Decontamination Guidelines
2nd Ed.,2013（Tentative Translation）

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

Introduction
The environmental pollution caused by radioactive materials discharged by the nuclear
power plant accident associated with the Earthquake that Occurred off the Pacific Coastof the Tohoku Region on March 11, 2011has made it an urgent issue to promptly reducethe impact of this pollution on human health and the living environment.
In light of these circumstances, in August 2011 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 (Act No. 110 of 2011; hereinafter
the “Act on Special Measures concerning the Handling of Radioactive Pollution”) was
passed and established as legislation by Diet members, and fully entered into effectstarting in January 2012.
Pursuant to the Act on Special Measures concerning the Handling of Radioactive
Pollution, initiatives for special decontamination areas in which the national
government would carry out decontamination as well as intensive contamination survey
areas wherein municipalities would implement decontamination were identified. As
such, decontamination will be implemented in the following order, with the long-termtarget of bringing the additional exposure dose to no more than 1 millisievert per year
(mSv/y).
1) Investigate and measure the status of the pollution and determine adecontamination zone in which decontamination and other measures are
implemented (related to Articles 34 and 36 of the Act)
2) Then implement decontamination and other measures based on thedecontamination plan (related to Article 40 of the Act)
3) Collect, transfer, and store the removed soil generated, in association withdecontamination and other measures (related to Article 41 of the Act)
The Ministry of the Environment has formulated Decontamination Guidelines to explainthese processes in a concrete and straightforward manner. These guidelines are divided
into four parts, with the Guidelines for Methods for Investigating and Measuring the
Status of Environmental Pollution in Intensive Contamination Survey Areas
corresponding to process 1), the Guidelines Pertaining to Decontamination and Other
Measures corresponding to process 2), and the Guidelines Pertaining to the Collection
and Transfer of Removed Soil, and Guidelines Pertaining to the Storage of Removed
Soil, both corresponding to process 3). There are some parts that are describedcollectively pertaining to the items that are related to each part, such as formeasurements. Note that although these guidelines primarily cover decontamination inmunicipalities, they also cover decontamination by the national government. *The first edition of these guidelines, which was formulated in December 2011, havebeen revised by incorporating knowledge and new technologies acquired since then inorder to promote more effective decontamination. These guidelines were revised based
upon responses to improper decontamination and by inquiring into the opinions ofspecialists, local governments, and others. In addition, they now also contain data thatwill be helpful in promoting the understanding among residents concerning theimplementation of decontamination and related procedures.
At present, the methods given in these guidelines are deemed to be appropriate for
implementing decontamination and related procedures, but the guidelines will berevised as needed in light of new knowledge accumulated along the way. In addition, aDecontamination Q&A has been formulated and released to serve as a supplementary
explanation for the Decontamination Guidelines and other materials in order topromptly accommodate the implementation of decontamination in accordance with theactual circumstances of areas, and these will be added to and otherwise revised asneeded.
* Excluding areas with especially high radiation doses.

Decontamination Guidelines
Table of Contents
Definitions of Terms
Units
Part 1
Guidelines for Methods for Investigating and Measuring the Status of Environmental Pollution
in Intensive Contamination Survey Areas

1.

Basic Concept .................................................................................................. 1-3

2.

Indicators of the Status of Contamination by Radioactive Materials .............. 1-6(1) Indicators of the Status of Contamination in Living Spaces (Air Dose Rate).................................................................................................................... 1-6(2) Indicators of the Status of Contamination in Objects Subject toDecontamination (Surface Contamination Density, Surface Dose Rate, etc.).................................................................................................................... 1-7

3.

Methods for Investigating and Measuring to Determine the Areas to be
Included in a Decontamination Plan ............................................................... 1-9(1) Basic Concept .............................................................................................. 1-9(2) Methods for Investigating and Measuring by Unit of Area ......................... 1-9(3) Methods for Investigating and Measuring of the Living Environment ofChildren, such as Schools and Parks ........................................................ 1-11

4.

Methods for Taking Detailed Measurements in Decontamination Zones ..... 1-13

5.

Assessments of the Decontamination Results ............................................... 1-14
(1) Assessments of the Air Dose Rate in Living Spaces ................................. 1-14
(2) Assessments of the Surface Contamination Density on the Objects Subject toDecontamination ....................................................................................... 1-14

6.

Measuring Apparatuses and Methods of Use ................................................ 1-15
(1) Types of Measuring Apparatuses ............................................................... 1-15
(2) Maintenance of the Measuring Apparatuses .............................................. 1-16
(3) Methods of Use of Measuring Apparatuses ............................................... 1-19

Endnotes.................................................................................................................. 1-33
References ............................................................................................................... 1-38

Part 2
Guidelines Pertaining to Decontamination and Other Measures

I.

Basic Concept....................................................................................................... 2-5
1.

The Role of these Guidelines .......................................................................... 2-5

2.

Important Points in Implementing Decontamination and Other Measures ..... 2-7

II.

Decontamination and Other Measures for Buildings and Other Structures ....... 2-101.

Preparation..................................................................................................... 2-11
(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ......................................................................................................... 2-11(2) Equipment and Materials ........................................................................... 2-122.

Prior Measurements ....................................................................................... 2-13
(1) Determination of Measurement Points ...................................................... 2-13
(2) Measurement Methods ............................................................................... 2-16

3.

Decontamination Methods ............................................................................ 2-17
(1) Decontamination of Roofs and Other Areas .............................................. 2-19
(2) Decontamination of Rainwater Guttering .................................................. 2-23
(3) Decontamination of Exterior Walls ............................................................ 2-27
(4) Decontamination of Fences, Outside Walls, Benches, Playground Equipment,
etc.............................................................................................................. 2-29
(5) Decontamination of Gardens and Other Areas .......................................... 2-32
(6) Decontamination of Street Drains, etc. ...................................................... 2-38

4.

Post-Work Measures ...................................................................................... 2-43
(1) Handling the Removed Soil, etc. ............................................................... 2-43
(2) Wastewater Treatment ................................................................................ 2-44
(3) Cleaning of Equipment and Materials ....................................................... 2-50

5.

Post-Work Measures ...................................................................................... 2-52

III.
1.

Decontamination and Other Measures for Roads .............................................. 2-53
Preparation..................................................................................................... 2-54
(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ......................................................................................................... 2-54
(2) Equipment and Materials ........................................................................... 2-54

2.

Prior Measurements ....................................................................................... 2-55
(1) Determination of Measurement Points ...................................................... 2-55
(2) Measurement Methods ............................................................................... 2-57

3.

Decontamination Methods ............................................................................ 2-59
(1) Decontamination of Paved Surfaces .......................................................... 2-61
(2) Decontamination of Unpaved Roads ......................................................... 2-65
(3) Decontamination of Roadsides and Street Drains ...................................... 2-70

4.

Post-Work Measures ...................................................................................... 2-73
(1) Handling the Removed Soil, etc. ............................................................... 2-73
(2) Wastewater Treatment ................................................................................ 2-73
(3) Cleaning of Equipment and Materials ....................................................... 2-74

5. Subsequent Measurements and Records ............................................................. 2-74
IV.

Decontamination and Other Measures for Soil .................................................. 2-751.

Preparation..................................................................................................... 2-76
(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ......................................................................................................... 2-76
(2) Equipment and Materials ........................................................................... 2-77

2.

Prior Measurements ....................................................................................... 2-78
(1) Determination of Measurement Points ...................................................... 2-78
(2) Measurement Methods ............................................................................... 2-82

3.

Decontamination Methods ............................................................................ 2-85
(1) Decontamination of Soil in Schoolyards, Kindergarten Yards, and Parks . 2-86
(2) Decontamination of Farmland ................................................................... 2-93

4.

Post-Work Measures ...................................................................................... 2-99

(1) Handling the Removed Soil, etc. ............................................................... 2-99
(2) Cleaning of Equipment and Materials ....................................................... 2-99
5.
V.

Subsequent Measurements and Records ..................................................... 2-100
Decontamination and Other Measures for Vegetation ..................................... 2-1011.

Preparation................................................................................................... 2-102(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ....................................................................................................... 2-102(2) Equipment and Materials ......................................................................... 2-102

2.

Prior Measurements ..................................................................................... 2-103(1) Determination of Measurement Points .................................................... 2-103(2) Measurement Methods ............................................................................. 2-105

3.

Decontamination Methods .......................................................................... 2-106(1) Decontamination of Lawns ........................................................................ 2-106(2) Decontamination of Trees in Living Spaces, such as Roadside Trees and thelike .......................................................................................................... 2-110(3) Decontamination of Forests ..................................................................... 2-112

4.

Post-Work Measures .................................................................................... 2-115(1) Handling the Removed Soil, etc. ............................................................. 2-115(2) Cleaning of Equipment and Materials ..................................................... 2-115

5.

Subsequent Measurements and Records ..................................................... 2-116

VI.

Others ............................................................................................................... 2-117(1) Decontamination and Other Measures for Sediment in Riverbeds .......... 2-117

Endnotes................................................................................................................ 2-119
Reference Materials .............................................................................................. 2-122

Part 3
Guidelines Pertaining to the Collection and Transfer of Removed Soil1.

Basic Concept .................................................................................................. 3-3

2.

Requirements for Collection and Transfer of the Removed Soil .................... 3-6(1) Requirements for Preventing Dispersion, Outflow, and Leakage ................ 3-6(2) Requirements for Radiological Protection ................................................... 3-8(3) Transfer Route Requirements ...................................................................... 3-9(4) Other Requirements ................................................................................... 3-10

3.

Concrete Actions ........................................................................................... 3-11

Endnotes.................................................................................................................. 3-14
Part 4
Guidelines Pertaining to the Storage of Removed Soil1.

Basic Concept .................................................................................................. 4-3(1) Outline.......................................................................................................... 4-3(2) Facility Design ............................................................................................. 4-4(3) Safety Management...................................................................................... 4-4

2.

Safety Measures and Requirements Necessary for Storage ............................ 4-7(1) Facility Requirements .................................................................................. 4-9(2) Management Requirements........................................................................ 4-17

3.

Concrete Examples of Storage Methods in Light of the Facility/Management
Requirements ................................................................................................. 4-21
On-site storage - 1): Above ground .................................................................... 4-22
On-site storage - 2): Underground ..................................................................... 4-23
On-site storage - 3): Above ground .................................................................... 4-25
On-site storage - 4): Underground ..................................................................... 4-26
Temporary storage site - 1): Above ground........................................................ 4-28
Temporary storage site - 2): Above ground........................................................ 4-31
Temporary storage site - 3): Underground ......................................................... 4-34
Temporary storage site - 4): Storage on sloped ground ..................................... 4-37

Endnotes.................................................................................................................. 4-40

Definitions of Terms
Term

Explanation
The Act on Special Measures Concerning the Handling of
The Act on Special
Environmental Pollution by Radioactive Materials Discharged by the
Measures concerning
NPS Accident Associated with the Tohoku District-Off the Pacificthe Handling of
Ocean Earthquake that Occurred off the Pacific Coast of the Tohoku
Radioactive Pollution
Region on March 11, 2011 (Act No. 110 of 2011)
Measures taken for soil, vegetation, structures, etc. contaminated with
Measures forradioactive materials discharged by the accident including the removal
decontamination of the of the contaminated soil, fallen leaves and twigs, sludge accumulatedsoil, etc.
in ditches, etc., preventive measures to keep the pollution fromspreading, and other measures (Article 2, Paragraph 3 of the Act)The soil generated from measures for decontamination of the soil, etc.,
Removed soil
implemented in a specific area for the decontamination zone (Article 2,
Paragraph 4 of the Act)The removed soil and waste generated from measures for
The removed soil, etc.
decontamination of the soil, etc.
Measures for decontamination of the soil, etc., as well as the
Decontamination andcollection, transfer, storage and disposal of the removed soil (Article
other measures
25, Paragraph 1 of the Act)An area found to have been significantly contaminated withradioactive materials discharged by the accident and where, taking
Specialother circumstances into account, the national government will
decontamination area implement decontamination and other measures. Such areas aredesignated by the Minister of the Environment. (Article 25, Paragraph
1 of the Act)
A plan for the implementation of decontamination and other measures
Decontamination plan applicable to special decontamination areas. Such plans are formulated
for a specific areaby the Minister of the Environment. (Article 28, Paragraph 1 of theAct)
An area in which intensive investigation and measurement of the status
Intensiveof the environmental pollution from radioactive materials discharged
contamination survey
by the accident shall be required. Such areas are designated by thearea
Minister of the Environment. (Article 32, Paragraph 1 of the Act)
A plan formulated for the implementation of decontamination andother measures applicable to a zone that is located in an intensive
contamination survey area and whose status of environmental pollution
from radioactive materials discharged by the accident is found not tomeet the requirements set forth in the relevant Ordinance of theDecontamination plan
Ministry of the Environment judging from the results of theinvestigation set forth pursuant to the Act, as well as othermeasurements. Such plans are formulated by the relevant prefectural
governors or mayors of municipalities. (Article 36, Paragraph 1 of theAct)
A zone subject to a decontamination plan. (Article 35, Paragraph 1 of
Decontamination zone
the Act)
The executor of decontamination and other measures. The national
government (Ministry of the Environment) in special decontamination
Decontaminatorareas, and the national, prefectural, or municipal government, etc. indecontamination zones. (Article 30, Paragraph 1 and Article 38,
Paragraph 1 of the Act)

UnitsCategory
Intensity ofradioactivity

UnitBq(becquerel)

Bq/cm2
Bq/kg
The amount of Gyenergy imparted (gray)by radiation

The effects from Sv
the radiation(sievert)
absorbed bypeopleIndicator of thecontamination ofan object

Sv/h
Sv/y
cpm

Explanation
Unit indicating the ability of a radioactive material to giveoff radiation
Indicates the number of atomic nuclei that decay (break down) *in one second (Bq=number of nuclei decay/second).
For example, for radioactive potassium, which has 370
becquerels of radiation, 370 atomic nuclei decay every secondand give off radiation, thereby changing into calcium or argon.
* Decay (break down): The phenomena whereby atomic nuclei
give off radiation and transform into
different atomic nuclei or stable atomic
nuclei.
The radioactive density of radioactive materials adhering to thesurfaces of objects.
The radioactive concentration of radioactive materials contained
within the soil, etc.
Unit indicating the amount of radioactive energy absorbed
within materials and human tissue
When radiation comes in contact with materials and the humanbody the energy that it contains is imparted to these materials.
One gray indicates when one kilogram of a material has received
one Joule* of energy from radiation (Gy=J/kg).
* Joule (J): Unit indicating the magnitude of energy.
Unit indicating the degree to which the human body isaffected by radiation
This is used as an indicator for safely managing radiation. The
extent of the impact that radiation has varies depending on
differences in the type of radiation and its energy, as well as thetype of human tissue and organ. Therefore, the differences in thetype of radiation and its energy, as well as the degree to whichradiation affects exposed tissue and organs, are corrected andcalculated as a common scale (indicator).
Radiation dose received per one hour.
Radiation dose received per one year.
Unit indicating the count (count rate) for the radiation
measured per one minute
Indicates the count for the radiation measured over one minutewith a radiation measuring equipment. The acronym cpm stands
for count per minute.

Part 1

Guidelines on the Methods for
Investigation and Measurement of
the Status of Environmental
Pollution in Intensive
Contamination Survey Areas
2nd Ed.,2013

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

1

1

Part 1
Guidelines for Methods for
Investigating and Measuring
the Status of Environmental
Pollution in Intensive
Contamination Survey Areas

1.

Basic Concept

2.

Indicators of the Status of Contamination by Radioactive
Materials

3.

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

4.

Methods for Taking Detailed Measurements in
Decontamination Zones

5.

Assessments of the Decontamination Results

6.

Measuring Apparatuses and Methods of Use

1-1

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Guidelines for Methods for Investigating and Measuring the Status ofEnvironmental Pollution in Intensive Contamination Survey Areas
Table of Contents
1.

Basic Concept .................................................................................................. 1-3

2.

Indicators of the Status of Contamination by Radioactive Materials .............. 1-6(1) Indicators of the Status of Contamination in Living Spaces (Air Dose Rate).................................................................................................................... 1-6(2) Indicators of the Status of Contamination in Objects Subject toDecontamination (Surface Contamination Density, Surface Dose Rate, etc.).................................................................................................................... 1-7

3.

Methods for Investigating and Measuring to Determine the Areas to be
Included in a Decontamination Plan ............................................................... 1-9(1) Basic Concept .............................................................................................. 1-9(2) Methods for Investigating and Measuring by Unit of Area ......................... 1-9(3) Methods for Investigating and Measuring of the Living Environment ofChildren, such as Schools and Parks ........................................................ 1-11

4.

Methods for Taking Detailed Measurements in Decontamination Zones ..... 1-13

5.

Assessments of the Decontamination Results ............................................... 1-14
(1) Assessments of the Air Dose Rate in Living Spaces ................................. 1-14
(2) Assessments of the Surface Contamination Density on the Objects Subject toDecontamination ....................................................................................... 1-14

6.

Measuring Apparatuses and Methods of Use ................................................ 1-15
(1) Types of Measuring Apparatuses ............................................................... 1-15
(2) Maintenance of the Measuring Apparatuses .............................................. 1-16
(3) Methods of Use of Measuring Apparatuses ............................................... 1-19

Endnotes.................................................................................................................. 1-33
References ............................................................................................................... 1-38

1-2

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

1.

Basic Concept

In proceeding with measures for decontamination of the soil, etc. which wascontaminated in areas where the additional exposure dose rate is 1 to 20 mSv/year inaccordance with 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 March 11, 2011 (hereinafter the “Act on Special Measures concerning
the Handling of Radioactive Pollution”), the necessary investigations and measurements
will be implemented in order to carry out the matters listed in the implementation items
in accordance with the following order.
Figure 1-1. The Implementation Items and Necessary Investigations andMeasurements for Carrying Out Decontamination<Implementation Items><Necessary Investigations andMeasurements>(1) Designate intensive contamination survey
area

Investigations and measurements to determine whether or
not a municipality meets the designation requirements(2) Determine decontamination zones where
decontamination and other measures will
be carried out

Investigations and measurements on the environmental
contamination status within the intensive contamination
survey areas(3) Implement detailed measurements in thedecontamination zones

Detailed measurements designed to determine if it is necessary to
conduct decontamination in individual facilities, as well as todecide on the methods for decontamination(4) Implement decontamination and othermeasures based upon the decontamination
plans

Perform measurements before and after thedecontamination measures(5) Collect, transfer, and store the removed
soil generated, in association withdecontamination and other measures

Monitor the air dose rate and the radioactivity
concentrations when the removed soil is being stored(6) Cancel the intensive contamination survey
area designation

Investigations and measurements to determine whether or
not a municipality meets the designation requirements*

In addition to the above, continuous investigations andmeasurements must also be carried out where appropriate for thesake of monitoring the changes in the dose rate

The Minister of the Environment shall designate any area where the radiation dose is0.23 Sv/hour or higher as an “intensive contamination survey area.” The designatedmunicipalities can subsequently conduct the investigation and measurement of the statusof environmental pollution due to radioactive materials discharged by the accident in theintensive contamination survey area in accordance with the methods defined under theOrdinance of the Ministry of the Environment(Note). If the results of such investigation

1-3

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areasand measurement, etc. show that the area has a radiation dose of 0.23 Sv/hour or
higher, such area shall be designated as a decontamination zone subject to adecontamination plan.
In addition to the above investigations and measurements, these guidelines introduce
measurement methods that are necessary for each item of the detailed measurements
within the decontamination zones, decontamination and other measures, and the storageof removed soil. They also introduce recommended measurement methods for
performing accurate measurements. This is designed for correctly grasping the status of
the decontamination and also for accurately assessing the effect of the decontamination.
So strive to conduct accurate measurements, particularly in cases where the radiationdose targeted for measurement is low. If an investigation and measurements are
conducted to determine whether a certain area falls under the requirements fordesignation as an intensive contamination survey area, basically employ the same
methods as described in these guidelines. In intensive contamination survey areas, theinvestigation and measurements are expected to be conducted not only to determine theareas to be decontaminated, but also to continuously conduct investigations andmeasurements to monitor the changes in the dose rate. In the latter case, too, conduct theinvestigation and measurements according to these guidelines.
As for measurements to be conducted before and after implementing decontaminationand other measures to confirm the effects of such decontamination and other measures,see “Part 2: Guidelines Pertaining to Decontamination and Other Measures.”
Additionally, for measurements to be conducted to monitor the radiation dose whenstoring the removed soil, see “Part 4: Guidelines Pertaining to the Storage of Removed
Soil,” and for measurements on the radiation dose from the waste generated inassociation with the decontamination and other measures, see the “Waste Guidelines”(March 2013, Vol. 2).
(Note) Ordinance for Enforcement of the Act on Special Measures concerning theHandling of Radioactive Pollution (Portion relevant to the Methods for Investigatingand Measuring the Status of Environmental Pollution in Intensive Contamination
Survey Areas)
Article 43: The investigation and measurements specified in Article 34, Paragraph 1 of
the Act shall be conducted according to the following requirements:
1. The status of environmental pollution due to radioactive materials discharged
by the accident shall be represented in terms of the radiation dose.
2. The radiation dose shall be measured using radiation measuring equipment that
can accurately detect the measured value.
3. The radiation dose shall be measured at a point 50 to 100 cm above the ground.
4. The radiation measuring equipment shall be regularly calibrated at least once a
year.

1-4

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-2. Descriptive Sections related to Measurements in the Decontamination
Guidelines
2. Indicators of the
Status ofContamination byRadioactive
Materials

1. Basic Concept

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

Air
dose
rate

4. Methods for Taking Detailed Measurements
in Decontamination Zones

Air
dose
rate

Buildings andRoads Soilotherstructures

5. Assessments oftheDecontamination
Results

6. Measuring
Apparatuses andMethods of Use*2*1

Vegetation

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

Determine the decontamination methos

Part 2:
Guidelines
Pertaining to
Decontaminati
on and Other
Measures

Air
dose
rate

Measure to confirm the decontamination
results (before decontamination)

Surfacedose rate
Surfacecontamination
density

Implement the decontamination work

Air
dose
rate

Measure to confirm the decontamination
results (after decontamination)

Surfacedose rate
Surfacecontamination
density

Assessments of the decontamination results

Part 3:
Guidelines
Pertaining to theCollection andTransfer of 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” are indicated with a
“.”

1-5

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

2.

Indicators of the Status of Contamination by Radioactive Materials

Figure 1-3. Indicators of the Status of Contamination by Radioactive Materials
Indicators of the Status of Contamination byRadioactive Materials<Status of contamination in living
spaces>Indicates the degree of external
exposure suffered by people livingin said spaces.

<Status of contamination of objects subject to decontamination>
Indicates the degree to which the target objects have been contaminatedwith radioactive materials.
In order to reduce the air dose rate in living spaces it is important to
reduce the amount of radioactive materials underlying this.

Air dose rate

Surface contamination density

Measured via a scintillation
survey meter*1

Measured via a GM survey
meter*2

Since these are not prone to being
affected by the background, they
allow the measurer to get a relatively
accurate reading of the surface
contamination status of the target
object.

Cases where a GM survey meter is lacking, etc.

Surface dose rate

Vary the distance for the air dose rate

Measured via a scintillation
survey meter (use acollimator*3)

Measured via a scintillation
survey meter (measure this byvarying the distance from themeasurement point)

Use a collimator to lessen theimpact of the backgroundgamma rays in order tomeasure the surface
contamination status of thetarget object.

In cases where the air dose rate rises
as the measurer approaches theobject subject to decontamination,
the determination can be made thatthe object is contaminated according
to the degree to which this rises.

*1: NaI scintillation survey meter, CsI scintillation survey meter, etc.
*2: Geiger-Müller counter tube survey meter*3: A collimator refers to an instrument that prevents gamma rays from radiation sources located outside of the object measured
from entering into the probe (detecting element) of the measuring apparatus. They are made of materials like lead that shield
gamma rays (shielding material) (see “6. Measuring Apparatus and Methods of Use” regarding collimators).

(1)

Indicators of the Status of Contamination in Living Spaces (Air Dose Rate)

Generally, indicators of the status of contamination by radioactive materials include “airdose rate,”*1 “surface contamination density,”*2 and “concentrations of radioactive
material.” The first one represents the amount of radiation per unit time in a space to bemeasured, and it indicates the degree of external exposure. Accordingly, it can be used
to indicate the status of contamination from a health protection point of view. In
addition, the air dose rate can be directly measured in a relatively short period of timeand so therefore it is a suitable method to promptly check the status of contamination of

1-6

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areasa wide area. Therefore, these guidelines use the air dose rate to indicate the status ofcontamination in an intensive contamination survey area.
These guidelines define the measurement points for determining the air dose rate inliving spaces as “No. 1 measurement points.” With No. 1 measurement points the air
dose rate is to be measured at a point 1 m above the ground via an NaI scintillation
survey meter* or other apparatus, in principle.
(2)

Indicators of the Status of Contamination in Objects Subject toDecontamination (Surface Contamination Density, Surface Dose Rate, etc.)

In order to reduce the air dose rate in living environments it is important to takemeasures such as ascertaining the contamination status of objects subject todecontamination and reducing the amount of radioactive materials. For this reason, thestatus of objects subject to decontamination is estimated by using their surface
contamination density or surface dose rate as indicators. When doing this it is crucial to
exclude the effects of radiation sources other than the object being measured(background*3) to the extent possible as shown in “5. Assessments of theDecontamination Results.”
These indicators are used for determining the decontamination methods and assessing
the extent to which the radioactive materials have been reduced as a result of thedecontamination work.
These guidelines define the measurement points for confirming the extent ofcontamination of objects subject to decontamination as “No. 2 measurement points.”
When measuring No. 2 measurement points it is recommended to use a Geiger-Müller
counter tube survey meter (hereinafter “GM survey meter”*) to measure the surface
contamination density of the objects subject to decontamination.
When a GM survey meter cannot be used, then the surface dose rate is to be measured
via an NaI scintillation survey meter* or other apparatus on the condition that the
gamma rays*4 from the outside be reduced by shielding it using lead or a similarmaterial (collimator*). Furthermore, the air dose rate of the target object is to bemeasured at positions at the object’s surface and at heights of 50 cm and 1 m. The target
object will be deemed to be contaminated if the measured values at its surface (itssurface dose rate) is significantly high.
* See “6. Measuring Apparatus and Methods of Use” regarding the various measuringapparatus and collimators.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Table 1-1. Summary of Indicators of the Status of Contamination by Radioactive
Materials
Assessment perspectives
Category
Measurement objective

•
•

•

•

Indicator(measurement position)

Examples of measuringapparatus••

Methods for using themeasurement results••

Status of contamination in living
Status of contamination of objects
spacessubject to decontamination
No. 1 measurement points
No. 2 measurements points
Determine the decisions of• Determine the scope for thedecontamination zones
decontamination in individual
facilities and determine theDetermine if it is necessary toamount of radioactive materials
conduct decontamination within(extent of the contamination) in
individual facilities in the
conjunction with the detailed
decontamination zones throughmeasurements carried out
detailed measurements in the zones
within the decontamination(determine by using mean dose rate)
zones
Determine the comprehensive•
Confirm the degree to which theresults of the decontamination
contamination of the objects
within the individual facilities fromsubject to decontamination has
the decontamination and otherabated due to themeasures (however, attention must
decontamination and otherbe paid to the fact that this is*3
measuresaffected by background radiation )Monitor the radiation dose when theremoved soil is stored
Surface dose rate (1cm)
Surface
Air dose ratecontaminati
Vary the(1 m*1)on density
Use adistance(1 cm)
collimatorandmeasure*2- GM survey • NaI scintillation
NaI scintillation survey meter
meter
survey meterCsI scintillation survey meter• CsI scintillation
survey meter
Determine the decontamination• Determine the decontamination
zones
methods
Assess the improvements in the• Assess the extent to which thecontamination status in living
radioactive materials havespaces through the decontamination
abated through theworkdecontamination work

*1: For the contamination status in living spaces, in principle, measurements should be taken at a heightof 1 m from the ground (it would also be fine to measure at a height of 50 cm at elementary andlower level schools, as well as special-needs schools, with consideration for the living 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 atheights of 50 cm and 1 m, and then the measured values are to be compared.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

3.
(1)

Methods for Investigating and Measuring to Determine the Areas to be
Included in a Decontamination Plan
Basic Concept

As a rule, the decontamination zone (areas to be included in a decontamination plan) aredetermined by the units of areas such as “aza” and municipal blocks, and determination
is made concerning whether the dose rate for each area falls under the planningrequirement of 0.23 Sv/hour or higher.
Concerning the living environment for children, such as schools and parks, it is possible
to determine a decontamination zone based on a facility rather than on an area such as
municipal block.
(2)

Methods for Investigating and Measuring by Unit of Area

Define the areas to municipal blocks as finely as possible in consideration of thecircumstances of the municipality after selecting the mesh for actual investigation andmeasurement. If the results of existing surveys, such as aerial monitoring using aircraft,indicate that the blocks fall under (do not fall under) the planning requirements, it is notnecessary to conduct any additional investigation and measurement.
This subsection provides examples of how to investigate and measure each block and to
determine whether it falls under the planning requirements. Different blocks havedifferent conditions, so it may be necessary to divide a block into the given meshes to
conduct the investigation and measurements or it may be possible to determine in amanner appropriate for the circumstances of each area in reference to the examples
described below.
[Example 1: Determination based on the measurement results at various points]a)Define the concrete measurement points and the number of points in eachmunicipal block according to the land use type and surrounding conditions (seeFigure 1-4). Make the determination according to the following points:• Compare the measurement points to identify any tendency for the wholearea.
• Avoid measurement points such as those that are under trees or in street
drains, where the dose rate may be locally high, since the purpose of themeasurement is to determine the average dose rate for the area as a whole.
• It is recommended to increase the number of measurement points in living
spaces that are used by many residents such as areas where there are manybuildings.
• It is not always necessary to conduct an investigation and measurements insuch areas as forest areas since this does not automatically reduce theradiation dose affecting people.
• If necessary, conduct the investigation and measurements efficiently, forexample, by using such means as a monitoring car.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areasb)c)

After the measurements have been taken at all the points, average the measured
values to find the mean dose rate for the whole area.
Determine whether the area falls under the planning requirements according to
the resulting mean dose rate.

Figure 1-4. Example of the determination of whether the area meets the planningrequirements based on the measurement results at various points
Certain area in a municipality

★
★
★
★

★
★
School

★

★

★
★

Park
★
★

★

★

★

★

★

★

★
★

★

★

★

★

★
★
Plant/building★: Measurement point[Example 2: Determination based on the measurement results in schools andparks]a)Define the concrete measurement points and the number of points in eachmunicipal area (see Figure 1-5). Make the determination in consideration of
the following points:• Take measurements mainly in the living environments used by children,
such as schools and parks, in the area.
• Avoid measurement points such as those that are under trees or in street
drains, where the dose rate may be locally high, since the purpose of themeasurement is to determine the average dose rate for the whole area.
• Set up about five measurement points in each school or park.
b) After the measurements have been taken at all of the points, average themeasured values to find the mean dose rate for the whole area.
c) Determine whether the area falls under the planning requirements according to
the resulting mean dose.

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Figure1-5. Example of the determination of whether the municipal area meets theplanning requirements based on the measurement results for schools and parks
Certain area in a municipality

Park
★
★

★

★

★

★

★

★

★

★

SchoolPlant/building★: Measurement point(3)

Methods for Investigating and Measuring of the Living Environment ofChildren, such as Schools and Parks

Concerning the living environment for children, such as schools and parks, it is possible
to determine a planning area based on a facility rather than on an area such as municipal
block.
This subsection shows how to investigate and measure each of the schools and parks aswell as to determine whether they fall under the planning requirements.
a)

b)
c)

Define the concrete measurements points and the number of points in thefacilities (see Figure 1-6). Determine these according to the following points:• Avoid measurement points such as those that are under trees or in street
drains, where the dose rate may be locally high, since the purpose of themeasurement is to determine the average dose rate for each facility.
• Set up about five measurement points in each facility.
After the measurements have been taken at all the points, average the measured
values to determine the mean dose rate for the facility.
Determine whether the facility falls under the planning requirements according
to the resulting mean dose rate.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-6. Example of the determination of whether the area meets the planningrequirements based on the measurement results only from facilities used bychildren, such as schools and parks
Certain area in a municipality
Facility-by-facility determination

Park
★
★

★

★

★

★

★

★

★

★

SchoolFacility-by-facility determination

Plant/building★: Measurement point

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

4.

Methods for Taking Detailed Measurements in Decontamination Zones

When implementing decontamination, detailed measurements must be carried out inorder to confirm the targets and contents of the decontamination work for the individual
facilities within the decontamination zone.
The measurement points for the detailed measurements shall be based on the locations
exemplified as No. 1 measurement points that are stipulated in “Part 2: Guidelines
Pertaining to Decontamination and Other Measures.” See “Part 2: Guidelines Pertaining
to Decontamination and Other Measures” for specifics.
Moreover, for the detailed measurements it is necessary to list information like themeasurement location, the measurement apparatus, the measurement time and date, theweather, a summary of the measurement results (measurement point number, themeasured object, the measurement conditions (measurement height, etc.), themeasurement results), a map of the measurement location (on which the measurement
point number and measured object have been listed), and so forth.
It is also possible to combine the detailed measurements with the measurements prior to
the start of the decontamination work (advance measurements). The
pre-decontamination measurements are essentially carried out immediately before thedecontamination work in order to accurately ascertain the decontamination results.
Therefore, when the results of the detailed measurements and the pre-decontamination
measurements are combined attention must be paid to ensure that there is not too muchof a gap left between when they are performed (make sure that the gap from the day
when the detailed measurements are taken until the targets and contents of thedecontamination work are confirmed (public notice of the work, etc.) are no longer thanroughly six months long).
In light of these results, the decontamination methods for the region in question are to
be determined based around the decontamination methods indicated in “Part 2:
Guidelines Pertaining to Decontamination and Other Measures.”See “Part 2: Guidelines Pertaining to Decontamination and Other Measures” regarding
the measurements before and after the decontamination is carried out.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

5.

Assessments of the Decontamination Results

The assessments of the decontamination results can largely be broken down into
assessments of the air dose rate of the living spaces in the decontamination zone as awhole and the individual targeted facilities, as well as assessments of the surface
concentration density of the objects subject to decontamination in the individual
instances of decontamination work.
(1)

Assessments of the Air Dose Rate in Living Spaces

After the decontamination has been carried out measurements of the air dose rates inliving spaces are to be performed. When doing so, the question of: “To what extent has
the exposure dose of the people living in said spaces been reduced throughdecontamination?” serves as the target for the results of the decontamination. As such,the “reduction rate” in the air dose rate can be used as an indicator to confirm the extent
to which the exposure dose has fallen from before and after the decontamination.*5(2)

Assessments of the Surface Contamination Density on the Objects Subject toDecontamination

It is important to assess the “decontamination results for each object subject todecontamination” both when confirming the extent to which the radioactive materials
have been removed through the individual cases of decontamination work, as well as
when comparing and verifying the individual decontamination methods by conducting
experiments. The “reduction rate” and “decontamination factor (DF)” can be used asindicators to confirm the extent to which the exposure dose has fallen from before andafter the decontamination.*5
When assessing the decontamination results, attention should be paid to the possibility
that the decontamination results will be assessed as being smaller than they actually are
if any of the background radiation*3 is contained in the measured values.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

6.

Measuring Apparatuses and Methods of Use

Here explanations will be provided of the necessary measurements throughout the
Decontamination Guidelines in their entirety, including not only measurements forformulating decontamination plans but also measurements for confirming the results ofradiation reductions through the decontamination work and more.
(1)

Types of Measuring Apparatusesi.

Measuring Apparatuses for Air Dose Rates and Surface Dose Rates

A calibrated scintillation survey meter (of the energy compensation type*6 as a rule) isused to measure the air dose rate and surface dose rate of gamma rays.*4 Any othermeasuring apparatus can be used if it can measure the air dose rate of gamma rays, but
be sure to use a measuring apparatus that has been calibrated.
Figure 1-7. Examples of Scintillation Survey Meters(NaI scintillation survey meters)ii.

Measuring Apparatuses for Surface Contamination Density(*Used for measurements to confirm the degree of contamination in objects
subject to decontamination (Part 2))

Use calibrated GM survey meters to primarily measure the beta rays*7 from the surfaceof the target object. With a GM survey meter 100% of the beta rays that enter the probe(detecting element) will be detected, whereas the detection rate for the gamma rays will
only be around several percent. What is more, since the beta rays can only enter via theentrance window at the tip of the probe *8 it is resistant to being affected by the radiationentering from outside of the measured object. This gives it the characteristic of being
effective for ascertaining the contamination status of the measured object.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-8. Examples of GM Survey Meters(2)

Maintenance of the Measuring Apparatuses

Measuring apparatuses may give incorrect readings for reasons like changes in thesensitivity of the detector caused by the measuring environment or any degradation ofcomponents in the electrical circuit. It is therefore essential that the precision of ameasuring apparatus be ensured by periodically conducting the calibration andadjustment of the measuring apparatus (confirmation of the readings).
i.

Scintillation survey meter

Confirm whether the required performance is being satisfied by conducting thecalibration in compliance with the calibration specified in the Japanese Industrial
Standards (JIS Z4511, JIS Z4333)*9 at least once a year.
If it is difficult to perform the calibration as described above, it is possible to substitutethis with the adjustment method shown in Figure 1-9 as a means of confirming that thelevel of performance required of the apparatus subject to calibration is being met. For
this adjustment method, prepare a separate calibrated energy compensation type
scintillation survey meter as a reference and simultaneously measure the radiation doseabout five times at the same point. Then confirm and record the ratio of the mean
measured values from the calibrated reference apparatus to the mean measured values
from the actual apparatus subject to calibration (average of the readings from thereference apparatus  average of the readings from the actual apparatus subject tocalibration), based upon which the actual measured values multiplied by this ratio shallbe taken as the correct value (note that if the ratio of the mean measured values to themean measured values from the calibrated reference apparatus differs by 20 percent*10
or greater than 1, it shall be deemed that the apparatus is not sufficiently reliable). When
doing this in a location where the dose is around the same level as in the region where
the apparatus will actually be used, you can confirm and record the difference in thereadings and find the correct value by adding or subtracting the mean value of thedifferences to or from the readings given by the actual apparatus. (note that if the meanvalue of difference from the mean measured values from the calibrated reference

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

apparatus exceeds 20 percent, it shall be deemed that the apparatus is not sufficiently
reliable.) If there is no other option but to measure the dose rate using a measuringapparatus that has not yet been calibrated, the measuring apparatus shall be calibrated
later, and the measurement results shall be evaluated after correcting the values, if
necessary. If the calibration results show that your apparatus is not reliable, do not
utilize the results of such a measurement apparatus as information for making any
decisions. Concerning measuring apparatuses with no energy compensation feature, it isrecommended that an adjustment be performed using a calibrated energy compensation
type scintillation survey meter for confirmation as an indicator to ensure that therequired performance targets can be satisfied even if it is still less than one year since it
was purchased.
In addition, perform daily inspections to check the remaining battery level, to detect any
breakage of cables or connectors, to check the operation of switches and measure thebackground dose (confirm that there are no significant variations in readings comparedto those in the past, by conducting measurement in the same area in which the resulting
background value does not vary significantly.) The purpose of this is to judge if there
are any abnormalities or breakages.

1-17Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-9. Method of Adjusting the Measuring Apparatus in the Field

Method for Adjusting via the Ratio in the Measured Values
1) Take about five measurements with the actual apparatus and a calibrated reference
apparatus simultaneously.
2) Calculate the ratio of the mean measured values from the calibrated reference
apparatus to the mean measured values from the actual apparatus (average of thereadings from the reference apparatus  average of the readings from the actual
apparatus).
3) If the measurement is taken with the actual apparatus, the actual measured value
multiplied by the ratio above shall be taken as the correct value.
(If the ratio of the mean measured values to the mean measured values from thecalibrated reference apparatus differs by 20 percent or greater than 1, it shall bedeemed that the apparatus is not sufficiently reliable)
Method for Adjusting via the Differences in the Measured Values
1) Take about five measurements with the actual apparatus and a calibrated reference
apparatus simultaneously (do this in a location where the dose is around the samelevel as in the region where the instrument will actually be used).
2) Calculate the mean value of differences between the measured values from thecalibrated reference apparatus and those of the actual apparatus.
3) Find the correct value by adding or subtracting the mean value of the differences toor from the measured values given by the actual apparatus.
(If the mean value of differences between the measured values from the calibrated
reference apparatus exceeds 20 percent, it shall be deemed that the instrument is not
sufficiently reliable).

ii.

GM survey meter

Confirm whether the required performance is being satisfied by having the
manufacturer perform maintenance*11 at least once a year. In addition, perform daily
inspections to check if there is any damage to the entrance window (cracks or holes) or
any breakage of cables or connectors, the remaining battery level, to check the operationof switches and measure the background dose (confirm that there are no significant
variations in readings compared to those in the past, by conducting measurement in thesame area in which the resulting background value does not vary significantly.) The

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

purpose of this is to judge if there are any abnormalities or breakages.
(3)

Methods of Use of Measuring Apparatusesi.

Scintillation survey meter (air dose rate measurements)

Take the measurements by taking into account the following precautions (see Figure1-10). For specific methods of use of measuring apparatuses, see the corresponding
instruction, etc. for each measuring apparatus.
a)

As the results of the investigations and measurements to determine thedecontamination zones are based on the average air dose rate of the areas
concerned, measurements in depressed areas and puddles, street drains, underrainwater guttering, water catchment wells, under or near trees, or in places
where raindrops falling from buildings land, as radioactive materials tend to
become concentrated in such places due to rainwater and drainage water.
Note: For the method of measurement to identify points that are responsible forrelatively high radiation dose, see the Guidelines Concerning Radiation
Measurement (issued by the Ministry of Education, Culture, Sports,
Science and Technology on October 21, 2011).

b)

Prevent the measuring apparatus from being contaminated by the subject to bemeasured by wrapping the main body and probe (detecting element) preferably
in a thin plastic sheet.

c)Take the measurements at a point 1 m above the ground, in principle. Note thatthe height can be 50 cm if measurements are conducted at an elementary
school, etc., while taking into account the living space for infants andschoolchildren in the lower grades.

d)

For measuring apparatuses that allow you to set a time constant,*12 perform themeasurements after a span of time that is more than three times longer than thetime constant has elapsed (see Figure 1-11).

e)

Hold the probe (detecting element) parallel to the ground surface while keeping
it as far away as possible from your body. When performing measurements inthe same location for the measurements from before and after thedecontamination, take the measurements with the probe and your body always
in the same position and facing the same direction.

f)Wait for the readings to become stable before reading the values (make a single
measurement at each point). The readings will change even after they havebecome stable, so take the mean value as the measured value.

