forcontinuous working. The lines on the roads and the locations vulnerable to damage
should be blasted at 5 MPa.
Table 6-22

Example results in residential areas, etc. of implementing high-pressure watercleaning and shot-blasting of pavement surface (Asphalt pavement)

Work Schedule

Suction Before
type high cleaningpressure Afterwatercleaning
BeforeShot
blasting
blasting
After
5mpa
blasting
BeforeShot
blasting
blasting
After
7mpa
blasting

Decontamination
Air dose rate Air dose
Surface
Decontamination Decontamination
rate of Air doseat 1 cm away rate at 1 m contamination
rate of Air dose rate of surface
rate at 1 cm
from theaway fromdensityrate at 1 m away contamination
away from thesurfacethe surface(withfrom the surface
densitysurface(μSv/h)(μSv/h) shielding cpm)
(%)
(%)
(%))
－

－

7.51×103

－

－

－

－

－

3.45×103

－

－

53

－

－

6.16×103

－

－

－

－

－

3.89×103

－

－

37

－

－

8.08×103

－

－

－

－

－

1.25×103－－

84※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The decontamination rate is the average value of decontamination rate at each measurement point.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

405

Table 6-23

Example results in residential areas, etc. of implementing high-pressure watercleaning and shot-blasting of pavement surface (Concrete pavement)

Work Schedule

Suction Before
type high cleaningpressure Afterwatercleaning
BeforeShot
blasting
blasting
After
7 MPa
blasting

Surface
Decontamination
Decontamination Decontamination
contamination rate of Air dose
rate of Air dose rate of surface
densityrate at 1 cm
rate at 1 m away contamination(withaway from thefrom the surface
densityshieldingsurface
(%)
(%)
cpm)
(%))

Air doserate at 1 cm
away fromthe surface(μSv/h)Air doserate at 1 m
away fromthe surface(μSv/h)－－2.45×104

－

－

－

－

－

1.06×104

－

－

56

－

－

2.08×104

－

－

－

－

－

7.92×103－－

63※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The decontamination rate is the average value of decontamination rate at each measurement point.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

406

（2） Schools1）Rooftops
A) High-pressure water cleaning.
Test decontamination was conducted on the rooftop of a kindergarten building covered bywater proof sheets using high-pressure water cleaning with vacuum water collection. The
discharge flow rate of 20 Lm3/m2 was used at two water pressure conditions of 10 MPa
and 15 MPa in the test.
No big difference in decontamination rates was observed for the two pressure conditions,
10 MPa and 15 MPa. No further significant decrease of decontamination rates was foundby the second and further cleaning, regardless of the cleaning pressure.
The standard cleaning method for rooftops was set as “one time cleaning at 15MPa.
Table 6-24

Example results of implementing high-pressure water cleaning of school roofs

Work Schedule

Cleaning
water
pressure(10mpa)Cleaning
water
pressure(15mpa)Beforecleaning
After
first
cleaning
Aftersecondcleaning
After
third
cleaning
Beforecleaning
After
first
cleaning
Aftersecondcleaning
After
third
cleaning

Air dose rate at 1
cm away fromthe surface(with shielding
μSv/h)

Surfacecontamination
density(with shielding
cpm)

Decontamination
rate of Air dose
rate at 1 cm
away from thesurface(%)

Decontamination
rate of Surface
contamination
density(%)－

3.12×102－－－

5.80×10－81－

3.40×10－89－

9.00×10－71－

3.90×102－－－

7.80×10－80－

7.80×10－80－

5.80×10－85※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

407

（3） Parks
1）Playgrounds and the likeA) Scraping topsoil and earth covering
Topsoil in a playground in a kindergarten facility was scraped and the scraped surface
was covered afterward with fresh soil. Two scraping depths of 5 cm and 10 cm were used.
It was found that even 5 cm scraping could obtain a decontamination rate of more than90%.
The standard decontamination method for parks (playgrounds) was set as scrapping
topsoil by 5 cm and earth covering by 5 cm.
Table 6-25

Example results of scraping topsoil followed by earth covering on park
playgrounds, etc.

