United Nations Scientific Committee on the Effects of Atomic Radiation

ATTACHMENT C-12

METHODOLOGY FOR THE ASSESSMENT OF DOSEFROM EXTERNAL EXPOSURE AND INHALATION OF
RADIOACTIVE MATERIALUNSCEAR 2013 Report, Annex A, Levels and effects of radiation exposure dueto the nuclear accident after the 2011 great east-Japan earthquake and tsunami,
Appendix C (Assessment of doses to the public)Content
This attachment describes the methodology used for assessing public exposure to radiationfrom the accident at the Fukushima Daiichi nuclear power station in March 2011 due toinhalation and to external irradiation.
The population data are taken from the Japan Census [MIC, 2011].

Acknowledgements
The Committee would like to acknowledge the work done by M. Balonov and V. Golikov(Institute of Radiation Hygiene, St. Petersburg, Russia), P. Bedwell (Public Health England,
Chilton, UK), and F. Gering (Bundesamt für Strahlenschutz, Neuherberg, Germany) who
conducted the analysis of doses from inhalation and from external exposure, and who preparedthis attachment.
Notes
The designations employed and the presentation of material in this publication do not imply theexpression of any opinion whatsoever on the part of the Secretariat of the United Nations
concerning the legal status of any country, territory, city or area, or of its authorities, orconcerning the delimitation of its frontiers or boundaries.
Information on uniform resource locators and links to Internet sites contained in the present
publication are provided for the convenience of the reader and are correct at the time of issue.
The United Nations takes no responsibility for the continued accuracy of that information or
for the content of any external website.
©

United Nations, September 2014. All rights reserved, worldwide.

This publication has not been formally edited.

Contents
CONTENT ................................................................................................................................... 1
ACKNOWLEDGEMENTS ......................................................................................................... 1
NOTES ......................................................................................................................................... 1
I. INTRODUCTION .................................................................................................................. 5
A. Basic approach ................................................................................................................. 5
B. Basic models for dose assessment .................................................................................... 6
1. External exposure ....................................................................................................... 6
2. Dose from inhalation .................................................................................................. 6
C. Input data for dose assessment ......................................................................................... 7
II. METHODOLOGY FOR ESTIMATION OF DOSE FROM EXTERNALEXPOSURE FROM DEPOSITED RADIONUCLIDES ....................................................... 8
A. Computational model ....................................................................................................... 8
1. Basic computational model ........................................................................................ 8
2. Population groups and exposure duration .................................................................. 9
3. Evacuation of the public ........................................................................................... 10
4. Environmental remediation and population return ................................................... 12
B. Model parameters and assumptions ............................................................................... 13
1. Dose- and kerma-rate conversion coefficients for deposited radionuclides
and attenuation of radiation ...................................................................................... 13
2. Location factors for Japan ........................................................................................ 14
3. Occupancy factors for Japan .................................................................................... 15
4. Dose conversion coefficients.................................................................................... 16
III. METHODOLOGY FOR ESTIMATION OF DOSE FROM EXTERNALEXPOSURE FROM RADIOACTIVE PLUMES ................................................................ 17
A. Computational model ..................................................................................................... 17
B. Model parameters ........................................................................................................... 19
IV. METHODOLOGY FOR ESTIMATION OF DOSE FROM INHALATION ..................... 20
A. Computational model ..................................................................................................... 20
B. Model parameters ........................................................................................................... 22
V. ASSESSMENT OF COLLECTIVE DOSES ....................................................................... 24
VI. INPUT DATA FOR DOSE ASSESSMENT ....................................................................... 25
A. Source term..................................................................................................................... 25
B. Composition of deposited radionuclides ........................................................................ 26
C. Data sets for the assessment of dose from external exposure from depositedradionuclides .................................................................................................................. 28

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4

1. Within 100 km of FDNPS and the entire Fukushima prefecture (Groups 1
and 2) ........................................................................................................................ 28
2. The six prefectures − Iwate, Miyagi, Tochigi, Gunma, Ibaraki and Chiba(Group 3) .................................................................................................................. 28
3. Distant prefectures of Japan (Group 4) .................................................................... 28
D. Data set for the assessment of dose from external exposure for the plume andinternal exposure from inhalation................................................................................... 28
E. Evacuation data .............................................................................................................. 29
REFERENCES ........................................................................................................................... 37

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I.

INTRODUCTION

A.

Basic approach5

1.
This attachment describes the methodology used for assessing public exposure in Japanand in some other countries resulting from the accident at the Fukushima Daiichi nuclear
power station (FDNPS) in March 2011 from the following exposure pathways:(a) External exposure from radionuclides deposited on the ground;(b) External exposure from radionuclides in the radioactive plumes;(c) Internal exposure from inhalation of radionuclides in the radioactive plumes.
2.
For the purpose of its assessment, the Committee has estimated the doses received in
the first year, over 10 years after the 2011 accident and over a lifetime (i.e. to age 80 years)
following the accident. The estimates of effective doses and absorbed doses to the thyroid, redbone marrow and female breast were based, to the extent possible, on measurement data andrealistic models and assumptions. Estimates were also made of collective doses to the public
incurred in the first year, over 10 years and until an attained age of exposed individuals of
80 years.
3.
For the purposes of the assessment, the Japanese territory was delineated into areas that
had comparable conditions that influenced the doses and for which environmental
measurement data of similar quality were available. At the time of the assessment,
measurement data of different quality were available for (a) the area up to 100 km fromFDNPS and the whole of Fukushima Prefecture, (b) six neighbouring or nearby prefectures(Iwate, Miyagi, Tochigi, Gunma, Ibaraki and Chiba) and (c) the rest of Japan. The Committee
focused on assessing doses to the public living in Fukushima Prefecture and the neighbouring
prefectures with elevated radiation levels.
4.

The Committee considered four groups of geographical areas in Japan:(a) Group 1 included settlements in Fukushima Prefecture where members of the public
were evacuated in days to months after the accident;(b) Group 2 included all non-evacuated districts of Fukushima Prefecture;(c) Group 3 included selected prefectures in eastern Japan that are neighbouring(prefectures of Miyagi, Tochigi, Gunma and Ibaraki) or nearby (prefectures of Iwate
and Chiba) Fukushima Prefecture;(d) Group 4 included all the remaining prefectures of Japan.

5.
The Committee considered three main age groups as at the time of the releases: adults,
children and infants. For the estimation of doses, 20-year-old adults were chosen to represent
all adults, 10-year-old children to represent all children older than 5 years old, and one-year-old
infants to represent all infants younger than five years old. The growth of one-year-old infantsand 10-year-old children was taken into account in the assessments of doses received overtime.
6.
The uncertainties associated with the assessed doses to the public were addressed to theextent possible.

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B.

Basic models for dose assessment

1.