* Since the measuring apparatus provide estimates of the times until a correct response can be obtained (timeconstants), the power to the measuring apparatus shall be turned on and the reading (measured value) shall be read off
only after waiting until the readings stabilize. If the readings on the measuring apparatus disappear, switch the range

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areasand 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 the measurements.*5 If
readings vary, the average value shall be read. Please refer to the Ministry of Education, Culture, Sports, Science andTechnology’s Guidelines Concerning Radiation Measurement (issued by the Ministry of Education, Culture, Sports,
Science and Technology on October 21, 2011) for more information about the handling of measuring apparatus.

g)

Write the measured value on the record sheet.

[Precautions]•
In cases where snow has accumulated at the measurement location there is thepossibility that the measured values will diminished as a result of being shieldedfrom the snow, so perform the measurements after the snow has melted. If youpress ahead with performing the measurements when there is accumulated snow,
clearly specify that there is accumulated snow and record the depth of the snow asneeded.
•Figure 1-10. Method of Use of a Measuring Apparatus (Scintillation Survey Meter)
 Notes on measurement
1) Determine the measurement points while avoiding any depressed areas and points inthe vicinity of a building, etc.
2) Take the measurements at a point 1 m above the ground, in principle (the height may
be 50 cm at elementary schools, etc.).
3) Hold the probe parallel to the ground surface while keeping it as far away as possible
from your body.
4) Perform the measurements after a span of time that is more than three times longer
than the time constant has elapsed (when you can set the time constant).
5) Wait for it to become stable before reading the measured value (mean value).
6) Write the measured value on the record sheet.

Note: Prevent the measuringapparatus from being
contaminated by the subject
to be measured by wrapping
the main body and probe(detecting element)
preferably in a thin plastic
sheet.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-11. Time ConstantReading (%)

 In order to accurately measure the radiation at the decontamination sites it is essential totake the measurements after the measured values have stabilized by allowing a span ofmore than three times as long as the time constant to elapse.

Time constant of 3 seconds
Time constant of 10 seconds
Time constant of 30 seconds

Measuring time (seconds)* The graph is an image※グラフはイメージii.

Scintillation survey meter (surface dose rate measurements)(*Used for measurements to confirm the degree of contamination in objects
subject to decontamination (Part 2))

Take the measurements by taking into account the following precautions. For specificmethods of use of measuring apparatuses, see the corresponding instructions, etc. foreach measuring apparatus.
a)

For the investigations and measurements to ascertain the degree ofcontamination of the objects subject to decontamination, it is necessary to
perform the measurements from before and after the decontamination in thesame point, which can be achieved by such means as marking the measurement
point.

b)

Prevent the measuring apparatus from being contaminated by the subject to bemeasured by wrapping the main body and probe (detecting element) preferably
in a thin plastic sheet.

c)Take the measurements at a point that is roughly 1 cm above the measured
object, in principle.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areasd)

Hold the probe (detecting element) parallel to the surface of the measured
object while keeping it as far away as possible from your body. Whenperforming measurements in the same location for the measurements frombefore and after the decontamination, take the measurements with the probe
and your body always in the same position and facing the same direction.

e)

For measuring apparatuses that allow you to set the time constant, perform themeasurements after a span of time that is more than three times longer than thetime constant has elapsed.

f)

Wait for the readings to become stable before reading the values (make a single
measurement at each point). The readings will change even after they havebecome stable, so take the mean value as the measured value.

g)

Write the measured value on the record sheet.

[Precautions]•

There is the possibility of assessing the results of the decontamination as being
lower than they actually were*13 as a result of background*3 radiation being
measured together with the readings. Therefore, one way to deal with cases where
the background radiation has a large impact on this is to use a collimator.
Figure 1-12. Example of a Collimator (Left) and an Example of Measurements
Using a Collimator

Provided by: Japan Atomic Energy Agency (JAEA)* Since collimators are used by being placed inside of probes (detecting
elements) they are oftentimes cylindrical in shape, and the thicker the shielding
material enveloping the probe the more that the gamma rays entering from theoutside can be reduced. With an NaI scintillation survey meter the tip of theprobe faces downwards when measurements are taken with the use of acollimator, so there are no particular problems with the measurements.
iii.

GM survey meter (Measurements of the surface contamination density)

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas(*Used for measurements to confirm the degree of contamination in objects
subject to decontamination (Part 2))
Take the measurements by taking into account the following precautions (seeFigure 1-13). For specific methods of use of measuring apparatuses, see thecorresponding instructions, etc. for each measuring apparatus.
a)

For the investigations and measurements to ascertain the degree ofcontamination of the objects subject to decontamination, it is necessary to
perform the measurements from before and after the decontamination in theexact same point, so mark the measurement point. GM survey meters are
susceptible to being affected by changes in the measurement point, so extra
care is required.

b)Prevent the measuring apparatus from being contaminated by the measured
object by wrapping the main body and probe (detecting element) preferably ina thin plastic sheet.

c)Take the measurements at a point that is roughly 1 cm above the measured
object, in principle.

d)Hold the surface of entrance window (window side) of probe (detecting
element) toward the surface of the measured object. When performing
measurements in the same location for the measurements from before and after
the decontamination or the like, take the measurements with the probe and yourbody always in the same position and facing the same direction.

e)

For measuring apparatuses that allow you to set the time constant, perform themeasurements after a span of time that is more than three times longer than thetime constant has elapsed (see Figure 1-11).

f)

Wait for the readings to become stable before reading the values (make a single
measurement at each point). The readings will change even after they havebecome stable, so take the mean value as the measured value.

g)

Write the measured value on the record sheet.

[Precautions]•
GM survey meters are characterized by the fact that they are comparatively
resistant to being affected by the background, but one way to carry out even moreaccurate measurements is to use a collimator.*14•
Depending on the circumstances, one way to assess the net beta ray dose emitted
from the measured object is to subtract the dose of gamma rays that enter theprobe (values measured by covering the entrance window with a plastic plate to
exclude the beta rays) from the net dose of radiation that enters the probe(detecting element) (values measured without the use of shielding).*14*15•
If the surface of the measured object is wet some of the beta rays will be shielded,

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

which could potentially produce measured values that are somewhat lower than
the actual values. Therefore, take measurement when the surface of measured
objects is dry to the extent possible.
Figure 1-13. Method of Use of Measuring Apparatus (GM Survey Meter)

 Notes on measurement
1) Determine the measurement points while avoiding any depressed areas and points inthe vicinity of a building, etc.
2) Take the measurements at a point that is roughly 1 cm above the ground, in principle.
3) Hold the window side of the probe (detecting element) toward the surface of themeasured object while keeping it as far away as possible from your body.
4) Perform the measurements after a span of time that is more than three times longer
than the time constant has elapsed (when you can set the time constant).
5) Wait for it to become stable before reading the measured value (mean value).
6) Write the measured value on the record sheet.

Note: Prevent the measuring apparatus frombeing contaminated by the subject to bemeasured by wrapping the main bodyand probe (detecting element) preferably
in a thin plastic sheet.

iv.

Precautions on Measurements in General Setting the measurement points•
Even when measured objects made of the same materials with the uniform
configuration extending in an open space are measured there is the potential forinequalities in the degree of their surface contamination depending on the location.
As such, for the measurements to confirm the decontamination results, it isnecessary to perform the measurements from before and after the decontamination

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas•in the same point, which can be achieved by means of marking the measurement
point in advance.
To measure the surface dose rate and surface contamination density of
playground equipment, trees, and other objects that lack flat, planar regions,perform the measurements by using a part where the decontamination results
can be confirmed as the measurement point.

 Shielding via collimators and plastic plates•
When using a collimator some of the gamma rays pass through the collimator,
while some gamma rays also enter into it through the gaps in the shielding
material. In light of these facts, you should take note that a collimator does notcompletely shield against the gamma rays coming from anything other than themeasured object.
•
When using a plastic plate to shield against beta rays, use spacers or the like toensure that the distance between the measured object and the entrance window is
the same to the extent possible.
•
Correct measurements cannot be taken if the collimator and the plastic plate arecontaminated, so cover them with plastic sheet when using them whereappropriate and wipe away any radioactive material that may be adhering to them.
 Causes for variance in the measured values•
The decay of radioactive materials occurs randomly, and so measured values forradiation doses are fraught with error.*16•
It is crucial to take into consideration the fact that houses and trees present in thevicinity around the measurement location, as well as the measurer and otherpeople around the measurement location, have an effect on the measured values inthat they serve as external radiation sources, shields, and scatterers.
•
It is difficult to strictly maintain a distance of 1 cm between the probe (detecting
element) and the measured object when measuring the surface dose rate and thesurface contamination density, and so variance will arise in the measured values
associated with the fluctuations in these distances. This tendency becomes
particularly pronounced when there is unevenness in the surface of the measured
object (one approach is to use spacers or the like to maintain a uniform distance).
•
Discrepancies may arise in the measured values obtained from different measuringapparatuses due to the differing features of the apparatuses. Discrepancies may
also arise in the measured values obtained when using collimators with different
materials and thicknesses due to their different shielding capabilities.
•
Even in cases where the amount of radioactive material found within a measured
object is the same, when the depth at which this radioactive material is founddiffers the radiation dose emitted from the surface will also differ, and thus themeasured values will not turn out the same.
•
GM survey meters primarily measure beta rays*7. Therefore, you must keep inmind the possibility that the beta rays given off by a radioactive material founddeeper in an object than the surface may be shielded by the material between it
and the surface.
•GM survey meters primarily measure beta rays. Therefore, when the surface of the

1-25

Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas•measured object is wet these beta rays will be partially shielded, which could
possibly produce measured values that are somewhat smaller than the actual
values.
Differences in the level of proficiency of the measurer are another source ofvariance. It is essential that the measurements be carried out by people who have afull understanding of the objective of the actual measurements being carried out,
the measurement methods, notes of caution, and so on. For this reason, it isimportant that initiatives to preserve measurement precision be instituted, such asby having the work manager ascertain and confirm the capabilities of those
involved in the measurements.
Table 1-2. Summary of Measuring Apparatuses and Methods of Use
Category
Purpose ofmeasurements
Object measured
Examples ofmeasuringapparatuses
Calibration

Daily check

Prevention ofcontamination

Measurement

No. 1 measurement point
No. 2 measurement point
Contamination status ofContamination status of objects subject toliving spaces
decontamination
Gamma rays
Gamma rays
Beta rays• NaI scintillation survey meter• GM survey meter• CsI scintillation survey meter• Measuring apparatuses shall be calibrated at least once a year in accordancewith JIS.
(Agent performing the calibration work)• Businesses registered in accordance with the Measurement Act*9• Measuring apparatus manufacturer• The remaining battery level, breakage of cables and connectors, and status ofhigh voltage application shall be checked, and inspections of switch
operability, etc. shall be carried out.
• Measurements shall be performed at the same places where the backgroundradiation does not vary substantially, and it shall be confirmed that there areno large variations by comparing with past values.
• If it is difficult to perform the calibrations more than once a year as describedin the above section, this can be substituted by a method (adjustment) tocompare the results with those obtained in the same location where
measurements were also taken by using a separate measuring apparatus thathas been fully calibrated and checked (this excludes GM survey meters).
• The body and detecting element of the measuring apparatus shall be
preferably covered with a thin plastic sheet, etc.
• The plastic sheet, etc. shall be replaced with new material when it gets dirty
or breaks.
• The air dose rate shall be [Using a collimator]
・Measurements shallmeasured at a height of 1 • The air dose rate shall
only be taken
m from the ground.
be measured at a heightroughly 1 cm away
• The air dose rates onof roughly 1 cm (afrom the surface.
roads and pedestrianheight where about one
overpasses near schools
finger will fit between
may be measured at a
the detector element
height of 50 cm from theand the measurement
ground for elementary
point) from the surface
schools and below, asof the measurement
well as special-needs
point while using aschools, withcollimator to shieldconsideration for theagainst external gamma
living space of infants
rays.
and schoolchildren in the [Measurements by

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

lower grades.

Records

varying the distance]• The air dose rate shallbe measured frompositions on the surface
and at heights of 50 cm
and 1 m away from it,and the measured
values shall becompared.
• Prior to measurement, it shall be confirmed whether the background value ofthe 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 with thedetecting 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, themeasurer shall wait until a period of time that is three times longer than thetime constant has elapsed before performing the measurements.
• If the readings on the measuring apparatus disappear, switch the range andtake 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 the measurements.
• 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).

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-14. Example of an Air Dose Rate Record Sheet
Air Dose Rate Recording Form
Measurement location

City:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination
Date measured
Time measured

Day:

(

)
:

Month:-

After Decontamination

Year:

Day:

:

(

)

Month:

:

-

Year:
:

Measurer
Weather
Air Dose Rate Measurement Results Entry Section
Before Decontamination

Measurement
heightAfter Decontamination

Measurement
heightNo. 1)-1 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-2 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-3 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-4 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-5 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-6 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-7 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-8 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-9 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-10 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

Notes

Schematic Diagram of Air Dose Rate Measurement Points* This is just a sample of a records form. These should be devised as appropriate depending on factors
like the objects measured and the measurement methods.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-15. Entry Sample of an Air Dose Rate Record Sheet
Air Dose Rate Record Sheet (Entry Sample)
Measurement location

City:

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

WeatherCloudyClear

Air Dose Rate Measurement Results Entry Section
Before Decontamination

Measurement
heightAfter Decontamination

Measurement
heightNo. 1)-1 measurement point

3.0 μSv/h

1m

50cm

0.51 μSv/h

1m

50cm

No. 1)-2 measurement point

0.55 μSv/h

1m

50cm

0.16 μSv/h

1m

50cm

No. 1)-3 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-4 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-5 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-6 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-7 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-8 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-9 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

No. 1)-10 measurement point

μSv/h

1m

50cm

μSv/h

1m

50cm

Notes

Schematic Diagram of Air Dose Rate Measurement Points(Example)

Garden1)-1×Parking lot

Building

Garden1)-2×*The arrows indicate the direction of the measurements.

* This is just a sample of a records form. These should be devised as appropriate depending on factors
like the objects measured and the measurement methods.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-16. Example of a Surface Contamination Density Record Sheet
Surface Contamination Density Record Sheet
Measurement location

City:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination
Date measured

Day:

Time measured():

Month:-

After Decontamination

Year:

Day:

:

(

)
:

Month:-

Year::

Measurer
Weather
Surface Contamination Density Measurement Results Entry Column
Before Decontamination

Collimator

After Decontamination

Collimator

No. 2)-1 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-2 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-3 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-4 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-5 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-6 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-7 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-8 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-9 measurement point

cpm

Yes

No

cpm

Yes

No

No. 2)-10 measurement point

cpm

Yes

No

cpm

Yes

No

Notes

Schematic Diagram of Surface Contamination Density Measurement Points* This is just a sample of a records form. These should be devised as appropriate depending on factors
like the objects measured and the measurement methods.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-17. Example of a Surface Dose Rate Record Sheet
Surface Dose Rate Record Sheet
Measurement location

City:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination
Date measured
Time measured

Day:

(

)
:

Month:-Year::

After Decontamination
Day:

(

)
:

Month:-

Year::

Measurer
Weather
Surface Dose Rate Measurement Results Entry Column
Before Decontamination

Measurement
heightAfter Decontamination

Measurement
heightNo. 2)-1 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-2 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-3 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-4 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-5 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-6 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-7 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-8 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-9 measurement point

μSv/h

1cm

μSv/h

1cm

No. 2)-10 measurement point

μSv/h

1cm

μSv/h

1cm

Notes

Schematic Diagram of Surface Dose Rate Measurement Points* Perform the measurements by using a collimator to reduce the impact of the background gamma rays.
* This is just a sample of a records form. These should be devised as appropriate depending on factors
like the objects measured and the measurement methods.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-18. Example of a Variable Distance Air Dose Rate Record Sheet
Air Dose Rate Record Sheet(For Measurements where the Distance from the Measured Object Is Varied)
Measurement location

City:

Town:

Measuring apparatus

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination
Date measured

Day:

Time measured()

Month:

:

-

Year:

After Decontamination
Day:

:

(

)

Month:

:

-

Year:
:

Measurer
Weather
Dose Rate Measurement Results Entry Column
Before Decontamination
Surface

1m

50cm

After Decontamination
Surface

1m

(1cm)

50cm

(1cm)

No. 2)-1 measurement point

μSv/h

μSv/h

No. 2)-2 measurement point

μSv/h

μSv/h

No. 2)-3 measurement point

μSv/h

μSv/h

No. 2)-4 measurement point

μSv/h

μSv/h

No. 2)-5 measurement point

μSv/h

μSv/h

No. 2)-6 measurement point

μSv/h

μSv/h

No. 2)-7 measurement point

μSv/h

μSv/h

No. 2)-8 measurement point

μSv/h

μSv/h

No. 2)-9 measurement point

μSv/h

μSv/h

No. 2)-10 measurement point

μSv/h

μSv/h

Notes
Schematic Diagram of Dose Rate Measurement Points* This is just a sample of a records form. These should be devised as appropriate depending on factors
like the objects measured and the measurement methods.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Endnotes
*1

:

*2

:

*3

:

*4

:

*5

:

The air dose rate is the radiation dose per unit time in the space in question, also known as the
air absorbed dose rate, and is generally expressed in units of μSv/h (microsieverts per hour) or
nGy/h (nano-Gray per hour).*17 Since the air dose rate indicates the level of external exposure,from a health preservation perspective it is suitable to measure the air dose rate in a way thatenables the ascertainment of the additional exposure dose. Moreover, since contamination is not
all the same, numerous measurements are required in order to confirm the status ofcontamination as a whole, and this ability to perform direct measurements in a short time frame
enables relatively simple handling even when there are numerous measurements to be made.
Based on the foregoing, as a general rule it is suitable to use the air dose rate when confirming
the decontamination effect. However, since the air dose rate normally measures gamma rays,
which easily penetrate materials, and since the radiation from radioactive materials present
around the measurement site and natural radiation from the earth are also readily detected(readily influenced by background radiation), the air dose rate is not suitable for confirmationof the contamination status of the surfaces or insides of objects to be decontaminated. Whennarrowing down the contamination sites that contain comparatively large amounts ofradioactive materials or otherwise confirming the contamination status of the surfaces ofobjects to be decontaminated, methods that measure surface contamination density via beta rays
are suitable as beta rays are not readily influenced by background radiation and have low
penetrating power.
The surface contamination density is an indicator that expresses the degree of surface
contamination of the measured object and is expressed in units of Bq/cm2. What is more, theunit with which surface contamination density is generally expressed by measuring apparatuses
is count rate (cpm). Since the count rate (cpm) indicated by the measuring apparatus at the timeof the measurement will vary for each apparatus even for the same measured object, it isnecessary to perform assessments by rigorously converting the measurements from eachapparatus into the unit of Bq/cm2. It is essential to keep in mind that leaving the unit as cpm
when dealing with the measured values could potentially cause discrepancies to arise in saidvalues. However, there is no problem with calculating using the count rate when calculating the
reduction rate from the measured values from before and after the decontamination.
The radiation dose is the total of the radiation dose received from the contamination sources ata site and the radiation dose received from the background. The background radiation dose is
the total of the radiation dose from the radioactive materials present in the vicinity around ameasurement position and the radiation dose from the natural radiation from the earth.
Gamma rays are measured by an NaI scintillation survey meter or similar apparatus. They havehigh penetrating power, and can even be measured when contamination has penetrated to withinsoil or other substances.
The reduction rate expresses the percentage by which the radiation dose (air dose rate, surface
dose rate, and surface contamination density, etc.) has been reduced via decontamination. It is
used for assessments of No. 1 and No. 2 measurement points, and is expressed via the following
formula.
Reduction rate [%] = 1-

Radiation dose after decontamination 
X 100
Radiation dose before decontamination

Moreover, the decontamination factor (DF) expresses the extent to which the contamination has
been removed from the objects subject to decontamination. It is used for assessments of No. 2
measurement points, and is expressed via the following formula.
Decontamination factor [-] = 

Surface contamination density before decontamination Surface contamination density after decontamination *6:Even under the same gamma rays, energy intensity varies depending on the types of radioactive

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

*7

:

*8

:

*9

:

*10

*11

:

:

*12

:

*13

:

*14

:

materials. Accordingly, for the accurate assessment of the air dose rate, it is appropriate to takemeasurement with measuring apparatuses that have energy compensation functions capable oftaking into account the energy intensity. Measuring apparatuses with no such energy
compensation function that have been calibrated for cesium radiation sources can only be
expected to provide accurate measurements in places where cesium is the only type ofradioactive material. However, the measured values will deviate if any radioactive materials
other than cesium are measured. It is therefore necessary to keep in mind that if measurement isconducted in areas with low levels of cesium, the radioactive material discharged by theaccident, or in areas where the natural radiation dose level is high, the accuracy of measurement
may degrade.
Beta rays are measured via a GM survey meter or similar apparatus. Since the penetrating
power of beta rays is not high, they cannot be accurately measured when contamination has
penetrated to within soil or other substances. In such cases it is necessary to first estimate thecontamination status by measuring the gamma rays via an NaI scintillation survey meter orsimilar apparatus and then confirm the depth at which the contamination is found by separately
scraping away the surface.
The probe (detecting element) on a GM survey meter measures the beta rays that enter from theentrance window at its tip, and so the measured values from this are values that reflect theamount of radioactive materials found locally around the tip of the probe.
A registered company or device manufacturer in accordance with the Measurement Act cancalibratemeasuringapparatuses(homepageaddress:
http://www.meti.go.jp/policy/economy/hyojun/techno_infra/sokuteikikousei.html)
JIS Z4333 specifies that the allowable range of relative intrinsic error for “Dose Equivalent
Rate Meters for X and  Rays” shall be within ± (15 + U) percent. While U indicates therange of uncertainty of the reference dose rate and is considered to be within the range of about
five percent, the allowance is determined to be 20 percent.
The calibration of GM survey meters in accordance with Japanese Industrial Standards (JISZ4329, JIS Z4505) relates to the method of calculating the surface contamination density(Bq/cm2) using a count rate (cpm). Consequently, when dealing with the measured values intheir original form as a count rate (cpm) the aforementioned calibration is not necessary.
Conversely, in some cases the readings for the count rate (cpm) will deviate from the correct
values for reasons such as the degradation of the GM counter tubes or electrical circuits, somaintenance must be performed at least once a year. Maintenance is performed by the apparatus
manufacturers, but in some cases calibration service providers may perform the maintenanceand calibration together, so you must confirm the details with each service provider.
When it comes to measuring apparatuses for radiation, there are those that use time constants
and those that use sampling times (the measuring time required to reduce statistical errors down
to a certain degree when measuring radiation) as guides for the response time until accurate
measured values are displayed.
[Measuring apparatuses that use time constants]
These display the mean values for the radiation dose over the most recent span of a fixed
length of time (the time constant, for example ten seconds, etc.).
You only have to wait a length of time that is three times longer than the time constant inorder to obtain an accurate response.
[Measuring apparatuses that use sampling times]
These display the radiation dose from integrated values (moving average) over a samplingtime.
You only have to wait the length of the sampling time in order to obtain an accurate
response.
The probe (detecting element) on a scintillation survey meter measures the gamma rays comingfrom every direction. Therefore, the measured values not only strictly consist of radiation doses
from localized radioactive materials near the probe, but also reflect the radiation from theradioactive materials present within the vicinity around the probe.
Cs-134 and Cs-137 (hereinafter “radiocaesium”) decay while emitting beta rays until they

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

become barium, which is unstable in terms of its energy, with this barium emitting gamma rays
over its short half-life. It is commonly claimed that gamma rays are emitted from cesium, but tobe precise these emissions come from the barium. In other words, the window surface of theprobe (detecting element) on GM survey meters detects almost 100 percent of the beta rays
given off by the cesium, as well as several percentage points of the gamma rays given off by thebarium as well.
GM survey meters are characterized by the fact that they are comparatively resistant to being
affected by background radiation (gamma rays) since they mainly measure beta rays. However,in cases where the impact from the background is thought to be significant, one conceivable
way of performing more accurate measurements would be to perform the measurements byusing a collimator as shown in Table 1-3. Another way would be to calculate the surface
contamination density from the net beta rays using a beta ray collimator. These approaches are
effective in cases such as correctly assessing the decontamination results when performing
experiments, for example.
Beta ray collimators can be used for determining to what depth contamination has penetrated.
More specifically, the determination can be made that the smaller the difference between thevalues measured when shielding against beta rays with a plastic plate and the unshielded values
are, the deeper the depth of the contamination is.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Table 1-3. Correct Measurement Methods for Surface Contamination Density
MethodContent

Gamma ray collimator
Beta ray collimator(Beta ray dose + gamma ray dose
(Beta ray dose assessments)
assessments)
Use a collimator to make measurements Calculate the surface contaminationby shielding the gamma rays from the density (C) using the net beta rays
objects other than the measured object. through the following formula.
C = C1 - C2
C1: Measured values measured with noshielding (beta rays + the gamma rays
that are measured at the same time)
C2: Measured values measured byshielding against beta rays by covering
the entrance window with a plastic plate(gamma rays)[Measure C1]
Collimatorß raysShielding theexternal γ rays

γ raysß raysγ raysγ rays[Measure C2]
γ raysPlastic plateß raysγ raysThe ß rays are shielded by theplastic plate*15: Investigating the degree to which beta rays are contained within the radiation given off by themeasured object allows you to estimate whether the contamination is found on the object’s
surface or inside of it. Materials like polypropylene and acrylic are used in plastic shield plates
for assessing beta rays, and require a certain thickness in order to shield against the said beta
rays. Figure 1-19 is an example of an instrument that was created so that a plate can be mounted
on the probe (detecting element) of a GM survey meter on which the shield plate portion is 3
mm thick and made of polypropylene. When measurements are taken without a shield plate you
should use a spacer or some other method to ensure that the distance between the measured
object and the entrance window is as similar as possible to instances where a shield plate is
used.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Figure 1-19. Example of a Plastic Shield Plate and Spacer (Left) and Mounting
Configuration for the Shield Plate and Spacer (Center, Right)

Provided by: JAEA
*16:

*17:

The decay of radioactive materials occurs randomly, and so there will be some statisticalvariance in the number of radioactive nuclei detected by the measuring apparatus. The larger
the number of radioactive nuclei detected the smaller this variance will be.
Gy (gray) is the unit for the “amount of energy radiation imparts to a material object,” while Sv(sievert) is the unit for the “dose at which radiation has a clear impact on the human body.”
When converting from Gy to Sv the affects that each type of radiation has on the human bodyare weighted. In the Ministry of Education, Culture, Sports, Science and Technology’s
Radiation in Everyday Life, conversions are performed wherein 1 Gy = 1 Sv for X-rays andgamma rays.

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Guidelines for Methods for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

References
Ministry of Education, Culture, Sports, Science and Technology, Japan Atomic
Energy Agency, Guidelines Concerning Radiation Measurement (October 21, 2011).
(http://www.kantei.go.jp/jp/tyoukanpress/201110/__icsFiles/afieldfile/2011/10/21/21
shiryou02.pdf)
Ministry of Education, Culture, Sports, Science and Technology, Japan Atomic
Energy Agency, Guide for Radiation Measurements at Schools and Other Public
Buildings (August 26, 2011).
(http://www.city.ome.tokyo.jp/kankyo/documents/gakou.pdf)
Fukushima Prefecture, Guide for Reducing Amount of Radiation in Living Spaces(October 31, 2011)(http://www.pref.fukushima.jp/j/tebiki1031.pdf)
National Consumer Affairs Center of Japan, Performance of Relatively Low-Cost
Radiation Measurement Instruments (September 8, 2011)(http://www.kokusen.go.jp/news/data/n-20110908_1.html)
Japan Atomic Energy Agency, Report on Experimental Decontamination Work
(Volume I, Section 3.2) (June 29, 2012)(http://www.jaea.go.jp/fukushima/kankyoanzen/d-model_report/3.2.pdf)

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Guidelines on the Method for Investigation and Measurement of the Status of Environmental Pollution in Intensive Contamination Survey Areas

Part 2

Guidelines Pertaining to
Decontamination andOther Measures
2nd Ed.,2013

Guidelines Pertaining to Decontamination and Other Measures

1

2

Part 2
Guidelines Pertaining to
Decontamination and Other
Measures
I.

Basic ConceptII.

Decontamination and Other Measures for Buildings andOther Structures

III.

Decontamination and Other Measures for Roads

IV.

Decontamination and Other Measures for Soil

V.

Decontamination and Other Measures for Vegetation

VI.

Others2-1

Guidelines Pertaining to Decontamination and Other Measures

Guidelines Pertaining to Decontamination and Other Measures
Table of Contents

I.

Basic Concept....................................................................................................... 2-5
1.

The Role of these Guidelines .......................................................................... 2-5

2.

Important Points in Implementing Decontamination and Other Measures ..... 2-7

II.

Decontamination and Other Measures for Buildings and Other Structures ....... 2-101.

Preparation..................................................................................................... 2-11
(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ......................................................................................................... 2-11(2) Equipment and Materials ........................................................................... 2-122.

Prior Measurements ....................................................................................... 2-13
(1) Determination of Measurement Points ...................................................... 2-13
(2) Measurement Methods ............................................................................... 2-16

3.

Decontamination Methods ............................................................................ 2-17
(1) Decontamination of Roofs and Other Areas .............................................. 2-19
(2) Decontamination of Rainwater Guttering .................................................. 2-23
(3) Decontamination of Exterior Walls ............................................................ 2-27
(4) Decontamination of Fences, Outside Walls, Benches, Playground Equipment,
etc.............................................................................................................. 2-29
(5) Decontamination of Gardens and Other Areas .......................................... 2-32
(6) Decontamination of Street Drains, etc. ...................................................... 2-38

4.

Post-Work Measures ...................................................................................... 2-43
(1) Handling the Removed Soil, etc. ............................................................... 2-43
(2) Wastewater Treatment ................................................................................ 2-44
(3) Cleaning of Equipment and Materials ....................................................... 2-50

5.

Post-Work Measures ...................................................................................... 2-52

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Guidelines Pertaining to Decontamination and Other Measures

III.
1.

Decontamination and Other Measures for Roads .............................................. 2-53
Preparation..................................................................................................... 2-54
(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ......................................................................................................... 2-54
(2) Equipment and Materials ........................................................................... 2-54

2.

Prior Measurements ....................................................................................... 2-55
(1) Determination of Measurement Points ...................................................... 2-55
(2) Measurement Methods ............................................................................... 2-57

3.

Decontamination Methods ............................................................................ 2-59
(1) Decontamination of Paved Surfaces .......................................................... 2-61
(2) Decontamination of Unpaved Roads ......................................................... 2-65
(3) Decontamination of Roadsides and Street Drains ...................................... 2-70

4.

Post-Work Measures ...................................................................................... 2-73
(1) Handling the Removed Soil, etc. ............................................................... 2-73
(2) Wastewater Treatment ................................................................................ 2-73
(3) Cleaning of Equipment and Materials ....................................................... 2-74

5. Subsequent Measurements and Records ............................................................. 2-74
IV.

Decontamination and Other Measures for Soil .................................................. 2-751.

Preparation..................................................................................................... 2-76
(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ......................................................................................................... 2-76
(2) Equipment and Materials ........................................................................... 2-77

2.

Prior Measurements ....................................................................................... 2-78
(1) Determination of Measurement Points ...................................................... 2-78
(2) Measurement Methods ............................................................................... 2-82

3.

Decontamination Methods ............................................................................ 2-85
(1) Decontamination of Soil in Schoolyards, Kindergarten Yards, and Parks . 2-86
(2) Decontamination of Farmland ................................................................... 2-93

4.

Post-Work Measures ...................................................................................... 2-99

2-3

Guidelines Pertaining to Decontamination and Other Measures(1) Handling the Removed Soil, etc. ............................................................... 2-99
(2) Cleaning of Equipment and Materials ....................................................... 2-99
5.
V.

Subsequent Measurements and Records ..................................................... 2-100
Decontamination and Other Measures for Vegetation ..................................... 2-1011.

Preparation................................................................................................... 2-102(1) Measures to Reduce Public Exposure in Connection with Decontamination
Work ....................................................................................................... 2-102(2) Equipment and Materials ......................................................................... 2-102

2.

Prior Measurements ..................................................................................... 2-103(1) Determination of Measurement Points .................................................... 2-103(2) Measurement Methods ............................................................................. 2-105

3.

Decontamination Methods .......................................................................... 2-106(1) Decontamination of Lawns ........................................................................ 2-106(2) Decontamination of Trees in Living Spaces, such as Roadside Trees and thelike .......................................................................................................... 2-110(3) Decontamination of Forests ..................................................................... 2-112

4.

Post-Work Measures .................................................................................... 2-115(1) Handling the Removed Soil, etc. ............................................................. 2-115(2) Cleaning of Equipment and Materials ..................................................... 2-115

5.

Subsequent Measurements and Records ..................................................... 2-116

VI.

Others ............................................................................................................... 2-117(1) Decontamination and Other Measures for Sediment in Riverbeds .......... 2-117

Endnotes................................................................................................................ 2-119
Reference Materials .............................................................................................. 2-122

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Guidelines Pertaining to Decontamination and Other Measures

I. Basic Concept

I. Basic Concept
1.

The Role of these Guidelines

These guidelines use cases and examples to explain in a concrete fashion the Ordinanceof the Ministry of the Environment (Note) pertaining to standards for the measures fordecontamination of the soil, etc. provided in Article 40, Paragraph 1 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
(hereinafter the “Act on Special Measures concerning the Handling of Radioactive
Pollution”).
Each municipality will formulate a decontamination plan based on prioritization andfeasibility in light of the actual conditions in each area. Appropriate decontamination
methods will be selected as needed from among those listed in these guidelines toadvance the decontamination work based on each decontamination plan.
At present, the methods given in these guidelines are deemed to be appropriate for
implementing decontamination and related procedures, but decontamination work andnew technologies are currently being developed and verified by various actors. These
guidelines will be revised as needed in light of trends in the development andverification of this knowledge and these technologies. In addition, a Decontamination
Q&A has been formulated and released to serve as a supplementary explanation for the
Decontamination Guidelines in order to rapidly accommodate the implementation of
decontamination that is suited to the actual circumstances of local regions, and thesewill be added to and otherwise revised as needed.
(Note) Ordinance for Enforcement of the Act on Special Measures concerning the Handling ofRadioactive Pollution (Portion relevant to Standards for Measures for Decontamination of
the Soil, etc.)
Article 54: The standards provided in the Ordinance of the Ministry of the Environment for
Article 40, Paragraph 1 of the Act are as follows.
1. The following shall be observed in executing measures for decontamination of the soil,
etc.
A.
Decontamination and other measures for structures and roads(1)
Cleaning(2)
Grass cutting or removal of sludge, fallen leaves, etc.
(3)
Scraping away of surfaces(4)
In addition to (1) through (3), other decontamination and other measures thathave similar or greater effects than (1) through (3)2-5Guidelines Pertaining to Decontamination and Other Measures

B.

I. Basic Concept

Decontamination and other measures for soil
Scraping away of topsoil
Covering with soil (including the replacement of the soil in the topsoil with thesoil in the layer below the topsoil)(3)
Deep tillage(4)
In addition to (1) through (3), other decontamination and other measures thathave similar or greater effects than (1) through (3)C.
Decontamination and other measures for vegetation(1)
Grass cutting (including trimming of lawns, pasture grass, etc.)(2)
Removal of underbrush, fallen leaves, or fallen twigs(3)
Pruning or logging of trees(4)
In addition to (1) through (3), other decontamination and other measures thathave similar or greater effects than (1) through (3)D.
Decontamination and other measures for other objects (excluding those in A throughC)(1)
Removal of sediment, etc.
(2)
In addition to (1), other decontamination and other measures that have similar or
greater effects than (1)2. The radiation dose shall be measured before and after implementing measures fordecontamination of the soil, etc. However, this shall not interfere with the measurementof radioactivity concentrations in relation to radioactive materials discharged by theaccident.
3. It shall be ensured that there is no dispersion or outflow of the removed soil, etc. in
implementing measures for decontamination of the soil, etc.
4. The necessary measures shall be taken to ensure that no hindrances to conservation of theliving environment arise due to offensive odors, noise, or vibrations associated withmeasures for decontamination of the soil, etc.
5. It shall be ensured that no damages pertaining to human health or the living environment
arise due to the removed soil, etc.
6. The removed soil, etc. shall be separated from other objects to ensure that there is nodanger of it mixing with other objects.
7. Records shall be created of the land for which measures for decontamination of the soil,
etc. were implemented, the types and quantities of removed soil, etc., the dates ofcommencement and completion of the measures, and other information pertaining todecontamination and other measures, and these records shall be stored for a five-year
period starting from the date of completion of the measures.
(1)
(2)

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Guidelines Pertaining to Decontamination and Other Measures

2.

I. Basic Concept

Important Points in Implementing Decontamination and Other Measures

There is a need to proceed with decontamination in the areas in which contamination
was produced by radioactive materials discharged in association with the Fukushima
Daiichi Nuclear Power Plant accident, in order to reduce human exposure doses*1 toradiation (see Figure 2-1).
The following aspects are important in implementing decontamination measures.
1) 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 andother necessary measures shall be taken with respect to consideration for thepreservation of the health of surrounding residents and for the conservation of
the living environment.
2) To effectively reduce the radiation doses due to contamination, places that arecontaminated at comparatively high concentrations that contribute substantiallyto the radiation dose must be identified, and appropriate methods ofdecontamination must be used in accordance with the characteristics of thecontamination. The effectiveness of these methods must also be confirmed bymeasurements before and after the decontamination to effectively reduce theradiation doses in human living environments.
3) The removed soil, etc. must be separated from other objects to ensure that there
is no danger of it mixing with other objects, and the removed soil must also be
separated from decontamination waste to the extent possible.
4) It is important to strive to minimize the quantity of removed soil, etc. generated
during decontamination. It is also important to ensure that the contamination
does not spread as a result of the decontamination work. For example, cleaning
using water produces drainage that contains radioactive materials. The
executors of decontamination and other measures shall, to the extent possible,
remove in advance those radioactive materials that can be removed by methods
other than cleaning with water, properly treat wastewater, and find other ways to
avoid affecting outflow destinations due to cleaning, etc. as much as possible.
Moreover, periodic monitoring shall be performed after the applicable measures
are implemented when deemed necessary on account of the actual conditions in
the area.
Moreover, the radioactivity of radioactive materials decays as time passes. In addition,
the appropriate responses must be taken by fully taking into account the changes in thecontamination status as a result of factors like the radioactive materials being moved
around due to rainwater and other factors.
Note that depending on the impact of radiation from objects other than those subject todecontamination work, as well as on the characteristics of the contamination, thelong-term target of bringing the additional exposure dose to no more than 1 millisievert
per year may not be immediately achievable even in cases where decontamination has
been carried out effectively. In such cases, it is important to judge whether to re-do

2-7Guidelines Pertaining to Decontamination and Other Measures

I. Basic Concept

decontamination work, considering the radioactive decay of the radioactive materials
with the passage of time and the movement of the radioactive materials due to rainwaterand other factors.
These guidelines indicate the measures and decontamination methods to be
implemented before, during, and after decontamination, methods of confirming the air
dose rate,*2 etc., and other measures for each of the objects subject to decontamination:buildings and other structures, roads, soil, and vegetation.*3

For the results of decontamination carried out in the past, the reduction rate for theradioactive materials via decontamination were compiled and announced as the Resultsof Decontamination Techniques in the Decontamination Work Carried Out thus Far by
the National and Local Governments (January 2013). Even with the same techniques theresults of decontamination differ depending on factors like the quality of the materialsof the target object, the surface conditions, the time that decontamination was carriedout, and so forth, so refer to the reference materials concerning the carrying out of
decontamination.
Figure 2-1. Conceptual view of the removal of radioactive materials from the living
environment through decontamination[Beforedecontamination]

Radioactive materials settled on soil, vegetation, and buildings[Afterdecontamination]

Radioactive materials consolidated and shielded

2-8Guidelines Pertaining to Decontamination and Other Measures

I. Basic Concept Natural decay of Cs-134 and Cs-137 (hereinafter “Radiocaesium”)
Since radioactive materials decay naturally over the course of time the radiation dose
will continue to decrease even if decontamination is not performed, but this will take along period of time (the half-life for Cs-134 is two years, while that for Cs-137 is 30
years).*4
Carrying out decontamination is effective for both reducing the radiation dose at alocation as well as shortening the length of time before the dose falls compared tosituations where decontamination is not carried out.
Furthermore, there is also a reduction effect via natural causes such as rain and wind
(weathering), and so in actuality this results in the radiation dose declining even more
quickly.
Figure 2-2. Decay of the radiation dose discharged by the accident

Radiation dose

Change in the radiation dose from natural decay when
decontamination is not carried out

Decrease in
the radiationdose fromdecontamination
Change in the radiation dose when the reduction effectfrom decontamination is added to natural decay

Number of elapsed years

2-9Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

II. Decontamination and Other Measures for
Buildings and Other Structures
This section explains 1. Preparation, 2. Prior Measurements, 3. Decontamination
Methods, 4. Post-Work Measures, and 5. Subsequent Measurements and Records, inchronological order, pertaining to decontamination and other measures for houses,
buildings, agricultural facilities, and other structures.
Figure 2-3. Basic flow for the decontamination and other measures for buildings
and other structures(1) Measures to reduce public exposure in connection with the work
1. Preparation(2) Equipment and materials

2. Prior
Measurements(1) Determination of measurement points(2) Measurement methods

3. Decontamination
Methods

Decontamination work
proceeds from high areas tolow areas

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 roofs and other areas(2) Decontamination of rainwater guttering(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

2-10Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

1.