Work schedule

Beforescraping
Scraping After
depth scraping
(5cm)
After
covering
Beforescraping
Scraping Afterdepthscraping(10cm)
Aftercovering

Air dose
Air dose
Surface
Decontamination
rate at 1 cm rate at 1 m
Decontamination Decontamination
contamination rate of Air doseaway from away fromrate of Air dose rate of surface
densityrate at 1 cm
the surface the surface
rate at 1 m away contamination(withaway from the
(with
(with
from the surface
densityshieldingsurfaceshielding shielding
(%)
(%)
cpm)
(%))
,μSv/h)μSv/h)－－

8.76×102

－

－

－

－

－

4.00×10

－

－

95

－

－

2.80×10

－

－

97

－

－

1.10×103

－

－

－

－

－

1.40×10

－

－

99

－

－

3.40×10－－97※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

408

（4） Large size facilities
1）Rooftops
A) High-pressure water cleaning
The standard method of high-pressure water cleaning was tested for the rooftop of a
hospital covered by waterproof sheets and cinder concrete. The discharge flow rate of 20
Lm3/m2 was used at two water pressure conditions of 10 MPa and 15 MPa in the test.
Higher decontamination rates were obtained by 15 MPa cleaning than 10 MPa cleaning.
For the waterproof sheet rooftops, the decontamination rate of 3% was obtained by thesecond cleaning. Therefore, the most effective decontamination method was twice
cleaning at 15MPa water pressure. For the cinder concrete rooftops, no significant
decontamination rate could be observed regardless of the number of cleaning times andwater pressure.
The standard decontamination method was set as one-time cleaning at 15MPa waterpressure for both types of rooftops of large size facilities, in due consideration of
workability and overlapping of work areas.
Table 6-26

Example results of implementing high-pressure water cleaning of roofs onlarge-size facilities (waterproof sheeting)Work Schedule

Cleaning waterpressure(10mpa)Cleaning waterpressure(15mpa)Beforecleaning
After firstcleaning
Aftersecondcleaning
Beforecleaning
After firstcleaning
Aftersecondcleaning
After thirdcleaning

Air dose rate at 1
cm away fromthe surface(with shielding
μSv/h)

Surfacecontamination
density(with shielding
cpm)

Decontamination
rate of Air dose
rate at 1 cm
away from thesurface(%)

Decontamination
rate of Surface
contamination
density(%)－

2.98×102－－－

1.48×102－50－

1.34×102－55－

2.04×102－－－

1.10×102－46－

6.80×10－67－

6.20×10－70※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

409

Table 6-27

Example results of implementing high-pressure water cleaning of roofs onlarge-size facilities (cinder concrete)

Work Schedule

Cleaning waterpressure(10mpa)Cleaning waterpressure(15mpa)Beforecleaning
After firstcleaning
Aftersecondcleaning
Beforecleaning
After firstcleaning
Aftersecondcleaning

Air dose rate at 1
cm away fromthe surface(with shielding
μSv/h)

Surfacecontamination
density(with shielding
cpm)

Decontamination
rate of Air dose
rate at 1 cm
away from thesurface(%)

Decontamination
rate of Surface
contamination
density(%)－

5.77×103－－－

2.54×103－56－

2.33×103－60－

6.50×103－－－

2.32×103－64－

1.98×103－70※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

4102）Paved surfacesA) Shot-blasting
The shot-blasting for paved surfaces in a hospital premise was tested with different
discharge pressures of steel shot, 7 MPa (the standard decontamination method) and 5
MPa. The low discharge pressure was tested in order to consider preventing the paved
surface from being damaged. The decontamination effect was also tested on the asphalt
surface and road surface markings (drawn by the thermoplastic method).
Decontamination rates and the degree of damage were compared between
decontamination methods.
The highest decontamination rate was obtained by the standard decontamination methodof shot-blasting (7 MPa discharge pressure of steel shot). But marks due to steel shot
remained on the paved surfaces and the white surface marking were erased.
It is necessary to lower the discharge pressure to about 5 MPa or to consider analternative method for places with road surface markings.
Table 6-28

Work schedule

7MPawith lap

7MPa
withoutlap

Example results of implementing shot-blasting on pavement surface(conventional pavement surface) of large-size facilities
Air dose rate Air dose rate
Surface
Decontamination
Decontamination Decontamination
at 1 cm away at 1 m away contamination rate of Air dose
rate of Air dose rate of surface
from thefrom thedensityrate at 1 cm
rate at 1 m away contamination
surface (with surface (with(withaway from thefrom the surface
densityshieldingshieldingshieldingsurface(%)(%),μSv/h)μSv/h)
cpm)(%))