External exposure

6

7.
The major (in chronological order) external exposure pathways following the releasesof radioactive material to the environment were those identified in (a) and (b) of paragraph 1.
8.
For the assessment of effective dose and absorbed doses to organs from external
exposure, information on the following was necessary:(a) The external gamma-radiation field;(b) Human behaviour in the radiation field;(c) Conversion coefficients relating the radiation field to effective dose and absorbed doseto organs 1.
9.
The kerma rate in air, Kair (t), at the height of 1 m above the surface of an open plot of
undisturbed ground (the reference site) was the basic parameter used to define the radiation
field. Its value was influenced both by the deposition density of radionuclides and natural
factors including the initial attenuation of radiation in soil, radioactive decay, vertical migrationof radionuclides into soil, and the presence of snow cover.
10.
The value of Kair (t) in an anthropogenic environment was taken into account by meansof location factors, fj, defined as the ratio of the kerma rate in air at a typical location (area), j,
inside a settlement to the kerma rate at the reference site [Golikov et al., 1999; Golikov et al.,
2002; Golikov et al., 1993; Jacob, 1996; Meckbach et al., 1988]. These location factors
declined with time because of weathering, street cleaning etc.
11.
Human behaviour in the radiation field was described by means of occupancy factors,pij, which represent the fraction of time spent by the representative of population group, i, in
typical location, j, of the settlement.
12.
The conversion coefficients, ki, relate the measured or modelled values of Kair (t) toeffective dose rate or absorbed dose rate to particular organs of the representative person in
population group, i. The conversion coefficients depend on irradiation geometry; for example,
they are different for radionuclides deposited on the ground and in a plume.
2.

Dose from inhalation

13.
Inhalation of radionuclides by the public was assumed to occur only during the passage
of a radioactive plume through a settlement where members of the public resided. The
contribution of resuspended radionuclides to dose from inhalation was negligible, much lessthan the uncertainty associated with the dose estimates.
14.
The radionuclides that were taken into account were those that had been measured in
the environmental samples collected in Japan and those for which their dispersion had beenmodelled (see appendix B). They include mostly radioisotopes of volatile elements including
iodine, tellurium and caesium.
1

Published values of conversion coefficients are often quoted in terms of the protection quantity, equivalent doseto particular organs. However, the numerical values of these conversion coefficients were taken to apply to theabsorbed doses to those organs because the doses of interest are due to low-LET radiation.

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C.

7

Input data for dose assessment

15.
Estimates of doses from external irradiation by radionuclides deposited on the groundwere based, primarily, on measurements. Systematic monitoring of the deposition density of
110m
Ag, 129mTe, 131I, 134Cs and 137Cs, in the vicinity of FDNPS was conducted during June andJuly 2011; soil was sampled on the basis of a grid of 2-km squares up to distance of 80 km andon the basis of a grid of 10-km squares up to distance of 100 km, and over the remaining areaof Fukushima Prefecture. In total, the data from about 2,200 measurements were available (seeattachments C-1 to C-4). In late 2011, an additional series of more than 1,000 measurements
was made by the national and local governments, either in situ or by soil sampling, on the basisof a grid of 10-km squares in the six prefectures of Japan neighbouring Fukushima Prefectureand some other prefectures of eastern Japan. The results of these measurements were includedin the dose assessment for the six neighbouring prefectures. In the distant prefectures of Japanthat were not substantially affected by radioactive fallout from the FDNPS accident, data werecollected by the local governments at a few (sometimes, one) monitoring posts; these data wereused as representative of the levels in the distant prefectures.
16.
Only a very limited number of measurements of activity concentration of radionuclides
in air, particularly for 131I, were available. As a result, the dose assessments were carried out on
the basis of an estimated source term and models to reflect the atmospheric dispersion and thedeposition of radionuclides on the ground. Those measurements of air concentration that wereavailable were used only for purposes of validation. Models were also used to estimate doses
beyond the first year because data from measurements were not available at the time of theCommittee’s assessment. Where possible, the same dosimetric and habit data were used toassess doses, regardless of whether the calculations were based on measurements or modelling.
17.
Doses were estimated for Japan and to a limited extent for nearby countries. The
radionuclides considered were 132Te, 131I, 132I, 133I, 133Xe, 134Cs, 136Cs and 137Cs. Priority was,however, given to assessing the doses from 131I, 134Cs and 137Cs. The estimated source term
spanned the period 03:00 JST on 12 March to 09:00 JST on 1 April 2011. The final source
term used was based on [Terada et al., 2012].
18.
Participants of the Fukushima Task Team (TT) set up by the World MeteorologicalOrganization (WMO) each ran their own atmospheric transport dispersion and deposition
models (ATDM) using various available meteorological data fields. The WMO–TT compared
the model estimates with the measurement data and used five statistical evaluation methods torank the performance of each model and meteorology combination. The Hysplit model of theUnited States National Oceanic and Atmospheric Administration (NOAA) combined with themeteorological data from the Global Data Assimilation System (GDAS) scored highest andtherefore was selected for use in the dose assessment. The details of the source term assumed
and the atmospheric transport, dispersion and deposition modelling performed are given inappendix B.
19.
The output from ATDM comprised estimates of time-averaged activity concentrations
in air and total deposition densities for each three-hourly period from 03:00 JST on 12 March
to 06:00 on 4 April 2011. Concentrations were estimated on a spatial grid of approximately
3,000 × 2,000 km in size and a resolution of approximately 5 × 5 km, covering all of Japan, allof the Republic of Korea, the majority of the Democratic People's Republic of Korea, and someregions in eastern China and in the south-eastern part of the Russian Federation.

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8II.

METHODOLOGY FOR ESTIMATION OF DOSE FROM EXTERNALEXPOSURE FROM DEPOSITED RADIONUCLIDESA.

Computational model1.

Basic computational model

20.
The computational model used [Golikov et al., 1999; Golikov et al., 2002; Golikov etal., 1993; Jacob, 1996] consists of four submodels for determining:(a) Kerma rate in free air at a reference site in the settlement;(b) Location factors defined by the ratio of kerma rates in air at a location of interest to thatat the reference site;(c) Occupancy factors for different population groups at various types of locations;(d) Conversion coefficients for different population groups from kerma rate in air toeffective dose rate or absorbed dose rate to the particular organ.
21.
The first submodel was used to calculate the time-dependent kerma rate in free air,
K air (t ) (nGy/h), at a height of 1 m above an undisturbed open field, lawn or meadow. This wasconsidered as the key parameter for the radiation field at the reference site. The value ofK air (t ) is influenced both by the deposition density of radionuclides and natural factors
including the initial attenuation of radiation in soil, radioactive decay, and the verticalmigration of radionuclides in soil:AK air (t ) = r (t ) ⋅ ACs137 ⋅ ∑ ( m ) ⋅ kmdep ⋅ exp(−λm ⋅ t ) , (nGy/h)
ACs137m(2.1)

where r(t) is the ratio of the kerma rate in air above undisturbed open ground to that for areference depth distribution of a radionuclide in soil (dimensionless); r(t) accounts for the
penetration of radionuclides in soil; Am is the deposition density of radionuclide, m, on the
ground (kBq/m2); k mdep is the kerma-rate conversion coefficient for a reference depth
distribution of radionuclide, m, in soil, that is, it is the ratio of the kerma rate in free air at aheight of 1 m above the ground to the deposition density of radionuclide, m, on soil (nGy/h per
kBq/m2); and λm is the decay constant of radionuclide, m (t-1). The most long-lived andradiologically significant radionuclide, 137Cs, was chosen as the reference radionuclide for area
mapping.
22.
In the second submodel, the kerma rate in air at location, j, was assessed by multiplying
the kerma rate, K air (t ) , in air at a height of 1 m above an undisturbed open field by the timedependent dimensionless location factor, fj (t), defined as the ratio of the air kerma rate at
location, j, inside a settlement to the kerma rate at the reference site [Golikov et al., 1999;
Golikov et al., 2002; Golikov et al., 1993; Jacob, 1996; Meckbach et al., 1988].
23.
The third submodel was used for the calculation of the dose rate in air for the
representative person of population group, i, taking into account human behaviour in theradiation field. This was accomplished by weighting the dose rate in air at location, j, by thedimensionless occupancy factor, pij, and summing the product over the locations of interest.
The value of pij is the fraction of time spent by the representative of population group, i, in the

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9typical location, j, of the settlement and was considered to be constant for a defined populationgroup, with the exception of the evacuated population groups (see next subsection).
24.
The sum of the products of fj(t) and pij is represented here by a single modifying factor,
the time-dependent aggregated dose reduction factor, RFi dep (t ) .
25.

