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

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

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

81

Fig.2-1

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

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

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

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

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

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

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

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

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

82

2.Indicators of
the Status ofContamination
by Radioactive
Materials

1.Basic Concept

6.Measuring
Apparatuses
and Methods of
Use

＊2

＊1

Riversand ponds

Air dose
rate

Vegetation

4.Methods for Taking Detailed Measurements
in Decontamination Zones

Soil

Air dose
rate

Roads

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

Buildings
and Otherstructures

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

5.Assessments oftheDecontamination
Results

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

Surfacedose rate

Measure to confirm the decontamination results(before decontamination)

Air doserate

Surfacecontamination
density

Implement the decontamination work

Measure to confirm the decontamination results(after decontamination)

Air doserate

Surfacedose rate
Surfacecontamination
density

Assessments of the decontamination results

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

Part 4:
Guidelines
Pertaining to
the Storage of
Removed Soil

Air dose
rate

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

Monitor the radiation dose

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

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

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

83

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

Status of contamination in living Status of contamination of objects

perspectives

spacescategory

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

Indicator

subject to decontamination(measurement

contamination cm)

position)

densityUse(1 cm)

collimatora Vary the
distance
andExamples ofmeasuring

NaI scintillation survey meterCsI scintillation survey meter

apparatus
Methods forusing themeasurement
results

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

GM
meter

surveymeasure*2
NaI
scintillation
survey meter
CsI
scintillation
survey meter

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

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

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

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

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

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

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

Certain area in a municipality

SchoolPark

Plant/building★= Measurement point

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

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

Park

SchoolPlant/building★: Measurement point

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

86

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

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

SchoolFacility-by-facility determination

Plant/building★= Measurement point

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

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

87

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

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

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

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

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

88

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

Records

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

90

Manufacturer: ModeCity:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination

After Decontamination

Date measured

Mon., April 22, 2013

Fri., April 26, 2013

Time measured

9:20~9:40

13:20~13:40

Measurer

Josen Taro

Josen Taro

WeatherCloudyClea

Air Dose Rate Measurement Results Entry Section
BeforeDecontamination

Measurement
heightAfter Decontamination

Measurement
height①-1 measurement point

3.0

μSv/h

1m 50cm

0.51

μSv/h

1m 50cm①-2 measurement point

0.55

μSv/h

1m 50cm

0.16

μSv/h

1m 50cm①-3 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-4 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-5 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-6 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-7 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-8 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-9 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm①-10 measurement point

μSv/h

1m 50cm

μSv/h

1m 50cm

Notes(Example)

Garden①－１x

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

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

91

Manufacturer: ModeCity:

Measuring apparatus

Town:

District:

Manufacturer:

Model:

Measurement Status Entry Column
Before Decontamination
Date measured

Day: ( ) Month:

After Decontamination

Year

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

Collimator①-1 measurement point

cpm

Yes Nocpm

Yes No①-2 measurement point

cpm

Yes Nocpm

Yes No①-3 measurement point

cpm

Yes Nocpm

Yes No①-4 measurement point

cpm

Yes Nocpm

Yes No①-5 measurement point

cpm

Yes Nocpm

Yes No①-6 measurement point

cpm

Yes Nocpm

Yes No①-7 measurement point

cpm

Yes Nocpm

Yes No①-8 measurement point

cpm

Yes Nocpm

Yes No①-9 measurement point

cpm

Yes Nocpm

Yes No①-10 measurement point

cpm

Yes Nocpm

Yes NoAfter Decontamination

Collimator

Notes

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

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

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

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

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

93

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

1.Preparation

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

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

3.Decontamination
Methods

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

(1) Handling the removed soil, etc.

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

5.Subsequent Measurements and Records

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

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

94

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

Signage

Preparation of
Equipment andMaterials
Preparation of
Equipment andMaterials

Generalequipment

Equipment forcleaning withwater

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

Equipment forcleaning withwater

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

95

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

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

96

Garden①②② WallBuilding②② Under eaves

Rooftop② Wall ② Under ② Rainwater
guttereaves

Parking lot①②②

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

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

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

97

Decontamination methods

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

Decontamination work proceeds from high to low areas

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

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

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

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

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

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

98

Decontamination of roofs and other areas

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

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

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

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

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

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

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

99

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

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

Remove sediment (fallen leaves, etc.)

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

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

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

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

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

101

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

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

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

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

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

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

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

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

103

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

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

104

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

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

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

Joints of metals that are
difficult to clean by wiping

High pressure water washing

Steam cleaning

Scraping away

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

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

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

105

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

106Decontamination of gardens and other areas.

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

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

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

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

concrete or asphalt

See “V. 3 (1)Decontaminationof Lawns”

See “III. Decontamination
and Other Measures forRoads”

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

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

107Gravel and crushed stone gardens,etc.

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

Gravel and crushed stonegardens, etc.

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

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

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

Brush cleaning
High pressure water washing

Wastewater treatment (*where needed)

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

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

109

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

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

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

110

Handling the removed soil, etc.
Removed soil

Decontamination waste(vegetation, protective equipment, etc.)