Beforeblasting

－

－

After
blasting－－

Beforeblasting

－

－

After
blasting－－

5.86×103
5.02×102 ※1

5.86×103 ※2

6.15×102 ※3

－

－

－

－

－

91 ※1

－

－

－

－

－

90 ※3

※1 The average of the values of measured at 5 locations※2 Since the value before decontamination was not consistent with the value after decontamination, it
was compared using the average of measurements in a decontamination targets.
※3 The average of the values of measured at 4 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be
decontaminated. Therefore, it does not assure that the equivalent effect can be attained by the samedecontamination method.

411

Table 6-29

Example results of implementing shot-blasting on pavement surface (whitesurface markings) of large-size facilities

Work schedule

Before5MPablasting
withoutAfterlapblasting
Before7MPablasting
withoutAfterlapblasting

Air dose rate Air dose rate
Surface
Decontamination
Decontamination Decontamination
at 1 cm away at 1 m away contamination rate of Air dose
rate of Air dose rate of surface
from thefrom thedensityrate at 1 cm
rate at 1 m away contamination
surface (with surface (with(withaway from thefrom the surface
densityshieldingshieldingshieldingsurface(%)(%),μSv/h)μSv/h)
cpm)
(%))
－

－

7.83×103 ※1

－

－

－

－

－

4.50×103 ※1

－

－

43 ※1

－

－

2.68×103 ※2

－

－

－

－

－

3.83×102 ※2

－

－

84 ※2

※1 The measurement were implemented at 3 locations. But, these data was abandoned, due to widelydiscrepancies.
※2 The average of 3 measurements. The decontamination rate is the average of the decontamination rate
which was calculated in every location.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be
decontaminated. Therefore, it does not assure that the equivalent effect can be attained by the samedecontamination method.

3）Wood decks
A) Wiping, high-pressure water cleaning and superhigh-pressure water cleaning
Wood decks of large facilities were decontaminated by wiping, high-pressure watercleaning and superhigh-pressure cleaning for tests.
The decontamination rate by wiping with wet cleaning cloths was about 10%. Both thedecontamination rates by superhigh-pressure water cleaning and high-pressure watercleaning were about 95%.
The superhigh-pressure water cleaning caused splinters on the wood deck surfaces due tothe high water pressure. Therefore, the high-pressure water cleaning was chosen as thestandard decontamination method for wood decks.

412

Table 6-30 Example results of implementing high-pressure water cleaning andsuperhigh-pressure water cleaning of wood decks of large-size facilities
Air dose
Air dose
Surface
Decontamination
rate at 1 cm rate at 1 m
Decontamination Decontamination
contamination rate of Air doseaway from away fromrate of Air dose rate of surface
densityrate at 1 cm
Work schedule the surface the surface
rate at 1 m away contamination(withaway from the
(with
(with
from the surface
densityshielding,surfaceshielding, shielding,
(%)
(%)
cpm)
(%)
,μSv/h)μSv/h)
BeforeWipingwipingby wetAfterragwipingBeforeHighcleaningpressure
After
15 mpacleaning
Superhi Before
cleaning
ghpressure After
70mpa cleaning－－

3.89×103

－

－

－

－

－

3.29×103

－

－

15

－

－

8.99×103

－

－

－

－

－

4.32×102

－

－

95

－

－

7.70×103

－

－

－

－

－

4.32×102－－

94※ The value shown in the table is the average of the value (s) measured at 5 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