Preparation

Before performing decontamination work, in addition to preparing the equipment
required for the decontamination work, preparations must be made to ensure safety
through means including prevention of exposure of the general public and workers suchas by inhaling dust generated during decontamination work. Among these preparations,please refer to the Ministry of Health, Labour and Welfare’s Ordinance on thePrevention of Ionizing Radiation Hazards related to Decontamination Work of Soil
Contaminated by Radioactive Materials Resulted from the Great East Japan Earthquake
and its Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
(1)

Measures to Reduce Public Exposure in Connection with Decontamination
Work

Table 2-1. Measures to reduce public exposure in connection with decontaminationand other work on buildings and other structures
Restriction ofentry

Signage• In cases where the general public is deemed likely to enter the area,
the area shall be cordoned off with pylons or rope, etc. to prevent
people from unnecessarily approaching the work site, and the entryof people and vehicles shall be restricted (see Figure 2-4).
• In cases where radioactive materials may be dispersed in connection
with the decontamination work, the perimeter of thedecontamination area shall be fenced in with sheets, etc., water shallbe sprayed, or other such measures shall be taken to prevent
dispersion and the area shall be cordoned 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.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-4: Examples of restriction of entry and signage(2)

SignageexamplesDecontamination
work in progress

Restriction using rope

Decontamination
work in progress

Restriction using pylons

Equipment and Materials
The required equipment and materials shall be arranged for decontamination and othermeasures, as well as for collection of the removed soil, etc., in accordance with the objects to
be decontaminated and the work environment.

Table 2-2. Examples of decontamination equipment and materials for buildings
and other structures
Example of generalequipment

Examples ofequipment forcleaning with water

Examples ofequipment forcleaning metal
surfaces

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 the on-sitestorage location (truck, two-wheeled cart, etc.), ladder
Hose, shower nozzle, high pressure water cleaner, brushes (scrub
brush, brush for cleaning vehicles, brush for cleaning highplaces), scrubbing brushes (circular scrubber, steel wool brush,etc.), wire brushes, tools for pushing away water (broom, scraper,etc.), bucket, detergent, dustcloth, sponges, paper towels
Brush, sandpaper, cloth, removing agents

2-12

Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Examples ofequipment forcleaning wood
surfaces
Examples ofequipment for work inhigh places
Examples ofequipment for
scraping away
Examples ofequipment forcovering the groundsurface2.

Brush, sandpaper, power sander, cloth, steam cleaner, water highpressure 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

Prior Measurements

To confirm the decontaminating effects of the decontamination work, the air dose rateprior to the commencement of decontamination work and after the completion of
decontamination work*2 and the surface contamination density of the objects subject todecontamination (hereinafter, “air dose rate, etc.,” which includes both the air dose rate
and the surface contamination density) shall be measured. Specifically, places
representative of living spaces, places contaminated at a comparatively highconcentration that is deemed to contribute substantially to the radiation dose in theliving space, etc. shall have their air dose rate, etc. measured in the same locations andby the same method both before contamination work starts and after it finishes, and theresults shall be recorded. This section gives information on methods for measuring the
air dose rate, etc. prior to the commencement of decontamination work.
Note that the air dose rate, etc. may also be measured near the surface of the objects
subject to decontamination as needed when ascertaining the degree of reduction in thelevel of contamination of the objects subject to decontamination during thedecontamination work. These measurements will be separately explained in “Section 3.
Decontamination Methods.”(1)

Determination of Measurement Points

Prior to decontamination work, the locations at which the air dose rate, etc. will bemeasured (hereinafter, “measurement points”) shall be decided and a schematic diagram(see Figure 2-5) illustrating the range of the measuring object, the measurement points,
structures to be used as markers, etc. shall be created.
There are two types of measurement points: those used to ascertain the average air dose
rate in living spaces within buildings and other structures subject to decontamination(No. 1 measurement points) and those used to confirm the level of contamination of theobjects that are to be decontaminated (No. 2 measurement points).
No. 1 measurement points are set primarily in a living space where residents, etc. spend

2-13

Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structureslarge amounts of time. In setting these measurement points, so-called “hotspots”(locations where the soil has been contaminated in a highly concentrated manner by
rainwater and the like containing radioactive materials where there is a high probability
that radiocaesium has become concentrated compared to the surrounding areas) that
contribute comparatively insubstantially to the radiation dose in the living space, andpoints near them, are not eligible to be measurement points unless the residents, etc. aredeemed likely to spend relatively large amounts of time there.
Examples of hotspots include depressed areas and puddles, street drains, underrainwater guttering, rainwater chambers, under or near trees, or in places whereraindrops falling from buildings land, as radioactive materials tend to become
concentrated in such places due to rainwater and the like.
The purpose of No. 2 measurement points is fundamentally to measure the level ofcontamination at the surface of the objects subject to decontamination, and they are
therefore set by considering places, etc. contaminated at comparatively highconcentrations and that are deemed to contribute substantially to the radiation dose in
the living space. When hotspots including areas under rainwater guttering are subject todecontamination, these are to be measured as No. 2 measurement points.
The specific methods are as provided in Table 2-3.
Table 2-3. Reasoning behind the measurement points for air dose rates and othermeasures for the decontamination of buildings and other structures
Measurement point
MeasurementtargetReasoning behindthe measurement
pointsNo. 1 measurement points
Air dose rate in living spaces• For detached housing, in gardensand other outdoor locations,approximately two to fivemeasurement points shall be set
from among places where people
are deemed likely to spend
relatively large amounts of time.
• For collective housing, public
facilities, and so forth, in gardensand other outdoor locations,approximately five measurement
points shall be set from amongplaces where people are deemed
likely to spend relatively large
amounts of time.

2-14

No. 2 measurement points
Surface contamination density, etc.
for objects subject to decontamination• Measurement points for roofs,
rooftops, and the sides of buildings
shall be set near the center of eachsurface.
• Measurement points for gardensand other grounds shall be set near
their centers. (Choose places along
the centerline for grounds that arelong and thin or otherwise notsquare.)• Measurement points for fences andwalls shall be set at intervals thatenable the distribution of the air
dose rate, etc. to be 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.

Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-5. Example of a schematic diagram for reporting measurement points foruse in decontamination and other measures for buildings and other structures

Garden2) Wall

Building

1) 2)

2)
2) Undereaves

Rooftop2) Wall

Parking lot2) Undereaves2) Rainwater
guttering1) 2)

Garden

2)

Road

1):
2):

Contamination status for living spaces(air dose rate: approximately two to five measurement points)
Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-6. Examples of No. 2 measurement points
Rooftop
Wall
Rainwater guttering
GardenUnder eaves

GardenWall

Under eaves

Parking lot(2)

Measurement Methods

When measuring the air dose rate at a No. 1 measurement point, a scintillation survey
meter or other measuring apparatus able to measure gamma rays shall be used.
In contrast, to avoid the effects of background radiation when measuring the level ofcontamination on or near surfaces at a No. 2 measurement point, it is recommended touse a Geiger-Müller counter tube type survey meter (hereinafter, “GM survey meter”)
able to measure beta rays, but it is also acceptable to perform the measurements using adosimeter capable of measuring gamma rays. For example, one way to make specialized
confirmation based on the levels of contamination at the relevant sites is to perform themeasurements under conditions where a collimator is used to shield against gamma raysfrom the outside. In addition, for instance, it is possible to confirm the effect of thedecontamination by determining the contamination status of the objects subject todecontamination from the air dose rate measured at the surface of the measurement
points and at heights of 50 cm and 1 m, and then comparing the results with those ofmeasurements taken in the same positions after the completion of the decontamination
work.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

In general, the same measuring apparatus shall be used when measuring at the samemeasurement points before and after decontamination work.
For the specific methods, see “6. Measuring Apparatuses and Methods of Use” in “Part
1: Guidelines on the Methods for Investigation and Measurement of the Status ofEnvironmental Pollution in Intensive Contamination Survey Areas.”3.

Decontamination Methods

Figure 2-7. Basic flow for the decontamination of buildings and other structures
Decontamination
methods
Measures to prevent the spread of contamination through dispersion, outflows, and soforth following the decontamination

Decontamination work proceeds from high to low areas(1) Decontamination of roofs andother areas<Examples of decontamination stages>
Removal of fallen leaves, sediment,
and so forth through manual labor(2) Decontamination of rainwater
guttering
Decontamination
results(3) Decontamination of exterior
walls

Effective(4) Decontamination of fences,
walls, benches, playgroundequipment, etc.

Not effective

Cleaning via discharged
water (for target objects forwhich cleaning by water ispossible)(Proceed to the decontaminationof low areas)

Conduct the decontaminationfrom (1) – (6) as needed.

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

Wastewater treatment (*as needed)

To decontaminate buildings and other structures effectively requires thedecontamination work to be focused on places that are contaminated with comparatively
high concentrations of radioactive materials that contribute substantially to the radiation
dose. For example, there are radiocaesium-containing fallen leaves, moss, mud, etc. on
the roofs (rooftops), rainwater guttering, street drains, etc. of houses and buildings open
to the public, and therefore removing these can reduce the radiation dose.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

In terms of decontamination stages, first the fallen leaves, etc., which contain large
amounts of radiocaesium, shall be removed by hand provided they are relatively easy toremove. If this results in no observable decontamination effect, cleaning by spraying
with water shall be used for those objects capable of being cleaned with water. Any
radioactive materials that can possibly be removed by methods other than cleaning withwater shall be removed in advance, and other measures shall be taken to prevent impact
on the outflow destination of the drainage resulting from cleaning, etc. as much as
possible.
In each stage, the air dose rates at the No. 1 measurement points shall be measured, andas a general rule no additional decontamination work shall be performed provided theair dose rate at a height of 1 m (a height of 50 cm from the measurement point is
acceptable for elementary schools and below, as well as special-needs schools, withconsideration for the living space of infants and schoolchildren in the lower grades) is
less than 0.23 microsieverts per hour.
When water is used in decontamination work on houses and buildings, such work shallin principle be performed starting from high places and continuing to low ones, taking
account of the possibility that radioactive materials could flow to gardens, etc.
Specifically, it is effective to start from roofs/rooftops and rainwater guttering, proceed
to exterior walls, and finally to gardens and other work on the ground and then street
drains. When there are trees near the houses that are higher than the roofs, such trees
shall be decontaminated first according to their contamination status. Depending on how
the radioactive materials are settled onto the surfaces, decontamination work shall
employ cleaning by hand, wiping, or cleaning with a scrubbing brush or brush.
The radioactivity of radioactive materials decays as time passes. What is more, thismust be appropriately handled with due consideration given to the fact that thecontamination status changes as a result of rainwater and other factors.
Moreover, when performing decontamination work, the necessary measures to secure
the safety of the workers and the general public must be taken, and measures to preventthe spread of contamination due to dispersion, outflow, etc. associated withdecontamination work must be implemented so as to minimize contamination beingbrought out from within the work zone, contamination being brought in from outside, orrecontamination of the decontaminated zones. Among these preparations, please refer tothe Ministry of Health, Labour and Welfare’s Ordinance on the Prevention of Ionizing
Radiation Hazards related to Decontamination Work of Soil Contaminated byRadioactive Materials Resulted from the Great East Japan Earthquake and its
Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
See “4. Post-Work Measures” with regard to matters like the handling of the removed
soil, the treatment of wastewater, and the cleaning of the equipment used for thedecontamination.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

This section covers methods of decontamination for roofs, rooftops, rainwater guttering,walls, gardens, street drains and other areas of buildings and other structures.
(1)

Decontamination of Roofs and Other Areas
Figure 2-8. Basic flow for the decontamination of roofs and other areas

Decontamination ofroofs and other areas
Work that is being considered for
implementation in regions where theair dose rate is comparatively highMeasures to prevent the spread of contamination
through dispersion, outflows, and so forth following thedecontamination

Remove sediment (fallen leaves, moss, dirt, etc.)
Washing away items that could
not be completely taken away
through the removal of sedimentwith water at the end is effective

Removal via manual labor
WipingCases 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 andother 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 roofs

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

Scraping away

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

Any fallen leaves, moss, mud, or other sediments on roofs, etc. may have radiocaesiumon or in them. Therefore, first the sediments that can be easily removed shall be
removed by hand, the dirt shall be wiped away with thick paper towels (see Figure 2-9).
Next, the roof, etc. shall be sprinkled with water and the sediments shall be removed bycleaning it off with a brush through the use of a deck brush or broom or the like. Special
attention shall be paid to cleaning the overlapping sections of roofs, places where themetal is corroded, and around the drain for rooftops on large buildings, because theseare places where there are comparatively large amounts of sediments (see Figure 2-10).
If no decontamination effect is adequately observed as a result it is presumed that thereis radiocaesium settled onto the roofing materials. However, since any radiocaesium thatwas not washed away by rainwater will have permeated into the roofing materials, theradiocaesium shall be washed away by cleaning with high-pressure (example: 15 MPa)
water spraying (hereinafter, “high pressure water cleaning”). Start by cleaning a portion

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structuresof the roof, etc. and then confirm whether this produces a decontamination effect before
cleaning the whole roof, etc., because the decontamination effect yielded by highpressure water cleaning depends on the surface materials of the roof and the like.
When conducting high pressure water cleaning or other decontamination that uses water,
the appropriate countermeasures against wastewater shall be taken to prevent thesecondary contamination of the environment (see ”4. (2) Wastewater Treatment”).
Using a method of water recovery-type high pressure water cleaning is also effective forpreventing the dispersal of radioactive materials. The advice of a specialist must also be
obtained when pressure washing due to the possibility of damage to the roofs of houses,
buildings, agricultural facilities, etc. depending on their constituent materials andstructure.
In cases where no decontamination effect is observed as a result of cleaning and highpressure water cleaning, decontamination of concrete roofs and rooftops by scraping
away or shot-blasting work shall be considered where deemed necessary and effectivein the reduction of the radiation dose, with due attention given to the possibility ofdamage to the building. When implementing decontamination by shot-blasting work orsimilar methods, measures must be taken to prevent dispersion of dust into thesurrounding environment that is generated by such processes.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of roofs are as provided in Tables 2-4 and 2-5.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-9. Example of the decontamination of roof tiles (wiping)

Figure 2-10. Example of the decontamination of roof tiles (cleaning)

Photo courtesy of: Fukushima City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-4. Necessary measures prior to the decontamination of roofs and otherareas
Category
Safety measures

Prevention ofdispersion

Ensuring drainage
channels andwastewater
treatment

Decontamination methods and notes of caution• When performing work in high places, appropriate safety measures
shall be taken, such as erecting scaffolding and allocating aerial
vehicles.
• If sidewalks and buildings are immediately adjacent, curing shall 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 of radioactive
materials.
• When using water to clean, the channel for cleaning water to flow
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Table 2-5. Decontamination methods for roofs and other areas and notes of caution

Cleaning

Removal of sediments

Category
Decontamination methods and notes of caution
Decontamination • Fallen leaves, moss, mud, and other sediments shall be removed
through manualby hand by people wearing rubber gloves and by shovel, etc.
labor
Wiping• Wiping shall be performed carefully through the use of paper
towels or dustcloths that have been dampened with water.
• All sides of folded paper towels, dustcloths, 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 contamination fromre-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 be smaller
due to effects from roofing materials like cement tiles, matte clay
tiles, and painted steel sheets, as well as from rust.
• When rust is present, the rust itself must be removed by being
wiped away.
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 forthatched or tiled roofs.
High pressure • Any possibility of breakage or damage to roofs, etc. from highwater cleaningpressure water cleaning shall be checked in advance (obtaining
advice from a specialist is recommended).
• To prevent dispersion of soil, etc. by water pressure, cleaning shallbe performed at low pressure initially and the pressure shall beraised gradually while checking the flow of cleaning water and thedispersion 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

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Scraping away

Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Blast work

Scraping away

(2)of roofs, places where the metal is corroded, and around the drain
for rooftops, because these are places where there arecomparatively large amounts of sediments.
• Attention must be paid to the fact that there is the possibility ofdamaging property, such as by potentially peeling off the surface ofobjects.
• Abrasive materials shall be shot at the surface with a shot blasterand 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 thedust shall be collected.
• For blast work, curing shall be performed to ensure that abrasive
materials and the like do not travel outside of the decontamination
work area. What is more, after the abrasive materials and othermaterials have been used they shall be collected in a manner that
ensures that they will not scatter the radioactive materials adheringto them to the surroundings.
• 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.)

Decontamination of Rainwater Guttering
Figure 2-11. Basic flow for the decontamination of rainwater guttering

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

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

Washing away items that could not
be completely taken away throughthe removal of sediment with waterat the end is effective

WipingCases where the results of decontamination cannot be adequately observed
Cleaning
Brush cleaning
High pressure water cleaning[Precautions] Take steps to prevent dispersal and outflows of the water andother 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

Wastewater treatment (*where needed)

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Work that is being considered for
implementation in regions where theair dose rate is comparatively high

Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Fallen leaves, etc. with radioactive materials on or in them, which have flowed downfrom roofs, etc. due to rain will have collected in rainwater guttering. Particularly by
removing the collected fallen leaves, etc., the radiation dose impinging on thesurrounding environment can be reduced.
For the decontamination of rainwater guttering, the fallen leaves, etc. collected in said
guttering shall be lifted out by hand using tongs, shovels, or other tools. The insides ofrainspouts, rainwater pipes, and drain pipes shall be wiped by hand using pipe cleaners,
thick paper towels, etc. (see Figure 2-12).
For cases where decontamination results are not adequately observed even when this isdone, cleaning shall be performed with the use of water. Cleaning with water generates
drainage that contains radioactive materials. To minimize the impact of the drainage
produced by cleaning, etc. on the outflow destination, any radioactive materials that canbe removed by a method besides cleaning with water shall be removed in advancewhenever possible through workarounds that include wiping. When carrying out highpressure water cleaning, attention must be paid to the fact that this has the potential todamage rainwater guttering.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of rainwater guttering are as provided in Tables 2-6
and 2-7.
Figure 2-12. Example of the decontamination of rainwater guttering (wiping)

Photo courtesy of: Date City

Photo courtesy of: Fukushima City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-13. Example of the decontamination of rainwater guttering(brush cleaning)

Photo courtesy of: Date City

Table 2-6. Necessary measures prior to the decontamination of rainwater guttering
Category
Prevention ofdispersion
Ensuring
drainage channels
and wastewater
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 to flow
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• Sediment in rainwater guttering shall be removed prior to cleaning
with water.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.
• Damage to the end-flow sections of rainwater guttering or places
where they are directly discharged into garden plots may result inhigh doses, so consideration shall be given to the decontamination ofgardens and similar sites.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-7. Decontamination methods for rainwater guttering and points to keep inmind

Cleaning

Removal of sediments

Category
Decontamination methods and notes of caution
Decontaminat • Fallen leaves, moss, and other sediments shall be removed by hand by
ion throughpeople wearing rubber gloves and by shovel, etc.
manual labor
Wiping• Wiping shall be performed carefully through the use of paper towels
or dustcloths that have been dampened with water.
• All sides of folded paper towels, dustcloths, 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
as these 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.
• Since large quantities of radioactive materials accumulate on thesediments in rainwater guttering, it is effective to remove said
sediments.
Brush• Cleaning shall be thoroughly performed by using scrub brushes orcleaning
scrubbing brushes.
• Sediment in downspouts (especially bend sections) tends to get
overlooked, so these should be cleaned with a wire brush.
• Cleaning shall be performed from high places to low ones so as to
avoid dispersing water to the surroundings.
High• High pressure water cleaners shall be used to clean via pressurepressure
washing with a water pressure of generally 5 MPa or less and aroundwater
2 liters of water used per 1 m to ensure that rainwater guttering is notcleaning
destroyed. This is primarily for narrow places where people cannot
reach and 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 thecleaning, and the cleaning shall be performed at the appropriate speedof movement.
• Washing shall be performed from the upstream to the downstream ofthe drainage slope to ensure that water does not disperse to thesurroundings.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures(3)

Decontamination of Exterior Walls
Figure 2-14. Basic flow for the decontamination of exterior walls

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

There is no need to carry out
decontamination in cases where thesurface contamination concentration
is sufficiently low.

WipingCases where the results of decontamination cannot be adequately observed

Cleaning

Brush cleaning

High pressure water cleaning[Precautions] Take steps to prevent dispersal and outflows of the water andother 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 rooftops

Wastewater treatment (*where needed)

Work that is being considered for
implementation in regions where theair dose rate is comparatively highSince the exterior walls of buildings have lower levels of contamination than roofs or
rainwater guttering in general, it is not necessary to perform decontamination on them incases where the surface contamination density is sufficiently low compared with otherplaces.
When decontaminating exterior walls, they shall be wiped or cleaned with water fromhigh positions on the walls to low ones in order to prevent recontamination. To
minimize the impact of the drainage produced by cleaning, etc. on the outflow
destination, any radioactive materials that can be removed by a method besides cleaning
with water shall be removed in advance whenever possible through workarounds that
include wiping.
The advice of a specialist must be obtained when performing high pressure watercleaning due to the possibility of damage to the exterior walls depending on theirconstituent materials and structure. In particular, pressure washing is not suitable forwooden exterior walls.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of exterior walls are as provided in Tables 2-8 and
2-9.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-8. Necessary measures prior to the decontamination of exterior walls
Category
Prevention ofdispersion
Ensuring
drainage channels
and wastewater
treatment

Decontamination methods and points to 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 to flow
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Table 2-9. Decontamination methods for exterior walls and notes of caution

Cleaning

Category
WipingBrushcleaning

Highpressurewater
cleaning

Decontamination methods and notes of caution• Wiping shall be performed carefully through the use of paper towels
or dustcloths that have been dampened with water.
• All sides of folded paper towels, dustcloths, 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
as these 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.
• 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 cleaning water and thedispersion 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 speedof 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.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures(4)

Decontamination of Fences, Outside Walls, Benches, Playground Equipment,
etc.

Figure 2-15. Basic flow for the decontamination of fences, outside walls, benches,playground equipment, etc.
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.

WipingJoints of metals that are difficult to clean by wiping

Steam cleaning

High pressure water cleaning

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

Scraping away

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

Work that is being considered for
implementation in regions where theair dose rate is comparatively high

The metal and wooden surfaces of fences, outside walls, benches, playgroundequipment, etc. shall be wiped with water using a brush, cloth, etc. and then cleaned bywiping (see Figure 2-16). Neutral detergent, etc. shall be used as needed during thiswork, taking care not to affect the surfaces. For rusted sections, it is effective to remove
the rust with sandpaper, and then wipe the sections off with a cloth, etc., but steps shallbe taken to avoid recontamination as radioactive materials may settle on the tools used
for wiping and scraping away.
Joints on playground equipment, etc. that are difficult to clean by wiping and wooden
and other surfaces that are difficult to decontaminate by wiping shall be steam cleaned,
washed by high pressure water cleaning (example: 15 MPa) (see Figure 2-17), or
scraped away.
To minimize the impact of the drainage produced by cleaning, etc. on the outflow
destination, any radioactive materials that can be removed by a method besides cleaning
with water shall be removed in advance whenever possible among other workarounds.
When implementing decontamination of gardens as indicated in “II.3.(5)Decontamination of Gardens and Other Areas” or decontamination of sandboxes as

2-29

Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structuresindicated in “IV.3.(1) Decontamination of Soil in Schoolyards, Kindergarten Yards, andParks” it is more efficient to perform such work after the decontamination work on
fences, outside walls, benches, playground equipment, etc.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of fences, outside walls, benches, playgroundequipment, etc. are as provided in Tables 2-10 and 2-11.
Figure 2-16. Example of decontamination of playground equipment (wiping)

Photo courtesy of: Hirono Town

Figure 2-17. Example of decontamination of playground equipment(high pressure water cleaning)

Photo courtesy of: JAEA

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-10. Necessary measures prior to the decontamination of fences, outside
walls, benches, playground equipment, etc.
Category
Prevention ofdispersion
Ensuring
drainage channels
and wastewater
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 to flow
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Table 2-11. Decontamination methods for fences, outside walls, benches,playground equipment, etc. and notes of caution
Category
WipingHigh pressure
water cleaning(metal joints)

Steam cleaning
Scraping away(woodenplaygroundequipment, etc.)

Decontamination methods and notes of caution• All sides of folded paper towels, dustcloths, 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
as these 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 dustcloth 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 byhand.
• High pressure water cleaning shall be performed on the joints ofplayground equipment and the like that are difficult to wipe down.
• 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 thedispersion 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 speedof movement.
• Wooden playground equipment shall be cleaned using a steam
cleaner.
• The surface wood of wooden playground equipment shall be scraped
away with electric power tools or the like.
• Dust collectors, etc. shall be used when scraping off wooden surfaces,
etc. to prevent dispersion to the surroundings.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures(5)

Decontamination of Gardens and Other Areas
Figure 2-18. Basic flow for the decontamination of gardens and other areas

Decontamination ofgardens and other areas
Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following thedecontamination

Deep plowing or removal of soil and other materials at
hotspots*
Removal of underbrush*Hotspots
Locations where the soil has been contaminated in a highly
concentrated manner by rainwater and wastewater containing
radioactive materials where there is a high probability thatradiocaesium has become concentrated compared to thesurrounding areas

Cases where the results of decontamination cannot be adequately observed

Soil gardens, etc.

Gravel and crushed stone gardens, etc.

Deep plowing

High pressure water cleaning of gravel
and crushed stone

Scraping away of topsoil

Removal of gravel andcrushed stones

Covering the soil surface
Wastewater treatment(*where needed)[Precautions] When scraping away the topsoil and removing gravel and crushed stones, itis necessary to confirm in advance the depth of the contamination from thesurface layer and establish the optimal depth for the scraping away andremoval in advance.

Lawn gardens, etc.

Gardens, parking lots,
and hard-packed floors
paved with concrete orasphalt

See “V. 3 (1)Decontaminationof Lawns”

See “III.
Decontamination
and Other
Measures forRoads”

Work that is being considered for
implementation in regions where theair dose rate is comparatively highIn gardens, etc. outside houses, radiocaesium is settled onto fallen leaves, garden trees,
and near the surface layer of the ground. Fallen leaves shall first be picked up andgarden trees shall be pruned in accordance with the extent of the radioactive materials
adhering to them. In places where weeding has not been carried out since after theaccident the underbrush shall be removed as needed, while in places where moss andunderbrush is being grown covering the surface it will be effective to scrape away
underbrush by using a scythe or similar tool.
Furthermore, since there may be comparatively large amounts of radiocaesium settled
onto rainwater guttering drains, drainage channels, rainwater chambers, and near theundereaves of roofs that have no rainwater guttering, as well as at the bases of trees, thesoil at such places shall be removed via manual labor and the like (see Figures 2-20 and2-21). If no decontamination effect is observed as a result of these measures, thendecontamination shall be carried out via the methods indicated below.

2-32Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

 Soil gardens, etc.
For soil gardens and the like, deep plowing, scraping away topsoil, or covering themwith soil (hereinafter “covering the soil surface”) shall be taken into consideration.
Deep plowing is the method of covering the soil surface by replacing theradiocaesium-containing upper layer of the soil with a lower layer of the soil that does
not contain radiocaesium (see Figure 2-19). Carrying out deep plowing can be expected
to reduce the radiation dose and to inhibit the diffusion of radiocaesium by shielding
with soil, etc. Moreover, these have the advantage of not generating removed soil,
because they do not scrape away the topsoil. When performing deep plowing,
approximately 10 cm of surface soil shall be placed at the lower layer and covered withapproximately 20 cm of excavated soil from the lower layer. When performing thisprocedure, it is necessary to avoid scattering the surface soil or mixing it with the soil
excavated from the lower layer. When implementing this over a large area, theimplementation area shall be partitioned in an appropriate manner.
When scraping away topsoil, it is important to select an appropriate thickness for thesoil to be scraped away in order to avoid generating too much removed soil. To be more
specific, for the soil surfaces to be scraped away, it is recommended to start with small
areas (an area of a size that enables the air dose rate, etc. of the soil surface to bemeasured with minimal interference from radiation outside the area) and scrape away
about 1 to 2 cm of topsoil while measuring the air dose rate, etc., then determine thethickness of the layer to be scraped away (see Figure 2-52 2), 3), and 4)). According toconventional wisdom it is believed that adequate results can be achieved by scraping
away at most about 5 cm of the soil surface. In places where the topsoil has been
removed, topsoil shall be brought from another location by using uncontaminated soil as
needed.
For covering the soil surface, the approach is to cover the top layer of soil that contains
radiocaesium with soil that does not contain radiocaesium through the use of small
heavy machinery. This can be expected to reduce the radiation dose via shielding and to
inhibit the diffusion of radiocaesium by shielding it with soil. This has the advantage of
not generating removed soil since the topsoil is not being removed. When performing
this covering, it is important to select an appropriate covering thickness for purposes ofshielding in order to avoid having the covering thickness become excessively large.
 Gravel or crushed stone gardens, etc.
For gravel or crushed stone gardens, etc., place the gravel or crushed stones in a watertank and remove the radioactive materials from them by agitating and high pressure
water cleaning, then lay them out again after they have been cleaned. See “4. (2)Wastewater Treatment” regarding the handling of wastewater when performing highpressure water cleaning.
For cases where results are not considered to have been adequately observed even after
cleaning has been carried out, then the gravel and crushed stones shall be removed

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

evenly with the use of a shovel or other instrument. When gravel or crushed stones are
removed, the area shall be covered by using the same type of gravel or crushed stones as
before as needed, and it shall be covered to the same standing height as before and toabout the same compactness as before.
On ground where gravel and crushed stones have been laid out there is the possibility
that radioactive materials have been accumulated in the soil below the gravel andcrushed stones as time passes. As such, there may be cases where it will be necessary to
make a determination on whether decontamination should be carried out on the gravel
and crushed stones or the soil below them. In doing so, it will be necessary to decide ona decontamination method by properly performing measurements and conducting
experiments.
 Lawn gardens, etc.
See “V. 3. (1) Decontamination of Lawns” regarding decontamination methods forlocations like lawn gardens, gardens where underbrush is growing thickly, or whereresidue from thatch and dried leaves and grass is found.
 Gardens, parking lots, and hard-packed floors paved with concrete or asphalt
See “III. Decontamination and Other Measures for Roads” regarding decontamination
methods for gardens, parking lots, and hard-packed floors paved with concrete orasphalt.
When water has been used for decontamination work on houses and buildings, it ismore efficient to perform the decontamination work on gardens and surrounding sites,
etc. after the work on the houses and buildings, because radioactive materials on theroofs, etc. could flow off in the process.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of gardens and other areas are as provided in Tables
2-12 and 2-13.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-19. Example of decontamination procedures via replacing the topsoil with
subsoil (deep plowing)

1) Dig out about 10 cm ofsurface soil.

2) Dig out about 20 cm oflower layer soil.

3) Place the surface soil atthe lower layer andcover it with the lower
layer soil.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-20. Example of decontamination of gardens, etc.
(removal of underbrush, etc.)

Photo courtesy of: Date City

Figure 2-21. Example of the decontamination of gardens and other areas(removal of soil, etc.)

Photo courtesy of: Date City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-12. Necessary measures prior to the decontamination of gardens and otherareas
Category
Prevention ofdispersion

Decontamination methods and notes of caution• If sidewalks and buildings are immediately adjacent, curing shall be
performed to prevent dispersion of water, etc.

Table 2-13. Decontamination methods for gardens and other areas and notes ofcautionCategory
Deep plowing or
removal of soil
and other
substances at
hotspots

Soil gardens, etc.

Removal ofunderbrush, etc.

Deep plowing

Gravel and crushed stone gardens, etc.

Scraping
away surface
soil

Covering thesurface soilHigh pressurewatercleaning ofgravel andcrushedstonesRemoval ofgravel andcrushedstones

Decontamination methods and notes of caution• Fallen leaves, moss, mud, and other sediments shall be removed byhand by people wearing rubber gloves and by shovel, etc.
• The soil at hotspots below rainwater guttering and the like shall be deep
plowed or removed. When this is implemented attention must be paid tothe depth of the contamination.
• In cases where it is difficult to perform deep plowing at a location, suchas with soil that has been packed into rainwater chambers and the like,consideration shall be given to performing deep plowing in the vicinityof said rainwater chambers.
• Before performing the deep plowing and the scraping away of topsoil,
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.
• 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 same as
it was before.
• A bamboo winnow or similar instrument shall be used to uniformly
scrape away the garden topsoil.
• Attention shall be paid to the fact that due to the planted vegetation andunevenness relative to the ground there may be reduced certainty withthe decontamination work.
• The surface soil shall be covered with soil that does not containradiocaesium.
• A shovel or the like shall be used to place the gravel or crushed stones
into a water tank and then perform high pressure water cleaning.
• 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 be raised gradually while
checking the flow of cleaning water and the dispersion conditions.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.
• The gravel or crushed stones shall be uniformly removed with a shovel
or the like.
• When gravel or crushed stones are removed, the area shall be coveredby using the same type of gravel or crushed stones as before as needed,
and it shall be covered to the same standing height as before and toabout the same compactness as before.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures• 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.

(6)

Decontamination of Street Drains, etc.
Figure 2-22. Basic flow for the decontamination of street drains, etc.

Decontamination ofstreet drains, etc.
Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following
the decontamination

Removal of sediments (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 the water andother materials

Brush cleaning
High pressure water cleaning

Wastewater treatment (*where needed)

Work that is being considered for
implementation in regions where theair dose rate is comparatively highFallen leaves, dirt, etc. with radioactive materials on or in them, which have flowed
down from roofs, etc. due to rain will have collected in street drains, rainwaterchambers, and other fixtures for collecting water and drainage, so therefore these shallbe removed with a shovel or the like (see Figures 2-23 and 24). When performing deep
plowing at rainwater chambers it will be difficult to carry this out in such locations, andso deep plowing shall be carried out in the vicinity of said rainwater chambers (seeFigure 2-25).
Furthermore, this shall be followed by cleaning with a brush or high pressure watercleaning (example: 15 MPa) as needed to reduce the radiation dose in the surrounding
vicinity. When performing cleaning using water, attention must be given to the drainage
channel, etc.
Cleaning with water generates drainage that contains radioactive materials. To minimize
the impact of the drainage produced by cleaning, etc. on the outflow destination, any
radioactive materials that can be removed by a method besides cleaning with water shallbe removed in advance whenever possible through workarounds that include wiping. If

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

the joints in the concrete of the street drain are thick, the decontamination effect will be
reduced. With plastic rainwater chambers and the like, it is effective to wipe these downwith sponges, waste cloth, or so forth.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of street drains and similar infrastructure are asprovided in Tables 2-14 and 2-15.
Figure 2-23. Example of the decontamination of a street drain(removal of sediments)

Photo courtesy of: Koriyama City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-24. Example of the decontamination of a rainwater chamber(removal of sediments)

Photo courtesy of: Fukushima City

Figure 2-25. Example of the decontamination of a rainwater chamber (removal of
sediments and deep plowing of the rainwater chamber sediments at the same site)

Photo courtesy of: Matsudo City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-26. Example of the decontamination of a street drain(high pressure water cleaning)

Photo courtesy of: Fukushima City

Figure 2-27. Example of the decontamination of a rainwater chamber(sponge cleaning)

Photo courtesy of: Matsudo City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-14. Necessary measures prior to the decontamination of street drains, etc.
Category
Prevention ofdispersion
Ensuring
drainage channels
and wastewater
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 to flow
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Table 2-15. Decontamination methods for street drains, etc. and notes of caution

Cleaning

Removal of sediments

Decontamination methods and notes of caution
Category
Decontamina • Fallen leaves, moss, mud, and other sediments that are easy to removetion throughshall be removed in advance by shovel, etc.
manual labor • When the concrete joints of street drains are deep, a spatula or the likeshall be used to remove the sediments from the joints.
• When performing deep plowing at rainwater chambers it will bedifficult to carry this out in such locations, and so deep plowing shallbe carried out in the vicinity of said rainwater chambers.
• In cases where sediment gets clogged in rainwater chambers and water
overflows out of street drains like when it rains contamination will
sometimes spread to the surroundings. In such cases the groundsurface of the surroundings shall be measured and decontamination
work shall be carried out in accordance with the configuration of
the ground surface.
Brush• Cleaning shall be thoroughly performed by using a deck brush or
cleaningbroom.
• 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, cleaning shall bepressure
performed at low pressure initially and the pressure shall be raisedwater
gradually while checking the flow of cleaning water and the dispersion
cleaning
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 speedof movement.

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4.

Post-Work Measures

Post-work measures, which include handling the removed soil and treating thewastewater generated by the decontamination work, as well as cleaning equipment, arelisted below.
(1)

Handling the Removed Soil, etc.
Figure 2-28. Basic flow for handling the removed soil, etc.

Handling the removed soil, etc.

Removed soil
Measures necessary to
prevent dispersion

Decontamination waste(vegetation, protective equipment, etc.)
Implement the appropriate
response in accordance with
the Waste Guidelines

Measure and record theradiation dose
On-site storage or transfer totemporary storage 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”

The removed soil, etc. shall be appropriately handled and transferred to on-site storage
or a temporary storage site. Please refer to “Part 4: Guidelines Pertaining to the Storageof Removed Soil” and “Part 3: Guidelines Pertaining to the Collection and Transfer ofRemoved Soil” for information on transfer to on-site storage and temporary storage sites.
Since the equipment and materials used for wiping and cleaning may have radioactive
materials on them, appropriate management is required for these items as well.
The other constituents of the removed soil, etc. shall be divided into removed soil anddecontamination waste (vegetation, protective equipment, etc.) to the extent possible
and placed in separate bags or other containers, among other measures necessary to
prevent dispersion. Since it will be necessary to ascertain the radiation dose whentransferring these items to temporary storage sites and storing them, to facilitate this the
air dose rate at the surface (1 cm from the surface) of the containers into which theremoved soil, etc. has been placed shall be measured and recorded. Please refer to the
Waste Guidelines (March 2013, Vol. 2) for information on the handling of thedecontamination waste generated during the decontamination process.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-16. Methods for the handling of removed soil, etc. and notes of caution
Category
Handling theremoved soil, etc.

(2)

Decontamination methods and notes of caution• To prevent dispersion, the removed soil, etc. shall be placed in bags orother containers and closed or sealed, or wrapped in sheets or similarmaterial.
• The removed soil, etc. shall be separated from decontamination waste
to the extent possible and placed in separate bags or other containers
to ensure 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
set of multiple containers holding the removed soil, etc. shall bemeasured, and the radiation dose of the removed soil, etc. generated
by the decontamination work shall be recorded and displayed in amanner that roughly 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.

Wastewater Treatment

In cases where wastewater is generated as a result of decontamination, wastewater
treatment shall be carried out as needed.
Most radiocaesium exists in a configuration in which it is strongly adsorbed on soil
particles, and it is characterized by the fact that it hardly elutes in water at all. Therefore,
it is effective to carry out activities like the removal of sediments and wiping.
For decontamination in decontamination zones (zones subject to the decontaminationplans established by municipalities) there is essentially no need to treat wastewater incases where sediments are removed. However, wastewater treatment shall essentially be
carried out in situations where the wastewater is highly turbid or for wastewater that has
been recovered from water recovery-type high pressure water cleaning.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-29. Basic flow for wastewater treatment
Wastewater treatment

Decontamination of roofs, rainwater guttering, roads, etc.

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

Cases wherewastewater treatment iscarried out

Water recovery-typehigh pressure watercleaning

Cases where thedestination thewastewater flows
to is the soil
Filtration
treatment via soil

Sedimentation treatment using
street drains

Sedimentation treatment using watertanks

Strippingaway anddeep plowing
of soil

Water collection (damming
street drains with sandbags)

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

Soil particles
withradiocaesium
adhering to them
are stopped by
the soil and thesoil is removed.

Sedimentation of suspended
solids (soil particles, etc.)

Water collection via
rainwater chambers
is also possible

SupernatantliquidSedimentation of suspended
solids (soil particles, etc.)

SupernatantliquidCollection of
the sediment

Discharge

Discharge

Use coagulants asneededCollection of
the sediment

Discharge

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

With regard to the wastewater from after the decontamination of rooftop rainwater
guttering and the like, there will be cases where rooftops lack such rainwater gutteringand cases where the areas under such guttering consist of soil. In such cases it will
presumably be possible to filter the radioactive materials present within the wastewater
through the soil found below since the destination to which it will flow will be soil. In
these cases it will be possible to recover the radioactive materials by removing this soil
after the decontamination of the rooftops and so forth by essentially adhering todecontamination work that proceeds from high places to low ones.
In cases where the discharge destination for the wastewater consists of street drains andthe like, the water shall be collected by damming up the street drains using sandbags orsimilar equipment as needed, then sedimenting out the particulate matter, collecting the

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

sediment, and discharging the supernatant liquid. As was stated above, since theradiocaesium adheres to the particulate matter found within the wastewater there are
hardly any radioactive materials contained within the supernatant liquid.
Other wastewater that is generated as a result of decontamination shall be collected tothe extent possible. Wastewater that has been collected via plastic containers andtemporary pools, as well as that recovered by water recovery-type high pressure watercleaning shall have its particulate matter sedimented out, then the water in the
supernatant liquid shall be discharged while the sediment is collected. For the
sedimentation of the particulate matter, agents to cause the liquid to undergo
coagulating sedimentation as well as filters for removing the particulate matter shall be
used as needed.

Figure 2-30. Example of wastewater treatment(sedimentation treatment using street drains)

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Figure 2-31. Example of wastewater treatment(sandbags installed in street drains)

Photo courtesy of: Fukushima City

Figure 2-32. Example of wastewater treatment(sedimentation treatment using water tanks)

Photo courtesy of: Koriyama City

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

Table 2-17. Necessary measures prior to wastewater treatment
Category
Ensuring
drainage channels
and wastewater
treatment

Decontamination methods and notes of caution• The channel down which the wastewater will flow shall be checked
beforehand and the drainage channel cleaned in advance to enablesmooth drainage.