In the fourth submodel, the effective dose rate, E idep (t ) , to the representative of

population group, i, (or absorbed dose rate to the particular organ of these individuals) was
calculated according to:E idep (t ) = K air (t ) ⋅ ki ⋅ ∑ f j (t ) ⋅ pij = K air (t ) ⋅ ki ⋅ RFi dep (t ) (nSv/h)

(2.2)

j

where ki is the dose conversion coefficient from kerma in air to effective dose or absorbed doseto the particular organ (dimensionless) for exposure from deposited radionuclides.
26.
For environmental contamination with gamma-emitting radionuclides released fromFDNPS, the model used dose conversion coefficients, ki, that are independent of location type
and time after the accident but that are dependent on the age group considered [Golikov et al.,2007; Jacob et al., 1990; Petoussi-Henss et al., 2012].
27.
Effective dose rates were also calculated using dose coefficients that directly relate thelevels of deposition of radionuclides on soil to the effective dose rate to the representative of
population group, i:AE idep (t ) = r (t ) ⋅ ACs137 ⋅ ∑ ( m ) ⋅ exp(−λm ⋅ t ) ⋅ emdep,i ⋅ ∑ f j (t ) ⋅ pij (nSv / h)ACs137mj(2.3)

where emdep,i = ki ⋅ kmdep is the effective dose-rate conversion coefficient for the reference activity
distribution of radionuclide, m, in soil; it is equal to the ratio of the effective dose rate for the
representative person of population group, i, to the deposition density of radionuclide, m, on
soil (nSv/h per kBq/m2).
28.

Regardless of whether E idep (t ) was assessed by (2.2) or (2.3), the effective dose,

Eidep (T ) , received in time, T (h), from deposited radionuclides can be calculated by:
Eidep (T ) = 10 −6 ⋅ ∫ E idep (t ) ⋅ dt (mSv)

(2.4)

T

2.

Population groups and exposure duration

29.
The external exposure of members of the public in an environment contaminated byradionuclides depends on the time spent outdoors and in different premises and also on theshielding properties of the premises and their body mass. On the basis of experience gained
following the Chernobyl accident [Golikov et al., 1999; Golikov et al., 2007; Golikov et al.,

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10

2002; Golikov et al., 1993; Jacob, 1996], deterministic estimates of the dose from external
exposure were considered for the following four social/age groups:(a) 20-year-old adults working mostly indoors;(b) 20-year-old adults working mostly outdoors;(c) 10-year-old children as representative of school children (aged 6–15 years in 2011);(d) One-year-old infants as representative of preschool children (aged 0–5 years in 2011).
30.
For these population groups, the shielding properties of the following three types ofdwelling typical for Japan were considered:(a) Wooden one-to-three-storey houses;(b) Wooden fireproof (plastered) one-to-three-storey houses;(c) Concrete multi-storey apartments
31.
In total, 12 combinations of social/age groups and types of dwelling were addressed.
The estimates of dose from external exposure for all the 12 groups are presented in appendix C.
Statistical data from the 2008 Housing and Land Survey of Japan [MIC, 2012a] indicates thatthe majority of the population of Fukushima Prefecture (80%) and neighbouring prefectures
resided in wooden or wooden fireproof one-to-two-storey houses.
32.
For the purposes of this assessment, the doses received over the first year (March 2011–
March 2012), the first ten years (2011–2021) and a lifetime (up to age 80 years) following theaccident were estimated. That means that as of 2011, the time integration of the dose rate for
one-year-old infants, was done, respectively, for one year, 10 years and 79 years; for 10-yearold children, for one year, 10 years and 70 years; and for 20-year-old adults, for one year,
10 years and 60 years, following the accident.
33.
The growth of both one-year-old infants and 10-year-old children was taken into
account in the assessment of doses integrated over the first 10 years and over the lifetime
following the accident. The same dose coefficients for the group of one-year-old infants wasconsidered to apply over the first five years of life (i.e. to preschool children, aged 0–5 years);from 15 March 2016, the dose coefficients for 10-year-old children were applied for the next
10 years (i.e. to school-age children, aged 6–15 years) and from 15 March 2026, the dosecoefficients for adults were applied (i.e. from age 16 years over the remainder of life). A
similar approach was applied to children aged 10 years as of 2011 (i.e. the dose coefficients for
10-year-old children were applied over the next five years and from 15 March 2016, the dosecoefficients for adults were applied).
3.

Evacuation of the public

34.
The methodology for the assessment of doses from external exposure and inhalation ofradionuclides did not account for any reduction in dose that may have resulted from theevacuation of residents in the Japanese spring of 2011 from the affected and potentiallyaffected areas of Fukushima Prefecture to less affected areas. In fact, the Government of Japanordered the evacuation of people, as a precautionary measure, from the area of the anticipatedradionuclide contamination (20 km around FDNPS). This evacuation took place from 12 to 15
March 2011 [NERHQ, 2011]. Thus, the residents of the whole of the towns of Futaba, Okuma,
Tomioka, Naraha and Hirono, and Kawauchi Village and also some residents of the cities of
Minamisoma and Tamura, Namie Town and Katsurao Village located partially within the

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11

20-km area were not present in the most affected areas when the major radionuclide releases
occurred.
35.
Following the major radionuclide releases that resulted in substantial deposition to thenorth-west of FDNPS, additional “deliberate evacuation” was initiated by the Government ofJapan on the basis of the environmental measurements. The residents of the whole of Iitate
Village and numbers of residents of Namie City, Kawamata Town and Katsurao Village were
evacuated between March and June 2011. Thus, the residents of those localities were mostly
exposed to elevated levels of radiation until evacuation took place.
36.
Therefore, in the general tables, doses to the residents of the nine totally evacuatedlocalities are not presented. For the three partially evacuated localities (the cities of
Minamisoma and Tamura, and Kawamata Village), doses were calculated only for thoseresidents who stayed in those localities following the major radionuclide releases (seetable 11). Use was made of any radiation measurements in the non-evacuated parts of theselatter localities when they were available.
37.
The doses received by the residents of the evacuated localities or parts of such localities
before and during the evacuation were assessed using the results of a survey conducted within
Fukushima Prefecture to ascertain their activities, notably their spatial and temporal
distribution during this period. A questionnaire was issued to all residents of Fukushima
Prefecture (~2 million people) and completed questionnaires were received fromapproximately 21% of the population. This survey was used by the National Institute ofRadiological Sciences (NIRS) to define 18 scenarios representative of the movements of theseresidents following the accident [Akahane et al., 2013] (see table 11). All estimations of dosein the first year to the evacuees for the 18 scenarios covered the period up to and including thefinal evacuation.
38.
The estimated doses to the evacuees for the 18 scenarios were obtained mostly using
the estimated source term and output of ATDM (three-hourly time-integrated activity
concentrations in air and cumulative deposition densities on a grid of 5-km squares, seesection I). Where a public place (e.g. town office or community centre) had been identified andthe associated coordinates had been provided, the four grid-points bounding the place wereconsidered and the environmental concentrations interpolated using an inverse distanceweighted approach. Where a public place had not been identified, a location was derived on thebasis of the information provided in [Akahane et al., 2013]. The average activity concentrations
in air for each three-hour period were converted to time-integrated activity concentrations in airand summed over the time the residents were assumed to have remained at each location (forthe period from 03:00 JST on 12 March to 09:00 JST on 1 April 2011). Where the temporal
movements of the residents were not aligned with the 3-hourly environmental concentrations,the fraction of time the residents remained at the location within that three-hour period wasestimated and the environmental concentration was weighted by this fraction.
39.
The dose per unit deposition density was applied to the mean of the total deposition
density of radionuclides at the start and at the end of each 3-hour period within the period from03:00 JST on 12 March to 09:00 JST on 3 April 2011. After 3 April 2011, it was assumed thatno further deposition occurred. For individuals exposed after this time, the total deposition
density at 09:00 JST on 3 April 2011 was used, and account was taken of radioactive decay andvertical migration of radionuclides in soil.
40.
Where the population in a specific scenario moved between two locations, the dose
received was assumed to be the average of the doses received at the locations of departure andATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