413

（4） Roads
1）Paved surfaces
A) Superhigh-pressure water cleaning
Decontamination by the superhigh-pressure water at the standard water pressure of 150
MPa may damage the road surface and erase road surface markings on it (center lines,
outer lines), just as occurred by the shot-blasting. To set the appropriate cleaningpressure, test decontamination was conducted by changing the water pressures as 15, 30,
50, 100 and 150 MPa, while observing damage conditions of the road surface and thedecontamination effect.
The standard pressure for superhigh-pressure water cleaning is 150 MPa. The working
pressure of 100 MPa does not show significant deterioration of decontamination rates.
Concerning the damage on the surface, no big damage was observed below 30 MPa. But
at 50 MPa, loosened materials were blown out and above 100 MPa, the lines (center lines
and outer lines) were erased.
It is necessary to consider lowering the water pressure below 100 MPa when working onroad marking areas and portions where noticeable damage was found on the pavement.
Table 6-31 Example results of implementing superhigh-pressure water cleaning of road pavement
surfaces
Air dose
Air dose
Surface
Decontamination
cleaning water rate at 1 cm rate at 1 m
Decontamination Decontamination
contamination rate of Air dosepressure of away from away fromrate of Air dose rate of surface
densityrate at 1 cm
superhighthe surface the surface
rate at 1 m away contamination(withaway from thepressure water
(with
(with
from the surface
densityshieldingsurfacecleaning
shieldingshielding
(%)
(%)
cpm)
(%))
,μSv/h)μSv/h)
Beforecleaning
15
MPa After
cleaning
Beforecleaning
30
MPa After
cleaning
Beforecleaning
50
MPa After
cleaning
Before100 cleaning
MPa After
cleaning
Before150 cleaning
MPa After
cleaning－－

4.09×103

－

－

－

－

－

1.99×103

－

－

51

－

－

5.11×103

－

－

－

－

－

2.08×103

－

－

60

－

－

4.32×103

－

－

－

－

－

1.21×103

－

－

72

－

－

4.58×103

－

－

－

－

－

7.20×102

－

－

83

－

－

3.10×103

－

－

－

－

－

6.30×102－－80※ The value shown in the table is the average of the value (s) measured at 3 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.
414

415

（5） Farmland
1）Rice fields
A) Scraping topsoil, covering by fresh soil, leveling of unevenness and double plowing
Topsoil of rice fields in relatively high dose areas in the target area was scraped off by soil
skimmers142, and plowed after being covered by fresh soil. Prior to the scraping, the field
was mowed, the cut materials were removed, the top soil was scraped and the unevenness
was leveled by rolling compaction followed by double plowing to a depth of 3 cm.
According to present knowledge, the radiocesium concentration in the layer below 5 cm
from the surface is less than 5,000 Bq/kg in most farmland, even if the radiocesium
concentration in the surface layer of about 5 cm exceeds 5,000 Bq/kg. The scraping
thickness is set as 5 cm. But according to the sampling survey of the radiocesium
concentration as a function of depth, there were cases in District D in which theconcentration below 5 cm from the surface still exceeded 5,000 Bq/kg. Therefore, three
scraping depths of 5 cm, 7 cm and 10 cm were applied in this test decontamination.
The cases in which decontamination rates of 7 cm scraping were lower (higher
contamination densities) than those of 5 cm scraping were considered to be due tolocalized conditions (a similar trend was noticed in the radiocesium concentration
analysis in the layer, i.e. higher radiocesium concentrations when scraped by 7 cm thanby 5 cm).
The evaluation based on decontamination rates using surface contamination densities isgenerally considered appropriate for surface contamination. But such results were notalways obtained in farmland. Contamination in farmland may not be surface
contamination, but penetration contamination. In this case, the evaluation using dose
equivalent rates would be more appropriate.
Based on a proposal by the decontamination business operator, test measurements in ahigh dose area were conducted using a collimator and placing lead blocks on the ground,in order to shield from the surrounding radiation and preclude the influence of radiation
sources other than those on the surface. The difference of air dose rates between the caseswith shielding and without shielding is equivalent to the dose rate due to only gamma
rays. This approach gave better (more accurate) values. But the difference was just a few
percent and lead blocks are needed for measurement. In view of the workload required,ordinary measurements using a collimator of air dose rate at 1 cm from the surface isconsidered appropriate for measurements related to decontaminating farmland.
Even with the scraping depth of 5 cm, the decontamination rate of more than 90% after
plowing was obtained in the air dose rates as well as in the surface contamination
densities.