Table 2-18. Methods for wastewater treatment and notes of caution
Category
Filtration
treatment via soil

Sedimentation
treatment using
water tanks

Sedimentation
treatment using
street drains

Decontamination methods and notes of caution• When the area under rainwater guttering consists of soil, radiation
shall be captured by flushing wastewater generated on rooftops down
to the soil via the rainwater guttering, and then said top layer of soil
shall be removed after the decontamination of the rooftop.
• Water shall be collected in plastic containers or temporary pools, thensedimenting out the particulate matter, and discharging the water fromthe 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.
• The water shall be collected by damming up the street drains using
sandbags, then sedimenting out the particulate matter, anddischarging 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.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

 Forms in which Radiocaesium Is FoundThe radioactive materials that resulted from the accident at the Fukushima Daiichi
Nuclear Power Plant were emitted, advectively diffused over a broad range in the formof aerosols and the like, and fell to and were deposited on the ground through rainfall.
The radiocaesium that presently accounts for the majority of the environmental
radiation is thought to have dissolved in rainwater and fallen in the form of ions.
Having fallen and been deposited on the ground’s surface, this radiocaesium hascurrently strongly been absorbed primarily within soil particles (Table 2-19).
The radiocaesium in the water in rivers, lakes, marshes, and so on exists in trace
amounts as dissolved bodies, with the majority of it present in a form in which it has
been absorbed into soil particles and other turbid materials. It has been learned from themonitoring of the water in rivers, lakes, marshes, and so on that these largely do notcontain radiocaesium (Table 2-20).
Moreover, it has also been learned that radiocaesium is largely not contained in thewastewater from when cleaning is carried out after the removal of sedimentation (Table
2-21).
 The radiocaesium adhering to soil hardly elutes into water at all.
Table 2-19. Elution of caesium from soil into water (results of an elution test)

Soil (1)Soil (2)Radiocaesium content(Bq/kg – wet)
16770
14250

Moisturecontent
29.8%
13.0%

Radiocaesium elution concentration(Bq/L)
Under the elution limit
Under the elution limit

Test method: JIS K0058-1 Agitation test with soil present
Test limits: 17.2 Bq/L for Soil (1) and 16.9 Bq/L for Soil (2)Source: National Institute for Environmental Studies, Japan: Proper Waste Disposal and Treatment from the
Perspective of the Behavior of Radioactive Materials (Technical Data: Volume 3) (December 20, 2012)

 Radiocaesium is hardly contained at all in the water of rivers, lakes, andmarshes.
Table 2-20. Monitoring data for public water areas
In a recent survey on the water quality in rivers, lakes, marshes, water sources, and the coastsof Fukushima Prefecture, radiocaesium was not detected (less than 1 Bq/L) at 201 locations
out of the 216 tested. Of the 15 locations where it was detected, 14 had less than 10 Bq/L, andfor the one location that is in an area where recovery will be difficult where the maximum
value (100 Bq/L) was detected, the location has a shallow water depth and turbid water.
Source: Ministry of the Environment: Measurement Results on the Monitoring of Radioactive
Materials in Public Water Areas within Fukushima Prefecture (extracted from December –March) (March 29, 2013)

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures

 When sediment is removed, there is almost no radiocaesium found within thewastewater that results from cleaning.
Table 2-21. Radiocaesium concentration within wastewater generated as a resultof cleaning
After the sediment was removed the radiocaesium concentration contained within thewastewater cleaned was 36 Bq/L on average (n=19, Minimum value: 4 Bq/L, Maximum value:
131 Bq/L).
* Air dose rate in regions subject to decontamination: 1.24 uSv/h (measurement height: 1 m)
Decontamination method: After the sediment was removed from rooftops and other places they were wiped
down, cleaned with a brush, or washed by high pressure water cleaning according to
the situation
Source: Fukushima City

(3)

Cleaning of Equipment and Materials

With regard to the post-work handling of the equipment and materials used fordecontamination, as a general rule the Ministry of Health, Labour and Welfare’s
Ordinance on the Prevention of Ionizing Radiation Hazards related to Decontamination
Work of Soil Contaminated by Radioactive Materials Resulted from the Great East
Japan Earthquake and its Guidelines for Prevention of Radiation Hazards for Workers
Engaged in Decontamination and Other Duties (Labour Standards Bureau Notification
0615 No. 6 dated June 15, 2012) are to be followed. Moreover, over and above these itis pertinent to keep in mind the items listed in the table below out of consideration for
the impact on the surroundings.

Table 2-22. Methods for cleaning equipment and materials and notes of caution
Category
Cleaning
equipmentandmaterials

Details• Heavy machinery, vehicles, and other objects used for which there is
the possibility that a great deal of contaminated soil is adhering tothem shall be checked to confirm the extent to which said soil isadhering to them. Those objects to which a great deal of contaminatedsoil is adhering shall be cleaned in a designated location, and othermeasures shall be taken to ensure that the contaminated soil, etc. is
not spread around indiscriminately.
• Likewise for shovels and other tools, shoes, and work clothes towhich lots of contaminated soil is adhering, these shall be checked toconfirm the extent to which said soil is adhering to them. Thoseobjects to which a great deal of contaminated soil is adhering shall becleaned in a designated location, and other measures shall be taken to
ensure that the contaminated soil, etc. is not spread aroundindiscriminately.
• The wastewater generated by the cleaning shall be treated as neededby referring to “(2) Wastewater Treatment.”• When cleaning, the workers shall take care to ensure that they are notbathed in the spray from this.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures• In addition, even equipment or materials with a low possibility ofcontamination shall be checked to confirm whether or notcontaminated soil 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 down with 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
shall be placed in a box or bag, etc. to minimize dispersal of theattached matter.
• 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.

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Guidelines Pertaining to Decontamination and Other Measures II. Decontamination and Other Measures for Buildings and Other Structures5.

Post-Work Measures

To confirm the decontamination effect, the air dose rate, etc. after completion of thedecontamination work shall be measured and compared with the air dose rate, etc. thatwas measured prior to the commencement of the decontamination work. Measurementof the air dose rate, etc. shall be performed in accordance with the measurement
methods given in “Part 1: Guidelines for Methods for Investigating and Measuring the
Status of Environmental Pollution in Intensive Contamination Survey Areas” for eachmeasurement point indicated in Table 2-3 of “2. (1) Determination of Measurement
Points.”In addition to the air dose rate, etc. at each measurement point, any other information
pertaining to the decontamination work shall be recorded and stored.
Table 2-23. Subsequent measurements and records for the decontamination ofbuildings and other structures
Measurement of
air dose rate, 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, namesof the decontaminators, type of objects decontaminated,decontamination methods, total decontamination area (of soil, etc.),
the approximate weight of the removed soil, etc., and the status ofstorage 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 the storage ofremoved soil.

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

III. Decontamination and Other Measures for Roads
This section explains 1. Preparation, 2. Prior Measurements, 3. Decontamination
Methods, 4. Post-Work Measures, and 5. Subsequent Measurements and Records, inchronological order, pertaining to measures for decontamination of the paved surfacesof roads (including sidewalks), street drains, curbs, guardrails, and pedestrian
overpasses.
Figure 2-33. Basic flow for the decontamination and other measures for roads

1. Preparation(1) Measures to reduce public exposure in connection with decontamination
work(2) Equipment and materials

2. Prior
Measurements(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 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

When it comes to roads, a distinction is made between roads immediately adjacent tourban or residential areas and roads built through farmland, pastureland, and othernon-residential areas, and decontamination is implemented taking account of the levelof impact on pedestrians and people using vehicles as modes of transport.

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Guidelines Pertaining to Decontamination and Other Measures

III. Decontamination and Other Measures for Roads

Furthermore, the gravel and dirt on sidewalks and curbs are prioritized in roaddecontamination, as are roadsides due to the higher radiation dose levels compared withroad centers.
1.

Preparation

Before performing decontamination work, in addition to preparing the equipment
required for the decontamination work, preparations must be made to ensure safety
through means including prevention of exposure of the general public and workers suchas by inhaling dust generated during decontamination work. Among these preparations,please refer to the Ministry of Health, Labour and Welfare’s Ordinance on thePrevention of Ionizing Radiation Hazards related to Decontamination Work of Soil
Contaminated by Radioactive Materials Resulted from the Great East Japan Earthquake
and its Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
(1)

Measures to Reduce Public Exposure in Connection with Decontamination
Work
Table 2-24. Measures to reduce public exposure in connection withdecontamination and other work for roads
Restriction ofentry

Signage(2)• In cases where the general public is deemed likely to enter the area,
the area shall be cordoned off with pylons or rope, etc. to prevent
people from unnecessarily approaching the work site, and the entryof people and vehicles shall be restricted.
• In cases where radioactive materials may be dispersed in connection
with the decontamination work, the perimeter of thedecontamination area shall be fenced in with sheets, etc., water shallbe sprayed, or other such measures shall be taken to prevent
dispersion and the area shall be cordoned 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 (see Figure 2-4).

Equipment and Materials

The required equipment and materials shall be arranged for decontamination and othermeasures, as well as for collection of the removed soil, etc., in accordance with theobjects to be decontaminated and the work environment.
Table 2-25. Examples of equipment and materials for the decontamination of roads
GeneralexamplesMower, 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, wheelbarrow, etc.), aerial vehicle, ladder, road sweeper

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

Examples forcleaning withwater
Examples for
scraping off

Examples forremoval of
topsoil
Examples ofequipment forcovering the soil
surface2.

Hose for water discharge, high pressure water cleaner, drainage
pavement functional recovery car, brushes (scrub brush, brush forcleaning vehicles, etc.), tools for pushing away water (broom, scraper,etc.), bucket, detergent, dustcloth, sponge, paper towels
Shot blaster, surface cutter, vibration drill, needlegun, grinding
machine, equipment for scraping away, ultra high pressure watercleaner, equipment needed to prevent dispersion (dust collector, curing
material)
Backhoe, bulldozer, hydraulic shovel

Self-propelled surface compaction roller, plywood for surface
compaction, sprinkling equipment

Prior Measurements

To confirm the decontaminating effects of the decontamination work, the air dose rateprior to the commencement of decontamination work and after the completion of
decontamination work*2 and the surface contamination density of the objects subject todecontamination (hereinafter, “air dose rate, etc.,” which includes both the air dose rate
and the surface contamination density) shall be measured. Specifically, places
representative of living spaces, places contaminated at a comparatively highconcentration that is deemed to contribute substantially to the radiation dose in theliving space, etc. shall have their air dose rate, etc. measured in the same locations andby the same method both before contamination work starts and after it finishes, and theresults shall be recorded. This section gives information on methods for measuring the
air dose rate, etc. prior to the commencement of decontamination work.
Note that the air dose rate, etc. may also be measured near the surface of the objects
subject to decontamination as needed when ascertaining the degree of reduction in thelevel of contamination of the objects subject to decontamination during thedecontamination work. These measurements will be separately explained in “Section 3.
Decontamination Methods.”(1)

Determination of Measurement Points

Prior to decontamination work, the measurement points at which the air dose rate, etc.
will be measured shall be decided and a schematic diagram illustrating the range of themeasuring object, the measurement points, structures to be used as markers, etc. shall becreated (see Figure 2-34).
There are two types of measurement points: those used to ascertain the average air dose
rate on roads subject to decontamination (No. 1 measurement points) and those used toconfirm the level of contamination of the objects that are to be decontaminated (No. 2
measurement points).

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Guidelines Pertaining to Decontamination and Other Measures

III. Decontamination and Other Measures for Roads

No. 1 measurement points are set primarily in a living space where residents, etc. spend
large amounts of time. In setting these measurement points, so-called “hotspots” that
contribute comparatively insubstantially to the radiation dose in the living space, andpoints near them, are not eligible to be measurements points unless the users, etc. aredeemed likely to spend relatively large amounts of time there.
Examples of hotspots include depressed areas and puddles, street drains, water
catchment wells, under or near trees, or in places where raindrops falling from buildings
land, as radioactive materials tend to become concentrated in such places due torainwater and the like..
The purpose of No. 2 measurement points is fundamentally to measure the level ofcontamination at the surface of the objects subject to decontamination, and they are
therefore set by considering places, etc. contaminated at comparatively highconcentrations and that are deemed to contribute substantially to the radiation dose in
the living space. When measuring street drains and other hotspots that are subject todecontamination, these are to be measured as No. 2 measurement points.
The specific methods are as provided in Table 2-26.
Table 2-26. Reasoning behind the measurement points for air dose rates and othermeasures for the decontamination of roads
Measurement
pointsObjects subject
to measurement

No. 1 measurement point

No. 2 measurement points

Air dose rate in living spaces

Reasoningbehind themeasurement
points• Measurement points shall be
set at intervals that allow the
air dose rate distribution to beascertained near thecenterline of sidewalks.
• If there are no sidewalks,appropriate points shall be
determined by confirming theusage status of the road.
(Example)
Pitch of approx. 10 – 30 m

Surface contamination density, etc.
for objects subject todecontamination• Measurement points shall be set atintervals that allow the air doserate, etc. distribution to beascertained for each road surface,road shoulder, street drain, andsidewalk.
(Example)
Pitch of approx. 10 – 30 m

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

Figure 2-34. Example of a schematic diagram for reporting measurement points
for use in decontamination and other measures for roads
10 m - 30 m
1)

Sidewalk

Shoulder

2)

1)

2)

2)

2)

Road
2)

2)

2)

1): Contamination status for living spaces
2): Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)(2)

Measurement Methods

When measuring the air dose rate at a No. 1 measurement point, a scintillation survey
meter or other measuring apparatus able to measure gamma rays shall be used. With
respect to the measurement locations, measurements shall be performed at one location
roughly every 10 – 30 m in locations where people spend a lot of time, such as in thevicinity over the median line down sidewalks. In cases where there are sidewalks on
both sides and decontamination and other measures are slated to be carried out on bothsides, then measurement shall be carried out on both sidewalks as well. Moreover, whenit comes to demarcating the measured sections, for those sections that are slated to betargeted for decontamination and other measures, demarcations are to be established byusing markers such as units of areas, municipal blocks, city road numbers, or the like(for privately-owned land, use the grounds of said privately-owned land) as guideposts.
The need to conduct decontamination and the contents of this shall be determined foreach of these sections based on the mean values for multiple measured values within thesections. Please pay due consideration to the fact that in some cases road measurements
are prone to being affected by things like the surrounding facilities on account of theirunique characteristics.
In contrast, to avoid the effects of background radiation when measuring the level ofcontamination on or near surfaces at a No. 2 measurement point, it is recommended touse a GM survey meter able to measure beta rays, but it is also acceptable to performthe measurements using a dosimeter capable of measuring gamma rays. For example,
one way to make specialized confirmation based on the levels of contamination at therelevant sites is to perform the measurements under conditions where a collimator isused to shield against gamma rays from the outside. In addition, for instance, it is2-57

Guidelines Pertaining to Decontamination and Other Measures

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possible to confirm the effect of the decontamination by determining the contamination
status of the objects subject to decontamination from the air dose rate measured at thesurface of the measurement points and at heights of 50 cm and 1 m, and then comparing
the results with those of measurements taken in the same positions after the completionof the decontamination work.
In general, the same measuring apparatus shall be used when measuring at the samemeasurement points before and after decontamination work.
When there are a large number of measurement points, the results of measurements, etc.
previously taken by local authorities, along with other monitoring technologies(monitoring cars, etc.), shall be utilized as needed.
For the specific methods, see “6. Measuring Apparatuses and Methods of Use” in “Part
1: Guidelines for Methods for Investigating and Measuring the Status of Environmental
Pollution in Intensive Contamination Survey Areas.”

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

3.

Decontamination Methods
Figure 2-35. Basic flow for the decontamination of roads

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

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

Decontamination results
Not effective
Effective
Conduct the decontamination from (1)– (3) as needed.

Cleaning via discharged
water (for target objects forwhich cleaning by water ispossible)(Proceed to the decontamination of low areas)

To decontaminate roads efficiently requires the decontamination work to be focused onplaces that are contaminated with comparatively high concentrations of radioactive
materials that contribute substantially to the radiation dose. For example, the radiationdose from roadsides, street drains, and curbs can be reduced by removing
radiocaesium-containing mud, grass, fallen leaves, and other sediments, because thesesediments frequently collect in such places.
In terms of decontamination stages, first the sediments that are relatively easy to removeby hand, etc. shall be removed, and if this results in no observable decontamination
effect, high pressure water cleaning (example: 15 MPa), covering the soil surface, or
scraping off shall be performed.
In each stage, the air dose rates at the No. 1 measurement points shall be measured, andas a general rule no additional decontamination work shall be performed provided theair dose rate at a height of 1 m (a height of 50 cm from the ground may be used forschool routes, etc. used primarily by students of elementary schools and below, as well

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as those of special-needs schools, with consideration for the living space of infants andschoolchildren in the lower grades) is less than 0.23 microsieverts per hour.
When water is used in decontamination work on roads or for similar work, radioactive
materials may be moved to the roadside or street drains. Therefore, when using water, it
is more efficient to first remove the sediments from the roadside and street drains, thenclean the road, and finally clean the roadside and street drains. Depending on how the
sediments are settled, decontamination work of the road surface shall employ cleaning
with a brush, drainage pavement functional recovery cars, high pressure water cleaning,or other methods.
Moreover, when performing decontamination work, the necessary measures to secure
the safety of the workers and the general public must be taken, and measures to preventthe spread of contamination due to dispersion, outflow, etc. associated withdecontamination work must be implemented so as to minimize contamination beingbrought out from within the work zone, contamination being brought in from outside, orrecontamination of the decontaminated zones. Among these preparations, please refer tothe Ministry of Health, Labour and Welfare’s Ordinance on the Prevention of Ionizing
Radiation Hazards related to Decontamination Work of Soil Contaminated byRadioactive Materials Resulted from the Great East Japan Earthquake and its
Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
When cleaning using water, it is important to ensure that no puddles are formed and nowater is splattered onto surrounding uncontaminated walls, etc., as well as to check thedrainage channel after cleaning. Furthermore, cleaning using water produces drainage
that contains radioactive materials. In such case, to avoid impact of the drainage on theoutflow destinations due to cleaning, etc. as much as possible, any radioactive materials
that can be removed by methods other than cleaning with water shall be removed inadvance whenever possible among other workarounds. Furthermore, one approach topreventing the dispersion of radioactive materials is to perform damming and similar
operations using sandbags and then remove the particulate matter from the wastewater
as needed. Using drainage pavement functional recovery cars, water recovery-type highpressure water cleaning, and so on are also effective for preventing the dispersion ofradioactive materials.
For example, when there is a concern that the drainage will flow into irrigation canals
for agricultural use, it is recommended to involve agriculture-related persons in the areaprior to the work and confirm that there is no impact by sampling at the irrigation canals
or similar methods. Also please arrange the overall schedule so as to avoid a large zone
undertaking decontamination within a municipality at the same time whenever possible,
in the interest of minimizing the impact of decontamination outside the zone.
See “4. Post-Work Measures” with regard to matters like the handling of the removed
soil, the treatment of wastewater, and the cleaning of the equipment used for thedecontamination.

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

This section covers decontamination methods for roadsides and street drains, which arethought to be places that are contaminated at comparatively high concentrations, as wellas paved surfaces and unpaved roads.
(1)

Decontamination of Paved Surfaces
Figure 2-36. Basic flow for the decontamination of paved surfaces
Decontamination of
paved roads
Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following
the decontamination

Remove sediment (fallen leaves, moss, dirt, etc.)
Removal via manual labor

Washing away items that could not becompletely taken away through theremoval of sediment with water at theend is effective

Cases where the results of decontamination cannot be adequately observed
Cleaning
Brush cleaning
High pressure water cleaning[Precautions] Take steps to prevent dispersal and outflows of the waterand 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

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]

Scraping away

 Take measures to prevent the dispersion of dust

Blast work
Ultra high pressure water cleaning
Scraping away

Wastewater treatment (* as needed)

Work that is being considered for
implementation in regions where theair dose rate is comparatively highAfter the prior removal of debris, etc. by hand or the like (fallen leaves, moss, grass,mud, dirt, etc.) from road and interlocking concrete surfaces, the asphalt joints andcracks shall be cleaned by brush. Curbs, guardrails, pedestrian overpasses, etc. shall becleaned using brushes, etc. and neutral detergents or high pressure water cleaning(example: 15 MPa). High pressure water cleaning is particularly effective for

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Guidelines Pertaining to Decontamination and Other Measures

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decontamination of joints and cracked portions. There is a possibility that theradioactive materials will have decreased as a result of rain and ordinary cleaning, so
first carry out cleaning in a partial manner and check to confirm that decontaminationfrom brush cleaning and high pressure water cleaning is effective before performing
overall cleaning.
After the cleaning work, the air dose rate, etc. shall be measured at the measurement
points to confirm that there has been no spread of the contamination to the outflow
destination for the drainage and that the decontamination has been effective.
In cases where the radiocaesium proves difficult to remove even with high pressure
water cleaning, shot-blasting work or ultra-high pressure water cleaning can be used toscrape away the surfaces of roads or other paved surfaces and thereby remove
radiocaesium in the joints of paved surfaces and in depressed areas that could not be
removed by cleaning or similar work, and this is expected to reduce the radiation dose.
However, this incurs greater costs than other decontamination methods, the work is
extensive, and large amounts of asphalt and concrete will be generated as a constituentof the removed soil, etc. It is therefore recommended that consideration be given to thescraping away of paved surfaces only when the road is adjacent to an urban orresidential area and the radiation dose cannot be sufficiently reduced using otherdecontamination methods. Whenever such work is performed, measures must be taken
to inhibit the dispersion of dust.
Moreover, when scraping away the material on interlocking concrete blocks, thereduction rate may decrease as a result of scrapings and radioactive materials remaining
behind in the gaps between the blocks. As such, using such methods as water
recovery-type high pressure water cleaning or ultra-high pressure water cleaning is also
effective for this. It is also effective to perform water recovery-type high pressure watercleaning on drainage pavement, rubber chip pavement, and similar types of paving(water permeable pavement, slab pavement, etc.).
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of paved roads are as provided in Tables 2-27 and
2-28.

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

Figure 2-37. Example of decontamination of paved surfaces(water recovery-type high pressure water cleaning)

Table 2-27. Necessary measures prior to the decontamination of paved surfaces
Category
Safetymanagement

Decontamination methods and notes of caution• If traffic cannot be stopped when the decontamination work is carriedout, 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 bedrainage channels
removed before cleaning with water.
and wastewater• When using water to clean, the channel for cleaning water to flow
treatment
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Table 2-28. Decontamination methods for paved surfaces and notes of caution

Cleaning

Removal of
sediments

Category
Decontamination methods and notes of caution
Removal• Fallen leaves, moss, mud, and other sediments shall be removed bythroughhand by people wearing rubber gloves, shovel, or road sweeper, etc.
manual labor
Brushcleaning• Cleaning shall be performed from high places to low ones so as 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 and drainage recovery

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functions may decline on surfaces where distortion or wear has
occurred due to the effects of earthquakes, etc.

Scraping awayHighpressurewater
cleaning

Blast work

Ultra-highpressurewater
cleaning
Scrapingaway• 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.
• Water recovery-type high pressure water cleaning is also effective.
• To achieve a decontamination effect, the spray nozzle shall be broughtnear the place to be decontaminated.
• When decontamination is carried out over a wide range, attention mustbe paid to ensure that no variance occurs between the work methods at
different points (height of the nozzle over the ground, work time perunit of surface area, etc.)• Abrasive materials shall be shot at the surface with a shot blaster andscraped away from said surface uniformly.
• In order to prevent dust from arising, curing, etc. shall be performed toprevent dispersion of dust to the surroundings and the dust shall becollected.
• For blast work, curing shall be performed to ensure that abrasive
materials and the like do not travel outside of the decontamination
work zone. What is more, after the abrasive materials and othermaterials 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.
• When scraping away material on interlocking concrete blocks,
attention must be paid to the fact that scrapings and radioactive
materials may be left behind in the gaps between the blocks.
• Ultra-high pressure water cleaner (cleaning water recovery-type) of
150 MPa or higher shall be used for scraping material away on paved
surfaces.
• A powerful vacuum truck shall be used to collect any scrapings thatarise.
• A surface cutter or the like shall be used to scrape away the 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.)

2-64Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads(2)

Decontamination of Unpaved Roads
Figure 2-38. Basic flow for the decontamination of unpaved roads

Decontamination of unpaved roads

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

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.

Deep plowing

Pressure wash gravel and crushedstonesScrape away the topsoil

Remove gravel and crushedstonesSlopes of roads
Remove underbrush, etc.

Scrape away the topsoil

Covering the soil surface
Wastewater treatment (*as 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 scraping away andremoval in advance.

Work that is being considered for
implementation in regions where theair dose rate is comparatively highFor unpaved roads surfaces, slopes, etc., first the debris, fallen leaves, moss, grass, mud,dirt, etc. shall be removed from the surface of the road, etc. by hand.
If this does not produce a decontamination effect, replacing the topsoil with subsoil(deep plowing), scraping away the topsoil, or covering the soil surface using heavymachinery, etc. can be expected to reduce the radiation dose, because the radiocaesium
is settled near the surface. However, deep plowing, covering the soil surface, andscraping away the topsoil incurs greater costs than other decontamination methods andinvolves extensive work. It is therefore recommended that consideration be given tosuch methods only when the road is adjacent to an urban or residential area and theradiation dose cannot be sufficiently reduced using other decontamination methods.
 Soil roads, etc.
Deep plowing is the method of covering the soil surface by replacing theradiocaesium-containing upper layer of the soil with a lower layer of the soil that does

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Guidelines Pertaining to Decontamination and Other Measures

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not contain radiocaesium. Carrying out deep plowing can be expected to reduce theradiation dose and to inhibit the diffusion of radiocaesium by shielding with soil, etc.
Moreover, these have the advantage of not generating removed soil, because they do not
scrape away the topsoil. When performing deep plowing, approximately 10 cm ofsurface soil shall be placed at the lower layer and covered with approximately 20 cm of
excavated soil from the lower layer. When performing this procedure, it is necessary to
avoid scattering the surface soil or mixing it with the soil excavated from the lower
layer. When implementing this over a large area, the implementation area shall be
partitioned in an appropriate manner (see Figure 2-19).
When scraping away topsoil, it is important to select an appropriate thickness for thesoil to be scraped away, in order to avoid generating too much removed soil, etc.
Specifically, for the soil surfaces to be scraped away, it is recommended to start withsmall areas (an area of a size that enables the air dose rate, etc. of the soil surface to bemeasured with minimal interference from radiation outside the area) and scrape away
about 1 to 2 cm of topsoil while measuring the air dose rate, etc., then determine thethickness of the layer to be scraped away (see Figure 2-52 2), 3), and 4)). According toconventional wisdom it is believed that adequate results can be achieved by scraping
away at most about 5 cm of the soil surface. If the thickness of soil to be removed is thin,another effective method is to use a solidification agent that enables the thickness of thesoil to be restricted to a level that is relatively easy to scrape away, depending on thetype of topsoil: sandy soil, silt, clay, etc. In places where the topsoil has been removed,
topsoil shall be brought from another location by using uncontaminated soil as needed.
For covering the soil surface, the approach is to cover the top layer of soil that contains
radiocaesium with soil that does not contain radiocaesium. This can be expected toreduce the radiation dose and to inhibit the diffusion of radiocaesium by shielding itwith soil. This has the advantage of not generating removed soil since the topsoil is not
being removed. When performing this covering, it is important to select an appropriate
covering thickness for purposes of shielding in order to avoid having the covering
thickness become excessively large.
The geometric area of unpaved roads adjacent to urban or residential areas is expected
to be relatively small, meaning that in some cases it will be more efficient to scrapeaway the soil than to cover the soil surface. Therefore, when employing either method,the optimal method shall be selected in consideration of the costs and the amount ofremoved soil, etc. expected to be generated by the two methods.
When the topsoil has been removed, soil from elsewhere shall be placed on the portions
where the topsoil has been removed, and it shall be compacted to restore it to thecondition it was in before the work. Care shall be taken to avoid landslides, etc. on thesides when adding on other soil and compacting it.
 Gravel and crushed stone roads, etc.
For gravel or crushed stones, etc., place the gravel or crushed stones in a water tank and2-66

Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

remove the radioactive materials from them by agitating and high pressure watercleaning, then lay them out again after they have been cleaned. See “II. 4. (2)Wastewater Treatment” regarding the handling of wastewater when performing highpressure water cleaning, etc.
For cases where results are not considered to have been adequately observed even after
cleaning has been carried out, then the gravel and crushed stones shall be removed
evenly with the use of a backhoe or other instrument. When gravel or crushed stones are
removed, the area shall be covered by using the same type of gravel or crushed stones as
before as needed, and it shall be covered to the same standing height as before and toabout the same compactness as before.
On roads where gravel and crushed stones have been laid out there is the possibility thatradioactive materials have been accumulated in the soil below the gravel and crushedstones as time passes. As such, there may be cases where it will be necessary to make adetermination on whether decontamination should be carried out on the gravel andcrushed stones or the soil below them. In doing so, it will be necessary to decide on adecontamination method by properly performing measurements and conducting
experiments.
 Slopes of roads
For the decontamination of the slopes of roads, decisions on carrying out thedecontamination shall be made in view of factors like the contamination status, as wellas the safety and usage status of the slope following the decontamination. During topsoil
removal in particular, consideration must be given to the properties of the slope (incline,
soil and rock quality) and the presence of any vegetation. If the slope has been sodded
to protect it and after first removing plants or decontaminating the protective structuralelements there is no decontamination effect, topsoil removal shall then be performed.
Specific methods include collecting the soil by hand using small shovels, etc., using
backhoes or other heavy machinery, and collecting the soil using an air suction pipe orother dedicated device. When implementing topsoil removal, the soil shall be removed
from the top, proceeding downward. For topsoil removal on slopes, the area of topsoil
removable in a single batch shall be removed and collected each time, but since the soil
is deemed likely to slide down due to the removal work, the work shall only be
performed after taking the necessary measures to prevent the outflow of soil. Since dust
will be generated during the removal of topsoil, dispersion must be prevented bysprinkling with water.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of unpaved roads are as provided in Tables 2-29 and
2-30.

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Guidelines Pertaining to Decontamination and Other Measures

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Figure 2-39: Example of the decontamination of an unpaved road (scraping away)

Photo courtesy of: Date City

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

Table 2-29. Necessary measures prior to the decontamination of unpaved roads
Category
Prevention ofdispersion

Decontamination methods and notes of caution• When scraping away the topsoil when it comes to dried soil, efforts
can be made to prevent the dispersion of dust by scatteringsolidification agents over the area in advance to solidify the soil
surface.

Table 2-30. Decontamination methods for unpaved roads and notes of caution

Slopes of roads

Gravel and crushed stone roads, etc.

Soil roads, etc.

Removal of
sediments

Category
Decontamination methods and notes of caution
Removal• Soil with fallen leaves, moss, mud, and other sediments shall bethroughremoved by hand by people wearing rubber gloves and by shovel,
manual laboretc.
• 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 backhoe or the like shall be used to uniformly scrape away theaway topsoil
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.)
Covering the • The surface soil shall be covered with soil that does not containsurface soilradiocaesium.
High• A backhoe or the like shall be used to place the gravel or crushedpressurestones into a water tank and then high pressure water cleaning will bewater
performed.
cleaning of• To prevent dispersion of soil, etc. by water pressure when performing
gravel andhigh pressure water cleaning, cleaning shall be performed at low
crushedpressure initially and the pressure shall be raised gradually whilestoneschecking the flow of cleaning water and the dispersion conditions.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.
Removal of • The gravel or crushed stones shall be uniformly removed with agravel andbackhoe or the like.
crushed• When gravel or crushed stones are removed, the area shall be coveredstonesby 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 thesame 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 of • Weed removal and weeding shall be conducted using a shoulder-type
underbrushmower or human power.
Removal of • Human power, a backhoe, or the like shall be used to uniformly scrape
topsoilaway the surface.
• Dispersion to the surroundings shall be prevented when scraping away
contamination.
Deepplowing2-69

Guidelines Pertaining to Decontamination and Other Measures

III. Decontamination and Other Measures for Roads(Example: use of dust collectors, sprinkling in advance, setting up
simple plastic housings, etc.)(3)

Decontamination of Roadsides and Street Drains
Figure 2-40. Basic flow for the decontamination of roadsides and street drains

Decontamination of roadsides andstreet 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 be adequately observed

Cleaning[Precautions] Take steps to prevent dispersal and outflows of the water andother materials

Brush cleaning
High pressure water cleaning

Wastewater treatment (*where needed)

Work that is being considered for
implementation in regions where theair dose rate is comparatively highFor places where rainwater readily collects, the roots of plants, places where moss is
growing, etc., any fallen leaves, mud, dirt, etc. on the roadside shall be collected, grassand other plants shall be trimmed, and sediment shall be removed, after which cleaning
shall be conducted with scrub brushes, scrubbing brushes, etc. using water (see Figure
2-41 and Figure 2-42).
In general, the decontamination of street drains shall be carried out in accordance with
“II. 3. (6) Decontamination of Street Drains, etc.” In the case of street drains that arecovered with thick concrete lids and closed conduits that do not have an impact on the
air dose rate, it is not necessary to remove sediments. But in the case of street drains
covered with lids that could conceivably have an impact on the air dose rate as a resultof outflows or the like, consideration shall be given to performing decontamination
through high pressure water cleaning or the like after measures such as damming up theway downstream have been carried out to prevent outflows and dispersion of sediments
due to water discharge.
After the cleaning work, the air dose rate, etc. shall be measured at the measurement
points to confirm that there has been no spread of the contamination to the outflow
destination for the drainage and that the decontamination has been effective.
The measures that are required in advance, specific decontamination methods, and notes

2-70Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roadsof caution for the decontamination of roadsides and street drains are as provided inTables 2-31 and 2-32.
Figure 2-41: Example of decontamination of street drains(sweeping up dirt and dust)

Photo courtesy of: Date City

Figure 2-42: Example of the decontamination of street drains(removal of sediments)

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Photo courtesy of: Fukushima City

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Guidelines Pertaining to Decontamination and Other Measures III. Decontamination and Other Measures for Roads

Table 2-31. Necessary measures prior to the decontamination of roadsides andstreet drains
Category
Prevention ofdispersion
Ensuring
drainage channels
and wastewater
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 to flow
shall be checked beforehand and the drainage channel cleaned inadvance to enable smooth drainage.
• See “4. (2) Wastewater Treatment” regarding the treatment ofwastewater.

Table 2-32. Decontamination methods for roadsides and street drains and notes ofcautionDecontamination methods and notes of caution• Fallen leaves, moss, mud, and other sediments that are easy to remove
shall be removed in advance by shovel, etc.
• When the concrete joints of street drains are deep, a spatula or the likeshall be used to remove the sediments from the joints.

Brushcleaning• 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 cleaning water and thedispersion conditions.
• To achieve a decontamination effect, the spray nozzle shall be broughtnear the place to be decontaminated.

Cleaning

Removal of
sediments

Category
Removalthroughmanuallabor

Highpressurewater
cleaning

4.

Post-Work Measures

Post-work measures, which include handling the removed soil and treating thewastewater generated by the decontamination work, as well as cleaning of equipment
and materials, are listed below.
(1)

Handling the Removed Soil, etc.

The removed soil, etc. shall be appropriately handled and transferred to on-site storage
or a temporary storage site.
Please refer to “II. 4. (1) Handling the Removed Soil, etc.” for specific methods forhandling the removed soil.
(2)

Wastewater Treatment

When carrying out decontamination that uses water, the appropriate countermeasuresagainst wastewater shall be taken to prevent the secondary contamination of theenvironment.

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Guidelines Pertaining to Decontamination and Other Measures

III. Decontamination and Other Measures for Roads

See “II. 4. (2) Wastewater Treatment” for specific methods for treating wastewater.
(3)

Cleaning of Equipment and Materials

With regard to the post-work handling of the equipment used for decontamination, theMinistry of Health, Labour and Welfare’s Ordinance on the Prevention of Ionizing
Radiation Hazards related to Decontamination Work of Soil Contaminated byRadioactive Materials Resulted from the Great East Japan Earthquake and its
Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) are to be followed.
See “II. 4. (3) Cleaning of Equipment and Materials” for specific methods for cleaning
the equipment and materials.
5. Subsequent Measurements and Records
To confirm the decontamination effect, the air dose rate, etc. after completion of thedecontamination work shall be measured and compared with the air dose rate, etc. thatwas measured prior to the commencement of the decontamination work. Measurementof the air dose rate, etc. shall be performed in accordance with the measurement
methods given in “Part 1: Guidelines for Methods for Investigating and Measuring the
Status of Environmental Pollution in Intensive Contamination Survey Areas for eachmeasurement point indicated in Table 2-26 of “2. (1) Determination of Measurement
Points.”In addition to the air dose rate, etc. at each measurement point, any other information
pertaining to the decontamination work shall be recorded and stored.
Table 2-33. Subsequent measurements and records for the decontamination ofroads
Measurement of
air dose rate, 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, namesof the decontaminators, type of objects decontaminated,decontamination methods, total decontamination area (of soil, etc.),
the approximate weight of the removed soil, etc., and the status ofstorage 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 the storage ofremoved soil.

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Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for SoilIV. Decontamination and Other Measures for Soil
This section explains 1. Preparation, 2. Prior Measurements, 3. Decontamination Methods, 4.
Post-Work Measures, and 5. Subsequent Measurements and Records, in chronological order,
pertaining to decontamination and other measures for soil in schoolyards, kindergarten yards, parks,
farmland, and other comparatively large land spaces.

Figure 2-43. Basic flow for decontamination and other measures for soil
(1) Measures to reduce public exposure in connection with decontamination work
1. Preparation(2) Equipment and materials

2. Prior
Measurements(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 the soil at schoolyards,
kindergarten yards, and parks

4. Post-Work
Measures(1) Handling the removed soil, etc.
(3) Cleaning the equipment and materials, etc.

5. Subsequent Measurements and Records

2-75(2) Decontamination of
farmlandGuidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

1.

Preparation

Before performing decontamination work, in addition to preparing the equipment
required for the decontamination work, preparations must be made to ensure safety
through means including prevention of exposure of the general public and workers suchas by inhaling dust generated during decontamination work. Among these preparations,please refer to the Ministry of Health, Labour and Welfare’s Ordinance on thePrevention of Ionizing Radiation Hazards related to Decontamination Work of Soil
Contaminated by Radioactive Materials Resulted from the Great East Japan Earthquake
and its Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
(1)

Measures to Reduce Public Exposure in Connection with Decontamination
Work
Table 2-34. Measures to reduce public exposure in connection withdecontamination and other measures for soil
Restriction ofentry

Signage• In cases where the general public is deemed likely to enter the area,
the area shall be cordoned off with pylons or rope, etc. to prevent
people from unnecessarily approaching the work site, and the entryof people and vehicles shall be restricted.
• In cases where radioactive materials may be dispersed in connection
with the decontamination work, the perimeter of thedecontamination area shall be fenced in with sheets, etc., water shallbe sprayed, or other such measures shall be taken to prevent
dispersion and the area shall be cordoned 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 (see Figure 2-4).

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Guidelines Pertaining to Decontamination and Other Measures(2)

IV. Decontamination and Other Measures for Soil

Equipment and Materials

The required equipment and materials shall be arranged for decontamination and othermeasures, as well as for collection of the removed soil, etc., in accordance with theobjects to be decontaminated and the work environment.
Table 2-35. Examples of decontamination equipment and materials for soil
Generalequipment
examplesDecontamination equipment for use on
farmland

Examples ofequipment forcleaning withwater
Examples ofequipment forremoval of
topsoil
Examples ofequipment forcovering soil
surfaces
Examples ofequipment
for scraping
away
topsoil
Examples ofequipment
for mixing
with water
Examples ofequipmentforinversiontillage anddeep tillage

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. to the on-sitestorage location or temporary storage site (truck, two-wheeled cart,etc.), aerial vehicle, ladder
Hose for water discharge

Bulldozer, hydraulic shovel

Self-propelled surface compaction roller, plywood for surface
compaction, sprinkling equipment

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

Tractor, deep-tillage plow, deep-tillage rotary, mower

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Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

2.

Prior Measurements

To confirm the decontaminating effects of the decontamination work, the air dose rateprior to the commencement of decontamination work and after the completion of
decontamination work*2 and the surface contamination density of the objects subject todecontamination (hereinafter, “air dose rate, etc.,” which includes both the air dose rate
and the surface contamination density) shall be measured. Specifically, places
representative of living spaces, places contaminated at a comparatively highconcentration that is deemed to contribute substantially to the radiation dose in theliving space, etc. shall have their air dose rate, etc. measured in the same locations andby the same method both before contamination work starts and after it finishes, and theresults shall be recorded. This section gives information on methods for measuring the
air dose rate, etc. prior to the commencement of decontamination work.
Note that the air dose rate, etc. may also be measured near the surface of the objects
subject to decontamination as needed when ascertaining the degree of reduction in thelevel of contamination of the objects subject to decontamination during thedecontamination work. These measurements will be separately explained in “Section 3.
Decontamination Methods.”
Moreover, for farmland it is necessary to check the concentration of radiocaesium in thesoil in the interest of inhibiting the absorption of radioactive materials, in addition to
reducing the exposure dose for surrounding residents.*5 This shall involve checking theconcentration of radiocaesium in the plow layer*6 of the soil, taking account of the depthof the roots of any crops that could absorb radiocaesium.
(1)

Determination of Measurement Points

Prior to decontamination work, the measurement points at which the air dose rate, etc.
will be measured shall be decided and a schematic diagram illustrating the range of themeasuring object, the measurement points, structures to be used as markers, etc. shall becreated (see Figure 2-44, Figure 2-45, and Figure 2-46).
There are two types of measurement points: those used to ascertain the average air dose
rate in the space for soil, etc. subject to decontamination (No. 1 measurement points)
and those used to confirm the level of contamination of the objects that are to be
decontaminated (No. 2 measurement points).
No. 1 measurement points are set primarily in a living space where residents, etc. spend
large amounts of time. In setting these measurement points, so-called “hotspots” that
contribute comparatively insubstantially to the radiation dose in the living space, andpoints near them, are not eligible to be measurements points unless the residents, etc.
are deemed likely to spend relatively large amounts of time there.
Examples of hotspots include depressed areas and puddles, street drains, underrainwater guttering, rainwater chambers, under or near trees, or in places whereraindrops falling from buildings land, as radioactive materials tend to become

2-78Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soilconcentrated in such places due to rainwater and the like.
The purpose of No. 2 measurement points is fundamentally to measure the level ofcontamination at the surface of the objects subject to decontamination, and they are
therefore set by considering places, etc. contaminated at comparatively highconcentrations and that are deemed to contribute substantially to the radiation dose in
the living space.
Furthermore, the measurement points shall be set with a density that particularly takes
work efficiency into account when measuring farmland and other spaces that have
uniform conditions.
The specific methods are as provided in Table 2-36.
Table 2-36. Reasoning behind the measurement points for air dose rates and othermeasures for the decontamination of soil
Measurement point
MeasurementtargetNo. 1 measurement points
Air dose rate in living spaces

Reasoning behindthe measurement
points• Measurement points shall be set at intervals
that allow the air dose rate distribution to beascertained.
 Schools (school buildings, schoolyards)• For schoolyards, the schoolyards shall be
divided up into meshes of about 10 – 30 m
and measurements shall be conducted at one
spot in each mesh (in cases where there will
presumably be little variance in the air doserate, measurements may also be taken inapproximately five locations that have been
uniformly dispersed). The need to conductdecontamination and the contents of thisshall be determined based on the meanvalues from this.
• For school buildings, measurements shall be
carriedoutinapproximately
fivemeasurement points at places where people
are deemed likely to spend relatively large
amounts of time in the vicinity aroundschool buildings. The need to conductdecontamination and the contents of thisshall be determined based on the meanvalues from this. For the school building as awhole, measurements can be carried out at
multiple points in places where people are
deemed likely to spend relatively large
amounts of time (roughly the total from theseveral measurement points in theschoolyard and school building mentioned
above), and the need to conductdecontamination and the contents of this canbe determined based on the mean values

2-79

No. 2 measurement points
Surface contamination
density, etc. for objects
subject to decontamination• Same as with No. 1
measurement points.

Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soilfrom this.
 Farmland and pastureland• Farmland and pastureland shall be divided
up into meshes of about 10 – 30 m andmeasurements shall be conducted at one spotin each mesh. However, changes can bemade to this in cases where said land has avast surface area according to the conditions.
The need to conduct decontamination andthe contents of this shall be determinedbased on the mean values from this.

2-80Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

Figure 2-44: Example of a schematic diagram for reporting measurement points
for use in decontamination and other measures for soil (schoolyards)

1)
2)

Planted
trees

1m
2)

Schoolbuilding

1m
2)Schoolyard

10 m

1)

2)

1)

2)

1)

2)

1)

2)

1)

2)

1)

2)

1)

2)

1)

2)

1)

2) 1)
2)

Sandbox

1)

2)

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

Figure 2-45: Example of a schematic diagram for reporting measurement points
for use in decontamination and other measures for soil (parks)

1m

1)

Planted
trees

1m
2)

2)

2)
Playgroundequipment

1)

2)

10m
Sandbox

10 m

2)

1)

2)

1)

2)

1)

2)

1)

2)

1)

2)
2)

1)

2)

2)
Plantedtrees1): Contamination status for living spaces
2): Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)

2-81

1)

2)
1)
2)

1)

2)
2)

Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

Figure 2-46: Example of a schematic diagram for reporting measurement points
for use in decontamination and other measures for soil (farmland)
Spacing that enables ascertainment of dose rate distribution (ex: 10 meters or more)

Building

1)

2)

1)

2)

1)

2)

1)

2)
See Figure 2-5 for measurement
points for buildings

Farmland
10 m
1)

2)

1) 2)
10 m

1)

2)

1)

2)

1)

2)

Shoulder
Road

10 m
2)

2)

2)

2)

1): Contamination status for living spaces
2): Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)(2)

Measurement Methods

When measuring the air dose rate at a No. 1 measurement point, a scintillation survey
meter or other measuring apparatus able to measure gamma rays shall be used.
In contrast, to avoid the effects of background radiation when measuring the level ofcontamination on or near surfaces at a No. 2 measurement point, it is recommended touse a GM survey meter able to measure beta rays, but it is also acceptable to performthe measurements using a dosimeter capable of measuring gamma rays. For example,
one way to make specialized confirmation based on the levels of contamination at therelevant sites is to perform the measurements under conditions where a collimator isused to shield against gamma rays from the outside. In addition, for instance, it ispossible to confirm the effect of the decontamination by determining the contamination
status of the objects subject to decontamination from the air dose rate measured at thesurface of the measurement points and at heights of 50 cm and 1 m, and then comparing
the results with those of measurements taken in the same positions after the completionof the decontamination work.
In general, the same measuring apparatus shall be used when measuring at the samemeasurement points before and after decontamination work.

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Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

When measuring the radiocaesium concentration in soil on farmland and similar areas,
the measurements must be performed within a detector that is shielded to prevent
influence from background gamma rays; generally germanium semiconductor detectors
calibrated using standard radiation sources with known amounts of radioactivity areused for this purpose. However, measurement using germanium semiconductor
detectors requires a fixed time period until analysis results are available, as well as
sophisticated measurement technology. It is permissible to estimate the radiocaesium
concentration from the air dose rate, for which measurement results can be obtained
relatively easily on site, by establishing the correlation between the air dose rate and theradiocaesium concentration in advance. As such, a simplified method for calculating theradiocaesium concentrations in farmland soil may be used (see Figure 2-47)
The specific calculation method for the radiocaesium concentration in soil shall be as
shown in Table 2-37. For other specific methods, see “6. Measuring Apparatuses andMethods of Use” in “Part 1: Guidelines on the Methods for Investigation andMeasurement of the Status of Environmental Pollution in Intensive Contamination
Survey Areas.” Simplified Method for Calculating the Radiocaesium Concentrations inFarmland Soil
The radiocaesium concentration (Bq/kg) of farmland soil can be simply calculated fromthe air dose rate (μSv/h) at a height of 1 m above the ground’s surface and the type ofsoil via the following formulas.
This method is prone to errors, so please take measurements with a germanium semiconductor
detector or similar apparatus when taking accurate measurements.

Figure 2-47. Simplified method for calculating the radiocaesium concentrations infarmland soil
Restricted Areas, Deliberate Evacuation Areas, andEvacuation-Prepared Areas in case of Emergency

Rice fields/
ordinary fields
Andosolsoil

Estimating
formulaA

Orchards

Pastureland

Non-andosol
soil

Estimating
formulaB

Estimating
formulaC

Other types of areas

Estimating
formulaD

Rice fields

FieldsAndosolsoil

Non-andosol
soil

Andosolsoil

Non-andosol
soil

Estimating
formulaEstimating
formulaEstimating
formulaEstimating
formula

E

F

G

H

Orchards

Pastureland

Estimating
formulaEstimating
formulaI

A

Estimated figures = Air dose rate  3210

E

Estimated figures = Air dose rate  2760 -139

B

Estimated figures = Air dose rate  2120

F

Estimated figures = Air dose rate  2390 -86

C

Estimated figures = Air dose rate  2790

G

Estimated figures = Air dose rate  2280 -47

D

Estimated figures = Air dose rate  1630

H

Estimated figures = Air dose rate  2270 -75

I

Estimated figures = Air dose rate  1360

J

Estimated figures = Air dose rate  800

2-83

J

Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

• This is a method for estimating the average concentration in the soil from the surface down to a depth of 15 cm.
• The coefficients for the estimating formulas were current as of November 5, 2011, and will continue to change as time passes.
Provided by: Ministry of Agriculture, Forestry and Fisheries

Table 2-37. Measurement methods for the radiocaesium concentration in farmland
soil
Measuringapparatus used
Calibration
Daily check

Prevention ofcontamination

Measurement

Records• Estimates from germanium semiconductor detectors, NaI scintillation
spectrometers,
LaBr3(Lanthanum
bromide)scintillation
spectrometers, and air dose rate
• At least once a year, calibration shall be performed using standard
radiation sources with known amounts of radioactivity.
• 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.
• The body and detecting element of the measuring apparatus shall becovered with thin plastic sheet, etc.
• The plastic sheet, etc. shall be replaced with new material when it getsdirty or breaks.
• For rice fields, soil shall be extracted from the surface of themeasurement point down to 15 cm deep in the ground, and after thesoil 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.
• 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.

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Guidelines Pertaining to Decontamination and Other Measures

3.

IV. Decontamination and Other Measures for Soil

Decontamination Methods
Figure 2-48. Basic flow for the decontamination of soil

Decontamination
methods
Measures to prevent the spread of contamination through dispersion, outflows, andso forth following the decontamination(1) Decontamination of schoolyards, kindergarten
yards, and parks(2) Decontamination of farmland Farmland (fields) that has not been plowed Farmland (fields) that has been plowed Agricultural water facilities
 Orchards
 Pastureland

Conduct the decontamination from(1) – (2) as needed.

Efficient decontamination requires the decontamination work to be focused on places
that are contaminated with comparatively high concentrations of radioactive materials
that contribute substantially to the radiation dose.
If this does not yield an observable decontamination effect, the soil surface shall becovered or scraped away.
For soil other than that in farmland, in each stage the air dose rates at the No. 1
measurement points shall be measured, and as a general rule no additional
decontamination work shall be performed provided the air dose rate at a height of 1 m (aheight of 50 cm from the measurement point may be used for schoolyards, etc., withconsideration for the living space of infants and schoolchildren in the lower grades) is
less than 0.23 microsieverts per hour.
Moreover, when performing decontamination work, the necessary measures to secure
the safety of the workers and the general public must be taken, and measures to preventthe spread of contamination due to dispersion, outflow, etc. associated withdecontamination work must be implemented so as to minimize contamination beingbrought out from within the work zone, contamination being brought in from outside, orrecontamination of the decontaminated zones. Among these preparations, please refer tothe Ministry of Health, Labour and Welfare’s Ordinance on the Prevention of Ionizing
Radiation Hazards related to Decontamination Work of Soil Contaminated byRadioactive Materials Resulted from the Great East Japan Earthquake and its
Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
Also please arrange the overall schedule so as to avoid a large zone undertaking
decontamination within a municipality at the same time whenever possible, in theinterest of minimizing the impact of decontamination outside the zone.

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Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

See “4. Post-Work Measures” with regard to matters like the handling of the removed
soil, the treatment of wastewater, and the cleaning of the equipment used for thedecontamination.
This section covers methods of decontamination for soil in schoolyards, kindergarten
yards, and parks, as well as farmland.
(1)

Decontamination of Soil in Schoolyards, Kindergarten Yards, and Parks

Figure 2-49. Basic flow for the decontamination of schoolyards, kindergarten yards,
and parks
Decontamination of schoolyards, kindergarten yards,
and parks
Measures to prevent the spread of contamination
through dispersion, outflows, and so forth following thedecontamination

Removal of soil and other materials at hotspots**Hotspots
Locations where the soil has been contaminated in a highly
concentrated manner by rainwater and wastewater containing
radioactive materials where there is a high probability thatradiocaesium has become concentrated compared to thesurrounding areas.

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 that it does notproduce removed soil.

Adding soil, etc.
(as needed)

Covering the soil surface has
the advantage that it does notproduce removed soil.

Removal of infill material
from artificial turf

When the depth that must be
scraped away is shallow it iseffective to use solidification
agents.
[Precautions] When scraping away the
topsoil, it is necessary toconfirm in advance thedepth of the contaminationfrom the surface layer andestablish the optimal depth
to be scraped away inadvance.

In schoolyards, kindergarten yards, and parks, radiocaesium is settled near the surface
layer of the ground. Since the dose may be partially high near drains from rainwater
guttering, and at the bases of trees, the soil at such places shall be removed by hand, etc.
Please refer to “V. 3. (2) Decontamination of Trees in Living Spaces, such as Roadside
Trees and the like.”

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Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

If no decontamination effect is observed as a result, the upper layer of the soil shall be
replaced with a lower layer of the soil (deep plowing) using heavy machinery, etc. or the
topsoil shall be scraped away (see Figure 2-19).
 Deep plowing
Deep plowing is the method of covering the soil surface by replacing theradiocaesium-containing upper layer of the soil with a lower layer of the soil that does
not contain radiocaesium. Carrying out deep plowing can be expected to reduce theradiation dose and to inhibit the diffusion of radiocaesium by shielding with soil, etc.
Moreover, these have the advantage of not generating removed soil, because they do not
scrape away the topsoil. When performing deep plowing, approximately 10 cm ofsurface soil shall be placed at the lower layer and covered with approximately 20 cm of
excavated soil from the lower layer. When performing this procedure, it is necessary to
avoid scattering the surface soil or mixing it with the soil excavated from the lower
layer. When implementing this over a large area, the implementation area shall be
partitioned in an appropriate manner (see Figure 2-19).
 Scraping away topsoil
When scraping away topsoil, it is important to select an appropriate thickness for thesoil to be scraped away, in order to avoid generating too much removed soil.
Specifically, for the soil surfaces to be scraped away, it is recommended to start withsmall areas (an area of a size that enables the air dose rate, etc. of the soil surface to bemeasured with minimal interference from radiation outside the area) and scrape away
about 1 to 2 cm of topsoil while measuring the air dose rate, etc., then determine thethickness of the layer to be scraped away (see Figure 2-52 2), 3), and 4)). According toconventional wisdom it is believed that adequate results can be achieved by scraping
away at most about 5 cm of the soil surface. If the thickness of soil to be removed is thin,another effective method is to use a solidification agent that enables the thickness of thesoil to be restricted to a level that is relatively easy to scrape away, depending on thetype of topsoil: sandy soil, silt, clay, etc.
However, since children will be in direct contact with sandboxes in parks, and are likely
to dig them up, and because park’s geometric areas are relatively small, a layer
descending 10 to 20 cm below the surface shall be removed using small shovels, etc. If
necessary, uncontaminated sand shall be used to cover the surface to restore it to how it
was prior to the work. When scraping away the sand and dirt, water shall be sprinkled toprevent re-suspension of soil particles and the dispersion of dust.
In places where the topsoil, etc. has been removed, uncontaminated soil shall be addedin from elsewhere.
 Covering the soil surface
For covering the soil surface, the approach is to cover the top layer of soil that contains
radiocaesium with soil that does not contain radiocaesium through the use of small
heavy machinery. This can be expected to reduce the radiation dose via shielding and to

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Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soilinhibit the diffusion of radiocaesium by shielding it with soil. This has the advantage of
not generating removed soil since the topsoil is not being removed. When performing
this covering, it is important to select an appropriate covering thickness for purposes ofshielding in order to avoid having the covering thickness become excessively large.
 Removal of infill material from artificial turf
For tennis courts and other types of artificial turf, the infill materials (joint sand, etc.)
for the artificial turf shall be removed.
For example, the infill material (joint sand, etc.) distributed throughout artificial turf
shall be absorbed by running a tractor or other vehicle to which machinery capable ofabsorbing and removing the infill material has been affixed.
Furthermore, if the area to be decontaminated is large, the work shall be coordinatedand the scheduling matched so that it is carried out all at the same time in order toensure that there is no recontamination following the decontamination work.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of schoolyards, kindergarten yards, and parks are asprovided in Tables 2-38 and 2-39.
Figure 2-50. Example of the decontamination of a schoolyard(scraping away of topsoil)

Photo courtesy of: JAEA

2-88

Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

Figure 2-51. Example of the removal of infill material from artificial turf

Photo courtesy of: JAEA

2-89

Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

Figure 2-52: Procedure for determining the thickness of soil to be scraped away
(1/2)
1)

Measure the air dose rate at the surface of the place to be decontaminatedPhoto courtesy of: Date City

2)

Strip away a thin layer of topsoil

Photo courtesy of: Date City

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Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

Figure 2-52: Procedure for determining the thickness of soil to be scraped away
(2/2)
3)

Measure the air dose rate at the surface of the place where the topsoil was strippedaway (using a collimator to reduce the effects of radiation from the surroundings)

Photo courtesy of: Date City

4)

Measure the air dose rate at the surface at several points in the test area

Photo courtesy of: Date City

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Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

Table 2-38. Necessary measures prior to the decontamination of schoolyards,
kindergarten yards, and parks
Category
Prevention ofdispersion

Decontamination methods and notes of caution• When scraping away the topsoil when it comes to dried soil, efforts
can be made to prevent the dispersion of dust by scatteringsolidification agents over the area in advance to solidify the soil
surface.

Table 2-39. Decontamination methods for schoolyards, kindergarten yards, andparks and notes of caution
Category
Removal of
sediments
Deep plowing

Scraping away
topsoilCovering thesurface soil

Removal of infill
material from
artificial turf

Decontamination methods and notes of caution• Fallen leaves, moss, mud, and other sediments shall be removed byhand by people wearing rubber gloves and by shovel, etc.
• 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.
• A backhoe or the like shall be used to uniformly scrape away thesurface.
• The remaining topsoil can be confirmed by means of sprinkling limearound in 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.)• The surface soil shall be covered with soil that does not containradiocaesium.
• 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.
• The infill material found in artificial turf and the like shall be takenout via machinery that can absorb and remove said infill material.

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Guidelines Pertaining to Decontamination and Other Measures(2)

IV. Decontamination and Other Measures for Soil

Decontamination of Farmland
Figure 2-53. Basic flow for the decontamination of farmland

Decontamination of farmland (fields)

Farmland (fields) that has been
plowedFarmland (fields) that has not been
plowedScraping away
topsoil

Agitation/removalof soil by water[Precautions] When scraping away the
topsoil, it is necessary toconfirm in advance thedepth of the contaminationfrom the surface layer andestablish the optimal depth
to be scraped away inadvance.

Inversion tillage

Deep tillage

Inversion tillage

It is permissible to carry out inversion tillage, which
does not generate removable materials (soil) for
farmland that has a concentration of 5,000 Bq/kg or lessof radiocaesium in the soil
[Precautions] When inversion tillage is carried out, the water tablemust 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
pastureland

Decontamination oforchards

Pastureland

Orchards

Cleaning of tree barkDebarkingPruning

Scraping away
topsoil[Precautions] When scraping away the topsoil, it is necessary toconfirm in advance the depth of the contaminationfrom the surface layer and establish the optimal
depth to be scraped away in advance.

Inversion tillage/plowing

Scraping away topsoil[Precautions] When inversion
tillage is carried out,
the water table must
be measured inadvance and its depth
must be taken into
account.

[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.
Work that is being considered for
implementation in regions where the air
dose rate is comparatively high2-93Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

Farmland soil has unique characteristics in that it has been cultivated through years offarming activities by farmers and has diverse aspects that include preservation of theecosystem. Accordingly, when decontaminating farmland, it is important to restore theconditions that enable agricultural activities to be resumed and safe crops to be provided
once again by reducing the concentration of radioactive materials in the soil, in addition
to reducing the radiation dose reaching surrounding residents. To achieve this in theprocess of farmland decontamination, since farmland that has been decontaminated byscraping away topsoil or through inversion tillage and similar methods is expected tolose its fertilizer components and organic characteristics, as well as experience a
degradation in permeability and other physical characteristics, care must be taken with
post-decontamination farmland to ensure the conditions that enable resumption ofagricultural production are restored, including soil analysis and diagnostics, followed byapplication of the necessary amount of soil from elsewhere, along with fertilizer,
organic materials, or soil conditioners.
Most of the radiocaesium that has precipitated onto farmland that has not been plowed
since the Fukushima Daiichi Nuclear Power Plant accident still remains on the surfaceof the farmland in large quantities. Therefore, even when farmland that has not been
plowed since the accident has the same radiocaesium concentrations as farmland thathas had its plow layer mixed by plowing, the former with its untouched topsoil will
exhibit a higher value for its air dose rate. In this way, appropriate methods must be
adopted for performing decontamination work on farmland depending on whether it has
been plowed yet, as well as its current land category and concentration of contaminants.
 Farmland (fields) that has not been plowed
For sections that have not been plowed, after weeding it is suitable to scrape away thesurface layer of soil where radiocaesium is deposited (see Figure 2-52). However, inconsideration of the concentration of radiocaesium in the soil, the current land category,the soil conditions, etc., in addition to scraping away the topsoil,*7 it is also permissible
to select soil agitation or removal by water,*8 inversion tillage,*9 or other methods.
When scraping away the topsoil, it is recommended to commence work only after
calculating the expected amount of soil that will be generated as removable material inadvance because the amount will be large, and also after developing an outlook on
securing temporary storage site, etc.
It is permissible to carry out inversion tillage, which does not generate removablematerials (soil),*10 for farmland that has a concentration of 5,000 Bq/kg or less ofradiocaesium in the soil, while for farmland that has a concentration of greater than
5,000 Bq/kg of radiocaesium in the soil, it is suitable to scrape away the topsoil,
implement soil agitation or removal by water, or perform inversion tillage.*11 Amongthese methods, since inversion tillage entails moving the radiocaesium to a lower soil
layer, which could result in radiocaesium being transported off the farmland through thegroundwater, please measure the water table in advance and take account of its depth
before performing inversion tillage as needed. Furthermore, the deeper the tillage, thegreater the reduction in the radiation dose at the ground surface, but because of thedanger of destroying the plow pan, especially for rice fields, it must be rebuilt if it is2-94

Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

destroyed.
 Farmland (fields) that has been plowed
For farmland that has already been plowed, inversion tillage, deep tillage, or similar
methods shall be used, because presumably the radiocaesium has already been mixed
into the whole plow layer by plowing. For example, for farmland with a plow layer of
15 cm, deep tillage of 30 cm will dilute the radioactive materials that had been
distributed in the range from the surface to 15 cm deep into the range from the surface
to 30 cm deep, which can be expected to reduce the radiocaesium concentration in theplow layer and reduce the radiation dose.
 Agricultural water facilities
Decontamination and other measures shall be considered for agricultural drainage
canals and other such facilities that meet all of the conditions in (1) – (3) below.
(1) Must be a facility on which soil is removed from canals near to paddy fields onwhich mud dredging is carried out primarily through manual labor by farmers or
managers in ordinary years in order to ensure cross-sectional flow areas and flow
volumes.
(2) Must be a region in which mud dredging that is carried out in ordinary years could
not be carried out due to the impact from the accident.
(3) Facilities for which no shielding effect via the water is expected during the
agricultural off season or other fixed periods of time for reasons like a lack of waterin said canals, but which clearly contribute to the air dose rate in the surrounding
areas.
 Orchards, etc.
For fruit trees, tea plantations, or places where other perennial crops are cultivated,
scraping away the topsoil in a range that will not harm tree bodies is deemed effective,
while inversion tillage, deep tillage, and similar methods are not suitable as they could
damage the roots and because the rooting zone is distributed into the lower layers of thesoil. In decontaminating such farmland, fruit trees shall be debarked (old bark strippedaway) or the bark shall be cleaned and the trees pruned, and tea trees shall have theirbranches pruned (old leaves and branches removed by deep pruning, medium pruning,
truncation, etc., after tea picking) or similar treatments in order to reduce the radiationdose and minimize the concentration of radiocaesium contained in the products.
If these measures have been taken but have produced inadequate results, scraping awayof all sections of topsoil, along with similar methods, shall be considered.
 Pastureland

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Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

For pastureland, inversion tillage, deep tillage, or scraping away the topsoil shall be
carried out. If the layers below the plow layer are rudaceous, pebbles will appear in theplow layer as a result of inversion tillage or deep tillage, and so in such cases measures
to remove the pebbles will be necessary. When scraping away the topsoil an enormous
amount of soil to be removed will be generated. Because of this, the amount that is
expected to be generated must be estimated in advance and prospects must be
established for securing temporary storage sites and the like before starting with thework.
Furthermore, there may be cases where it is difficult to perform inversion tillage on
pastureland due to a shallow plow layer or lots of rocks and pebbles, and where it isdifficult to store the soil following the removal of topsoil at storage sites. In such cases
consideration shall be given to performing plowing via a disc harrow or a rotary tiller byconfirming that adequate results can be achieved from the decontamination.
Weeding, etc. of ridges and slopes and other measures shall be implemented as needed.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of farmland are as provided in Tables 2-40 and 2-41.

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Guidelines Pertaining to Decontamination and Other Measures

IV. Decontamination and Other Measures for Soil

Figure 2-54: Example of scraping away of soil from farmland using farmmachinery
1) Harrowing of farmland

Photo courtesy of: Ministry of Agriculture, Forestry and Fisheries

2) Scraping away of soil from farmland

Photo courtesy of: Ministry of Agriculture, Forestry and Fisheries

2-97Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

Table 2-40. Necessary measures prior to the decontamination of farmland
Category
Prevention ofdispersion

Decontamination methods and notes of caution• When scraping away the topsoil when it comes to dried soil, efforts
can be made to prevent the dispersion of dust by scatteringsolidification agents over the area in advance to solidify the soil
surface.

Table 2-41. Decontamination methods for farmland and notes of caution

Orchards

Water
facilities

PlowedUnplowed

Category
Decontamination methods and notes of caution
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 limearound in advance.
Soil• After the upper layer of soil has been agitated (shallow puddled), theagitation or
turbid water with fine soil particles floating in it shall be forcefully
removal bydrained via a pump. Then solid-liquid separation shall be performed inwater
a grit chamber or similar device that has been covered with a plastic
sheet to collect the soil particles.
Inversion• A plow shall be used to invert the soil so that the contaminated soil intillagethe top layer is moved to the bottom layer and the uncontaminated soil
from the bottom layer is placed on the top layer.
• The tillage depth for inversion tillage shall be 30 cm in principal.
However, in cases where soil that is not suitable for use as the plowlayer 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 accountwhen performing inversion tillage as needed.
• Attention must be paid to the fact that small tractors cannot be used toagitate the soil in cases where the topsoil is frozen due to cold
temperatures.
Inversion(Same as above)tillage
Deep tillage • A deep tillage rotary tiller shall be used to deeply till cultivated land
about two times. The tillage depth of deep tillage shall be about 30 cm
in principal.
Removal of • Mud and other sediments that have accumulated in agricultural
sediments
drainage canals and other such facilities shall be removed through theuse of a shovel or the like.
DebarkingCleaning
tree barkPruning• Tree bark shall be removed by primarily concentrating on the tops andsides of main trunks and main branches.
• A dedicated chipping tool shall be used to scrape away so as to takeoff tree bark that has grown old.
• Tree species that do not have a configuration in which old tree bark
can be removed from their branches and trunks (peach trees, cherrytrees, etc.) shall be subject to cleaning.
• When cleaning bark or debarking with the use of a high pressure watercleaner, 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.
• Old branches to which it is thought that radiocaesium is directly

2-98Pastureland

Guidelines Pertaining to Decontamination and Other Measures

4.

IV. Decontamination and Other Measures for Soiladhering shall be removed.
• The branches shall be removed during the tree’s dormant stage so that
this does not affect its growth.
Scraping• The soil shall be removed by human power or via an earth blade on aaway topsoil
small backhoe. Or a rotary tiller shall be attached to a small tractor andthe 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.
Inversion• A plow shall be used to invert the soil so that the contaminated soil intillage /the top layer is moved to the bottom layer and the uncontaminated soil
plowingfrom the bottom layer is placed on the top layer.
• The tillage depth for inversion tillage shall be 30 cm in principal.
However, in cases where soil that is not suitable for use as the plowlayer 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 accountwhen performing inversion tillage as needed.
• Attention must be paid to the fact that small tractors cannot be used toagitate the soil in cases where the topsoil is frozen due to cold
temperatures.
Scraping• A backhoe or the like shall be used to scrape away the surface.
away topsoil

Post-Work Measures

Post-work measures, which include handling the removed soil, etc. generated by thedecontamination work, as well as cleaning of equipment and materials, are listed below.

(1)

Handling the Removed Soil, etc.

The removed soil, etc. shall be appropriately handled and transferred to on-site storage
or a temporary storage site.
Please refer to “II. 4. (1) Handling the Removed Soil, etc.” for specific methods forhandling the removed soil.
(2)

Cleaning of Equipment and Materials

With regard to the post-work handling of the equipment used for decontamination, theMinistry of Health, Labour and Welfare’s Ordinance on the Prevention of Ionizing
Radiation Hazards related to Decontamination Work of Soil Contaminated byRadioactive Materials Resulted from the Great East Japan Earthquake and its
Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) are to be followed.
See “II. 4. (3) Cleaning of Equipment and Materials” for specific methods for cleaning
the equipment and materials.

2-99Guidelines Pertaining to Decontamination and Other Measures IV. Decontamination and Other Measures for Soil

5.

Subsequent Measurements and Records

To confirm the decontamination effect, the air dose rate, etc. and concentration ofradiocaesium in the soil (in the case of farmland) after completion of thedecontamination work shall be measured, and the results shall be compared with thevalues measured prior to the commencement of the decontamination work.
Measurement of the air dose rate, etc. and the radiocaesium concentration shall be
performed in accordance with the measurement methods given in “Part 1: Guidelines
for Methods for Investigating and Measuring the Status of Environmental Pollution in
Intensive Contamination Survey Areas” and Table 2-37 of “2. (2) Measurement
Methods” for each measurement point indicated in Table 2-36 of “2. (1) Determinationof Measurement Points.”
In addition to the air dose rate, etc. and radiocaesium concentration at eachmeasurement point, any other information pertaining to the decontamination work shallbe recorded and stored.
Table 2-42. Subsequent measurements and records for the decontamination of soil
Measurement of
air dose rate, etc.
and radiocaesium
concentration,
etc.
Recordkeeping• The air dose rate, etc. and radiocaesium concentration in the soil (inthe 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.
• 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,
types of objects subject to decontamination, method of
decontamination, total area decontaminated (soil, etc.), theapproximate weight of the removed soil, etc., and the status ofstorage 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 the storage ofremoved soil.

2-100Guidelines Pertaining to Decontamination and Other Measures

V. Decontamination and Other Measures for Vegetation

V. Decontamination and Other Measures for
Vegetation
This section explains 1. Preparation, 2. Prior Measurements, 3. Decontamination
Methods, 4. Post-Work Measures, and 5. Subsequent Measurements and Records, inchronological order, pertaining to measures for the decontaminations of lawns, roadsidetrees, trees in living spaces such as in parks and gardens, forests near residences, etc.
Figure 2-55. Basic flow for decontamination and other measures for vegetation(1) Measures to reduce public exposure in connection with decontamination work
1. Preparation(2) Equipment and materials

2. Prior
Measurements(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(1) Handling the removed soil, etc.
(3) Cleaning of equipment and materials

5. Subsequent Measurements and Records

2-101(3) Decontaminationof forests

Guidelines Pertaining to Decontamination and Other Measures

1.

V. Decontamination and Other Measures for Vegetation

Preparation

Before performing decontamination work, in addition to preparing the equipment
required for the decontamination work, preparations must be made to ensure safety
through means including prevention of exposure of the general public and workers suchas by inhaling dust generated during decontamination work. Among these preparations,please refer to the Ministry of Health, Labour and Welfare’s Ordinance on thePrevention of Ionizing Radiation Hazards related to Decontamination Work of Soil
Contaminated by Radioactive Materials Resulted from the Great East Japan Earthquake
and its Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6
dated June 15, 2012) for the measures required to ensure the safety of workers.
(1)

Measures to Reduce Public Exposure in Connection with Decontamination
Work
Table 2-43. Measures to reduce public exposure in connection withdecontamination work for vegetation
Restriction ofentry

Signage(2)• In cases where the general public is deemed likely to enter the area,
the area shall be cordoned off with pylons or rope, etc. to prevent
people from unnecessarily approaching the work site, and the entryof people and vehicles shall be restricted.
• In cases where radioactive materials may be dispersed in connection
with the decontamination work, the perimeter of thedecontamination area shall be fenced in with sheets, etc., water shallbe sprayed, or other such measures shall be taken to prevent
dispersion and the area shall be cordoned 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 (see Figure 2-4).

Equipment and Materials

The required equipment and materials shall be arranged for decontamination and othermeasures, as well as for collection of the removed soil, etc., in accordance with theobjects to be decontaminated and the work environment.
Table 2-44. Examples of equipment and materials for the decontamination ofvegetation
Example ofgeneralequipment

Examples ofequipment for
pruning trees

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.)
Hatchet, pruner, chainsaw, stepladder, mobile lift

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Guidelines Pertaining to Decontamination and Other Measures

2.

V. Decontamination and Other Measures for Vegetation

Prior Measurements

To confirm the decontaminating effects of the decontamination work, the air dose rateprior to the commencement of decontamination work and after the completion of
decontamination work*2 and the surface contamination density of the objects subject todecontamination (hereinafter, “air dose rate, etc.,” which includes both the air dose rate
and the surface contamination density) shall be measured. Specifically, places
representative of living spaces, places contaminated at a comparatively highconcentration that is deemed to contribute substantially to the radiation dose in theliving space, etc. shall have their air dose rate, etc. measured in the same locations andby the same method both before contamination work starts and after it finishes, and theresults shall be recorded. This section gives information on methods for measuring the
air dose rate, etc. prior to the commencement of decontamination work.
Note that the air dose rate, etc. may also be measured near the surface of the objects
subject to decontamination as needed when ascertaining the degree of reduction in thelevel of contamination of the objects subject to decontamination during thedecontamination work. These measurements will be separately explained in “Section 3.
Decontamination Methods.”(1)

Determination of Measurement Points

Prior to decontamination work, the measurement points at which the air dose rate, etc.
will be measured shall be decided and a schematic diagram illustrating the range of themeasuring object, the measurement points, structures to be used as markers, etc. shall becreated (see Figure 2-56 and Figure 2-57).
There are two types of measurement points: those used to ascertain the average air dose
rate for roadside trees, trees in parks and other living spaces, forests near residences, etc.
that are subject to decontamination (No. 1 measurement points) and those used toconfirm the level of contamination of the objects that are to be decontaminated (No. 2
measurement points).
No. 1 measurement points are set primarily in a living space where residents, etc. spend
large amounts of time. In setting these measurement points, so-called “hotspots” that
contribute comparatively insubstantially to the radiation dose in the living space, andpoints near them, are not eligible to be measurements points unless the residents, etc.
are deemed likely to spend relatively large amounts of time there.
Examples of hotspots include depressed areas and puddles, street drains, underrainwater guttering, rainwater chambers, under or near trees, or in places whereraindrops falling from buildings land, as radioactive materials tend to become
concentrated in such places due to rainwater and the like..
The purpose of No. 2 measurement points is fundamentally to measure the level ofcontamination at the surface of the objects subject to decontamination, and they are
therefore set by considering places, etc. contaminated at comparatively high2-103Guidelines Pertaining to Decontamination and Other Measures

V. Decontamination and Other Measures for Vegetation

concentrations and that are deemed to contribute substantially to the radiation dose in
the living space.
The specific methods are as provided in Table 2-45.
Table 2-45. Reasoning behind the measurement points for air dose rates and othermeasures for the decontamination of vegetation
Measurement
point
MeasurementtargetReasoningbehind themeasurement
pointsNo. 1 measurement points

No. 2 measurement points

Air dose rate in living spaces

Surface contamination density,
etc. for objects subject todecontamination• Measurement points shall be set atintervals that allow the air dose rate
distribution to be ascertained.
 Lawns• Lawns shall be divided up into meshes ofabout 10 – 30 m and measurements shallbe conducted at one spot in each mesh.
 Forests• Measurements shall be conducted at one
spot about every 20 – 50 m*12 near the• Same as with No. 1
measurement points for lawns.
• For roadside trees,measurement points shall beestablished within a range thatwill presumably be affected by
the roadside tree (example: aposition that is about 1 m awayfrom the side of the roadsidetree).

forest edge and the geographical centerof the forest where work will be
performed.

• For forests, the points shallbe as with No. 1
measurement points.

Figure 2-56: Example of a schematic diagram (trees and grass) for reporting
measurement points for use in decontamination and other measures for vegetation(parks)1m

Gardentrees

Playgroundequipment

1m
2)

2)
10 m
Sandbox

10 m

1)
2)

2)
2)

1)

2)

1)

2)

1)

2)
2)

1)

2)

Garden trees
1): Contamination status for living spaces
2): Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)

2-104

1)

2)
1)
2)

1)

2)
2)

Guidelines Pertaining to Decontamination and Other Measures

V. Decontamination and Other Measures for Vegetation

Figure 2-57: Example of a schematic diagram for reporting measurement points
for use in decontamination and other measures for vegetation (forests)

Lawn
50 m
1)

2)

1)

2)

1)

2)

1)

2)

Forest edge
Scope ofdecontamination
20 m

1)

2)

1)

2)

Forest1): Contamination status for living spaces
2): Contamination status for objects subject to decontamination(surface contamination density, surface dose rate)(2)

Measurement Methods

When measuring the air dose rate at a No. 1 measurement point, a scintillation survey
meter or other measuring apparatus able to measure gamma rays shall be used.
In contrast, to avoid the effects of background radiation when measuring the level ofcontamination on or near surfaces at a No. 2 measurement point, it is recommended touse a GM survey meter able to measure beta rays, but it is also acceptable to performthe measurements using a dosimeter capable of measuring gamma rays. For example,
one way to make specialized confirmation based on the levels of contamination at therelevant sites is to perform the measurements under conditions where a collimator isused to shield against gamma rays from the outside. In addition, for instance, it ispossible to confirm the effect of the decontamination by determining the contamination
status of the objects subject to decontamination from the air dose rate measured at thesurface of the measurement points and at heights of 50 cm and 1 m, and then comparing
the results with those of measurements taken in the same positions after the completionof the decontamination work.
In general, the same measuring apparatus shall be used when measuring at the samemeasurement points before and after decontamination work.
When there are a large number of measurement points, the results of measurements, etc.
previously taken by local authorities shall be utilized as needed.

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Guidelines Pertaining to Decontamination and Other Measures

V. Decontamination and Other Measures for Vegetation

For the specific methods, see “6. Measuring Apparatuses and Methods of Use” in “Part
1: Guidelines on the Methods for Investigation and Measurement of the Status ofEnvironmental Pollution in Intensive Contamination Survey Areas.”3.

Decontamination Methods
Figure 2-58. Basic flow for the decontamination of vegetation

Decontamination
methods
Measures to prevent the spread of contamination through dispersion, outflows, and so forthfollowing the decontamination(1) Decontamination of lawns(2) Decontamination of trees in living
spaces, such as roadside trees and thelike(3) Decontamination of forests

The decontamination of vegetation shall be implemented in accordance with the land
use configuration (lawns, trees in living spaces, such as roadside trees and the like, orforests).
See “4. Post-Work Measures” with regard to matters like the handling of the removed
soil, the treatment of wastewater, and the cleaning of the equipment used for thedecontamination.
(1) Decontamination of Lawns
Figure 2-59. Basic flow for the decontamination of lawns
Decontamination of lawns
Work that is being considered for
implementation in regions where the air
dose rate is comparatively highMeasures to prevent the spread of contamination throughdispersion, outflows, and so forth following thedecontamination

Cases where it is clear that
adequate decontamination
results cannot be obtained

Deep trimming

Grass removal[Precautions] Measures to prevent the inhalation of dust shall betaken.
 Determinations on the decontamination results fromdeep trimming shall be made via tests andexperiments, etc.

[Precautions] Deep trimming shall first be carried out in anexperimental manner, with grass removal being
performed in cases where results are not observed.

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For lawns, what is different from immediately after the accident at the nuclear power
plant is that there is the possibility that the radioactive materials currently on thesurfaces of the grass may have decreased as a result of factors like the affects fromprecipitation. As a result, please determine the need for decontamination according to
the extent to which radiocaesium is adhering to the lawn. On the other hand, rainwater
may have run off the roofs of the structures and accumulated in grass near houses orbuildings. As such, the appropriate decontamination will have to be carried out by
taking the changes in the contamination status as a result of factors like precipitation
into consideration.
When taking these measures, it is important to consider applying methods that enable
the grass to be re-grown. Specifically, a grass removal method using “deep trimming” toremove the sediment layer of withered grass and clippings is recommended because it
can limit the amount of removed soil, etc. that is generated, and is favorable from theperspective of re-growing the grass. Deep trimming is a technique whereby the leaves
and thatch of turfgrass is removed. Since the underground rhizomes and roots of theturfgrass are left behind, this aims to encourage the germination of new sprouts in aneffort to restore the grass while at the same time decontaminating it (see Figure 2-60
and Figure 2-61). In places where the radiation dose is high and it is clear from deep
trimming tests and experiments that it will not produce a decontamination effect,
turfgrass shall be removed by the roots.
In each stage, the air dose rates at the No. 1 measurement points shall be measured, andas a general rule no additional decontamination work shall be performed provided theair dose rate at a height of 1 m (a height of 50 cm from the measurement point may be
used for lawns, etc. mainly used by students of elementary schools and below, as well as
special-needs schools, with consideration for the living space of infants andschoolchildren in the lower grades) is less than 0.23 microsieverts per hour.
Dust is generated during grass removal, so the process requires equipment to prevent
inhalation.
Furthermore, if the area to be decontaminated is large, the work shall be coordinatedand the scheduling matched so that it is carried out all at the same time in order toensure that there is no recontamination following the decontamination work.
After trimming the lawn, removing the topsoil, etc., the air dose rate, etc. at themeasurement points shall be measured to confirm the decontamination effect.
In addition, in cases where the amount of removed soil, etc. to be generated is deemed
likely to be enormous, in implementing measures for decontamination of the soil, etc.,
the soil scraped away must be kept to the minimum necessary thickness and otherwise
care must be taken to minimize the generated quantity of removed soil, etc. wheneverpossible in order for the decontamination and other measures to be advanced in a speedy
and efficient manner.
The measures that are required in advance, specific decontamination methods, and notes

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V. Decontamination and Other Measures for Vegetationof caution for the decontamination of lawns are as provided in Tables 2-46 and 2-47.
Table 2-46. Necessary measures prior to the decontamination of lawns
Category
Prevention ofdispersion

Decontamination methods and notes of caution• If sidewalks and buildings are immediately adjacent, curing shall be
performed to prevent the dispersion of dust, etc.

Table 2-47. Decontamination methods for lawns and notes of caution
Category
Deep trimming

Grass removal

Decontamination methods and notes of caution• If large mowers will fit, then deep trimming shall be carried out usinglarge mowers (shallow cutting down to approximately 3 cm, which isa level 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.)• The flat claw for a backhoe bucket shall be installed and the grass andsod shall be removed (about 5 cm).