12

arrival over the time taken to travel between the locations. For populations of the deliberately
evacuated settlements — Namie Town (Tsushima District), most of Katsurao Village and thewhole of Iitate Village — the dose from external exposure from deposited radionuclides overthe period from 11 to 15 March 2011 was calculated from the modelling data and, after
15 March 2011 until evacuation (from 21 March to 21 June 2011 for various localities), fromthe measured radionuclide deposition densities, in the same way as was done for the nonevacuated populations.
41.
The additional radiation doses incurred by the evacuated populations following arrivalat the evacuation destinations (mostly in less affected cities of Fukushima Prefecture) wereassessed using the measured radionuclide deposition densities in the same way as was done forthe non-evacuated populations. The assessed doses at the evacuation destinations are alsopresented in appendix C.
42.
Within the 18 evacuation scenarios, four types of human activities were considered:normal living conditions, evacuation preparation, evacuation and sheltering. For normal living
conditions, the habit data assumed were the same as those applied in the main calculations ofdoses from external exposure and inhalation (see section II.B). For evacuation preparation, it
was assumed that adults were outdoors 100% of the time (50% on hard surfaces and 50% on
dirt surfaces) with the breathing rate of an active person; children and infants were assumed to
be indoors 100% of the time with an average breathing rate (see section IV.B). For evacuation,
it was assumed that people of all age groups were outdoors 100% of the time on hard surfaces
with the breathing rate of a person at rest. For sheltering, it was assumed that people of all age
groups were indoors 100% of the time with an average breathing rate. The building types (oneto-two-storey wooden houses and concrete multi-storey apartments) were identified andattributed to the respective location.
4.

Environmental remediation and population return

43.
Experimental studies of environmental remediation technologies started in the affectedareas of Japan in the Japanese summer of 2011. Since then, extensive remediation work has
been underway or is being planned in the regions of Japan with the higher deposition densities,
to reduce the dose rate and concentrations of radionuclides in areas where people live or growfood. This work includes the use of technologies for decontamination of inhabited areas, and ofcountermeasures in agriculture (such as phytoremediation) and in forestry. The experimental
studies and tests in Fukushima Prefecture were planned to be completed by the first half of
2012.
44.
At that time, a large-scale environmental remediation programme was planned to belaunched in the affected areas of Fukushima Prefecture. In some affected areas beyond therestricted area, local authorities initiated decontamination activities, mostly focused on publicareas and especially on children’s facilities (kindergartens, schools, hospitals and so on).
Similar work, although in the temperate European environment, was intensively conducted in
the Chernobyl-affected areas two decades ago, and the conclusions and recommendations fromthis work were summarized by the Chernobyl Forum [IAEA, 2006] and UNSCEAR[UNSCEAR, 2011, Vol. II].
45.
It was not possible to include consideration of remediation in the dose assessment at
this stage, because the effectiveness of the different measures to be applied in Japan was notknown at the time of this assessment. Estimates of the effective doses from external irradiationthat would be received by those who were evacuated if they were to return to their homes andATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

13

regular lifestyles without any environmental remediation having been implemented are
however shown in table C19 of appendix C. These estimates provide an upper bound to thedoses that might be received in the future.
B.

Model parameters and assumptions

1.

Dose- and kerma-rate conversion coefficients for deposited radionuclides
and attenuation of radiation

46.
A plane radionuclide source below a soil layer with a mass per unit area of 0.5 g/cm2
was chosen as the reference initial distribution of radionuclide with depth. This model was
verified by numerous dose-rate measurements and calculations following both the Chernobyl
and FDNPS nuclear accidents.
47.
The kerma-rate conversion coefficients in air at a height of 1 m due to a reference
deposition density of radionuclide, m, at a depth of 0.5 g/cm2 in soil ( k mdep in equation (2.1)) arepresented in table 1 [ICRU, 1994; Jacob et al., 1990]. The values are for the radionuclides thatwere systematically measured in soil samples throughout Japan or derived by modelling fromthe source term, and they include, as appropriate, the contributions of the progeny of theradionuclides produced after deposition.
dep

Table 1. The values of kerma-rate conversion coefficients, k m

cland k m , used in equations (2.1)

and (3.1, 3.2), respectively [ICRU, 1994; Jacob et al., 1990]
Kerma-rate conversion coefficient (nGy/h per kBq/m2)
Radionuclide
110m+110Ag

129m+129

Te

132

Te

k mdep

k mcl

8.12

0.65

0.23

0.018

0.71

0.052

131

I

1.18

0.087

132

I

6.66

0.53

133

I

1.84

0.14

133

Xe
Cs

4.68

0.0097
0.36

Cs

6.34

0.51

Cs + 137mBa

1.72

0.13

134
136
137

48.
In order to calculate the projected doses, account was taken of the reduction in dose ratewith time through radioactive decay of the released radionuclides and the attenuation of the
gamma-radiation dose rate due to the vertical migration of the long-lived radionuclides such as
137
Cs down the soil column. The influence of the radionuclide migration in soil on the gamma
dose rate is represented in the model by the attenuation function, r(t). The attenuation function,r(t), for the future can be calculated using the empirical function [Golikov et al., 2002;
Likhtarev et al., 2002]:

 ln 2  ln 2 ⋅ t 
r (t ) = p1 ⋅ exp −⋅ t  + p2 ⋅ exp −
T
T
1
2




where p1 and p2 are empirically-derived constants and time, t, is in years.

(2.5)

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1449.
The parameters of this function were determined from gamma-spectrometric analysesof over 400 soil samples taken between 1986 and 2003 in areas of Germany (Bavaria), theRussian Federation, Sweden and Ukraine after the Chernobyl accident [Golikov et al., 2002;
Jacob, 1996; Likhtarev et al., 2002]. On the basis of these data and the fact that the long-term
exposure of the public following the FDNPS accident is caused by the same volatile
radionuclides, 134Cs and 137Cs, as was the case in areas distant from the Chernobyl accident, theCommittee decided to use for Japan the same function and parameters: p1 = 0.5; p2 = 0.5;
T1 = 1.5 years; and T2 = 50 years.
50.
For the areas of Japan with deposited radionuclides, this region-specific assessment isstill to be done. The influence of the migration of 137Cs in soil on the absorbed dose rate in air
is shown in figure I.
Figure I. The influence of the migration of radiocaesium in soil on absorbed dose rate in air for137
2
an initial deposition density of Cs of 1 MBq/m
The isotopic composition of radiocaesium was taken from [IRSN, 2011]
5.50
4.50
3.50
2.50

without migration
with migration

Dose rate in air, µGy/h

1.50

0.50

10

30

50

70

90 110Time, years

2.