142

Topsoil scrapping and recovering machine

416

Table 6-32

Example results of scraping topsoil, bringing topsoil from another place, leveling
unevenness, and implementing double plowing of rice fields

Work Schedule,
Scraping depth

Scraping
5 cm

Scraping
7cm

Scraping
10 cm

Beforescraping
Afterscrapping
Afterbringing
topsoilfromanotherplace
Afterplowing
Beforescraping
Afterscraping
Afterbringing
topsoilfromanotherplace
Afterplowing
Beforescraping
Afterscraping
Afterbringing
topsoilfromanotherplace
Afterplowing

Air dose
Air dose
Surface Decontamination
rate at 1 cm rate at 1 m
Decontamination Decontamination
contamination rate of Air doseaway from away fromrate of Air dose rate of surface
densityrate at 1 cm
the surface the surface
rate at 1 m away contamination(withaway from the
(with
(with
from the surface
densityshieldingsurfaceshieldingshielding
(%)
(%)
cpm)
(%))
,μSv/h)μSv/h)
8.1

－

－

－

1.6

－

－

77

5.6×10-1

－

－

90

－

92

6.0×10-1

－

－

89

－

91

6.4

－

－

－

－

－

1.6

－

－

71

－

70

6.0×10-1－－

88

7.6×10-1

－

－

87

－

88

8.1

－

－

－

－

－

2.6×10-1

－

－

92

－

91

2.0×10-1－－

95

1.0×10-1

－

－

96

－

－
73

91

94

－

95

※ The value shown in the table is the average of the value (s) measured at 3 locations.
※ The effect of decontamination depends on the various factors such as the material and the surface
condition of decontamination target, their deterioration status and so on. The results shown above are
the results which have been implemented in a tentative way for the specific target to be decontaminated.
Therefore, it does not assure that the equivalent effect can be attained by the same decontamination
method.

417

7． Conclusion
The Act on Special Measures Concerning Nuclear Emergency Preparedness of Japan (Law
No.156, 1999) stipulated that the Nuclear Emergency Response Headquarters under the
Cabinet Office was responsible for preventing the release of radioactive materials to theenvironment. But the concrete legal framework was not in place before the Fukushima
Daiichi Nuclear Power Station (1FNPS) accident for emergency responses to contamination
due to radioactive materials released to the public environment.
Under such circumstances, relevant government authorities including the MOE and local
governments such as Fukushima Prefecture have been engaged in large scaledecontamination works for diverse and vast areas including housing areas, public facilities,
roads, farmland, forests near residential areas, etc. These works have been undertaken to
ensure public safety for facilitating early return of residents to their homes and restoration of
their daily lives. Such decontamination works are unprecedented worldwide and have been
implemented with all possible ideas, accumulated experiences and knowledge in atrial-and-error approach.
The decontamination works continue. Key experience and knowledge of significanceobtained to date are reviewed and summarized below.

（1） Fixing of legal, institutional and technical foundations
In August 2011, the Act on Special Measures Concerning the Handling of Radioactive
Pollution by the Accident at the Nuclear Power Station caused by the Great East Japan
Earthquake which occurred on March 11, 2011 (Law No. 110, 2011) (the “Act on Special
Measures”) was enacted in response to the 1FNPS accident. Thereafter, competent authorities
including the MOE formulated relevant ministry ordinances, standards, guidelines, etc. as
needed.
The MOE started the decontamination works under its direct jurisdiction based on the
Common Specifications provisionally formulated in a trial-and-error approach, using the thenexisting rules and mechanisms practiced by the Ministry of Land, Infrastructure andTransport (MLIT), the Ministry of Agriculture, Forestry and Fisheries (MAFF), etc. In doing
so, the MOE needed assistance from the experienced staff of MLIT and MAFF. The MOE
lacked experienced personnel for public works under its direct jurisdiction. The MOE
continued thereafter improving the Common Specifications step-by-step throughtrial-and-error in field experiences. Consequently, the whole framework of decontamination
works has been specified to a certain degree, including concrete work implementation details.
Prompt initiation of decontamination works, as needs emerged, has become possible, andquality of work has been pursued for improvement.
（2） Roles borne by the decontamination business operators in decontamination

works
There were two big requirements to implement large scale decontamination works, besides
technical competence for decontamination: one was the capacity to deliver the large amountsof equipment and human resources needed to the decontamination sites appropriately and ina timely manner, and the other was the project management capability to implement large
scale decontamination works efficiently and effectively under tight time pressures.
Especially to note in the decontamination works after the Great East Japan Earthquake in2011 was that the works had to be implemented under limited lifeline infrastructures. Under
such circumstances, it was absolutely a must to involve credible local construction industry
members for the decontamination works. They had experience and relevant technologies,
which they accumulated by quickly restoring the area after such things as severe weather
storms (e.g. typhoons and heavy snow). The decontamination business operators, whose key
players were construction companies, have been engaged in the decontamination works while
introducing non-conventional ideas by accumulating further experiences and knowledge.
Since the works which could be mechanized were limited in the decontamination works,418