 Decontamination via Deep Trimming (Lawns Where Rhizomes Are Growing)
The structure of grass starting from the top consists of the leaves of the grass, the thatch,and then the soil (which includes the grass rhizome and root). Thatch refers to the layerof withered turfgrass and clippings intermixed with soil, and it is believed that the vast
majority of the radiocaesium is absorbed into this layer.
Deep trimming is a technique whereby the leaves and thatch of turfgrass is removed.
Since the underground rhizomes and roots of the turfgrass are preserved, this aims toencourage the germination of new sprouts in an effort to restore the grass while at thesame time decontaminating it.
As for the specific work, the grass shall be trimmed down to a depth of about 2 – 3 cm(*) and the remains from the thatch and withered leaves that have accumulated on the
ground’s surface shall be removed.
The extent to which decontamination can be achieved through deep trimming will
depend on the precision of the work. If the work is not carried out thoroughly then thereis the risk that it will not be possible to perform adequate decontamination because thesoil particles on the thatch will peel off and will not all be collected.
What is more, the time period in which it is carried out also has an effect on theregeneration of the grass, so please ask the opinion of experts on the matter as needed.
* The trimming depth is the depth from the ground line (the uppermost position when the turfgrass leaves
are laid flat by being pushed over with one’s hand), not the depth from the uppermost position when theleaves are standing.

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Figure 2-60. Example of decontamination work for a lawn (deep trimming)

Photo courtesy of: Date City

Figure 2-61. Image of the cut section of the grass and topsoil subject todecontamination

Leaves

Surface rhizomes
ThatchCut section image(About 10 – 20 mm deep)
Underground rhizomes
Roots
Photo courtesy of: JAEA

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Decontamination of Trees in Living Spaces, such as Roadside Trees and thelikeFigure 2-62. Basic flow for the decontamination of trees in living spaces, such as
roadside trees and the like
Decontamination of trees in living spaces,such as roadside trees and the likeWork that is being considered for
implementation in regions where theair dose rate is comparatively highMeasures to prevent the spread of contamination
through dispersion, outflows, and so forth following thedecontamination

Removal of sediments, etc.

Cases where the results of decontamination cannot beadequately observed

When branches and othersuch parts arecontaminatedScraping away the topsoil

Pruning branches, etc.

[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 and high pressure
water cleaning as needed.

One difference between now and immediately after the accident at the nuclear power
plant is that now there is the possibility that the radioactive materials currently on thesurfaces of roads may have decreased as a result of factors like the effects fromprecipitation and fallen leaves. As a result, please determine the need fordecontamination for roadside trees according to the extent to which radiocaesium isadhering to the trees.
For roadside trees or trees in parks, gardens, and other living spaces, the radiation dosecan be reduced by removing the radiocaesium that have settled down through theremoval of fallen leaves and other sediment organic materials on the surrounding
ground surfaces, cleaning and pruning the trees, or other methods.
First the fallen leaves, grass, and other vegetation on the ground surface near the trees
shall be removed.
If this does not result in an observable decontamination effect, the top layer of the soil
shall be removed to a depth of approximately 5 cm by hand or by using compact heavymachinery. Care shall be taken so as not to damage the rootstocks of the trees in theprocess. Care shall also be taken to avoid digging too deeply in order to prevent
generating excessive amounts of removed soil, etc. For the sections from which the top
layer of soil was removed, soil with straw or other organic matter shall be transplanted
in from elsewhere, the soil shall be consolidated, or other measures shall be taken asnecessary. Care shall be taken with sloped areas to prevent outflow of soil, sand, etc. or

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the collapse of the sides.
If removing the fallen leaves and weeding result in no observable decontamination
effect and it is believed that the branches or other parts of the trees are contaminated,
there are also methods that entail pruning the branches or other parts of the trees.
Since cutting down a tree generates a large amount of decontamination waste, thedecision to do so shall be considered by taking into account the role of the tree, whether
it is in a place that many people visit, and whether other methods can be expected to
produce a decontamination effect. It is also permissible to decontaminate shrubs, garden
trees, and other small trees by high pressure water cleaning.
In each stage, the air dose rates at the No. 1 measurement points shall be measured, andas a general rule no additional decontamination work shall be performed provided theair dose rate at a height of 1 m (a height of 50 cm from the measurement point may be
used for facilities, etc. used by students of elementary schools and below, as well as
special-needs schools, with consideration for the living space of infants andschoolchildren in the lower grades) is less than 0.23 microsieverts per hour.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of trees in living spaces, such as roadside trees andthe like are as provided in Tables 2-48 and 2-49.
Table 2-48. Necessary measures prior to the decontamination of trees in living
spaces, such as roadside trees and the like
Category
Prevention ofdispersion

Decontamination methods and notes of caution• If sidewalks and buildings are immediately adjacent, curing shall be
performed to prevent the dispersion of dust, etc.

Table 2-49. Decontamination methods for trees in living spaces, such as roadsidetrees and the like and notes of caution
Category
Removal of
sediments
Scraping away
topsoilRemoval ofbranches, etc.

Decontamination methods and notes of caution• Fallen leaves, moss, mud, and other sediments shall be removed byhand by people wearing rubber gloves and by shovel, etc.
• Accumulated fallen leaves and soil shall be picked up by using a
shovel or rake, etc.
• Delimbing and pruning shall be carried out on roadside trees by using
a 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.

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V. Decontamination and Other Measures for Vegetation

Decontamination of Forests

Much of the radioactive materials in forests reside in foliage, fallen leaves, and othersediment organic matter, with the contamination level dropping substantially at depthsof 3 cm or more from the ground surface. However, forests cover large areas, andimplementing decontamination methods that involve stripping away the leaf mulch
generates an enormous amount of removed soil, etc. and could damage the multifaceted
functions of forests, including disaster prevention. Forests, therefore, shall initially bedecontaminated with a view to reducing the radiation dose in the living environment of
the residents near the forest.
The discharge of radiocaesium associated with the Fukushima Daiichi Nuclear Power
Plant accident concentrated in March when the earthquake occurred, which means thatin deciduous broad-leaf forests where new leaves had not developed at that time, theradioactive materials fell to the forest floor and tended to settle onto fallen leaves andother sediment organic matter. Accordingly, removal of fallen leaves, etc. in such places
is expected to yield a large decontamination effect (see Figure 2-63).
From the perspective of reducing the radiation dose in the living environment ofresidents near the forest, it is effective and efficient to remove fallen leaves, etc. up to
about 20 m in from the edge of the forest, but this range shall be determined while
confirming the status of the reduction in radiation dose after removal of the fallen leaves,etc.
In cedar, Japanese cypress, and other evergreen forests, a larger proportion of theradiocaesium tends to be settled onto the branches and leaves in comparison withdeciduous broad-leaf forests. Into the future, it is recommended that the removal of
fallen leaves, etc. be performed not just once but continually during a period of about
three to four years, because that is how long it normally takes the radiocaesium settled
onto branches, leaves, etc. to fall to the forest floor with rain or fallen leaves.
On the other hand, it is also important not to allow the exposed topsoil to run off due torainfall, in the interests of preserving the forests and preventing the re-diffusion ofradiocaesium. Radiocaesium moves into the soil as fallen leaves decompose, but sincecaesium has the property of being readily absorbed into clay, it is thought that most of
the substance stays in the top layer of the soil.*13 This means that rather than removing
the fallen leaves, etc. in a wide area all at once, it is suitable to gradually expand thearea while monitoring the situation.*14 Lining up sandbags at the edge of the forest orother measures to prevent soil movement and runoff must be taken when removing
fallen leaves and other sediment organic matter on steep slopes in forests and wheneversoil runoff has been observed during rainfall after the removal.
Since the radiocaesium in cedar, Japanese cypress, and other evergreen forests isthought to be settled onto branches and leaves, the branches, leaves, etc. of standing
trees around the edge of such forests shall be removed if the removal of fallen leaves,etc. alone does not produce a sufficient decontamination effect—that is, in cases where
the radiation dose in the living environment of residents near the forest does not

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decrease. In particular, since the trees at the edge of an evergreen forest generally havemore leaves on them and are therefore deemed to have comparatively high amounts ofradiocaesium settled onto them, when feasible, it is recommended to remove branches
and leaves up to as high a point on the trees as possible (see Figure 2-64). In such cases
it is preferable to perform the removal over a range that does not significantly impact
the growth of the trees; specifically, branches and leaves shall be removed up to about
half the length of the tree canopy.
The measures that are required in advance, specific decontamination methods, and notesof caution for the decontamination of forests are as provided in Tables 2-50 and 2-51.

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Figure 2-63: Example of the decontamination of a forest (removal of fallen leaves)Photo courtesy of: JAEA

Figure 2-64. Example of the decontamination of a forest(decontamination of branches and leaves, etc.)

Photo courtesy of: Date City

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Table 2-50. Necessary measures prior to the decontamination of forests
Category
Prevention ofdispersion
Cutting

Decontamination methods and notes of caution• If sidewalks and buildings are immediately adjacent, curing shall be
performed to prevent the dispersion of dust, etc.
• The cutting of weeds, shrubs, and other vegetation shall be carried out
using a chainsaw or shoulder-type mower, etc.

Table 2-51. Decontamination methods for forests and notes of caution
Category

Decontamination methods and notes of caution

Removal of fallen
leaves, etc.

• Fallen leaves, moss, mud, and other sediments shall be removed byhand by people wearing rubber gloves and by shovel, etc.
• Masks shall be worn to avoid inhaling suspended particulates
produced during removal work.
• The pruning of limbs and other tree parts shall be carried out to an
extent that does not give rise to any pronounced impact for the growthof trees, and the felled leaves and branches shall be collected.
• Generally , the very edges of the peripheral areas around forests
contain a large volume of leaves affixed to trees, and so there is thepossibility that a comparatively 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 thelength of the tree canopy).
• Masks shall be worn to avoid inhaling suspended particulates
produced during removal work.

Removalofbranches, leaves,
etc.

4.
(1)

Post-Work Measures
Handling the Removed Soil, etc.

The removed soil, etc. shall be appropriately handled and transferred to on-site storage
or a temporary storage site.
Please refer to “II. 4. (1) Handling the Removed Soil, etc.” for specific methods forhandling the removed soil.
When it comes to handling the vegetation, transfer and storage can be carried out more
efficiently by means of pre-treatment such as crushing, reducing the volume via
compression, or drying the vegetation as needed.
(2)

Cleaning of Equipment and Materials

With regard to the post-work handling of the equipment used for decontamination, theMinistry of Health, Labour and Welfare’s Ordinance on the Prevention of Ionizing
Radiation Hazards related to Decontamination Work of Soil Contaminated byRadioactive Materials Resulted from the Great East Japan Earthquake and its
Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6

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dated June 15, 2012) are to be followed.
See “II. 4. (3) Cleaning of Equipment and Materials” for specific methods for cleaning
the equipment and materials.

5.

Subsequent Measurements and Records

To confirm the decontamination effect, the air dose rate, etc. after completion of thedecontamination work shall be measured and compared with the air dose rate, etc. thatwas measured prior to the commencement of the decontamination work. Measurementof the air dose rate, etc. shall be performed in accordance with the measurement
methods given in “Part 1: Guidelines for Methods for Investigating and Measuring the
Status of Environmental Pollution in Intensive Contamination Survey Areas” for eachmeasurement point indicated in Table 2-45 of “2. (1) Determination of Measurement
Points.”In addition to the air dose rate, etc. at each measurement point, any other information
pertaining to the decontamination work shall be recorded and stored.
Table 2-52. Subsequent measurements and records for the decontamination ofvegetation
Measurement of
air dose rate,
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 the priormeasurements 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 of thedecontaminators, type of objects decontaminated, decontamination
methods, total decontamination area (of soil, etc.), the approximate weightof the removed soil, etc., and the status of storage and disposal.
• The equipment used in decontamination and the method of disposal afteruse.
• 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.

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VI. Others(1)

Decontamination and Other Measures for Sediment in Riverbeds

Radiocaesium that flowed into rivers as a result of the weather may have accumulated in
the sediment of riverbeds.
Despite this, in a survey conducted from May to September, 2011, almost no radioactive
materials were detected in river water,*15 and even supposing radioactive materials havesettled onto riverbeds, the impact on the exposure dose for residents is thought to belimited given the shielding effect of the river water as well.
Moreover, rivers have the characteristic that their bed conditions change due to floods
and other natural phenomena, and the impact at sites downstream must be taken into
account when performing decontamination work on a river.
Regarding the handling of riverbed sediment, considering the foregoing, it is suitable toconsider implementation after the decontamination work detailed in chapters II throughV has advanced to a certain level, while carrying out periodic monitoring. This section
will be revised in light of monitoring performed in the future pertaining to riverbed
contaminants and accumulated knowledge on the removal of riverbed sediment invarious projects.

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VI. Others

Column: Gamma Cameras
Gamma cameras are a new technology when it comes to decontamination. A gamma
camera is a camera that combines images photographed via a camera with the
distribution of measurements for the dose of radiation (gamma rays) emitted byradioactive materials to enable the user to color code how high or low the radiation dose
is so that it can be confirmed via a visual image. Since gamma cameras can visualize
radiation that is invisible to the naked eye, they make it possible to provide explanationsof the contents and results of decontamination work and explanations regarding thesafety of temporary storage sites in a more easy to understand manner. For these reasons,their use is being considered at venues for communicating risks to local residents.
Figure 2-65. Example of a gamma camera

Usage example

Figure 2-66. Image of the creation of a gamma camera visual image

Camera image

Distance
information

Distribution of
measurements

Combining(Allows the user to visually confirm the distribution of radioactive materials at sites where
decontamination is carried out.)

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Endnotes
*1

:

*2

:

*3

:

*4

:

The additional exposure dose due to the radioactive materials discharged during the Fukushima
Daiichi nuclear accident.
The air dose rate is the radiation dose per unit time in the space in question, also known as the
air absorbed dose rate, and is generally expressed in units of nGy/h (nano-Gray per hour) or
μSv/h (microsieverts per hour). Since the air dose rate indicates the level of external exposure,from a health preservation perspective it is suitable to measure the air dose rate in a way thatenables the ascertainment of the additional exposure dose. Moreover, since contamination is not
all the same, numerous measurements are required in order to confirm the status ofcontamination as a whole, but measuring apparatus are available that are portable for themeasurement of the air dose rate, and this ability to perform direct measurements in a short timeframe enables relatively simple handling even when there are numerous measurements to be
made. Based on the foregoing, as a general rule it is suitable to use the air dose rate when
confirming the decontamination effect. However, since the air dose rate normally measures
gamma rays, which easily penetrate materials, and since the radiation from radioactive
materials present around the measurement site and natural radiation from the earth are also
readily detected (readily influenced by background radiation), the air dose rate is not suitablefor confirmation of the contamination status of the surfaces or insides of objects to be
decontaminated. When narrowing down the contamination sites that contain comparatively
large amounts of radioactive materials or otherwise confirming the contamination status of thesurfaces of objects to be decontaminated, methods that measure beta rays are suitable as beta
rays are not readily influenced by background radiation and have low penetrating power.
This covers primarily decontamination work for regions in which the yearly dose is from 1 to
20 millisieverts. In such regions, since currently almost all of the radioactive materials
discharged by the accident that are factors in contamination are deemed to be Cs-134 andCs-137, the radioactive materials subject to decontamination are in basically radiocaesium.
However, in the vicinity of the Fukushima Daiichi Nuclear Power Plant and in other regions
where contamination by other radioactive materials is also possible, the decontamination work
must also cover radioactive materials other than radiocaesium as necessary.
The half-life refers to the length of time needed for a radioactive material to decay down to halfof its starting size. Cs-134 halves over two years, while this takes 30 years for Cs-137.
Figure 2-67 shows an image of the decrease in the air dose rates from radiocaesium that has
been separated out for Cs-134 and Cs-137. The horizontal axis indicates the number of years
that have elapsed since the accident. It can be understood from the figure that even though theradiation dose (Bq) for both Cs-134 and Cs-137 were largely the same right after the accident,
the air dose rate (Sv/h) for Cs-134 grew to more than twice as high as that for Cs-137. This isbecause the number of gamma rays emitted by Cs-134 is greater than that from Cs-137, and so
as a result the impact that these have on the human body is more than twice as great. What ismore, since Cs-134 decreases rapidly in the early stages, this speeds up the decline ofradiocaesium on the whole.

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Figure 2-67. Decline in the radiation doses of Cs-134 and Cs-137
Cs-134Air dose rate

Cs-137Total

No. of years elapsed (years)
*5

:

*6

:

*7

:

*8

:

*9

:

*10

*11

:

:

*12

:

*13

:

*14

:

The concentration of radiocaesium in the soil must be measured within a detector that isshielded so as not to be influenced by background gamma rays, and for this purpose it iscommon to use a germanium semiconductor detector that has been calibrated using a standard
radiation source with known amounts of radioactivity. It is therefore difficult to measure in ashort time and directly on site, requiring more labor for measurement than what is required forthe measurement of the air dose rate.
Normally for rice fields the depth is 15 cm from the surface, while for dry fields the depth is 15
to 30 cm from the surface.
Scraping away 3 to 5 cm of topsoil yields a reduction of radiocaesium concentration in the soilof 75 to 90% or more (Radioactive Decontamination Technique for Farm Land Soil (Ministryof Agriculture, Forestry and Fisheries press release dated September 14, 2011)).
This results in a 30 to 70% reduction in the radiocaesium concentration in the soil, dependingon the type of soil (Radioactive Decontamination Technique for Farm Land Soil (Ministry ofAgriculture, Forestry and Fisheries press release dated September 14, 2011)).
When using 30-cm reverse plowing, the surface-layer radiocaesium is placed between 15 and20 cm beneath the surface, yielding a decreased concentration in the surface layer (Radioactive
Decontamination Technique for Farm Land Soil (Ministry of Agriculture, Forestry and
Fisheries press release dated September 14, 2011)).
For instance, scraping away 4 cm of topsoil generates roughly 40 cubic meters of removed
materials (soil) for every 10 ares.
Based on Radioactive Decontamination Technique for Farm Land Soil (Ministry of Agriculture,
Forestry and Fisheries press release dated September 14, 2011).
Based on the results of decontamination verification tests and air dose rate reduction
simulations conducted by the Ministry of Agriculture, Forestry and Fisheries, it was found thatwhen the removal radius for fallen leaves, etc. from a certain measurement point exceeds about
20 m, the decontamination effect decreases. In other words, it is possible to assess thedecontamination effect up to a radius of 20 m from the measurement point, which means that it
is suitable to space the measurement points about 50 m apart. Also, when setting a location thatis 20 m away from the outer edge of a forest as a measurement point, it is suitable to use theedge of the forest when residences, etc. are in contact with a hill behind them as it will not be
possible to set measurement points 20 m away from the edge.
In continuing monitoring since the Chernobyl nuclear power plant accident as well, it has cometo light that much of the radiocaesium is deposited in the top layer of the soil and elsewhere
within the forest ecosystem.
Forests differ from farmland in that generally no fertilization management is carried out. Since
fallen leaves and other sediment organic matter present are being relied upon for the supply of

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nutrients, the removal of the sediment organic matter could degrade fertility. However, provided
the area where this matter is to be removed is small, the fertility will be restored by nutrients
supplied by newly fallen leaves and rainfall, which means that although the growth of the trees
could decline temporarily, there should be no major impact on the functioning of the forest.
*15: Results of the Measurement of Concentration of Radioactive Substances in
Groundwater-Quality Monitoring in Fukushima (Preliminary Report) by the Ministry of theEnvironment (released on June 3 and August 1, 2011) and Results of the Measurement ofRadioactive Substances Monitoring in Groundwater in Fukushima (released on November 15,2011) also by the Ministry of the Environment.

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Reference Materials
The Results of Decontamination Techniques in the Decontamination Work Carried out
thus Far by the National and Local Governments, Decontamination Team, Ministry of
the Environment (January 2013)(http://josen.env.go.jp/material/pdf/effects.pdf)
Comparative Survey on Radiation Dose Rates Before and After Topsoil Stripping,
Burying, and Replacement in the Schoolyards of Fukushima University Attached
Junior High School and Fukushima University Attached Kindergarten, Japan Atomic
Energy Agency and Fukushima University (July 27, 2011)(http://www.jaea.go.jp/jishin/kiji/kiji110810.pdf)
Guidelines for Municipal Decontamination Work, Nuclear Emergency Response
Headquarters (August 26, 2011)(http://www.meti.go.jp/press/2011/08/20110826001/20110826001-6.pdf)
Guide for Radiation Measurements at Schools and Other Public Buildings, Ministryof Education, Culture, Sports, Science and Technology and Japan Atomic Energy
Agency (August 26, 2011)(http://www.city.ome.tokyo.jp/kankyo/documents/gakou.pdf)
Guidelines Concerning Radiation Measurement, Ministry of Education, Culture,
Sports, Science and Technology and Japan Atomic Energy Agency (October 21, 2011)(http://www.kantei.go.jp/jp/tyoukanpress/201110/__icsFiles/afieldfile/2011/10/21/2
1shiryou02.pdf)
Decontamination Technology Catalog, Cabinet Office’s Team in Charge of Assisting
the Lives of Disaster Victims, Cabinet Office (November 22, 2011)(http://www.meti.go.jp/earthquake/nuclear/pdf/20111122nisa.pdf)
Radioactive Decontamination Technique for Farm Land Soil, Agriculture, Forestry
and Fisheries Research Council, Ministry of Agriculture, Forestry and Fisheries(September 14, 2011)(http://www.s.affrc.go.jp/docs/press/pdf/110914-10.pdf)

2-122

Guidelines Pertaining to Decontamination and Other Measures

2-123

VI. Others

Guidelines Pertaining to the Collection and Transfer of Removed Soil

Part 3

Guidelines Pertaining to theCollection and Transfer of theRemoved Soil
2nd Ed.,

3-1

2013

Guidelines Pertaining to the Collection and Transfer of Removed Soil

1

3

Part 3
Guidelines Pertaining to theCollection and Transfer ofRemoved Soil1.

Basic Concept2.

Requirements for Collection and Transfer of the Removed
Soil

3.

Concrete Actions

3-1

Guidelines Pertaining to the Collection and Transfer of Removed Soil

Guidelines Pertaining to the Collection and Transfer of theRemoved Soil
Table of Contents
1.

Basic Concept .................................................................................................. 3-3

2.

Requirements for Collection and Transfer of the Removed Soil .................... 3-6(1) Requirements for Preventing Dispersion, Outflow, and Leakage ................ 3-6(2) Requirements for Radiological Protection ................................................... 3-8(3) Transfer Route Requirements ...................................................................... 3-9(4) Other Requirements ................................................................................... 3-10

3.

Concrete Actions ........................................................................................... 3-11

Endnotes.................................................................................................................. 3-14

3-2

Guidelines Pertaining to the Collection and Transfer of Removed Soil1.

Basic Concept

These guidelines use cases and examples to explain in a concrete fashion the Ordinanceof the Ministry of the Environment(Note) pertaining to standards for the collection andtransfer of the removed soil provided in Article 41, Paragraph 1 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
(hereinafter the “Act on Special Measures concerning the Handling of Radioactive
Pollution”).
The removed soil generated during decontamination will be transferred to facilities suchas temporary storage sites by truck. 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 the living environment. The concrete necessary
actions include 1) preventing the radioactive materials from dispersing or outflowing
when the removed soil is loaded, unloaded, or transferred, and 2) preventing the publicfrom being exposed to radiation emitted from the removed soil being collected ortransferred.
Dispersion and outflow of radioactive materials as described in 1) can be prevented byputting the removed soil in containers, while radiation dose as described in 2) can be
decreased by reducing the volume of the removed soil to be collected and transferred orshielding it. The nearer people are to the removed soil during transfer or the longer theperiod of time they are in its vicinity, the higher the exposure dose. It is therefore
necessary to take measures to prevent people from recklessly coming close to theremoved soil for long periods of time during transfer.
These guidelines organize and describe the requirements for collecting and transferring
the removed soil as well as concrete actions to be taken in accordance with the safetymeasures mentioned above while also referring to*2 the existing rules related to thetransfer of radioactive materials*1.
The guidelines do not apply to cases where decontaminators move the removed soil tofacilities such as temporary storage sites as part of decontamination and other measures.
For information about such cases, see Part 2: Guidelines Pertaining to Decontamination
and Other Measures.
For information about necessary measures to ensure the safety of workers involved in
the collection and transfer, see the Ministry of Health, Labour and Welfare’s Ordinanceon the Prevention of Ionizing Radiation Hazards related to Decontamination Work ofSoil Contaminated by Radioactive Materials Resulted from the Great East Japan
Earthquake and the Guidelines for Prevention of Radiation Hazards for Workers
Engaged in Decontamination and Other Duties (Labour Standards Bureau Notification
0615 No. 6 dated June 15, 2012).
(Note): Ordinance for Enforcement of the Act on Special Measures concerning the

3-3Guidelines Pertaining to the Collection and Transfer of Removed Soil

Handling of Radioactive Pollution (Portion relevant to the collection andtransfer of the removed soil)
Article 57: The standards for the collection and transfer of the removed soil defined
under the Ordinance of the Ministry of the Environment in accordancewith Article 41, Paragraph 1 of the Act refer to the examples set forth in
Article 23 (except Items 4C (3), 5, and 6, and Paragraph 2).
(Start of the excerpt)
Article 23
1. The collection or transfer shall be carried out as follows:
A. Prevent occurrence of any damage pertaining to human health or theliving environment caused by the specified waste.
B. Take necessary measures, for example by putting the specified waste incontainers, to prevent the specified waste (including wastewater resulting
from the specified waste) from dispersing, outflowing, or leaking from thetruck.
C. Take necessary measures to prevent rainwater from permeating thespecified waste, for example by covering the surface of the specified
waste with a water shielding sheet.
D. Take necessary measures to prevent adverse effects upon the conservationof the living environment from offensive odors, noise, or vibration caused
in association with the collection or transfer.
E.
Distinguish the specified waste from other refuse to eliminate the risk ofthe specified waste being mixed with other refuse.
2. When a facility is constructed for the collection or transfer of the specified
waste, the necessary measures shall be taken so that the facility has no
possibility of adversely affecting the conservation of the living environment.
3. Any truck and container to be used for the transfer shall not pose risk ofdispersion or outflow of the specified waste, or leakage of offensive odors.
4. Collection and transfer of the specified waste by the use of a truck shall be
conducted in the following manner:
A. The following matters shall be displayed on the exterior of the truck.
(1) Precautions to the effect that the truck is being used to collect ortransfer the specified waste.
(2) Name of the person or entity in charge of the collection or transfer.
B. The information provided under A(1) and A(2) shall be indicated byeasy-to-identify colors and letters. The letter size of the precautions asprovided under A(1) shall be not less than 140 points as specified in JIS Z
8305, and the letter size of the precautions as provided under A(2)shall be not less than 90 points as specified in JIS Z 8305.
C. In accordance with the categories of entities or persons as set forth in (1)to (3) below, respective documents as defined in (1) to (3) shall be kept in
the truck used.
(1) The national, prefectural, or municipal government and the carrier whocollects or transfers the specified waste according to a contract withany of these governments shall keep a document that proves such fact
and other documents that show the following information (referred toas the “necessary documents” in (2) and (3)):

3-4Guidelines Pertaining to the Collection and Transfer of Removed Soil(a) Name and address of the person or entity in charge of thecollection or transfer, and the name of the representative if thecarrier is a corporation.
(b) Type and amount of the specified waste to be collected ortransferred (if such specified waste includes any specified waste
specified in the following item, information to this effect shall be
included).
(c) Date on which the collection or transfer has started.
(d) Names, addresses, and contacts for the site where the specified
waste is loaded for collection or transfer, and of the destination
where the waste is transferred to.
(e) Precautions in handling of the specified waste.
(f) Emergency measures in case of accidents.
(2) Any subcontractor who collects or transfers the specified waste
according to a contract with a primary contractor who undertakes thework of collection and transfer from the national government shallkeep: a document to this effect; a document proving the fact that suchsubcontractor is the person who has been listed as those to whom suchprimary contractor intends to subcontract the work of collection andtransfer of the specified waste under the contract document pertaining
to the agreement made between the national government and theprimary contractor; and the necessary documents to show this.
(Item 4C(3) is excluded)
D. The necessary measures, for example shielding from radiation, shall betaken so that the maximum dose equivalent rate at 1 cm does not exceed
100 Sv/hour at a point 1 m from the front, rear, and both sides of thetruck containing the specified waste. If the truck has an open cargo area,
both vertical planes in contact with the external outline shall be usedinstead of both sides.
E.
The tools and other materials for taking the measures specified in C(1)(f)shall be kept in the truck.
(Items 5 and 6 are excluded)
7. Records of the following information shall be prepared and retained for five
years from the day on which the collection or transfer ends.
A. The type and amount of the specified waste collected or transferred (ifsuch waste includes any specified waste specified in items 5A to 5C,
information to this effect shall be included).
B. Dates on which the collection or transfer of each of the specified waste
collected and transferred started and ended, the name of the person in
charge of the collection or transfer, the names and addresses of the sitewhere the waste is loaded and the destination where the waste istransferred to, and the registration or vehicle number of the truck if any
truck is used for the collection or transfer of the specified waste.
(Paragraph 2 is excluded)

3-5

Guidelines Pertaining to the Collection and Transfer of Removed Soil

2.
(1)

Requirements for Collection and Transfer of the Removed Soil
Requirements for Preventing Dispersion, Outflow, and Leakage

It is possible to prevent the radioactive materials from dispersing by putting theremoved soil in containers, such as sandbags, large sandbags, flexible containers, ordrums (hereinafter “container”) (see Figure 3-1), or wrapping it in a sheet, or delivering
it by boxcar*3. If the moisture content of the removed soil is high, prevent the waterfrom outflowing or leaking by dehydrating the soil to the extent possible. When nowaterproof container is used, lay a waterproof sheet or implement other necessary
measures before transfer. To prevent the rainwater from penetrating the removed soil
during collection and transfer, cover the soil with a waterproof sheet such as a water
shielding sheet or implement other necessary measures if no waterproof container isused.
When the containers with the removed soil are being loaded or unloaded onto or from atruck, take care not to disperse or discharge the removed soil to the outside. Should anyof the removed soil outflow during loading, unloading, or transfer due to the rollover or
falling of a container, place a rope or tape barrier around the area to keep people out,
quickly communicate with the operation site, collect the discharged removed soil, andcarry out decontamination. Therefore, it is essential to carry the tools and equipmentused for collecting the removed soil in the truck. Moreover, be sure to carry fire
extinguishers in case of vehicle fires.
In addition, when the removed soil is being loaded onto the truck, take care not to place
the soil directly on the surface of the truck. Before starting to drive the truck from an
on-site or temporary storage site, wash the exterior and tires at a predefined vehicle
washing area.

3-6

Guidelines Pertaining to the Collection and Transfer of Removed Soil

Figure 3-1. Examples of containers used for the collection and transfer

Sandbag

Plastic case

Sheet

Large sandbag
Flexible container

3-7

Drum

Guidelines Pertaining to the Collection and Transfer of Removed Soil

 Storing Removed Soil in Large Sandbags and Flexible Containers Different varieties of large sandbags and flexible containers are shown in Table 3-1.
In cases where the removed soil will be stored for a certain period of time (several
years) or when said soil contains large amount of moisture, it is most effective to use
highly durable containers such as cloth-type flexible containers that are weather
resistant and lined with an inner pouch, running-type flexible containers, or weather
resistant large sandbags lined with an inner pouch. In doing so, the properties andweight of the removed soil being stored and the storage period should be taken into
consideration.
Table 3-1. Types of Large Sandbags and Flexible Containers
Type
Flexible
container(cloth-type)*1

PhotographCharacteristics• The assumption is that they will only be
used once.
• Not as good as the running-type in terms of
weather resistance and waterproofness.
• Some have improved weather resistance asa result of UV treatment and the like, while
another type has improved waterproofness
as a result of being lined with inner pouches
and having an inner coating, etc.
• The assumption is that they will be used byhaving soil repeatedly stored in andremoved from them.
• Outstanding weather resistance andwaterproofness

Flexible
container(running-type)*1• Water permeable.
• Some have improved weather resistance asa result of UV treatment and the like, while
another type has improved waterproofness
as a result of being lined with innerpouches, etc.

Large sandbag*2*1: Pursuant to JIS Z 1651.
*2: The photograph shows a weather resistant container.

(2)

Requirements for Radiological Protection

The intensity of the radiation varies depending on the concentration and amount of theradioactive materials. The maximum air dose rates at a position that is 1 m away from a
relatively large truck when said vehicle has been loaded with removed soil and similar
substances are shown in Table 3-2 for concentrations of both Cs-134 and Cs-137(hereinafter “radiocaesium”), respectively.

3-8Guidelines Pertaining to the Collection and Transfer of Removed Soil

Table 3-2. Examples of Trial Calculations for Air Dose Rates at a Point that Is 1 m
Away from a Truck*4
Mean radioactivity concentration (Bq/kg)

Air dose rate
(Sv/h)

3,000

8,000

0.27

0.72

Maximum dose
equivalent rate 1 mfrom the truck
30,000 150,000 500,000 1,000,000(vehicle transfer
rules)
2.7

13

44

1m

89

100

1m
1m
1m

1m

1m

It is believed that since the truck will only be stopped at any one place for a short periodof time, the exposure dose of residents and others in the vicinity around the road onwhich the truck is traveling will be minimal.*5
The Rules for Transferring Radioisotopes by Vehicle (Rule No. 33 by the Ministry ofTransport, November 17, 1977) and the Rules for Transferring Nuclear Fuel Materials
by Vehicle (Rule No. 72 by the Ministry of Transport, December 28, 1978; hereinafter
the “Vehicle Transfer Rules”) stipulated as the standard for appropriate shielding
measures during transfer specify that the maximum air dose rate shall not exceed 100
Sv/hour at a point 1 m from the exterior surface of the truck.*6 This criterion is thought
to be reasonable from a public protection point of view. Therefore, when the removed
soil is being transferred, confirm that the maximum dose rate is not more than 100
Sv/hour at a point 1 m from the surface of the truck carrying the removed soil. If thedose is beyond the limit, take shielding measures or reduce the amount of the removed
soil to be transferred. Since the truck must comply with the related laws, if it is modified
for shielding, consult the nearest transport bureau as appropriate.
Assuming that removed soil with a radiocaesium concentration of as high as about 1
million Bq/kg is loaded on a relatively large truck, the maximum air dose rate should beless than 100 Sv/hour at a point 1 m from the truck. When using a truck to carry theremoved soil generated during the decontamination of areas whose dose does notexceed 200 mSv/year,*7 it is not necessary to measure the dose rate around the truck.
(3)

Transfer Route Requirements

When selecting the route for transfer, it is necessary to avoid residential areas, shopping
streets, school routes, and narrow roads to the extent possible in order to prevent any

3-9Guidelines Pertaining to the Collection and Transfer of Removed Soil

damage pertaining to human health or the living environment as well as to reduce any
effects on local residents. Moreover, it is also necessary to collect and transfer theremoved soil while avoiding peak times for heavy traffic and the periods when children
are going to schools or kindergartens. When the removed soil is being loaded onto thetruck, use low-noise heavy machinery in an effort to reduce noise and vibration.
(4)

Other Requirements

When the removed soil is collected and transferred by truck, the related laws including
the Road Traffic Act must be followed and it is not allowed to carry the soil together
with other dangerous materials, such as explosives or flammable waste. If the removed
soil is mixed with other soil or similar materials, even if they are not dangerous
materials, it becomes unclear whether the material is removed soil requiring storage atthe destination storage facility. If it is necessary to load the removed soil and otherwaste together on a truck, clearly distinguish both from each other and make certain
they cannot become mixed. To ensure that the removed soil is reliably delivered to thestorage facility, the person in charge of the transfer or those who are instructed by such
person shall load and unload the removed soil.
To prevent people from being exposed to radiation due to them approaching recklessly
during the transfer of the removed soil, put a sign on the exterior of the truck that shows
the following information: precautions to the effect that the truck is being used to collector transfer the removed soil and the name of the person or entity in charge of thecollection or transfer. Secure the sign to a place where it can easily be seen in such amanner that it cannot easily be removed.
In addition, keep the following documents in the truck: a copy of the contract and theform that shows the name of the person in charge of collection or transfer, the amount of
the removed soil, the dates on which the collection or transfer started, the name of thedestination to be transferred to, precautions for handling, and emergency measures totake in case of an accident.

3-10

Guidelines Pertaining to the Collection and Transfer of Removed Soil

3.

Concrete Actions

Table 3-3 shows the concrete actions to be taken in the collection and transfer of theremoved soil by truck in consideration of the requirements shown in Part 2, “Section 2.
Requirements for Collection and Transfer of the Removed Soil”.
If the condition of the collection and transfer exceeds the upper limit of radioactivity
concentration of the removed soil or the capacity of the container of respective
containers, it is necessary to make the shielding calculation separately and prepare
shielding in accordance with the results.
Table 3-3. Requirements for collecting and transferring the removed soil
Prevention ofdispersion,
outflow, andleakage

Shielding• When collecting and transferring the removed soil, put it in sandbags,
flexible containers, or drums with a lid, or wrap it in sheets. No special
measures are necessary if the soil is transferred by boxcar.
• If the removed soil contains sharp or heavy materials such as relatively
large stones, prevent the container from being torn, for example byusing a container with an inner liner.
• Before the transfer of removed soil with a high water content, dehydrate
it to the extent possible and take measures such as putting the soil in animpermeable container or laying down a waterproof sheet.
• When using a non-waterproof container, measures shall be taken such as
covering the removed soil with a waterproof sheet to prevent rainwaterfrom permeating the soil during collection and transfer. No suchmeasures are necessary when using a truck such as a boxcar to which
necessary measures are taken to prevent rainwater from penetrating theremoved soil.
• Visually check each container for tears or cracks and securely close themouths of any sandbags or flexible containers to prevent the contentsfrom being discharged if the container collapses or falls down, or a fire
breaks out. Be sure to select drums that have locking mechanisms.
• Before starting the truck from the on-site area in which removed soil isstored or temporary storage site for removed soil and traveling on publicroads, wash the exterior and tires at a car wash if soil is adhering to thetruck. If water is used for washing, check the channel for the cleaningwater in advance and clean the drainage channel to ensure smoothdrainage.
• Keep fire extinguishers in the truck as a means of controlling any fires.
Moreover, for the handling of any removed soil that has spilled out,
prepare cleanup implements, bags for collection, a barrier rope or tapeto indicate the area where people should keep out, a flashlight, andcommunication device such as a mobile phone. Note that if the carrier isa business operator, it is recommended to carry a measuring apparatus
to check for radioactive contamination (calibrated *8 scintillation survey
meter).
• When transferring the removed soil from areas where the radioactive
dose rate exceeds 200 mSv/year, use a calibrated*8 scintillation survey
meter (hereinafter referred to as the “measuring apparatus”) to measure
the air dose rate around the truck loaded with containers.
• Cover the measuring apparatus with a plastic bag to avoid contamination.
• Hold the detecting element parallel to the ground surface during
measurement.

3-11

Guidelines Pertaining to the Collection and Transfer of Removed Soil

• Turn the power of the measuring apparatus ON and wait until the reading
becomes stable. After this, take the reading five times and the average of
those values will be the measured value.
• Take the measurements at a point 1 m from the front, rear, and both sides ofthe vehicle. If it has an open cargo area, use both vertical planes in contact
with the external outline instead of both sides.
• Conduct measurement at the point that shows the highest air dose rate after
implementing screening on each surface of the vehicle. If the point of highest
air dose rate is unknown, take the measurements at the center of each face.
• Make sure that the maximum of the measured values (dose equivalent rates at
1 cm) does not exceed 100 Sv/hour, and record the results.
• If the maximum dose exceeds 100 Sv/hour, reduce the amount of theremoved soil to be transferred or add shielding materials to the containers
holding the soil or to the truck.

Loading
limitations
Signage• If loading the removed soil together with other waste on the truck,
distinguish them from each other during the collection and transfer.
• Collection and transfer of the removed soil by the use of a truck shall be
conducted in the following manner:
A. The following matters shall be displayed on the exterior of the truck.
(1) Precautions to the effect that the truck is being used to collect or transfer
the removed soil.
(2) Name of the person or entity in charge of the collection or transfer.
B. The information provided under (1) and (2) above shall be indicated byeasy-to-identify colors and letters. The letter size of the precautions asprovided under (1) shall be not less than 140 points as specified in JIS Z
8305, and the letter size of the precautions as provided under (2) shall be
not less than 90 points as specified in JIS Z 8305.
• Avoid transfer during the night as much as possible. This is for conceivablereasons like the fact that visibility generally deteriorates at night, and so for
example it would be harder to see the signage that is being displayed.

Figure 3-2. Examples of Signage

140 points or larger
除去土壌
運 搬 車

90 points orlarger○○運搬株式会社

Other matters• Keep documents showing the following information in the truck.
(When any of the national, prefectural, and municipal governments
conducts or commissions a carrier to conduct the collection or transferof the removed 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 the name 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 isloaded for the collection or transfer, and of the destination where thesoil is transferred to.
• Cautions pertaining to handling the removed soil.

3-12

Guidelines Pertaining to the Collection and Transfer of 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 such work to another carrier)• As a document to prove this fact, a copy of the contract between the
primary contractor and the carrier (subcontractor).
• A document proving the fact that such subcontractor is the person
who has been listed as those to whom such primary contractor
intends to subcontract the work of collection and transfer of theremoved soil under the contract document pertaining to theagreement made between the national government and the primarycontractor.
• Name and address of the person in charge of the collection or transfer
and the name 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.
• Name, address, and contact for the site where the removed soil isloaded for collection or transfer.
• Name, address, and contact for the destination to which the removed
soil is transferred.
• Cautions pertaining to handling the removed soil.
• Emergency measures in case of an accident.
• The carrier shall load and unload the removed soil by itself or instructanother worker to do this.
• If there are records on the decontamination*9, keep the document
showing the air dose rate on the surface of each bag or container in thetruck.
• When selecting the transfer route, avoid residential areas, shopping
streets, school routes, and narrow roads to the extent possible in order toprevent damage to human health and the living environment as well as
to reduce any effects on local residents. Moreover, collect and deliver
the removed soil while following the legally permitted speeds andavoiding the peak times for heavy traffic and the time periods whenchildren are going to or returning from schools or kindergartens. Whenthe removed soil is being loaded onto the truck, use low-noise heavymachinery to reduce noise.
• Record the amount of the removed soil collected or transferred, thedates on which each arrangement for the collection or transfer of theremoved soil starts and ends, the name of the person in charge of thecollection or transfer, the names and addresses of the sites where theremoved soil is loaded and unloaded, and the registration or vehicle
number of the truck if one is used for the collection or transfer, andretain the resulting records for five years from the date when thecollection or transfer ends.