Location factors for Japan

51.
Location factors for typical western-European buildings have been determined by both
calculation [Jacob et al., 1987a; Meckbach et al., 1988] and gamma-spectrometricmeasurement [Andersson et al., 1995; Jacob et al., 2000; Jacob et al., 1987b]. Following theChernobyl accident, the location factors in urban environments and their variation with time
were determined for western Europe, the Russian Federation [Golikov et al., 1999; Golikov etal., 2002] and Ukraine [Likhtarev et al., 2002].
52.
As specific location factors for Japanese settlements were lacking, the Committee
decided to use those from the European experience for the following locations: indoors (insidehouses, offices and other buildings) and outdoors (in paved and unpaved environments).
Buildings were divided into three types, account being taken of Japanese national statistics:

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15

wooden one-to-three-storey houses, wooden fireproof one-to-three-storey houses and concrete
multi-storey apartments with the initial values of location factors 0.4, 0.2 and 0.1, respectively[MIC, 2012b]. The time dependence of the outdoor and indoor location factors based on postChernobyl studies [Golikov et al., 1999; Jacob et al., 1987b] were obtained as follows (time, t,
is in years):(a) For paved surfaces (asphalt, concrete, etc.):

f hard = 0.50 ⋅ exp(−

ln 2 ⋅ t) + 0.1
0.9(2.6)(b) For unpaved surfaces (lawn, meadow, etc.):ln 2 ⋅ t) + 0.25
f dirt = 0.50 ⋅ exp(−
2.2(c) For buildings:
 ln 2 ⋅ t 
f build = a1 ⋅ exp − + a2
T 


(2.7)

(2.8)

Table 2. Parameter values used in equation (2.8)
Type of building

Parametera1(dimensionless)0.2

a2(dimensionless)0.2

T(years)
1.8

Wooden fireproof one-to-three-storey house

0.1

0.1

1.8

Concrete multi-storey buildings

0.05

0.05

1.8

Wooden one-to-three-storey house3.

Occupancy factors for Japan53.
The occupancy factors, pij—the fraction of time spent by the representative persons of
the different population groups, i, in the various location types, j—were derived from thenational survey data for Japan from the official web site [MIC, 2012b]. The results arepresented in table 3.
Table 3. Occupancy factors, pij, for Japan
Type of location, j

Occupancy factor, pij (dimensionless)1-year old

10-year old

Outdoor worker

0.80

0.85

0.70

Indoor worker or
pensioner
0.90

Paved environment

0.10

0.05

0.20

0.05

Unpaved environment

0.10

0.10

0.10

0.05

0.20

0.15

0.30

0.10

Indoors
Outdoors

Total

54.
The occupancy factors presented in table 3 in combination with the location factors
presented in the previous subsection, including table 2 for buildings, were used for thecharacterization of the 12 social/age groups and types of dwelling. However, only the data for
two typical population groups — adults living in wooden houses and working indoors andinfants living in wooden houses — are presented. The choice of these two population groups
was based on statistical data that indicated that the majority of the population of Fukushima

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16

Prefecture and neighbouring prefectures reside in wooden or wooden fireproof one-to-twostorey houses [MIC, 2012b] in particular, typical adults were estimated to spend 0.6 of theirtime in wooden one-to-two-storey houses and 0.3 of their time at work in concrete multi-storey
buildings. Typical preschool children were estimated to spend all of their time indoors inwooden houses.
4.

Dose conversion coefficients

55.
The dose conversion coefficients, ki (Sv/Gy) (i.e. the effective dose per unit kerma in air
1 m above ground), for the reference computational phantoms of the International Commission
on Radiological Protection (ICRP) and other voxel phantoms of different ages for incident
photon energy in the range of 0.1–1 MeV and two exposure geometries, submersion in aradioactive plume and exposure from an infinite plane source at a depth of 0.5 g/cm2 in the
ground, are presented in table 4 [Golikov et al., 2007; Petoussi-Henss et al., 2012].
Table 4. Dose conversion coefficients, ki, for incident photon energy of 0.1–1 MeV [Golikov et al.,2007; Petoussi-Henss et al., 2012]
These coefficients were used in equations (2.2), (3.1) and (3.2)
Dose conversion coefficient, ki (Sv/Gy)
ICRP reference phantom(adult)Child phantom(aged 7–12 years)

Baby phantom(aged <1 year)

Submersion in a semi-infinite radioactive plume (volume source in air)Calculated for different photon
energies

0.65–0.72

0.70–0.76

0.89–0.91

Recommended regardless ofphoton energy

0.68

0.73

0.85 aInfinite plane source at a depth of 0.5 g/cm2 in the groundab

Calculated for different photon
energies (measured)

0.73–0.75 (0.69) b

0.80–0.81 (0.77) b

1.04–0.99 (0.88) a

Recommended regardless ofphoton energy

0.72

0.80

0.93 aExtrapolated from baby phantom of 4.2 kg to one-year-old infant of 10 kg.
Results of thermoluminescent dosimeter (TLD) measurements with the adult (Alderson Rando) and child phantoms (aged 10 and 1 year,
respectively) in the areas affected by the Chernobyl accident [Golikov et al., 2007].

56.
The results of TLD measurements and calculations for an adult phantom and a phantomof a 10-year-old child agree within 4–7%. For a phantom of a one-year-old child, the differenceis 15%, partly because in the measurements, the physical phantom of a one-year-old child(about 10 kg) was used, whereas in the calculations, the baby phantom aged 8 weeks (4.2 kg)
was used. Thus, the calculated conversion factors were slightly overestimated for a one-yearold child (this also applies to the data in table 6).
57.
Where the dose conversion coefficients were not available, the values for effective dose
rate and absorbed dose rate to the thyroid per unit deposition density of radionuclides wereobtained or derived from Petoussi-Henss et al. [Petoussi-Henss et al., 2012] (see table 5).
58.
Analysis of the data presented in table 5 shows that the numerical values of theeffective dose-rate conversion coefficients and the absorbed dose-rate conversion coefficientsfor the thyroid differ by no more than 5%. The numerical values of the absorbed dose-rate
conversion coefficients for the red bone marrow are also similar to those for the effective dose
rate based on data published by ICRP [ICRP, 1996, Publication 74] and Petoussi-Henss et al.

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

17[Petoussi-Henss et al., 2012]. Therefore, only the effective dose-rate conversion coefficientswere used in the assessment. The absorbed dose-rate conversion coefficients for the breast are
numerically 5–10% larger than the effective dose-rate conversion coefficients.
dep

Table 5. Effective dose-rate conversion coefficients, em ,i , and absorbed dose-rate conversiondepcoefficients for the thyroid, hm ,i ,th , for photon exposure from an infinite plane source at a depth
2of 0.5 g/cm in the ground [Petoussi-Henss et al., 2012]

These were used in equation (2.3)
Radionuclide

Absorbed dose-rate conversion coefficient for the
thyroid (nGy/h per kBq/m2)

1-year old a

1-year old a10-year old

Adults10-year old

Adults110m+110

Ag

8.04

6.48

6.07

8.10

6.35

6.25

129m+129

Te

0.21

0.16

0.15

0.24

0.18

0.18

132

0.66

0.51

0.47

0.67

0.50

0.50

131

I

1.17

0.92

0.85

1.17

0.90

0.89

132

I

6.67

5.35

5.00

6.65

5.19

5.10

133

I

1.84

1.47

1.37

1.85

1.43

1.40

134

4.63

3.7

3.46

4.62

3.60

3.53

136

6.20

4.99

4.67

6.17

4.83

4.75

137

1.69

1.34

1.25

1.69

1.31

1.29

Te

Cs
Cs
Cs + 137mBa

a

Effective dose-rate conversion coefficient(nSv/h per kBq/m2)

In order to interpolate from baby phantom of 4.2 kg to a one-year-old infant of 10 kg, the conversion coefficients presented in the column
should be multiplied by 0.93.