large workforces were needed. But in nearby areas (especially Miyagi and Iwate Prefectures),large workforces were also in big demand for restoring the areas from the aftermaths of theearthquake and tsunami and for reconstruction. The decontamination business operators
could manage to recruit a large number of workers with the cooperation of local construction
companies, and the like. However, many of these workers were not experienced in site worksof civil engineering and construction. These workers needed education, not only technicalknowledge on decontamination or radiation protection, but also occupational safety andhealth for civil engineering and construction. Consequently, the decontamination business
operators had to spend a large amount of time and do a lot of work to provide those many
workers with education on decontamination and regular training of occupational safety andhealth.
Furthermore, the decontamination business operators often found it necessary to be very
flexible in updating the work schedules, depending on the progress: for example, acquisitionof agreement to land use for temporary material storage required before commencing
decontamination work; or its progresses at each temporary storage site did not proceed as
quickly as initially planned. The situation has been different from ordinary contracts for
public construction works, in which the order is awarded after the land use conditions, andthe like are fixed.

（3） Significance of decontamination model projects and existing technologies usedin decontamination
Soon after the accident, several pilot projects of decontamination were implemented
including “decontamination model projects” of the Cabinet Office. Such pilot decontamination
projects did not necessarily show standard decontamination models, but they certainly
brought good outcomes in identifying efficient and effective decontamination methods, andmeasures to ensure radiation workers’ safety. It was a very meaningful step toward large
scale decontamination works thereafter. The experiences and knowledge obtained from thesepilot projects have also shown that the technologies having been accumulated in theconstruction industry or their improved technologies can be effectively used indecontamination works, too, and that improvement in working procedures and management
is equally important in implementing decontamination works.
Another point to note is that accurate and efficient air-dose monitoring is needed in
evaluating the appropriateness of the decontamination works and to this end various
innovative monitoring technologies have been developed and applied, including mobile
monitoring vehicles and drone monitoring helicopters.
Further to note is that such decontamination pilot projects have also worked, not only inaccumulating technical knowledge, but in developing competent field workers with technicalknowledge. They also could facilitate the understanding of local community residents about
the decontamination works and their outcomes.

（4） Considerations in choosing decontamination methods and operation conditions
Decontamination methods to be applied, their operation conditions and the decontamination
effects depend on various environmental conditions such as site situations, material properties
or surface conditions of the objects subject to decontamination, or their aging variation withtime. Therefore, the best decontamination methods or conditions are difficult to specify
beforehand, even for a particular object to be decontaminated. For example, fordecontaminating paved road surfaces, high-pressure water cleaning was effective to someextent in the early stage, but after some time, when radioactive cesium migrated from theground surface deep into the materials, scraping of the paved road surface by shot-blasting
became a practical and effective approach, instead of cleaning the surface.
It should be noted that the decontamination effect was not the only criterion for choosing thedecontamination method and operation conditions. Construction workability as well as419

maintainability of target objects was also considered. Final selection of the decontamination
methods and conditions were made only when the consent of local residents was obtained in
the respective communities.