3-13

Guidelines Pertaining to the Collection and Transfer of Removed Soil

Endnotes
*1:

*2:

*3:

*4:

These rules include the following two ministerial ordinances based on the Act on the Regulationof Nuclear Source Materials, Nuclear Fuel Materials and Reactors (hereinafter the “Reactor
Regulation Act”), which are the “Rules Related to the Transfer of Nuclear Fuel Materials
Outside Plants or Operating Sites (hereinafter the “external transfer rules”)” and “Rules forTransferring Nuclear Fuel Materials by Vehicle (hereinafter the “vehicle transfer rules”),” aswell as the ministerial ordinance based on the Act on the Prevention of Radiation Hazards Dueto Radioisotopes, etc. (hereinafter the “Prevention Act”), which is the “Rules for Transferring
Radioisotopes by Vehicle (hereinafter the “vehicle transfer rules”)”.
The removed soil described in these guidelines shall meet the criteria set forth in the ministerial
ordinance based on the Act on Special Measures, but the Reactor Regulation Act and thePrevention Act do not apply to it. Moreover, the external and vehicle transfer rules do not apply
as they are because of the following concept: the removed soil is collected and transferred fromthe living environment, so even if the soil is discharged into the environment for certain
unlikely reasons including traffic accidents, it may be collected appropriately. However, theseguidelines have been developed in consideration of the concept of protecting the public fromradiation as set forth in the existing rules.
The external transfer rules define some types of materials to be transferred according to the
maximum radioactive dose stored. The removed soil has characteristics and radiocaesium
concentrations similar to the concept of material type LSA-2. Applicable materials fall underpackage type IP-2. The rules specify that at the design stage, it is necessary to check whether
the containers used have a technical performance that meets the standard of an IP-2 package. To
put it concretely, it must be proven that the container can endure any possible adverse event
during transfer, such as exposure to heavy rain, falling due to mishandling when the material isloaded on or unloaded from a truck, and being left standing exposed to the hot sun. Meanwhile,the basic concept described in endnote *2 above is that the soil described in these guidelines iscollected and transferred from the living environment, and even if the soil is discharged into theenvironment, it may be collected appropriately. Therefore, in light of this point, when collecting
and transferring the removed soil, based on a concept that a container shall be selected from theperspective of preventing dispersion or outflowing mainly at the time of loading, the container
is not required to meet the level of performance of an IP-2 package.
According to the results of evaluation of the exposure dose during transfer with a 20-ton truck
whose container is filled with the removed soil, the maximum dose rate is 89 Sv/hour at apoint 1 m from the surface of the container if the radioactivity concentration of the soil is not
more than 1 million Bq/kg and the container is not exceeding 530 cm long, 220 cm wide, and120 cm high.
Key parameters for this analysis• The truck without a lid has a container filled with the removed soil (the density is 2.0 g/cm3
and the radioactivity ratio of Cs-134 and Cs-137 is 1:1).
• The container is 530 cm long, 220 cm wide, and 120 cm high (this is based on the innerdimensions of the platform), and no shielding effect by the container is considered.
• The measurement points (MP) are 100 cm from the centers of the side face (530 cm  120cm) and front face (220 cm  120 cm) of the container.

3-14

Guidelines Pertaining to the Collection and Transfer of Removed Soil

530 cm

220 cmMP 1

100 cm120 cm100 cm

MP 2 (driver side)

Analysis results
Mean radioactivity concentration (Bq/kg)

Air dose rate
(Sv/h)

3,000

8,000

30,000 150,000

MP 1

0.27

0.72

2.7

13

MP 2

0.20

0.53

2.0

10

Maximum dose
equivalent rate 1 mfrom the truck
1,000,00
500,000(vehicle transfer
0rules)
100 (front, rear, and44
89both sides of thecontainer)
20 (front of the
33
66
truck)(In cooperation with the Japan Atomic Energy Agency)
*5:

*6:

*7:

*8:

At the 16th Review Meeting on Safety Assessment of Disaster Waste (which was held on
March 4, 2013), the results of calculations were submitted that indicated that residents 3 m to
10 m in the vicinity around street corners along the transfer routes would receive an annual
additional exposure dose of 0.0047 mSv to 0.040 mSv from the external exposure received
from the waste loaded into the vehicles. This was based on an assumed scenario in which there
were 1,050 trucks loaded with waste with a radiocaesium concentration of 50,000 Bq/kg
running each month, of which half of the vehicles would be stopped at red lights for one
minute.
The vehicle transfer rules specify that the maximum dose equivalent rate shall not exceed 100
Sv/hour at a point 1 m from the front, back, and both sides of the container, and 20 Sv/hour
at a point 1 m from the front of the truck. The latter is defined to protect the carrier fromexposure to radiation. For more information about measures for protecting workers fromexposure to radiation, see the Ministry of Health, Labour and Welfare’s Ordinance on thePrevention of Ionizing Radiation Hazards related to Decontamination Work of Soil
Contaminated by Radioactive Materials Resulted from the Great East Japan Earthquake and the
Guidelines for Prevention of Radiation Hazards for Workers Engaged in Decontamination andOther Duties (Labour Standards Bureau Notification 0615 No. 6 dated June 15, 2012).
The radioactivity concentration of the soil corresponding to an air dose rate of about 40
Sv/hour corresponding to 200 mSv/year is about 700,000 Bq/kg, which is given by converting
the soil monitoring data shown by the Ministry of Education, Culture, Sports, Science andTechnology as well as soil monitoring results including air dose rates obtained at elementary
schools in Fukushima Prefecture to the value on June 1, 2011, and using the resulting regression
formula “Log (Air dose rate) = 0.815  Log (radiocaesium concentration)  3.16” (Japan
Nuclear Energy Safety Organization).
See Part 1: Guidelines on the Methods for Investigation and Measurement of the Status ofEnvironmental Pollution in Intensive Contamination Survey Areas. It is possible to not only ask

3-15

Guidelines Pertaining to the Collection and Transfer of Removed Soil

*9:

a registered company to calibrate your measuring apparatus, but also to use another calibrated
instrument to perform measurements at the same particular location as a way of adjusting theapparatus.
See Part 2: Guidelines Pertaining to Decontamination and Other Measures, which specify thatthe air dose rate shall be measured at a point 1 cm from each container with the removed soil,
and the results shall be recorded so that the radioactive dose distribution (range) of the removed
soil generated during decontamination can be roughly determined.

3-16

Guidelines Pertaining to the Collection and Transfer of Removed Soil

Part 4

Guidelines Pertaining to
the Storage of theRemoved Soil
2nd Ed.,2013

Guidelines Pertaining to the Storage of Removed Soil

1

4

Part 4
Guidelines Pertaining to the
Storage of Removed Soil1.

Basic Concept2.

Safety Measures and Requirements Necessary for Storage

3.

Concrete Examples of Storage Methods in Light of the
Facility/Management Requirements

4-1

Guidelines Pertaining to the Storage of Removed Soil

Guidelines Pertaining to the Storage of Removed Soil
Table of Contents
1.

Basic Concept .................................................................................................. 4-3(1) Outline.......................................................................................................... 4-3(2) Facility Design ............................................................................................. 4-4(3) Safety Management...................................................................................... 4-4

2.

Safety Measures and Requirements Necessary for Storage ............................ 4-7(1) Facility Requirements .................................................................................. 4-9(2) Management Requirements........................................................................ 4-17

3.

Concrete Examples of Storage Methods in Light of the Facility/Management
Requirements ................................................................................................. 4-21
On-site storage - 1): Above ground .................................................................... 4-22
On-site storage - 2): Underground ..................................................................... 4-23
On-site storage - 3): Above ground .................................................................... 4-25
On-site storage - 4): Underground ..................................................................... 4-26
Temporary storage site - 1): Above ground........................................................ 4-28
Temporary storage site - 2): Above ground........................................................ 4-31
Temporary storage site - 3): Underground ......................................................... 4-34
Temporary storage site - 4): Storage on sloped ground ..................................... 4-37

Endnotes.................................................................................................................. 4-40

4-2

Guidelines Pertaining to the Storage of Removed Soil

1.
(1)

Basic Concept
Outline

These guidelines use cases and examples to explain in a concrete fashion the Ordinanceof the Ministry of the Environment (Note) pertaining to standards for the storage of theremoved soil provided in Article 41, Paragraph 1 of the Act on Special Measures
Concerning the Handling of Environmental Pollution by Radioactive Materials
Discharged by the NPS Accident Associated with the Tohoku District-Off the Pacific
Ocean Earthquake That Occurred on March 11, 2011 (hereinafter the “Act on Special
Measures concerning the Handling of Radioactive Pollution”).
It is necessary to properly store the soil that is removed during operations todecontaminate radioactive materials discharged in association with the Fukushima
Daiichi Nuclear Power Plant accident (hereinafter, “removed soil”) until its final
disposal.
The following three forms are considered as the forms of storage.
1)
2)
3)

The form in which removed soil is stored at the decontaminated sites, etc.
(hereinafter “on-site storage”).
The form in which removed soil is stored in temporary storage sites establishedin each municipality or community.
The form in which removed soil is stored in interim storage facilities(established only in Fukushima Prefecture where a large amount of theremoved soil, etc. is expected to be generated.)For 1) on-site storage and 2) storage in temporary storage sites, these guidelines
organize the facility requirements and management requirements necessary for storing
the removed soil safely in accordance with its quantity and radioactivity concentration.
In light of the above, these guidelines illustrate by example concrete facility
specifications that are considered to meet such requirements as well as details andmethods of safety management continuing beyond the end of the storage period. Whenstoring the removed soil together with decontamination waste, see the “Waste
Guidelines” (March 2013, Vol. 2).
For the prevention of the effect of radioactive materials on human health and the living
environment, the following two safety measures are required: Construction of storage facilities (hereinafter “facilities”) that can ensure safetyaccording to the radioactivity concentration and amount of the removed soil
(facility design).
 Carrying out proper safety management of the removed soil during and after its
delivery. If any trouble occur, take measures (safety management).
Sections below demonstrate the concepts of the facility design and safety management,
two measures for storing the removed soil safely.

4-3

Guidelines Pertaining to the Storage of Removed Soil

(2)

Facility Design

There are two methods of constructing facilities that are able to ensure safety: one is amethod of evaluating the safety of each facility designed, *1 and the other is a method toevaluate the safety of a typical virtual facility to predefine the facility requirements andto require each facility to meet such requirements. In light of the current situation where
prompt design and installation of many temporary storage sites are required, the lattermethod is basically considered reasonable but the former can also be employed.
(3)

Safety Management

The removed soil is monitored to ensure that radiation and radioactive materials will nothave any effect on human health or the living environment by carrying out safety
management in accordance with management requirements during the period from thestart of bringing in the removed soil until the time when the removed soil is taken out
after the end of the period of storage. If any problems occur, safety will be promptly
ensured by taking response measures such as carrying out the repair of the facility.
Another important practice of safety management is to confirm that after temporarily
storing the removed soil in on-site storage or temporary storage sites, no contamination
remains at sites from which the facilities have been removed.
The following section clarifies the specifications required for the facility to carry out
safe storage (hereinafter “facility requirements”) and the details required for safety
management (hereinafter “management requirements”).
(Note) Ordinance for Enforcement of the Act on Special Measures concerning theHandling of Radioactive Pollution (Portion relevant to Standards for Storage of theRemoved Soil)
Article 58: The standards of storage provided in the Ordinance of the Ministry of theEnvironment for Article 41, Paragraph 1 of the Act are as follows.
1. Temporary storage of the removed soil (hereinafter simply referred to as“storage”) shall be subject to the examples specified under the provisions ofArticle 15 (except Items 1, 6, 8, 9, and 11-13).
(Following is the excerpt from the portion relevant to the above)
Article 15(Item 1 is excluded)
2. The following measures shall be taken to prevent the designated wastefrom dispersing or outflowing from the storage space.
A. Take necessary measures, including placing the waste in containers or
wrapping it.
B. If the designated waste is stored outdoors with no containers, theheight of the designated waste shall not exceed the value specified in(1) or (2) below in accordance with the category provided under (1) or(2).
(1) If there is no structural part on which the weight of the designatedwaste to be stored is directly loaded on any part of the fence of the

4-4Guidelines Pertaining to the Storage of Removed Soil

3.

4.

storage space (hereinafter referred to as “direct loading part”), theheight is given by defining an arbitrary point in such storage space,drawing a vertical line passing through such arbitrary point from theground, making a plane that includes the lower end of the fence ofsuch storage space and with a grade of 50% respective to thehorizontal surface, and finding the intersection point of the line andthe plane. If the lower end of the fence does not reach the ground,the intersection line of a vertical plane passing through the end andthe ground surface is defined as the lower end. If two or moreintersection points are found, the nearest one to the ground isselected.
(2) If the fence has a direct loading part, the height is defined in (a) and(b) shown below in accordance with the part provided under (a) and(b).
(a) In an area within a horizontal distance of 2 m toward suchstorage space from the line of a vertical distance of 50 cm below
the upper end of the direct loading part (or the bottom end if thefence with respect to the direct loading part is less than 50 cmhigh) (hereinafter referred to as the “reference line”), the heightat an arbitrary point in the area is specified in (i) shown below.
Note that if the fence of the storage space has a part that is not a
direct loading part, the height is either (i) or (ii), whichever islower.
(i) Height from the ground surface to the intersection point of avertical line passing through the arbitrary point and ahorizontal plane including the reference line having theshortest horizontal distance from the vertical line.
(ii) Height specified in (1).
(b) In an area more than 2 m from the reference line toward thestorage space, the height at an arbitrary point within such area
more than 2 m is specified in (i) shown below. Note that if thefence of the storage space has a part that is not a direct loading
part, the height is (i) or (ii), whichever is lower.
(i) Height from the arbitrary point to the intersection point of avertical line passing through the point and a plane that
includes a line of horizontal distance of 2 m from thereference line toward the storage space and that forms a gradeof 50% with respect to the horizontal surface. If two or moreintersection points are found, the nearest one to the ground isselected.
(ii) Height specified in (1).
To prevent public water areas and the groundwater from being
contaminated with wastewater generated in association with the storage ofthe designated waste, necessary measures shall be taken, for example bycovering the bottom of the storage space with a water shielding sheet.
To prevent rainwater or groundwater from permeating the designatedwaste, necessary measures shall be taken, for example by covering the

4-5

Guidelines Pertaining to the Storage of Removed Soil

surface of the designated waste with a water shielding sheet.
5. To prevent emanation of offensive odor from the storage space, necessary
measures shall be taken.
(Item 6 is excluded)
7. To prevent the designated waste from being mixed with other objects in thestorage space, necessary measures shall be taken, for example by installing
partitions.
(Items 8 and 9 are excluded)
10. To avoid the adverse effects of radiation, necessary measures shall betaken, for example by prohibiting people from unnecessarily entering thestorage place, by constructing fences or signboards along the boundary, orby covering the surface of the designated waste with soil for shielding
radiation.
(End of the excerpt)
2. The storage shall be carried out at a site surrounded by a fence (if the fence
directly receives a load of the removed soil to be stored, the structural strength
shall be sufficient to safely support the load). However, this shall not apply tocases where the removed soil generated in association with measures fordecontamination of the soil, etc. pertaining to a special decontamination areaor decontamination zone is stored on the land in which measures fordecontamination of the soil, etc. were implemented.
3. The storage shall be carried out in an area where signboards meeting thefollowing requirements are posted at a place easily visible to the public.
However, this shall not apply in cases stipulated under the exceptional clauseof the preceding item.
A. The length and width shall be at least 60 cm each.
B. The signboard shall indicate the following matters:(1) Precautions to the effect that the area is the place for the storage of theremoved soil.
(2) Contact details in the event of an emergency.
(3) Maximum height specified in Article 15, Item 2B that shows examples
in accordance with Item 1 if the removed soil is stored outdoors
without using containers.
4. In accordance with the following matters, water quality inspections shall be
conducted to check the quality of the groundwater sampled from a place
where it is possible to determine the presence or absence of any impact ofwastewater generated in association with the storage of the removed soil upon
the water quality of the groundwater in the periphery of the place of storage.
However, this shall not apply to the exceptional clause of Item 2.
A. Before the commencement of the storage, radioactive materials
discharged by the accident shall be measured and recorded according to
the method defined by the Minister of the Environment as provided in
Article 24, Paragraph 1, Item 3A.
B. After the commencement of the storage, radioactive materials discharged
by the accident shall be regularly measured and recorded according to themethod defined by the Minister of the Environment as provided in Article
24, Paragraph 1, Item 3A.

4-6

Guidelines Pertaining to the Storage of Removed Soil5.

The radiation dose shall be regularly measured and recorded at the boundaries
including the place of storage according to the method defined by the Ministerof the Environment as provided in Article 15, Item 11. Note that if the
exceptional clause of Item 2 applies, the radiation dose shall be measured andrecorded immediately before and after the commencement of storage.
6. The record of following matters shall be made and kept until abolishment ofsuch place of storage. Note that if the exceptional clause of Item 2 applies, therecord of measurement in accordance with the exceptional clause of thepreceding item shall be made, and kept until the storage of the removed soil
ends.
A. Amount of the removed soil stored.
B. Dates on which the storage starts and ends for each batch of the removed
soil stored, and the names and addresses of the receiving site anddestination of the removed soil after storage.
C. Concerning delivery and receipt of the removed soil, names of the persons
in charge of receiving and delivering such removed soil, and theregistration or vehicle number of any truck in case where such truck wasused for the transfer pertaining to the delivery.
D. Measurements, inspections, tests, and other measures (including water
quality checks specified in Item 4 and measurements defined in thepreceding item) carried out to maintain and control the storage place.
2.

Safety Measures and Requirements Necessary for Storage

When storing the removed soil, proper safety measures shall be taken in accordancewith the radioactivity concentration, the amount, and the storage method to reduce thedose of radiation that people receive.
In light of the concepts of related regulations,*3 this section organizes the facility andmanagement requirements based on the safety measures that are considered to berequired to be commonly applied when storing the removed soil.*4 (see Figures 4-1 and
4-3). For information about necessary measures for the safety of workers, see theOrdinance on the Prevention of Ionizing Radiation Hazards related to Decontamination
Work of Soil Contaminated by Radioactive Materials Resulted from the Great East
Japan Earthquake and the Guidelines for Prevention of Radiation Hazards for Workers
Engaged in Decontamination and Other Duties (Labour Standards Bureau Notification
0615 No. 6 dated June 15, 2012).

4-7

Guidelines Pertaining to the Storage of Removed Soil

Figure 4-1: Basic diagram of the safety measures for on-site and temporary storagesites
Water shielding
Fence
layer
Sandbags

Earth
mound

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

Containers
Fence

Monitoring ofradioactive materials
in the groundwater Basic diagram of the safety measures for on-site and temporary storage sites
1) 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.

4-8

Guidelines Pertaining to the Storage of Removed Soil

(1)

Facility Requirements

Cs-134 and Cs-137 (hereinafter, “radiocaesium”) are expected to account for most of
the radioactive materials contained in the removed soil generated from decontamination
zones where the dose is 1 to 20 mSv/year. Therefore, the design of a facility requires
taking account of the characteristics of the radiocaesium as shown below.
• Radiocaesium emits gamma rays, so, according to the concentration, it requires
proper radiation shielding or securing of distance from residential areas.
• In general, adsorptive property of radiocaesium relative to soil is high, so it isexpected to stay close to the topsoil and it is considered highly unlikely to betransferred by groundwater within several years.
• There is a possibility that the removed soil to which radiocaesium has become
adsorbed may itself be transferred due to wind or rain.
1)

Shielding and isolation

Because the removed soil emits gamma rays,*5 measures to reduce additional exposure
dose of radiation to the public are needed. Said measures include performing shieldingby covering facilities with uncontaminated soil (hereinafter “covering with soil”) andproperly isolating them so as to prohibit people from unnecessarily entering the storage
place by means of constructing fences or signboards. Moreover, it may also benecessary to isolate the facilities from residential areas depending on the circumstances.
The facility shall be designed so that the additional exposure dose of radiation from theremoved soil to which the public is exposed does not exceed 1 mSv/year even during
the delivery of the removed soil, while the radiation dose outside of the site boundary offacility is almost the same as that of the surrounding environment after the delivery iscompleted.
To put it concretely, a site boundary shall be set up around the facility while maintaining
the necessary isolation distance, and shielding materials, such as covering with soil,
earth mound, sandbags, and flexible containers filled with soil, shall be installed asnecessary during and after the delivery of the removed soil in order to shield the facility.
If the scale of the facility is relatively large, promptly install the shielding materials on
the sides and the top of the facility during the delivery of the removed soil to minimize
radiation emitted from it. When using sandbags as a shielding material, distinguish themfrom bags containing the removed soil. If various types of removed soil with different
radioactivity concentrations are stored in the same facility, it is possible to put the one
with the higher radioactivity concentration in the center or on the bottom, and emplace
the other type with a lower concentration in such a way as to enclose or cover theformer type to reduce the radiation dose .
Table 4-1 and Table 4-2 show estimates of the required isolation distances according to
the radioactivity concentration and amount of the removed soil, storage methods, and

4-9

Guidelines Pertaining to the Storage of Removed Soil

facility configuration.
Table 4-1. Relationship between shielding measures and site boundary positions
according to the radioactivity concentration of the removed soil and theconfiguration of the facility (additional exposure dose: 1 mSv/year or less) (above
ground method) *6*7 (1/2)
Storage configuration
Shielding
LengthWidth

Height

2m×

2m×

1m

5m×

5m×

2m

10 m ×10 m ×1m

20 m ×20 m ×2m

20 m ×20 m ×4m

50 m ×50 m ×100 m ×50 m ×50 m ×100 m ×

2m

4m

2m

Mean radioactivity concentration (Cs: Bq/kg)
3,000 –
8,000 –
30,000 –8,000
30,000100,000
Estimates of the air dose rate in regions where
removed soil has been generated*7
App. 0.5
App. 0.5 – App. 1 – 3 App. 3 μSv/h
μSv/h/or
1 μSv/hμSv/hor higher
less
1m
2m
4m
8m
1m
1m
4m
4m
0m
0m
1m
2m
0m
0m
0m
1m
0m
0m
0m
0m
4m
6m
10 m
20 m
1m
2m
4m
8m
0m
0m
1m
4m
0m
0m
0m
1m
0m
0m
0m
0m
1m
4m
6m
10 m
0m
0m
1m
4m
0m
0m
0m
1m
0m
0m
0m
0m
1m
4m
8m
20 m

Up to 3,000

No shielding
Successive lateral shielding
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
No shielding
Successive lateral shielding
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
Successive lateral shielding
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
Successive lateral shielding
Successive lateral shielding, with an area without
covering with soil not exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
Successive lateral shielding
Successive lateral shielding, with an area without
covering with soil not exceeding 20 m × 20 m
Successive lateral shielding, with an area without
covering with soil not exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
Successive lateral shielding
Successive lateral shielding, with an area without
covering with soil not exceeding 20 m × 20 m
Successive lateral shielding, with an area without
covering with soil not exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness

4-10

1m

4m

6m

10 m

0m
0m
0m
0m
0m
0m
2m

0m
0m
0m
0m
0m
0m
4m

1m
0m
0m
2m
0m
0m
20 m

6m
1m
0m
10 m
4m
0m
-

1m

4m

8m

20 m

1m

4m

6m

10 m

0m
0m
0m
0m
0m
0m
2m

0m
0m
0m
0m
0m
0m
6m

1m
0m
0m
2m
0m
0m
-

6m
1m
0m
20 m
4m
0m
-

1m

4m

8m

20 m

1m

4m

6m

10 m

0m
0m
0m

0m
0m
0m

2m
0m
0m

8m
1m
0m

Capacity

4m3

50 m3

100 m3800 m31,600 m3

5,000 m3

10,000 m3

20,000 m3

Guidelines Pertaining to the Storage of Removed Soil

Table 4-1. Relationship between shielding measures and site boundary positions
according to the radioactivity concentration of the removed soil and theconfiguration of the facility (additional exposure dose: 1 mSv/year or less) [above
ground method] *6*7 (2/2)

Storage configuration
Shielding
LengthWidth

100 m × 100 m ×

200 m ×200 m ×Mean radioactivity concentration (Cs: Bq/kg)
3,000 –
8,000 –
30,000 –8,000
30,000100,000
Estimates of the air dose rate in regions where
removed soil has been generated*7
App. 0.5
App. 0.5 – App. 1 – 3 App. 3 μSv/h
μSv/h/or
1 μSv/hμSv/hor higher
less
0m
0m
2m
20 m
0m
0m
0m
4m
0m
0m
0m
0m
2m
10 m
-

Up to 3,000

Height2m

2m

After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
Successive lateral shielding
Successive lateral shielding, with an area without
covering with soil not exceeding 20 m × 20 m
Successive lateral shielding, with an area without
covering with soil not exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness

1m

4m

8m

20 m

1m

4m

6m

10 m

0m
0m
0m

0m
0m
0m

2m
0m
0m

10 m
1m
0m

Capacity

40,000 m3

80,000 m3

Figure 4-2. Example of the relationship between shielding measures via sandbags
and site boundary positions

4 m or more of
separation
5m
2m

Soil

4 m ormore ofseparation
5m

Sandbags
Thicknessof 30 cm

When shielding the lateral sides of removed soil of 20,000 Bq/kg(5 m long × 5 m wide × 2 m tall) with sandbags (30 cm)

4-11

Guidelines Pertaining to the Storage of Removed Soil

Table 4-2. Relationship between shielding measures and site boundary positions
according to the radioactivity concentration of the removed soil and theconfiguration of the facility (additional exposure dose: 1 mSv/year or less)[underground method] *6*7

Storage configuration
Shielding
LengthWidth

Height

2m×

2m×

1m

10 m ×10 m ×1m

20 m ×20 m ×2m

50 m ×100 m ×200 m ×50 m ×100 m ×200 m ×

10 m

10 m

10 m

Mean radioactivity concentration (Cs: Bq/kg)
3,000 –
8,000 –
30,000 –8,000
30,000100,000
Estimates of the air dose rate in regions where
removed soil has been generated*7
App. 0.5
App. 0.5 – App. 1 – 3 App. 3 μSv/h
μSv/h/or
1 μSv/hμSv/hor higher
less
1m
2m
4m
4m
0m
0m
1m
1m
0m
0m
0m
1m
0m
0m
0m
0m
1m
4m
6m
10 m
0m
0m
1m
1m
0m
0m
0m
1m
0m
0m
0m
0m
1m
4m
8m
20 m
0m
0m
1m
1m
0m
0m
0m
1m
0m
0m
0m
0m
2m
4m
20 m
-

Up to 3,000

No shielding
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
No shielding
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
No shielding
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
No shielding
With an area without covering with soil not
exceeding 20 m × 20 m
With an area without covering with soil not
exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
No shielding
With an area without covering with soil not
exceeding 20 m × 20 m
With an area without covering with soil not
exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness
No shielding
With an area without covering with soil not
exceeding 20 m × 20 m
With an area without covering with soil not
exceeding 10 m × 10 m
After covering with soil of 30 cm in thickness
After covering with soil of 40 cm in thickness
After covering with soil of 50 cm in thickness

4-12

1m

4m

8m

20 m

1m

4m

6m

10 m

0m
0m
0m
2m

0m
0m
0m
6m

1m
0m
0m
-

1m
1m
0m
-

1m

4m

8m

20 m

1m

4m

6m

10 m

0m
0m
0m
2m

0m
0m
0m
10 m

1m
0m
0m
-

2m
1m
0m
-

1m

4m

8m

20 m

1m

4m

6m

10 m

0m
0m
0m

0m
0m
0m

1m
0m
0m

2m
1m
0m

Capacity

4m3

100 m3800 m325,000 m3

100,000 m3

400,000 m3

Guidelines Pertaining to the Storage of Removed Soil

Step 1 (Lateral shielding)
Uncontaminated
soil

20 m

Step 4 (Delivery to the second area)

20 m

Step 2 (Delivery)

Removed soil

Step 5 (Shielding of the second area
completed)* When the delivery period extends over along period of time, outflows of the removed
soil must be taken into consideration.

Step 3 (Shielding using a covering with soil, etc.
completed)• Shield the lateral sides as a general rule.
• Take care so that any areas on the top
surface without covering with soil, etc. do
not exceed 20 m × 20 m, in principle.

Figure 4-3: Diagram of the delivery to a large-scale temporary storage site(with lateral shielding)

4-13

Guidelines Pertaining to the Storage of Removed Soil

2)

Prevention of dispersion of the removed soil

To prevent radioactive materials from dispersing during the delivery of the removed soil
to the facility, it is required to put it into bags whose opening can be closed or in drums
with a lid, or wrap it in a dustproof sheet before delivery. Using a highly durable
container*8 makes it possible to prevent dispersion when the removed soil is taken out of
the facility after the period of storage ends.
After the delivery of the removed soil, it is required to prevent any dispersion of theremoved soil by covering with a sheet or with soil.
3)

Prevention of penetration of rainwater, etc.

If rainwater penetrates the removed soil, there is a possibility of an outflow ofradioactive materials. Accordingly, during and after the delivery of the soil, cover it witha waterproof sheet such as a water shielding sheet to avoid exposure to the rain. Takemeasures to ensure that the cover will not be lifted or turned over by a typhoon or heavy
rain, and, if possible, raise the center slightly to prevent the rainwater from forming
stagnant pools on the surface. If the removed soil is stored in waterproof containers or
kept in a facility with a roof, such special measures are unnecessary.
If using a waterproof sheet or container without taking measures to shield them from
UV light, such as by covering with soil or protection mats, it is necessary to replace orrepair them as necessary if any deteriorated parts are identified, while taking theweatherability*9 into consideration. From the viewpoint of protecting the waterproof
sheet or the like, it is effective to cover the waterproof sheet, etc. with soil, etc.
In addition, when a water shielding sheet, etc. is spread to prevent the rainwater fromaccumulating on the bottom surface of the removed soil, arrange the soil to be placed ona position higher than the water shielding sheet in order to provide good drainage, andinstall a drainage facility to drain it as necessary during the delivery. Note that none ofthese measures are necessary when the removed soil is stored in waterproof containers
or kept in a facility with a roof.
As a rule, it is necessary to prevent groundwater including spring water frompermeating the removed soil by constructing any underground facility on a position
higher than the water table.

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Guidelines Pertaining to the Storage of Removed Soil

 Storing Removed Soil in Large Sandbags and Flexible Containers Types of large sandbags and flexible containers are shown in Table 4-3. In cases
where the removed soil will be stored for a certain period of time (several years) or
when the removed soil to be stored has a high water content, it is effective to use
highly durable containers such as cloth-type flexible containers that are weather
resistant and lined with an inner pouch, running-type flexible containers, or weather
resistant large sandbags lined with an inner pouch. In doing so, the properties andweight of the removed soil being stored and the storage period should be taken into
consideration.
 In cases where removed soil with high water content is stored in large sandbags,
flexible containers, and other such containers, as well as cases where a large amountof water content such as snow is mixed with the removed soil, etc., water may soakout under the containers’ own weight if they are piled on top of one another.
Therefore, storing the containers by piling them up must be avoided to the extent
possible.
 In cases where the removed soil, etc. is stored in large sandbags, flexible containers,
and other containers that are piled up, an appropriate height for piling up thecontainers must be established from the viewpoint of preventing collapses andbreakage.
Table 4-3 Types of large sandbags and flexible containers
Type
Flexible
container(cloth-type)*1

PhotographCharacteristics
 The assumption is that they will only be usedonce.
 Not as good as the running-type in terms of
weather resistance and waterproofness.
 Some have improved weather resistance as aresult of UV treatment and the like, while
another type has improved waterproofness as aresult of being lined with inner pouches andhaving an inner coating, etc.
 The assumption is that they will be used byhaving soil repeatedly stored in and removed
from them.
 Outstanding weather resistance andwaterproofness

Flexible
container(running-type)*1

 Water permeable.
 Some have improved weather resistance as aresult of UV treatment and the like, while
another type has improved waterproofness as aresult of being lined with inner pouches, etc.

Large sandbag*2*1: Pursuant to JIS Z 1651.
*2: The photograph shows a weather resistant container.

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Guidelines Pertaining to the Storage of Removed Soil

4)

Prevention of outflow of the removed soil and radioactive materials

It is required to take measures to prevent soil, public water areas, and the groundwaterfrom being contaminated due to an outflow of wastewater containing the removed soil
and radioactive materials. It is known that radiocaesium generally has high adsorption
to soil, so it is thought that radiocaesium will not easily transfer through the soil.
However, when the removed soil is kept in an on-site or temporary storage site forseveral years, a water shielding layer should be placed, for example, by spreading aweatherproof or waterproof sheet such as a water shielding sheet over the bottom inorder to prevent the radiocaesium from outflowing. Water shielding sheets come indifferent types with thicknesses of 0.5 mm, 1.0 mm, 1.5 mm, and so on. The appropriate
type of water shielding sheet and thickness shall be selected by taking into consideration
factors like the conditions at the storage site and the envisioned storage period. If awater shielding sheet, etc. is laid, place a protective layer by putting soil between theremoved soil and the water shielding sheet as necessary to prevent the sheet frombreaking apart during the delivery. If heavy machinery is used, provide curing by suchmeans as laying protective steel plates as necessary. In this case, mixing clay or zeolitethat easily absorbs radiocaesium with the protective layer makes it possible to better
restrain the movement of the radioactive substances. When the removed soil is stored incontainers that can maintain their waterproof capabilities over the period of storage, it is
not necessary to place a water shielding layer such as laying of a waterproof sheet.
There is the risk that contaminated water will emerge and flow out as a result of a large
amount of water content such as snow mixed with the removed soil, and so it isnecessary to reduce the water content within the removed soil as much as possible.
5)

Prevention of effect from substances other than radioactive materials

It is assumed that removed soil generated by scraping away of the soil where vegetation
grows may contain organic substances including roots of vegetation. Because grass
cutting is mandatory before scraping away of soil (see “Part 2: Guidelines Pertaining to
Decontamination and Other Measures”), the removed soil is expected to only contain asmall amount of roots and weeds. Accordingly, it is not necessary to take any special
measures against the generation of combustible and corrosive gases, a rise in thetemperature, or the emission of offensive odors due to decaying of organic matter.
However, if the facility has a structure that does not allow for the discharge of gases due
to its airtightness, or the mixtures have a high proportion of organic matter and this isunavoidable for certain reasons, take any necessary measures such as gas venting toprevent generation of foul odors or fires.
What is more, when piling up containers containing the removed soil, attention shall be
paid when setting out containers that may possibly contain vegetation in order to avoid
subsidence and collapses as a result of the decay of such materials.
For information about these measures including gas venting, see the “Waste Guidelines”(March 2013, Vol. 2).

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Guidelines Pertaining to the Storage of Removed Soil

6)

Resistance to earthquakes, etc.

Any facility that is expected to have functions such as shielding and containment isrequired to have a design that will not lose such functions in the event of expectedearthquakes, and established countermeasures are required for the event of collapse of
the facility. In particular, if containers containing the removed soil are piled up outdoors
for the purpose of storage, it is required to ensure that the side slope is gradual. For
concrete information, see the provisions of Article 15, Item 2B of the Ordinance for
Enforcement of the Act on Special Measures concerning the Handling of Radioactive
Pollution among the standards for storage as shown in “1. (3) Safety Management”(Note).
7)

Other necessary measures

To control radioactive materials properly, store the removed soil separately from anyother waste to eliminate the risk of cross-contamination.
(2)
1)

Management Requirements
Restriction of entry

Prevention of radiation hazards requires certain measures. Firstly, define a point where
the additional exposure dose from the removed soil does not exceed 1 mSv/year during
the delivery as the boundary of the temporary storage site.
Secondly, for temporary storage sites construct a fence along the site boundary to
prevent people from unnecessarily entering the facility. Thirdly, install signboards thatgive precautions to the effect that the site is the place for storage of the removed soil
and contact details in the event of an emergency.
In the case of on-site storage at home or at the site of a school, the installation of fences
and signboards are not mandatory. In addition, in cases where there are risks such asunspecified people coming and going and land being dug up at the site of on-site storage,
it is preferable to inform people to the effect that storage is being carried out.
2)

Monitoring the radiation dose and carrying out repairs

To ensure that the removed soil is stored safely during and after delivery, regularly
monitor the air dose rate along the site boundary (see 1)), check that the additional
exposure dose due to removed soil does not exceed 1 mSv/year during the delivery andthat it is of similar level as that of the surrounding environment after delivery, andrecord the results. Furthermore, visual inspection to confirm that there are noabnormalities with its external appearance shall be conducted to ensure that the facility
has not been pierced by bamboo or other plants and that it has not suffered damage fromanimals.
As for on-site storage to be conducted at decontamination sites, monitor and record the

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Guidelines Pertaining to the Storage of Removed Soil

additional dose when the on-site storage starts after the delivery of removed soil. As forstorage at a temporary storage site, take these measurements at least once a week*10 andconduct measurements whenever heavy rain or a typhoon affects the site. To measure
the air dose rate, use a scintillation survey meter in principle. For information about how
to handle the meter and take the measurements, see “Part 1: Guidelines on the Methods
for Investigation and Measurement of the Status of Environmental Pollution in Intensive
Contamination Survey Areas.”
Moreover, to monitor any outflow of radioactive materials from the facility, conduct
monitoring of the groundwater around the facility at an appropriate frequency andrecord the results. If necessary, also consider monitoring of the leachate from the bottomof the facility.
As a concrete groundwater monitoring method, install a sampling pipe on the peripheryof the facility to sample the groundwater from a place where it is possible to determine
the presence or absence of any effect on the quality of the groundwater , and conduct
quality inspections (measure the concentration of radiocaesium, etc. in the groundwater)of the groundwater sampled at least once a month after the start of the delivery of theremoved soil.
In addition, while not being a standard for storage, when monitoring leachate, insert acollection/drainage pipe into the protective layer at the bottom of the facility in order tocollect the leachate and to check whether water has accumulated in the tank at least
once a month. If water has accumulated, sample the leachate to measure theradiocaesium concentration in the sampled leachate. For information about how to takethe measurements, see the “Waste Guidelines” (March 2013, Vol. 2).
Compare the air dose rate and the radiocaesium concentration of the groundwatermeasured in the temporary storage site after commencement of the delivery (thestorage) of the removed soil with a variation range of the air dose rate and radioactivity
concentration measured before commencement of the delivery (storage) (hereinafter“background values”). As an indication of the upper limit of variation, the measured
value*11 shall be basically such that the “Mean background value + (3  Standard
deviation).” Therefore, it is important to assess the background value before theremoved soil is delivered to the temporary storage site. In particular, it is known that the
air dose rate varies depending on measurement points and that radiation dose fromnaturally-occurring radioactive materials increases during rain. Accordingly, to assess
the background value accurately, acquire the data at many points on various days
including rainy ones.
If it is difficult to acquire sufficient number of background values, determine thevariation range by subtracting the minimum value from the maximum value of the
background value acquired.
If the measured value is within the variation range of the background value, this meansthat the removed soil has been delivered and is stored safely. If any measured value
exceeding the variation range is observed, proceed to identify the possible cause. If it is4-18

Guidelines Pertaining to the Storage of Removed Soilfound that the temporary storage site is the cause of such problem, take any necessary
measures, such as adding shielding materials, repairing the facility, or collecting theremoved soil.
For the storage to be conducted at a place such as decontamination sites where thevolume of the removed soil to be stored is relatively less than that of a temporarystorage site, measure and check the air dose rate once after each delivery and removal of
the removed soil. It is not necessary to monitor the groundwater during the period ofstorage.
Table 4-4. Monitoring items for storage facilities
Category
Monitoring item
Notes
Site boundary
Air dose rate
External appearance Visual inspection
Groundwater around Concentration of - Samples of the groundwater should be taken
the facility
radiocaesium
when there is no turbidity
Leachate
Concentration of - Performed as neededradiocaesium Radioactivity concentration in groundwaterWith the periodic monitoring* of the groundwater at temporary storage sites set up
through the model demonstration project being carried out by the Cabinet Office, themeasurement results for concentrations of radiocaesium came in at under the detection
limits.
*Summary of monitoring by the Cabinet Office’s model demonstration project
No. of temporary
14 locations in 11 municipalities
storage sites
Observation period
March 2012 – March 2013
Observation
frequency
Measurement results

3)

About once a month
All of the locations were either under the detection limit orunder 10 Bq/L
*Radiocaesium was detected in three of the data points, but
this was detected as a result of performing measurements
on turbid water. It was reported that there is the possibility
that topsoil or surface water was mixed with thegroundwater, and that it was the intermixed materials thatwere detected.

Keeping records

The entities that store the removed soil shall record the items listed in Table 4-5 and

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Guidelines Pertaining to the Storage of Removed Soil

retain it until use of the facility is discontinued.
The records have an important role in ensuring traceability when the removed soil istransferred to and kept in temporary storage sites or interim storage facilities. It is also
possible to record the air dose rate on the surface of each container by keeping suchrecord during decontamination, collection, and transfer. For information about how torecord the air dose rate on the surface, see “Part 1: Guidelines on the Methods for
Investigation and Measurement of the Status of Environmental Pollution in Intensive
Contamination Survey Areas” and “Part 3: Guidelines Pertaining to the Collection andTransfer of Removed Soil.”
Table 4-5. Items to record pertaining to the storage of removed soil
Category
Basic matters

Items• 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 soildelivery and• Names 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 the delivery)
Maintenance and • Details of the measurement, inspection, and testing carried out to maintain andcontrol ofcontrol the place for storage
storage sites
Measurement of • Position of the site boundary (fence) and position of the measurement points
the air dose rate • Dates measured• Measuring methods• Measuring apparatuses used for the measurements• Measurement results (background and air dose rate along the site boundary)• Name of the inspector
Radioactive• Air dose rate on the surface of each container
concentration of(On the surface of each container with the removed soil, or each group of multiple
the removed soil, containers)
etc.
* The receiving sites indicate the locations prior to when the removed soil is transferred to thestorage sites. They essentially correspond to the sites where the decontamination is carried out.