III. METHODOLOGY FOR ESTIMATION OF DOSE FROM EXTERNALEXPOSURE FROM RADIOACTIVE PLUMES
59.
External radiation exposures from radionuclides in the air are particularly important for
releases of noble gases which do not deposit on the ground and for which the doses frominhalation are negligible. Other radionuclides also contribute to such exposures. Insufficientmeasurements of dose rates and activity concentrations of radionuclides in air were available
for the estimation of dose received over the first few days after the start of the release. The
concentrations in air were therefore obtained from the results of ATDM. Those data were usedeither directly or in combination with the data on deposition density of radionuclides. A semiinfinite cloud modelling approach was used to estimate the doses from external exposure fromthe time-integrated activity concentrations in the air.
A.

Computational model60.
Two approaches were used to calculate the effective dose from external exposure fromthe radioactive plume, Eicl , to the representative person of population group, i. In the first case,the effective dose during the passage of the radioactive plume was estimated on the basis ofmeasured or modelled radionuclide concentrations in the surface air:
Eicl = 10 −6 ⋅ ki ⋅ RFi cl ⋅ ∑ k mcl ⋅ ∫ Cmair (t ) ⋅ dt
m

Tcl

(mSv)

(3.1)

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

18

where ki is the dose conversion coefficient from air kerma to effective dose for exposure fromradionuclides in an infinite cloud (Sv/Gy); RFi cl is the aggregated dose reduction factor for
exposure from radionuclides in an infinite to that in a semi-infinite cloud (dimensionless); k mcl is
the kerma-rate conversion coefficient for a semi-infinite volume source in air, that is, the ratioof the kerma rate in free air at a height of 1 m above the ground to the uniform activity
concentration of radionuclide, m, in air (nGy/h per Bq/m3); Tcl is the time duration of human
exposure from the passage of a radioactive plume over a site of interest (h); and C mair (t ) is thetime-dependent activity concentration of radionuclide, m, in surface air (Bq/m3).
61.
This approach was applied for both the precautionary and deliberately evacuatedsettlements of Fukushima Prefecture.
62.
In the second case, when measurements of radionuclide concentrations in air werelacking, the effective dose, Eicl , was calculated from measurements of the deposition density ofradionuclides as follows:( Am / ACs137 ) cl
⋅ km
Vm
m

Eicl = 2.8 ⋅10 −10 ⋅ ACs137 ⋅ ki ⋅ RFi cl ⋅ ∑

(mSv)

(3.2)

where Am is the deposition density of radionuclide, m, on the ground (kBq/m2); Vm is theaggregated deposition velocity of radionuclide, m, for particular weather and surface conditions(m/s); and the other symbols are the same as above.
63.
The aggregated deposition velocities were estimated from the ATDM results for theradionuclides in the plume and deposited on the ground as a function of time and location
within Fukushima Prefecture; in other prefectures, average values for the deposition velocities
were used. The aggregated deposition velocities applied were based on the ratios of theestimated time-integrated activity concentrations in air to the deposition densities of theradionuclides. This approach was applied to non-evacuated settlements of Fukushima
Prefecture and the rest of Japan.
64.
As in subsection II.A.1, both equations (3.1) and (3.2) were converted into a format
where the dose-rate conversion coefficients from activity concentration in surface air ordeposition density of the radionuclides to effective dose rate for the representative person of
population group, i, were used:
Eicl = 10 −6 ⋅ RFi cl ⋅ ∑ emcl,i ⋅ ∫ Cmair (t ) ⋅ dt
m

(mSv)

(3.3)

Tcl

( Am / ACs137 ) cl
⋅ em ,iVmmEicl = 2.8 ⋅10 −10 ACs137 ⋅ RFi cl ⋅ ∑

(mSv)

(3.4)

where emcl,i = k i ⋅ k mcl is the effective dose-rate conversion coefficient for a semi-infinite volume
source in air equal to the ratio of the effective dose rate for the representative person of
population group, i, to the uniform activity concentration of radionuclide, m, in air (nGy/h per
Bq/m3) (see table 6); other terms are as defined as above.

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19

clTable 6. Effective dose-rate conversion coefficients, em ,i , and absorbed dose-rate conversionclcoefficients for the thyroid, hm ,i ,th , for photon exposure from submersion in a radioactive plume[Petoussi-Henss et al., 2012]
These were used in equations (3.3) and (3.4)
Radionuclide

129m+129

Te

Absorbed dose-rate conversion coefficient for the
thyroid (nGy/h per Bq/m3)

1-year old a10-year old

Adults1-year old a10-year old

Adults

0.01440.01220.01110.01420.01370.0133

132

0.043

0.034

0.032

0.043

0.038

0.039

131

0.07740.06380.05980.07740.06890.0711

132

0.48

0.4

0.38

0.48

0.42

0.44

Te
I
I

133

0.128

0.106

0.100

0.126

0.113

0.117

133

0.006770.004770.00435

0.00699

0.00538

0.00638

I
Xe

134

0.328

0.272

0.257

0.328

0.289

0.299

136

0.453

0.376

0.356

0.460

0.400

0.413

137

0.118

0.097

0.092

0.117

0.104

0.108

Cs
Cs
Cs + 137mBa

a

Effective dose-rate conversion coefficient(nSv/h per Bq/m3)

In order to extrapolate from baby phantom of 4.2 kg to a one-year-old infant of 10 kg, the conversion coefficients presented in that column
should be multiplied by 0.94.

65.
The durations of the passage of the radioactive plumes were relatively short (a few
hours) and the contribution to dose from external exposure from the plumes was relatively
minor compared with that from deposited radionuclides. The Committee therefore decided touse a value of RFi cl equal to 1. This is a somewhat conservative assumption because it does notaccount for any shielding provided by buildings and the plumes are assumed to be semi-infinite
in size.
66.
Implicit in this approach is the assumption that the activity concentrations ofradionuclides in air were uniform over the volume of a plume from which photons can reachthe point at which the dose was delivered. The Committee considered this assumption to bereasonable because the assessment considered only the population groups that resided beyond a
few kilometres from the release point or were evacuated to larger distances before the major
releases started.
B.

Model parameters

67.
The kerma-rate conversion coefficients, k mcl , for a semi-infinite volume source ofradionuclide, m, in air (nGy/h per Bq/m3) are given in table 1 for the gamma-emitting
radionuclides that were detected in soil samples during June–July 2011 as partially seen in
attachments C-1 to C-4 and for some additional radionuclides used in ATDM (see table 10).
68.
The values of the absorbed dose-rate conversion coefficient for the red bone marrow
were extracted from Petoussi-Henss et al. [Petoussi-Henss et al., 2012] for the respective
radionuclides and used for the assessment of doses to the red bone marrow from a semi-infinite
volume source of radionuclides in air.

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20

IV. METHODOLOGY FOR ESTIMATION OF DOSE FROMINHALATION69.
The assessment of dose from the inhalation of radionuclides in air was based on theconcentrations of radionuclides in air obtained from ATDM, either directly or in combination
with the data on the deposition density of radionuclides, the age-dependent breathing rates andthe appropriate dose conversion coefficients (i.e. the radiation dose that results from breathing
in a unit amount of a radionuclide).
A.