（5） Strengthening management for appropriate decontamination works
It was necessary to systematically fix documented work procedures, mechanisms, etc. forsmooth operation of the decontamination works, in order to implement unprecedented
large-scale decontamination works.
Nevertheless there were cases when the decontamination works not specified in theguidelines or in the Common Specifications became necessary, because the decontamination
works had been implemented under the relevant knowledge being limited. In such cases,
government supervisory personnel and the decontamination business operators jointly
worked out the appropriate procedures to apply. Some of these procedures have been
incorporated into the standard work procedures when it was deemed as being possible togeneralize them. Thus, the PDCA cycle (Plan – Do – Check – Act) has been pursued for
improvement.
In January 2013 it was reported that decontamination had been questionable in some cases.
The report was about an incident which could have damaged public trust in the community.
The MOE launched immediately the “Headquarters for Proper Decontamination Promotion” andformulated the “Appropriate Decontamination Program” consisting of three main pillars:
Thorough responsibility for decontamination works by the decontamination business
operators; Establishment of comprehensive management systems; and Strengthening of MOE
organizational settings.
Based on this “Appropriate Decontamination n Program,” emergency hotline telephone number“Decontamination Dial 110 (Hotline)” was set up at the MOE to receive information onquestionable cases of decontamination. The information received was examined for
confirming the facts and, as needed, attention of the decontamination business operators was
drawn to the problems. Their responses to the information were disclosed on the MOE
homepage.
（6） Communication with local residents
When implementing a big undertaking like the decontamination works, sufficient time isneeded for preparation. But on the other hand, strong desires were expressed by the local
residents to initiate decontamination works at the earliest possible time. It was very
important, therefore, to establish mutual trust with the local residents through sincere
communication, in implementing decontamination works, empathy with them in mind.
In the areas such as the Special Decontamination Areas, from where residents had
evacuated, they could not witness the decontamination works by themselves. When planningdecontamination work in such areas, opportunities were arranged for them to visit the site for
their prior consent to the work or to confirm the decontamination works for themselves. For
facilitating their prior consent, significant efforts were made to sincerely respond to them byhearing and evaluating their requests, and repeating explanatory responses to their concerns.
Since the decontamination works affect the buildings, houses and land directly, priorconsent of their owners is legally required for the works. Therefore, drawings and photos wereattached as appropriate to the document of consent in order to clearly stipulate the contents
of agreement for both parties. The results of dose measurements before and after thedecontamination works were also reported using drawings, and the like to relevant parties asappropriate including the owners.

（7） Collaboration with relevant organizations and information dissemination
It was absolutely indispensable, in implementing the decontamination works, to respond to420

all kinds of concerns and dissatisfactions of local residents about the decontamination
methods and decontamination works, and concerns about safety of temporary storage sites.
The MOE cooperated with Fukushima Prefecture and set up the “Decontamination
Information Plaza,” in order to disseminate relevant information on decontamination andradiation, and to set up an activity base for experts. The Decontamination Information Plaza
has promoted communication with local communities by providing various exhibits andpamphlets, arranging workshops or opinion exchange meetings, dispatching registeredexperts to local governments or communities upon request, or responding to consultations
from the local residents. The MOE has also made efforts to facilitate people’s understanding
through operating its websites and the Call Center, and information dissemination via mass
media.
The MOE has kept close contacts with international organizations such as the IAEA in
implementing the decontamination works and in parallel promoted information sharing with
the international communities based on bilateral national cooperation agreements, and the
like.

421

This report assembled comprehensively, with key attention to the decontamination works
by the MOE, the basic policy of decontamination, its implementation framework, knowledge
about managing the decontamination works based on the actual decontamination works
experienced in the fields, and individual decontamination methods, conditions and effects
thereof. The report was compiled by the Editorial Committee, which determined its structure,contents, items to survey, division of responsibilities, etc. Its members are listed below (The
Mitsubishi Research Institute, Inc. served as the secretariat).
The report has assembled the experiences and knowledge concerning decontamination ofradioactive materials in Japan, focusing on the activities of the MOE. But it is important tocollect and preserve all relevant documents and data, not only those of MOE but those of
relevant ministries, local governments, research institutes and other related institutions, inorder to prepare for possible accidents in the future at nuclear facilities and also to contributeto the relevant research activities.

The Editorial Committee for the “Decontamination Report”
Tadashi INOUE (Chair)

Clean-up Sub-committee Chief, Atomic Energy Society of Japan
Research Advisor Emeritus, the Central Research Institute ofElectric Power Companies
Shinichi NAKAYAMA
Japan Atomic Energy Agency
Yoshitake SHIRATORI Japan Atomic Energy Agency
Shinichiro ASAZUMAJapan Atomic Energy Agency
Kazuto ENDO
National Institute for Environmental Studies
Takeshi IIMOTO
University of Tokyo
Kazuro SATO
Taisei Corporation
Yoshio OSHINO
Kajima Corporation
Ken WATANABE
Shimizu Corporation
Shoko YASHIO
Obayashi Corporation
Takahiro NAKAJIMA
Hazama Ando Corporation
Shintaro HAYASHI
Maeda Corporation
Katsuhide MORIMOTO Okumura Corporation
Yuichi OZUTSUMITokyo Power Technology Ltd.
Takashi TOMIOKAATOX Co., Ltd.
Takashi OHMURA
Ministry of the Environment, Government of Japan422