4)

Confirmation that the vacant site is not contaminated

After the removed soil is collected and taken out after the period of storage ends,
confirm that contamination does not remain at the vacant sites of the facilities. To put it
concretely, sample the earth on which the removed soil had been placed, measure theconcentration of radiocaesium contained in the sample, and check that the measured
value is of similar level as that of concentration of radioactive materials in the soil, etc.
before the delivery of the removed soil. In the case of on-site storage, the air dose rate
may be measured instead.

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Guidelines Pertaining to the Storage of Removed Soil3. Concrete Examples of Storage Methods in Light of the Facility/Management
Requirements
This section provides concrete examples of details of the on-site and temporary storage
specifications and safety management in light of the facility and management
requirements described in “2. Safety Measures and Requirements Necessary for
Storage.”
In these examples, the position of the site boundary takes into account the isolation
distance corresponding to a mean radioactivity concentration of 8,000 Bq/kg as shownin Table 4-1. When setting up an isolation distance, select an appropriate distance from
Table 4-1 in consideration of the radioactivity concentration of the removed soil and thescale of the facility.
When delivering the removed soil to the temporary storage site, conduct prescribedshielding and maintain an isolation distance so that the additional exposure dose does
not exceed 1 mSv/year at the site boundary during delivery. In addition, strive to makesure that the radiation dose on the boundary (setting position of fence) is of similar level
as that of the surrounding environment by delivering the removed soil while conducting
shielding, putting removed soil with higher radioactivity concentration in the center orat the bottom of the facility, and surrounding it with removed soil with lower
radioactivity concentration to reduce the radiation dose during delivery.
If the storage conditions of the facility exceed the upper limit of the radioactivity
concentration of the removed soil or the facility size as shown in Table 4-1, it is required
to design a facility that is deemed to be able to secure safety by conducting a safety
evaluation in light of details of individual facility specifications and safety management.

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Guidelines Pertaining to the Storage of Removed Soil

On-site storage - 1): Above groundFigure 4-4: Mound (2  2 × 1 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hour

Earth moundAt least
1 m*

Sandbags

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

Table 4-6. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.
Prevention of
outflow

Monitoring

Recordkeeping• After the delivery of the removed soil, shield it by putting sandbags containing
uncontaminated soil on the sides and top or cover it with soil. The sandbags orcovering with soil shall be at least 30 cm thick. In this case, it is not necessary tomaintain an isolation distance from residential buildings such as private houses.
• If the top surface is not shielded, place the removed soil at least 1 m away fromresidence buildings such as private houses.
• 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 theremoved soil is not put into any containers such as sandbags, wrap it in a dustproof
sheet.
• Cover the removed soil with a waterproof sheet and fix the ends so that the sheet
cannot be blown by the wind.
• Raise the center to prevent rainwater from accumulating on the surface of the sheet.
• Spread a waterproof sheet over areas where the removed soil is placed. No special
measures are necessary if the removed soil is stored in waterproof flexible containers,
etc.
• When placing the removed soil, take care not to damage the waterproof sheet, etc.
• After completing covering with soil, etc. for the removed soil, use a calibrated
scintillation survey meter to measure the air dose rate at places 1 m apart from four
spots on the outer perimeter of the area where the removed soil has been placed and at
1 m height (four spots), and record the results.
• If it is impossible to conduct such measurements at a place 1 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by drawing a rough sketch to identify the place ofmeasurement.
• Keep the records of measurement results of the air dose rates until the removed soil istaken out.

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Guidelines Pertaining to the Storage of Removed Soil

On-site storage - 2): UndergroundFigure 4-5: Pit (2 × 2 × 0.5 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hour

Earth mound (at least 30 cm)

Sandbags

At least
1 m*

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

Table 4-7. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.

Prevention of
outflow

Monitoring

Recordkeeping• 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 withsoil shall be at least 30 cm thick. In this case, it is not necessary to maintain an
isolation distance from residential buildings, such as private houses.
• If the top surface is not shielded, place the removed soil at least 1 m away fromresidential buildings such as private houses.
• To prevent any radioactive material from dispersing, put the removed soil insandbags or flexible containers whose openings can be closed, and close themsecurely. If the removed soil is not put into any containers such as sandbags, wrap it
in a dustproof sheet.
• Cover the removed soil with a waterproof sheet and fix the ends so that the sheet
cannot be blown by the wind as needed. For fixing, sandbags and blocks can beused.
• Raise the center to prevent rainwater from accumulating on the surface of the sheet
as needed.
• Spread a waterproof sheet over areas where the removed soil is placed. No special
measures are necessary if the removed soil is stored in waterproof flexible
containers, etc.
• When placing the removed soil, take care not to damage the waterproof sheet, etc.
• After completing covering with soil, etc. for the removed soil, use a calibrated
scintillation survey meter to measure the air dose rate at the center (one spot) andplaces 1 m apart from four spots on the outer perimeter of the area where theremoved soil has been placed and at a height of 1 m (four spots), and record theresults.
• If it is impossible to conduct such measurements at a place 1 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by drawing a rough sketch to identify the place ofmeasurement.
• Keep the records of measurement results of the air dose rates until the removed soil
is taken out.

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Guidelines Pertaining to the Storage of Removed Soil

Figure 4-6: Example of on-site storage (underground)1) Delivery is complete.

Photo courtesy of: Fukushima City

2) The entirety of the removed soil is covered with a sheet.

Photo courtesy of: Fukushima City

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Guidelines Pertaining to the Storage of Removed Soil

On-site storage - 3): Above groundFigure 4-7: Mound (20  20 × 1 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hour

Earth mound(at least 30 cm thick)

Sandbags

At least
4 m*
Water shielding layer

Livingspace* Shielding distance(0) m if the covering with soil exceeds 30 cm in thickness.

Table 4-8. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.
Prevention of
outflow

Monitoring

Recordkeeping• After the delivery of the removed soil, shield it by putting sandbags containing
uncontaminated soil on its sides and top or cover it with soil. The sandbag orcovering with soil shall be at least 30 cm thick. In such cases it is not necessary tomaintain a distance from residence buildings such as private houses.
• To prevent any radioactive material from dispersing, put the removed soil insandbags or flexible containers whose openings can be closed, and close themsecurely. If the removed soil is not put into any containers such as sandbags, wrap it
in a dustproof sheet.
• Cover the removed soil with a waterproof sheet and fix the ends so that the sheet
cannot be blown by the wind.
• Raise the center to prevent rainwater from accumulating on the surface of the sheet.
• Spread a waterproof sheet over areas where the removed soil is placed. No special
measures are necessary if the removed soil is stored in waterproof flexible
containers, etc.
• When placing the removed soil, take care not to damage the waterproof sheet, etc.
• After completing covering with soil, etc. for the removed soil, use a calibrated
scintillation survey meter to measure the air dose rate at places 4 m apart from four
spots on the outer perimeter of the area where the removed soil has been placed andat a height of 1 m (four spots), and record the results.
• If it is impossible to conduct such measurements at a place 4 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by drawing a rough sketch to identify the place ofmeasurement.
• Keep the records of measurement results of the air dose rates until the removed soil
is taken out.

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Guidelines Pertaining to the Storage of Removed Soil

On-site storage - 4): UndergroundFigure 4-8: Pit (20 × 20 × 1 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hour
At least
4 m*
Earth mound (at least 30 cm thick)

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

Table 4-9. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion
Prevention ofpenetration of
rainwater, etc.

Prevention of
outflow

Monitoring

Recordkeeping• 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 withsoil shall be at least 30 cm thick. In such cases it is not necessary to maintain adistance from residence buildings such as private houses.
• To prevent any radioactive material from dispersing, put the removed soil insandbags or flexible containers whose openings can be closed, and close themsecurely. If the removed soil is not put into any containers such as sandbags, wrap it
in a dustproof sheet.
• Cover the removed soil with a waterproof sheet and fix the ends so that the sheet
cannot be blown by the wind, as needed. For fixing, sandbags and blocks can beused.
• Raise the center to prevent rainwater from accumulating on the surface of the sheet,as needed.
• Spread a waterproof sheet over areas where the removed soil is placed. No special
measures are necessary if the removed soil is stored in waterproof flexible
containers, etc.
• When placing the removed soil, take care not to damage the waterproof sheet, etc.
• After completing covering with soil, etc. for the removed soil, use a calibrated
scintillation survey meter to measure the air dose rate at the center (one spot) andplaces 4 m apart from four spots on the outer perimeter of the area where theremoved soil has been placed and at a height of 1 m (four spots), and record theresults.
• If it is impossible to conduct such measurements at a place 4 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by drawing a rough sketch to identify the place ofmeasurement.
• Keep the records of measurement results of the air dose rates until the removed soil
is taken out.

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Guidelines Pertaining to the Storage of Removed Soil

Figure 4-9: Example of on-site storage (school: underground storage)(Photo courtesy of: Shirakawa City)
1) Construction machineries such as graders areused to remove the soil from the groundsurface.

5) The entire topsoil is covered by the water
shielding sheet.

2) A pit is excavated to bury the removed soil.

6) The pit is filled up with covering with soil andthe whole schoolyard is leveled.

3) After the pit is excavated, a water shielding
sheet is laid.

7) The schoolyard is put in place.

4) The topsoil is buried in the water shielding
sheet.

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Guidelines Pertaining to the Storage of Removed Soil

Temporary storage site - 1): Above groundFigure 4-10: Mound (20  20 × 2 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hour

At least
4m

Earth mound(at least 30 cm thick)Flexible containers(containing the removed soil)
At least
Water shielding
4m
layer

Fence
Sandbag

Rainwater
drain

Water
shielding sheet

Collection tank(for checking radioactive materials
as necessary)

Collection/
drainage pipe

Water tableProtective layer (watercollection assistant layer)
Monitoring of radioactive
materials in the groundwater

Table 4-10. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.

Prevention of
outflow• When the delivery work extends over a lengthy period of time, keep the removed
soil at least 4 m away from residential buildings such as private houses from theviewpoint of curbing the public’s additional exposure dose to not more than 1
millisievert 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 it with soil. The sandbag orcovering 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 withsoil shall be at least 30 cm thick.
• When delivering removed soil, to prevent any radioactive material from dispersing,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.
• During and after the delivery of the removed soil, cover it with a weatherproof andwaterproof sheet such as a water shielding sheet to prevent the soil from being
exposed to the rain as much as possible. Fix the end of the water shielding sheet sothat it cannot be blown by the wind. 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.
• 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 isproperly applied to prevent rainwater from coming in.

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Guidelines Pertaining to the Storage of Removed Soil

Backgroundmeasurement

Air dose rate
• Before the delivery of the removed soil, use a calibrated scintillation survey meter tomeasure the air dose rate at points along the site boundary and at 1 m height on bothsunny and rainy days, and record the results.
• The measurement points shall have an interval of about 2 m along the site boundary
and include the points on the site boundary nearest to the place of storage ofremoved soil.
• If it is impossible to conduct such measurements at a place 4 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by putting a mark on the ground or drawing a roughsketch to identify the place of measurement.
• Derive the approximations for the upper limit of variation from the measured air
dose rate values (at tens of points) and the following equation:( s1  m) 2  ( s 2  m) 2  ...  ( s k  m) 2  ...  ( s N  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 intermixing of topsoil
and surface water. In addition, implement measures to prevent 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 the leachate, install pipes into theprotective layer to sample the leachate, and install a collection tank (e.g. working
water tank or concrete measuring tank) on the outside of the temporary storage site
to collect the sampled leachate.
Radioactivity concentration of soil
• Before the delivery of the removed soil, sample the soil in the planned temporarystorage site, measure the radiocaesium concentration of the sample, and record theresults.
• The measurement points shall be at the center and four corners of the area in whichremoved soil is placed.
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 of removed 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 groundwater from thesampling hole, measure the radiocaesium concentration of the sample, 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 is accumulated in
the collection tank at least once a month.
• If water has accumulated, sample the leachate and measure the concentration ofradiocaesium, 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 endsm3

Monitoring

Recordkeeping

4-29

Guidelines Pertaining to the Storage of Removed Soil

RepairRestriction of
entry

Vacant sitecheck

for each batch of the removed soil stored, and the names and addresses of thereceiving site and destinations of the removed soil after the storage.
• The names of the persons in charge of receiving and delivering the removed soil
concerning such removed soil received, and the registration or vehicle number of
any truck in case where such truck was used for the transfer pertaining to thedelivery.
• The results of an air dose rate measurement and water quality test (measurementof the radioactivity concentration of groundwater).
• Confirm that the measured values of the air dose rate and the radiocaesium
concentration of the groundwater are within the allowable 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 rateequivalent to 1 mSv/year.)• If the measured value is observed to be exceeding the allowable variance range, etc.,
identify the cause. If it is found that the temporary storage site is the cause of suchproblem, take any necessary measures, such as adding shielding materials, repairing
the facility, or collecting the removed soil.
• Construct fences (e.g. ropes, nets, or iron wire) at the periphery of the area at least 4m away from the temporary storage site.
• Install signboards at least 60 cm × 60 cm in visually obvious places to indicate
precaution to the effect that the area is the place of storage of the removed soil, thecontact details in the event of an emergency, and the height of the piled-up removed
soil.
• After the period of storage ends and the removed soil is taken out of the temporarystorage spite, measure the Cs-134 and Cs-137 concentration of soil at the vacant siteand confirm that the resulting values are within the variation range of the
background concentration.
• The measurement points shall be at the center and four corners of the area in whichremoved soil had been placed.
• If the measured value is observed to be exceeding the allowable variation range,
decontaminate the site.

4-30

Guidelines Pertaining to the Storage of Removed Soil

Temporary storage site - 2): Above groundFigure 4-11: Mound (100  100 × 2 m) of removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hour

At least
4m

Earth mound (at least 30 cm
thick)

Fence

Flexible containers(containing the removed soil)
Water shielding
At least
layer
4m

Sandbag

Rainwaterdrain

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

Collection/
drainage pipe

Water tableProtective layer (watercollection assistant layer)
Monitoring of radioactive
materials in the groundwater

Table 4-11. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.

Prevention of
outflow• When the delivery work extends over a lengthy period of time, keep the removed
soil at least 4 m away from residential buildings such as private houses from theviewpoint of curbing the public’s additional exposure dose to not more than 1
millisievert 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 it with soil. The sandbag orcovering with soil shall be at least 30 cm thick.
• During the delivery of the removed soil, shield it by putting sandbags containing
uncontaminated soil on the top or cover it with soil to prevent the uncovered area ofthe top from exceeding 20 m × 20 m. The sandbag or covering with soil shall be atleast 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 withsoil shall be at least 30 cm thick.
• When delivering removed soil, to prevent any radioactive material from dispersing,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.
• During and after the delivery of the removed soil, cover it with a weatherproof andwaterproof sheet such as a water shielding sheet to prevent the soil from being
exposed to the rain as much as possible. Fix the end of the water shielding sheet sothat it cannot be blown by the wind. 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.
• Spread a weatherproof and waterproof sheet such as water shielding sheet over areas
where the removed soil is placed.

4-31

Guidelines Pertaining to the Storage of Removed Soil

Backgroundmeasurement• Place a protective layer around ten to tens of cm thick by putting soil over the water
shielding sheet.
• If a heavy machine is used, use measures such as temporarily placing metal plates
over the protective layer to avoid damage to the protective layer and water shielding
sheet, etc. as much as possible when placing the removed soil.
• 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 isproperly applied to prevent rainwater from coming in.
Air dose rate
• Before the delivery of the removed soil, use a calibrated scintillation survey meter tomeasure the air dose rate at points along the site boundary and at 1 m height on bothsunny and rainy days, and record the results.
• The measurement points shall have an interval of about 10 m along the siteboundary and include the points on the site boundary nearest to the place of storageof removed soil.
• If it is impossible to conduct such measurements at a place 4 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by putting a mark on the ground or drawing a roughsketch to identify the place of measurement.
• Derive the approximations for the upper limit of variation from the measured air
dose rate values (at tens of points) and the following equation:( s1  m) 2  ( s 2  m) 2  ...  ( s k  m) 2  ...  ( s N  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 intermixing of topsoil
and surface water. In addition, implement measures to prevent 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 the leachate, install pipes into theprotective layer to sample the leachate, and install a collection tank (e.g. working
water tank or concrete measuring tank) on the outside of the temporary storage site
to collect the sampled leachate.
Radioactivity concentration of soil
• Before the delivery of the removed soil, sample the soil in the planned temporarystorage site, measure the radiocaesium concentration of the sample, and record theresults.
• The measurement points shall be given by dividing the area in which removed soil
is placed into a mesh of about 10 m intervals.
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 of removed 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 groundwater from thesampling hole, measure the radiocaesium concentration of the sample, and record
the results.
• Samples of the groundwater should be taken when there is no turbidity.
m3

Monitoring

4-32

Guidelines Pertaining to the Storage of Removed Soil

Recordkeeping

RepairRestriction of
entry

Vacant sitecheck

• 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 is accumulated in
the collection tank at least once a month.
• If water has accumulated, sample the leachate and measure the concentration ofradiocaesium, 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 andends, and the names 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 the removed soil
concerning such removed soil received, and the registration or vehicle number of
any truck in case where such truck was used for the transfer pertaining to thedelivery.
• The results of an air dose rate measurement and water quality test (measurementof the radioactivity concentration of groundwater).
• Confirm that the measured values of the air dose rate and the radiocaesium
concentration of the groundwater are within the allowable 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 rateequivalent to 1 mSv/year.)• If the measured value is observed to be exceeding the allowable variation range,
etc., identify the cause. If it is found that the temporary storage site is the cause ofsuch problem, take any necessary measures, such as adding shielding materials,
repairing the facility, or collecting the removed soil.
• Construct fences (e.g. ropes, nets, or iron wire) at the periphery of the area at least 4m away from the temporary storage site.
• Install signboards at least 60 cm × 60 cm in visually obvious places to indicate
precaution to the effect that the area is the place of storage of the removed soil, thecontact details in the event of an emergency, and the height of the piled-up removed
soil.
• After the period of storage ends and the removed soil is taken out of the temporarystorage site, measure the Cs-134 and Cs-137 concentration of soil at the vacant siteand confirm that the resulting values are within the variation range of the
background concentration.
• The measurement points shall be given by dividing the area in which removed soil
had been placed into a mesh of about 10 m intervals.
• If the measured value is observed to be exceeding the allowable variation range,
decontaminate the site.

4-33

Guidelines Pertaining to the Storage of Removed Soil

Temporary storage site - 3): UndergroundFigure 4-12: Pit (50  50 × 2 m) for removed soil generated during thedecontamination of an area whose air dose rate is about 1 Sv/hourFence

At least
4m

Earth mound(at least 30 cm)

Flexible containers
At least(containing the removed soil)
4m
Water shielding layer

ManholeRainwaterdrain
Water shielding sheet
Collection tank(for checking radioactive materials
as necessary)
Monitoring of radioactive
materials in groundwater

Collection/
drainage pipe

Protective layer (water collection
assistant layer)

Water table

Table 4-12. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.

Prevention of
outflow• When the delivery work extends over a lengthy period of time, keep the removed
soil at least 4 m away from residential buildings such as private houses from theviewpoint of curbing the public’s additional exposure dose to not more than 1
millisievert per year during the delivery.
• 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 withsoil shall be at least 30 cm thick.
• When delivering removed soil, to prevent any radioactive material from dispersing,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.
• During and after the delivery of the removed soil, cover it with a weatherproof andwaterproof sheet such as a water shielding sheet to prevent the soil from being
exposed to the rain as much as possible. Fix the end of the water shielding sheet sothat it cannot be blown by the wind. 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.
• Spread a weatherproof and waterproof sheet such as water shielding sheet over areas
where the removed soil is placed.
• Place a protective layer around ten to tens of cm thick by putting soil over the water
shielding sheet.
• If a heavy machine is used, use measures such as temporarily placing metal plates
over the protective layer to avoid damage to the protective layer and water shielding
sheet, etc. as much as possible when placing the removed soil.
• Installation of water shielding layer such as laying waterproof sheet can be omitted

4-34

Guidelines Pertaining to the Storage of Removed Soil

Backgroundmeasurement

if the removed soil is stored in waterproof containers and a waterproof cover isproperly applied to prevent rainwater from coming in.
Air dose rate
• Before the delivery of the removed soil, use a calibrated scintillation survey meter tomeasure the air dose rate at points along the site boundary and at 1 m height on bothsunny and rainy days, and record the results.
• The measurement points shall have an interval of about 5 m along the site boundary
and include the points on the site boundary nearest to the place of storage ofremoved soil.
• If it is impossible to conduct such measurements at a place 4 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by putting a mark on the ground or drawing a roughsketch to identify the place of measurement.
• Derive the approximations for the upper limit of variation from the measured air
dose rate values (at tens of points) and the following equation:( s1  m) 2  ( s 2  m) 2  ...  ( s k  m) 2  ...  ( s N  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 intermixing of topsoil
and surface water. In addition, implement measures to prevent 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 you measure the leachate, install pipes into
the protective layer to sample the leachate, and install a collection tank (e.g.
working water tank or concrete measuring tank) on the outside of the temporarystorage site to collect the sampled leachate.
Radioactivity concentration of soil
• Before the delivery of the removed soil, sample the soil in the planned temporarystorage site, measure the radiocaesium concentration of the sample, and record theresults.
• The measurement points shall be given by dividing the area in which removed soil
is placed into a mesh of about 10 m intervals.
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 of removed 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 groundwater from thesampling hole, measure the radiocaesium concentration of the sample, 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 is accumulated in
the collection tank at least once a month.
• If water has accumulated, sample the leachate and measure the concentration ofradiocaesium, etc. in the sampled leachate.
m3

Monitoring

4-35

Guidelines Pertaining to the Storage of Removed Soil

Recordkeeping

RepairRestriction of
entry

Vacant sitecheck

• 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 andends, and the names 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 the removed soil
concerning such removed soil received, and the registration or vehicle number of
any truck in case where such truck was used for the transfer pertaining to thedelivery.
• The results of an air dose rate measurement and water quality test (measurementof the radioactivity concentration of groundwater).
• Confirm that the measured values of the air dose rate and the radiocaesium
concentration of the groundwater are within the allowable 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 rateequivalent to 1 mSv/year.)• If the measured value is observed to be exceeding the allowable variation range,
etc., identify the cause. If it is found that the temporary storage site is the cause ofsuch problem, take any necessary measures, such as adding shielding materials,
repairing the facility, or collecting the removed soil.
• Construct fences (e.g. ropes, nets, or iron wire) at the periphery of the area at least 4m away from the temporary storage site.
• Install signboards at least 60 cm × 60 cm in visually obvious places to indicate
precaution to the effect that the area is the place of storage of the removed soil, thecontact details in the event of an emergency.
• After the period of storage ends and the removed soil is taken out of the temporarystorage site, measure the Cs-134 and Cs-137 concentration of soil at the vacant siteand confirm that the resulting values are within the variation range of the
background concentration.
• The measurement points shall be given by dividing the area in which removed soil
had been placed into a mesh of about 10 m intervals.
• If the measured value is observed to be exceeding the allowable variation range,
decontaminate the site.

4-36

Guidelines Pertaining to the Storage of Removed Soil

Temporary storage site - 4): Storage on sloped groundFigure 4-13. Mound on sloped ground (20  20 × 2 m) of removed soil generated
during the decontamination of an area whose air dose rate is about 1 Sv/hour
Fence

Earth mound(at least 30 cm)

At least
4m

Flexible containers(containing the removed soil)
Watershieldinglayer

At least 4 m

Fence
Rainwaterdrain

Water shielding Collection/
drainage pipe
sheetCollection tank(for checking radioactive materials
Water table
as necessary)Protective layer(water collection
assistant layer)
Monitoring ofradioactive materials
in groundwater

The place of storage is essentially to be situated on level ground from the viewpoint ofsafety, but when the place of storage has to be situated on sloped ground forunavoidable reasons then particular attention must be paid to preventing the soil fromcollapsing. Specifically, install retaining walls or embankments along the lower areas
according to the slope, perform cutting of earth and piling of earth mound according to
the inclination of the sloped surface, and ensure a flat surface through creation of land.
Moreover, during installation, confirm information like the strength of ground and thewater table in advance, and take countermeasures for matters such as groundmaintenance or for surface water.
Table 4-13. Examples of facility specifications and safety management details
Shielding andisolation

Prevention ofdispersion

Prevention ofpenetration of
rainwater, etc.

• When the delivery work extends over a lengthy period of time, keep the removed
soil at least 4 m away from residential buildings such as private houses from theviewpoint of curbing the public’s additional exposure dose to not more than 1
millisievert 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 it with soil. The sandbag orcovering 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 withsoil shall be at least 30 cm thick.
• When delivering removed soil, to prevent any radioactive material from dispersing,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.
• During and after the delivery of the removed soil, cover it with a weatherproof andwaterproof sheet such as a water shielding sheet to prevent the soil from being
exposed to the rain as much as possible. Fix the end of the water shielding sheet sothat it cannot be blown by the wind. For fixing, sandbags and blocks can be used.

4-37

Guidelines Pertaining to the Storage of Removed Soil

Prevention of
outflow

Backgroundmeasurement

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.
• Take any countermeasures against spring water that may be necessary in cases
where spring water is a possibility.
• 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 isproperly applied to prevent rainwater from coming in.
Air dose rate
• Before the delivery of the removed soil, use a calibrated scintillation survey meter tomeasure the air dose rate at points along the site boundary and at 1 m height on bothsunny and rainy days, and record the results.
• The measurement points shall have an interval of about 2 m along the site boundary
and include the points on the site boundary nearest to the place of storage ofremoved soil.
• If it is impossible to conduct such measurements at a place 4 m apart from the outer
perimeter, select other measurement points.
• Record the measurement points by putting a mark on the ground or drawing a roughsketch to identify the place of measurement.
• Derive the approximations for the upper limit of variation from the measured air
dose rate values (at tens of points) and the following equation:( s1  m) 2  ( s 2  m) 2  ...  ( s k  m) 2  ...  ( s N  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 intermixing of topsoil
and surface water. In addition, implement measures to prevent 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 the leachate, install pipes into theprotective layer to sample the leachate, and install a collection tank (e.g. working
water tank or concrete measuring tank) on the outside of the temporary storage site
to collect the sampled leachate.
Radioactivity concentration of soil
• Before the delivery of the removed soil, sample the soil in the planned temporarystorage site, measure the radiocaesium concentration of the sample, and record theresults.
• The measurement points shall be at the center and four corners of the area in whichremoved soil is placed.
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 spotm3

Monitoring

4-38

Guidelines Pertaining to the Storage of Removed Soil

Recordkeeping

RepairRestriction of
entry

Vacant sitechecknearest to the place of storage of removed 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 groundwater from thesampling hole, measure the radiocaesium concentration of the sample, 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 is accumulated in
the collection tank at least once a month.
• If water has accumulated, sample the leachate and measure the concentration ofradiocaesium, 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 the names and addresses of thereceiving site and destinations of the removed soil after the storage.
• The names of the persons in charge of receiving and delivering the removed soil
concerning such removed soil received, and the registration or vehicle number of
any truck in case where such truck was used for the transfer pertaining to thedelivery.
• The results of an air dose rate measurement and water quality test (measurementof the radioactivity concentration of groundwater).
• Confirm that the measured values of the air dose rate and the radiocaesium
concentration of the groundwater are within the allowable 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 rateequivalent to 1 mSv/year.)• If the measured value is observed to be exceeding the allowable variance range, etc.,
identify the cause. If it is found that the temporary storage site is the cause of suchproblem, take any necessary measures, such as adding shielding materials, repairing
the facility, or collecting the removed soil.
• Construct fences (e.g. ropes, nets, or iron wire) at the periphery of the area at least 4m away from the temporary storage site. When it is physically impossible for people
to enter the area then fences and the like are unnecessary.
• Install signboards at least 60 cm × 60 cm in visually obvious places to indicate
precaution to the effect that the area is the place of storage of the removed soil, thecontact details in the event of an emergency, and the height of the piled-up removed
soil.
• After the period of storage ends and the removed soil is taken out of the temporarystorage site, measure the Cs-134 and Cs-137 concentration of soil at the vacant siteand confirm that the resulting values are within the variation range of the
background concentration.
• The measurement points shall be at the center and four corners of the area in whichremoved soil had been placed.
• If the measured value is observed to be exceeding the allowable variation range,
decontaminate the site.

4-39

Guidelines Pertaining to the Storage of Removed Soil

Endnotes*1: The evaluation assumes a variety of processes in which residents living around the facility (the

*2:

*3:

*4:

*5:

*6:

public) and workers are exposed to radiation (exposure scenarios) in light of the radioactivity
concentration and amount of the removed soil, facility specifications, and details of safety
management, calculates exposure dose of the public and workers according to these exposure
scenarios, and confirms that it satisfies predefined levels.*2
The exposure in association with the storage of radioactive waste is the “Planned Exposure
Situations” under ICRP Publ. 103, and the dose constraint for the public exposure during operation isa dose of 1 mSv/year or less. In addition, according to the “Near-term policy to ensure the safety fortreating and disposing contaminated waste around the site of Fukushima Daiichi Nuclear Power
Plant (June 3, 2011)” issued by the Nuclear Safety Commission, the dose of radiation to which thesurrounding residents are exposed in association with the treatment, etc. shall not exceed 1 mSv/year.
See the “Basic Guide for Safety Review of Category 2 Radioactive Waste Disposal (August 2010)”
and the “Rules for the Category 2 Waste Disposal Activity of Nuclear Fuel Materials or Materials
Contaminated with Nuclear Fuel Material” issued by the Nuclear Safety Commission. However, it isassumed that restrictions are put on specific activities, such as living, excavation activities, farming,and stockbreeding within the facility site as well as public access to the facility during the operationof the storage facility.
For information about measures for protecting workers from radiation, see the Ministry of Health,Labour and Welfare’s Ordinance on the Prevention of Ionizing Radiation Hazards related to
Decontamination Work of Soil Contaminated by Radioactive Materials Resulted from the Great East
Japan Earthquake and its Guidelines for Prevention of Radiation Hazards for Workers Engaged in
Decontamination and Other Duties (Labour Standards Bureau Notification 0615 No. 6 dated June 15,2012). In these guidelines, “Dose” or “Exposure” applies to the public. In addition, measures forprotecting the public from radiation pertaining to the collection of the removed soil and the transfer
to the facility are indicated in “Part 3: Guidelines Pertaining to the Collection and Transfer ofRemoved Soil.”
The gamma rays include radiation (skyshine gamma rays) that is emitted from the removed soil andthat returns to the ground after scattering in the sky, and direct gamma rays that are emitted from thearea surrounding the facility.
In reference to the results of evaluating skyshine and direct radiation, Table 4-1 and Table 4-2 show
two cases: one is when shielding is conducted by covering with soil (whose density is 1.5 g/cm 3 andwhose thickness is 30 cm) and the other is when there is no shielding. For example, if removed soil
having 30,000 Bq/kg is kept as a mound 20 m long, 20 m wide, and 2 m high (above ground facility),
the isolation distance by which additional external exposure dose per year becomes 1 mSv or less is
8 m when the side is shielded (see the underground facility without a shield). However, the distancedecreases to 6 m when the side is shielded and the uncovered area does not exceed 10 m × 10 m, to 1
m after completion of covering with soil 30 cm in thickness, and to zero (0) m when the coveringwith soil thickness increases to 40 cm. These values are based on the assumption that radionuclides
included in the removed soil are Cs-134 and Cs-137 only, and the radioactivity ratio is 1:1. The
average of the radiocaesium concentration of the removed soil is categorized into four ways: 3,000
Bq/kg, 8,000 Bq/kg, 30,000 Bq/kg, and 100,000 Bq/kg, and the facilities are classified into above
ground facilities and underground facilities. The facility size (length  width  height (depth)) isclassified into the following six types: 2 × 2 × 1 m, 5 × 5 × 2 m, 10 × 10 × 1 m, 20 × 20 × 2 m, 50 ×
50 × 2 m (10m), and 200 × 200 × 2 m (10m). For above ground facilities, additional calculations
were performed for three other types: 20 × 20 × 4 m, 50 × 50 × 4 m, and 100 × 100 × 4 m. Note thatJapan Atomic Energy Agency cooperated in this work.
Table 4-2 also indicates the thickness of the covering with soil at which the isolation distancebecomes zero (0) m (condition under which additional exposure dose per year on the covering withsoil is 1 mSv or less) after the covering with soil is complete for underground storage. For example,
if removed soil having an average radioactivity concentration of 8,000 Bq/kg is kept undergroundand the covering with soil is 30 cm thick, the additional exposure dose per year above the coveringwith soil does not exceed 1 mSv. This is based on the assumption that a cylinder of 500 m in radiusacts as an infinite plane, measurements are made at 1 m above the ground, and the radioactivity ratioof Cs-134 and Cs-137 is 1:1 (JAEA-Data/Code 2008-003, “External Effective Dose Conversion

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Guidelines Pertaining to the Storage of Removed Soil

Factors for Activity Concentration Limit Evaluation for Disposal of Radioactive Waste”).
When the removed soil contains a significant amount of radioactive materials other thanradiocaesium (e.g. soil contaminated in the vicinity of Fukushima Daiichi Nuclear Power Plant), it isnecessary to evaluate its safety individually, to install the necessary shielding, and to maintain an
appropriate isolation distance.
*7: The radioactivity concentration of soil at an air dose rate of 3.84 Sv/hour equal to 20 mSv/year isabout 39,000 Bq/kg, which is obtained by converting soil monitoring data given by the Ministry of
Education, Culture, Sports, Science and Technology as well as soil monitoring results including air
dose rates obtained at elementary schools in Fukushima Prefecture to the value on June 1, 2011, andusing the resulting regression formula “Log (Air dose rate) = 0.815  Log (Cs concentration)  3.16”(Japan Nuclear Energy Safety Organization).
*8: For example, the flexible container can be classified into running and cloth types (according to JIS Z
1651). In addition, bags similar to sandbags are commercially available although they are notcertified by JIS. It is necessary to select containers after confirming that they meet the storage
requirements. If the period of storage is relatively long or the waste has a high water content or isrelatively heavy, it is recommended to double wrap in two cloth containers or use a running
container featuring high durability. If the removed soil is kept in an outdoor space exposed to thewind, rain, and UV light, it is recommended to select containers that are highly weatherable such as a
UV-resistant cloth or running container.
*9: Weatherability (UV rays)
Flexible container• Flexible containers are defined in JIS Z 1651, and come in cloth, running, and other varieties.
Their weatherability is tested by the weatherability tester defined in JIS B 7753, with thosecontainers that have been confirmed as maintaining strength that is equivalent to or above acertain threshold being sold commercially. For example, under the Japan Flexible Container
Association’s own standards, 900-hour weatherability tests are performed to confirm whether
they can retain 70% of their initial strength, for instance, and they are designed to withstandbeing collected and transferred by heavy machinery even after being stored for about three
years.
Large sandbags• The weatherability of large sandbags is tested by the weatherability tester defined in JIS B 7753,
with those sandbags that have been confirmed as maintaining strength that is equivalent to or
above a certain threshold being sold commercially. For example, those sandbags that comply
with the Public Works Research Center’s Design and Construction Manual for Laminating
Techniques for Weather Resistant Large Sandbags have been confirmed as maintaining tensile
strength of 240 N/cm or greater after 900-hour weatherability tests, for instance, and they aredesigned to withstand being collected and transferred by heavy machinery even after being
stored for about three years.
Water shielding sheet• The principal factor behind the performance degradation of water shielding sheets is believed
to be degradation resulting from UV light, but thus far they have been confirmed as having
durability of at least 15 years. What is more, if they are used under the soil then there is nodegradation due to UV light, and so they have a track record of being used for more than 30
years from the time they are first put in landfills at the final disposal sites for waste landfill(Source: Japan Geosynthetics Technologies Association).
• The sheet has a degradation risk due to UV light, damage from heavy machinery during
installation, or damage caused by birds.
• Care must be taken with the joints during installation.
*10: See information about the patrolling and inspection of waste disposal facilities under the “Rules for
the Category 2 Waste Disposal Activity of Nuclear Fuel Materials or Materials Contaminated with
Nuclear Fuel Material.”*11: According to the “Guideline for Environmental Radiation Monitoring (partially revised in April2010)” issued by the Nuclear Safety Commission,(1) If many significant measured values are acquired under well controlled conditions as in cases
where they have been obtained from a single monitoring post over time, statistical processingof the data shall be conducted, and an average of the past measured values  (3  standard

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Guidelines Pertaining to the Storage of Removed Soil

deviation) shall be the variation range under normal condition.
(2) If it is difficult to find the value under the method (1), the range from the minimum to the
maximum values among the past measured values can be defined as the variation range undernormal condition.

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Index
Terminology
aerial vehicle ................................................................................................................ 2-13
Agricultural water facilities ......................................................................................... 2-95
air dose rate.................................................................................................................. 1-33
artificial turf ................................................................................................................. 2-88
Assessing the beta ray (measurement with a plastic plate)background .................................................................................................................... 1-7
Basic diagram of the safety measures for on-site and temporary storage sites ............. 4-8
beta rays ....................................................................................................................... 1-15
Blast work .................................................................................................................... 2-23

calibration .................................................................................................................... 1-16
Causes for variance in the measured values ................................................................ 1-25
closed conduits ............................................................................................................ 2-70
collimator ..................................................................................................................... 1-22
covering the soil surface .............................................................................................. 2-33

Decontamination Equipment and Materials
decontamination factor (DF) ....................................................................................... 1-14
Decontamination Method
Decontamination of Farmlands
Decontamination of Gardens and Other Areas, Schoolyards, Kindergarten Yards, Parks,and Lawns
decontamination procedures via replacing the topsoil with subsoil (deep plowing) ... 2-35
Decontamination of Roads
Decontamination of Street Drains
Deep plowing............................................................................................................... 2-33
deep trimming ............................................................................................................ 2-107
deep-tillage plow ......................................................................................................... 2-77

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Guidelines Pertaining to the Storage of Removed Soil

deep-tillage rotary ........................................................................................................ 2-77
Diagram of the delivery to a large-scale temporary storage site ................................. 4-13
drainage pavement ....................................................................................................... 2-62
drainage pavement functional recovery car ................................................................. 2-55

energy compensation type ........................................................................................... 1-15
estimate whether the contamination is found on the object’s surface or inside of it ... 1-36
Example of on-site storage (school: underground storage) ......................................... 4-27
Example of the relationship between shielding measures via sandbags and site boundary
positions ................................................................................................................... 4-11

Farmland ...................................................................................................................... 2-93
Farmland (fields) that has been plowed ....................................................................... 2-95
Farmland (fields) that has not been plowed................................................................. 2-94
Flexible Containers ...................................................................................................... 4-15
Flexible Containers ........................................................................................................ 3-8
Forms in which Radiocaesium Is Found ..................................................................... 2-49
fruit trees ...................................................................................................................... 2-95

Gamma Cameras........................................................................................................ 2-118
gamma ray ................................................................................................................... 1-33
Gardens and Other Areas ............................................................................................. 2-32
Gy (gray)hard-packed floors ....................................................................................................... 2-34
hotspots ........................................................................................................................ 2-14

interlocking .................................................................................................................. 2-61
inversion tillage ........................................................................................................... 2-94
Items Related to Decontamination
Items Related to Measurements
Items Related to the Storage of Removed Soil

Guidelines Pertaining to the Storage of Removed Soil

Items to record pertaining to the storage of removed soil ........................................... 4-20

Measurements Using a Collimator .............................................................................. 1-22
Monitoring items for storage facilities ........................................................................ 4-19

No. 1 measurement points ............................................................................................. 1-7
No. 2 measurement points ............................................................................................. 1-7

Orchards ...................................................................................................................... 2-95
Othersparking lots .................................................................................................................. 2-34
Pastureland .................................................................................................................. 2-95
Procedure for determining the thickness of soil to be scraped away........................... 2-90

Radiocaesium concentration within wastewater.......................................................... 2-50
Recording Measurement Results (Samples of Record Sheet)
Reduction rate .............................................................................................................. 1-33
Relationship between shielding measures and site boundary positions according to theradioactivity concentration of the removed soil and the configuration of the facility(above ground method)
Relationship between shielding measures and site boundary positions according to theradioactivity concentration of the removed soil and the configuration of the facility(underground method)
Removal of infill material from artificial turf ............................................................. 2-88
removing agents ........................................................................................................... 2-12
road sweeper ................................................................................................................ 2-54
rubber chip pavement .................................................................................................. 2-62

sandboxes .................................................................................................................... 2-87
scraping away the topsoil ............................................................................................ 2-65
Self-propelled surface compaction roller .................................................................... 2-13

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Guidelines Pertaining to the Storage of Removed Soil

Slopes .......................................................................................................................... 2-67
soil agitation or removal by water ............................................................................... 2-94
Soil gardens ................................................................................................................. 2-33
Soil in Schoolyards, Kindergarten Yards, and Parks ................................................... 2-86
steam cleaner ............................................................................................................... 2-13
street drains that are covered with thick concrete lids ................................................. 2-70
Summary of Measuring Apparatuses and Methods of Use ......................................... 1-26
surface contamination density ....................................................................................... 1-6
Surface Dose Rate ......................................................................................................... 1-7time constant ................................................................................................................ 1-19
Time Constant .............................................................................................................. 1-21

ultra-high pressure water cleaning............................................................................... 2-62
Unpaved Roads ............................................................................................................ 2-65

vehicle transfer rules .................................................................................................... 3-14

Wastewater Treatment ................................................................................................. 2-20
water permeable pavement .......................................................................................... 2-62
water recovery-type high pressure water cleaning ...................................................... 2-63
weather resistant large sandbags .................................................................................. 4-15
Weatherability (UV rays) ............................................................................................. 4-41

Guidelines Pertaining to the Storage of Removed Soil

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Guidelines Pertaining to the Storage of Removed Soil