Computational model70.
Two methods of dose assessment were applied. The first method was based solely on
the ATDM results for the time-dependent activity concentrations in air of a number ofradionuclides, 132Te, 131I, 132I, 133I, 133Xe, 134Cs, 136Cs and 137Cs, which were available on a gridof 5-km squares covering the whole of Japan and the neighbouring countries. The ATDM
results were based on the best available data on the source term and used models that included
detailed information on the meteorological conditions that prevailed at the time. Nevertheless,significant uncertainties are associated with the ATDM results at specific locations and times.
This approach was applied for the evacuated settlements of Fukushima Prefecture.
71.
The second method was based on the estimated time-integrated activity concentrations
in air derived from the measured deposition densities of radionuclides and the aggregateddeposition velocities, estimated from the ATDM results as a function of time and location
within Fukushima Prefecture; in other prefectures, average values for the deposition velocities
were used. The aggregated deposition velocities applied were based on the ratios of theestimates of the time-integrated activity concentration in air to the deposition density ofradionuclides. This approach was applied to non-evacuated settlements of Fukushima
Prefecture and the rest of Japan.
72.
The generic equation used for the assessment of the committed effective dose, Eiinh , tothe representative person in population group, i, from the inhalation of airborne radionuclides
is as follows:airEiinh = 10 −6 ⋅ν i ⋅ RFi inh ⋅ ∑ eiinh, m ⋅ k m ⋅ ∫ C m (t ) ⋅ dt
m

(mSv)

(4.1)

Tcl

where νi is age-dependent breathing rate (m3/s); RFi inh is the inhalation reduction factor forstaying indoors (dimensionless); eiinh,m is the dose conversion coefficient to assess the committed
effective dose to the representative person of population group, i, from the inhalation ofradionuclide, m, under reference conditions (default particle size of 1 μm and typicalabsorption type [ICRP, 1995, Publication 71]) (nSv/Bq); km is the factor accounting for particle
size and absorption type for radionuclide, m, that are different from those assumed underreference conditions (dimensionless); Tcl is the time duration of inhalation from a radioactive
plume passing over a site of interest (h); and C mair (t ) is the time-dependent activity concentrationof radionuclide, m, in surface air (Bq/m3).
73.
When the activity concentrations of key radionuclides in surface air were not available,
the assessment of dose from inhalation was based on the available deposition densities ofradionuclides as follows:ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

( Am / ACs137 ) inh⋅ ei ,m ⋅ k m
Vmm

Eiinh = 10 −3 ⋅ν i ⋅ RFi inh ⋅ ACs137 ⋅ ∑

(mSv)

21

(4.2)

where Am is the deposition density of radionuclide, m, on the ground (kBq/m2); Vm is theaggregated deposition velocity of radionuclide, m, for particular weather and surface conditions(m/s); the other symbols are as defined above.
74.
The values of the dose conversion coefficients, eiinh,m , for inhalation were taken from
ICRP [ICRP, 1995, Publication 71]. These were based on generic anatomical and physiologicalhuman data for a reference person as defined by ICRP, and as such are not intended to be
specific to inhabitants of any specific region. The use of these dose conversion coefficients
may have resulted in some overestimation of absorbed doses to the thyroid for Japaneseindividuals because the high iodine content of the Japanese diet (e.g. from sea fish, shellfish
and seaweed) may have reduced the uptake of radioiodine by the thyroid [Zava et al., 2011].
Further consideration of the anatomical and physiological characteristics of Asian people (see,for example [IAEA, 1998; IAEA, 2008]) and the implications for the doses estimated in thisstudy, are considered in section IV of appendix C.
75.
Values of age-dependent breathing rates, νj, were taken from ICRP [ICRP, 1994,
Publication 66]. The inhalation rates applied are the average rates over a day from the ICRP
model of the respiratory tract and include time spent sleeping, at home and at work, and hence
they are suitable for someone exposed for 24 hours a day. For time spent at work, theinhalation rate is modelled on the male sedentary worker and male heavy worker. The ICRP
dose coefficients for inhalation, based on inhalation rates for males, [ICRP, 1996, Publication72], were used in the assessment of doses to adults.
76.
The estimates of the deposition density of radionuclides were based on measurements
whenever they were available. Such data were available for 134Cs and 137Cs for each settlement.
If, for a particular settlement, data on 131I were available, their values were used directly. For
129m
Te and 132Te/132I, missing values were obtained from the ratio of the deposition densities of
the respective radionuclide to that of 137Cs (see table 9). For the short-lived radionuclide, 133I,
the activity concentration in air was estimated directly from the calculated concentration of 131I
in air by applying the radionuclide ratio derived from ATDM.
77.
In the absence of specific information, the default particle size and absorption types
specified by ICRP [ICRP, 1995, Publication 71] were assumed, that is, km was taken as one.
Similarly, RFi inh was also assigned a value of one, because infiltrating gaseous radionuclides
were assumed to have dominated the exposure of the representative individual.
78.
The values of aggregated deposition velocity, Vm, for radionuclide, m, were derived
from the ATDM calculations based on the ratios of the estimates of the time-integrated activity
concentration in air to the deposition density.
79.
A similar approach was used for the assessment of the committed absorbed dose to thethyroid of the representative person in population group, i, from the inhalation of airborne
radionuclides, H iinh
,th :
inh
−6
H iinh⋅ ∑ hthinh,i ,m ⋅ k m ⋅ ∫ Cmair (t ) ⋅ dt
,th = 10 ⋅ν i ⋅ RFi
m

Tcl

(mSv)

(4.3)

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

or( Am / ACs137 ) inh⋅ hth ,i ,m ⋅ k m
Vm
m

−3
inh
H iinh⋅ ACs137 ⋅ ∑,th = 10 ⋅ν i ⋅ RFi

(mSv)

22

(4.4)

where hthinh,i ,m is the committed absorbed dose conversion coefficient for the thyroid of therepresentative person in population group, i, due to inhalation of radionuclide, m, underreference conditions (default particle size of 1 μm and typical absorption type) (nSv/Bq); otherterms are defined as above.
Similar equations were used for the assessment of doses to the red bone marrow and breast.
B.

Model parameters

80.
Breathing rates were considered as a function of age and occupation (for adults).
Representative inhalation rates were derived from data given in ICRP publications [ICRP,
1994, Publication 66; ICRP, 1995, Publication 71]. These data were based on an assumed
combination of activity, rest and sleep (see table 7).
Table 7. Breathing rates, νi, for adults, children and infants (averaged over a day) [ICRP, 1994,
Publication 66]
These were used in equations (4.1) to (4.4)
Age group

Inhalation rate (m3/s)

Adult (outdoor worker)

2.92 × 10-4

Adult (indoor worker or pensioner)

2.57 × 10-4

10-year old

1.77 × 10-4

One-year old

6.02 × 10-5

81.
The effective dose conversion coefficients and the absorbed dose conversion
coefficients for the thyroid and red bone marrow from inhalation were taken or derived from
ICRP publications [ICRP, 1995, Publication 71; ICRP, 1996, Publication 72] (see table 8).
These take account of age, particle size (a default particle size of 1 µm was assumed),
radionuclide (and for certain elements such as iodine, chemical form), absorption type (F, M,
or S), organ/tissue and time-integration period. The numerical values of the absorbed doseconversion coefficients for the breast from inhalation of 134Cs and 137Cs are lower than thosefor the red bone marrow by a factor of about 0.8 (0.74 to 0.85 for different age groups) and 0.9(0.86 to 0.93), respectively.