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

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

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

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

111

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

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

Cases where wastewater
treatment is carried out

Water recovery-type highpressure water cleaning

Cases where the destination thewastewater flows to is the soil

Filtration
treatment via soil

Sedimentation treatmentusing street drains

Sedimentation treatment using
water tanks

Scraping awayand deep
plowing of soil

Water collection (damming
street drains withsandbags)

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

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

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

Collection of
the sediment
Discharge

Discharge

Use
coagulants
as needed

Discharge

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

Figure 2-18 Basic flow for wastewater treatment.

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

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

112

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

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

113

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

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

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

1.Preparation

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

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

5.Subsequent Measurements and Records

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

115

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

Restriction ofentry

Signage

Preparation of
Equipment andMaterials

Generalequipment

Equipment forcleaning withwater

Equipment for
scraping off

Equipment
for removal of
topsoilEquipment forcovering thesoil surface

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

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

10m to 30 m
Sidewalk

Shoulder

①②

①②

②

②
Road

②

②

②

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

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

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

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

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

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

Decontamination
results

Effective

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

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

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

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

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

Cleaning
Brush cleaning
High pressure water cleaning

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

Wastewater treatment (* as needed)

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

119

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

Decontamination of unpaved roads

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

Soil roads, etc.

Gravel and crushed stone roads, etc.

Slopes of roads

Deep plowing

Pressure wash gravel andcrushed stones

Remove underbrush, etc.

Remove gravel andcrushed stones

scraping away the topsoil

scraping away the topsoil
Covering the soil surface

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

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

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

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

121

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

Removalthroughmanuallabor

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

Soil
roads, etc.

Deepplowing

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

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

Covering
the surface
soil

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

Highpressurewater
cleaning ofgravel andcrushedstones

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

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

Removal ofunderbrush

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

Removal of
topsoil

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

Gravelandcrushedstoneroads, etc.

Slopes of
roads

122

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

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

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

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

Brush cleaning
High pressure water cleaning

Wastewater treatment(*where needed)

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

123

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

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

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

Brushcleaning
Highpressurewater
cleaning

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

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

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

124

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

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

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

1.Preparation

2.PriorMeasurements

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

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

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

5.Subsequent Measurements and Records

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

125

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

Equipment
for scraping
away topsoil

Equipment
for mixing
with water
Equipment
for inversion
tillage anddeep tillage

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

126

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

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

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

Planted trees
1m

1m
②

①
②

Building②

Schoolyard
① ②

10 m

① ②

① ②

① ②

① ②

① ②

① ②

① ②

① ②

①
②

Planted
trees
① ②

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

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

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

128

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

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

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

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

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

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

Scraping away the topsoil

Covering the soil surface

Deep plowing
has theadvantage thatit does notproduceremoved soil.

Adding soil, etc.
(as needed)

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

Removal of infill
material from
artificial turf

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

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

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

130

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

131

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

Agitation/remov
al of soil bywater

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

Inversion tillage

Inversiontillage

Inversiontillage

Deep tillage

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

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

Decontamination of pastureland
Pastureland

Orchards
Cleaning of tree bark

Cleaning of tree
bark

Pruning

Scraping away topsoil

Inversion tillage/plowing

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

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

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

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

132

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

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

133Pruning

Scraping
away topsoil

Pastureland

Inversiontillageplowing/

Scraping
away topsoil

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

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

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

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

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

1.Preparation

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

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

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

5.Subsequent Measurements and Records

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

135

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

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

136

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

Lawn
① ②

50m

① ②

① ②

Forest edge
Scope ofdecontamination
Approximately
20m

②

②

②

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

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

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

137

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

Decontamination methods

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

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

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

Decontamination of lawns

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

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

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

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

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

138

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

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

Grass removal

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

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

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

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

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

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

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

139

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

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

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

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

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

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

Prevention measures for running–off
soil ,etc.

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

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

141

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

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

Removal oforganic
sediment
residue

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

Removal ofbranches
and leaves(only forevergreentrees)

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

Prevention
measures ofrunning off soil

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

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

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

142

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

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

143

1.Preparation

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

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

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

5.Subsequent Measurements and Records

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

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

144

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

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

145

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

Linear living spaces such as roads
and promenades, etc.

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

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

The covered partby water in thereservoir

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

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

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

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

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

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

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

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

147

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

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

Scraping andremoval of
sediments

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

Covering
sediments

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

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

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

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

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

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

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

150

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

151

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

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

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

152

Containers

Water shielding layer
Earth mound

Fence

Fence

Sandbags

Drain ditch

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

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

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

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

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

153

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

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

154

Storagesite
On-sitestorage

Temporary
Storage site

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

155

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

Sandbags

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

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

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

Prevention
dispersionof

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

Preventionofpenetrationofrainwater, etc.

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

Prevention
outflow

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

Monitoringof

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

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

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

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

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

Fence

At least 4m

At least 4m

Sandbag

Rainwaterdrain

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

Collection/
drainage pipe

Protective layer(water collection
assistant layer)

Water table

Monitoring of radioactive
materials in the groundwater

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

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

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

Prevention
dispersion

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

Preventionofpenetrationofrainwater, etc.

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

Prevention
outflow

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

Backgroundmeasurementof

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

Record keeping

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

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

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

Vacant site check

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

Restriction
entry160