Table 8. Committed dose coefficients for inhalation by members of the public [ICRP, 1996, Publication 72]

Dose conversion coefficients for effective dose,
respectively
Radionuclide
form

Lung
absorption
type, and absorbed dose to organs,

Effective dose conversion coefficient(Sv/Bq)hthinh,i ,m, were used in equations (4.1) and (4.2), and (4.3) and (4.4),

Absorbed dose conversion coefficient forthyroid (Gy/Bq)

Absorbed dose conversion coefficient for
red bone marrow (Gy/Bq)

Adults10-year old

1-year old

Adults10-year old

1-year old

Adults10-year old

1-year old

129m

Te

AerosolM

6.6 × 10-9

9.8 × 10-9

2.6 × 10-8

1.0 × 10-9

2.5 × 10-9

1.2 × 10-8

1.2 × 10-9

2.8 × 10-9

1.2 × 10-8

132

Te

AerosolM

2.0 × 10-9

4.0 × 10-9

1.3 × 10-8

4.3 × 10-9

1.1 × 10-8

5.3 × 10-8

2.2 × 10-10

3.6 × 10-10

8.5 × 10-10

VapourF

2.0 × 10-8

4.8 × 10-8

1.6 × 10-7

3.9 × 10-7

9.5 × 10-7

3.2 × 10-6

9.3 × 10-11

1.4 × 10-10

3.4 × 10-10

AerosolF

7.4 × 10-9

1.9 × 10-8

7.2 × 10-8

1.5 × 10-7

3.7 × 10-7

1.4 × 10-6

3.7 × 10-11

6.0 × 10-11

1.6 × 10-10

AerosolF

9.4 × 10-11

2.2 × 10-10

9.6 × 10-10

1.4 × 10-9

3.4 × 10-9

1.6 × 10-8

1.1 × 10-11

2.1 × 10-11

6.1 × 10-11

VapourF

4.0 × 10-9

9.7 × 10-9

4.1 × 10-8

7.6 × 10-8

1.9 × 10-7

8.0 × 10-7

4.4 × 10-11

8.0 × 10-11

2.3 × 10-10

AerosolF

1.5 × 10-9

3.8 × 10-9

1.8 × 10-8

2.8 × 10-8

7.4 × 10-8

3.5 × 10-7

1.8 × 10-11

3.5 × 10-11

1.1 × 10-10

134

AerosolF

6.6 × 10-9

5.3 × 10-9

7.3 × 10-9

6.3 × 10-9

5.1 × 10-9

6.3 × 10-9

6.3 × 10-9

4.7 × 10-9

5.2 × 10-9

136

AerosolF

1.2 × 10-9

2.0 × 10-9

5.2 × 10-9

1.0 × 10-9

1.6 × 10-9

3.9 × 10-9

9.8 × 10-10

1.4 × 10-9

3.2 × 10-9

137

AerosolF

4.6 × 10-9

3.7 × 10-9

5.4 × 10-9

4.4 × 10-9

3.5 × 10-9

4.4 × 10-9

4.4 × 10-9

3.3 × 10-9

4.0 × 10-9

131

I

132

I

133

I

Cs
Cs
Cs

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Radionuclide

eiinh
,m

23

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

24

V. ASSESSMENT OF COLLECTIVE DOSES82.
The collective dose to the general public provides an aggregated metric associated withthe radiological detriment arising from an activity or event, in this case, the FDNPS accident.
For comparison with other events associated with radionuclide releases to the environment(e.g. global fallout following the testing of nuclear weapons in the atmosphere, and theChernobyl accident), the long-term collective dose commitment over decades has beenpreviously assessed.
83.
The Committee assessed both the collective effective dose and the collective absorbed
dose to the thyroid. The collective absorbed dose to the thyroid in the first year following theaccident was of particular interest because of the substantial release of radioiodine—the major
contributor was the intake of 131I via inhalation and ingestion. The main contributors to thecollective effective dose to the public are the long-term exposure pathways, that is, external
exposure from 134Cs and 137Cs deposited on the ground and internal exposure from ingestion of
the same radionuclides in foods.
84.
The collective effective dose commitment and collective absorbed dose to the thyroid
were assessed for the population residing in all localities of Fukushima Prefecture and otherprefectures of Japan for the three age groups of the population (adults, 10-year-old children and
one-year-old infants).
85.
According to the recent Japan 2010 Census [MIC, 2011], the total population of Japan
in 2010 was 128 million persons. Among them, 108.9 million persons, (85.1%) were aged
16 years and above, 11.7 million persons (9.1%) were in the age range of 6 to 15 years, and
7.4 million persons (5.8%) were in the age range of 0 to 5 years.
86.
The collective doses were assessed for the following geographical areas: (a) Fukushima
Prefecture (Groups 1 and 2 districts); (b) the six neighbouring or nearby prefectures (Group 3
prefectures, i.e. Iwate, Miyagi, Tochigi, Gunma, Ibaraki and Chiba); (c) the rest of Japan(Group 4 prefectures); and (d) the whole of Japan.
87.
The collective dose (both effective and absorbed dose to the thyroid) from external
exposure for a particular area depends on the population size and its distribution with respect tothe deposition density of the radionuclides, dwelling type and occupancy factor. On the basis ofnational statistics for Japan, the Committee assumed that about 30% of the entire population of
the country live in wooden one-to-three-storey houses, another 30% live in wooden fireproof
one-to-three-storey houses and about 40% of the population live in concrete multi-storey
apartments [MIC, 2012b]. Regarding occupancy factors for the adult population, theCommittee assumed that about 10% were outdoor workers and about 90% were indoor workers
including various industries, office workers, students and pensioners. The occupancy factors
for preschool and school children are presented in table 3. The time integration to infinity of
the appropriate external dose rate was made using the equations (2.1) to (2.4) presented in
section II.

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25

VI. INPUT DATA FOR DOSE ASSESSMENT
A.

Source term

88.
The source term for the radionuclides released during the period from 11 to 31 March2011 was available in the form of a MS Excel workbook. The file contained data for the release
rates of the radionuclides 132Te 131I, 132I, 133I, 133Xe, 134Cs, 136Cs, and 137Cs in becquerels perhour (Bq/h) in three-hourly time steps within the 21-day period. All release rates detailed in the
spreadsheet were corrected for radioactive decay to the time of the reactor shutdown:
14:46 JST on 11 March 2011. Tellurium-132 and radiocaesium were assumed to be inparticulate form. Xenon-133 was assumed to be in gaseous form. Iodine-131 and iodine-133
were assumed to be in both gaseous and particulate forms in equal proportions. Iodine-132 wasassumed to be in equilibrium with its radioactive parent, 132Te, and therefore also in particulateform—the source term indicated no actual release of 132I from FDNPS because of its very shorthalf-life.
89.
The source term was primarily used in the model to reconstruct the concentrations ofradionuclides in air over Japan; the results of the modelling were available on a grid of 5-km
squares covering Japan and the neighbouring countries for eight radionuclides (seesection 1V.A). A significant release of all the radionuclides started in the evening of 11 March
2011. The major release that resulted in a substantial deposition of radionuclides overFukushima Prefecture and the adjacent regions occurred three days later, in the evening of
14 March, from Unit 2 of FDNPS, when the wind was blowing towards the land and it was
raining.
90.
Significant exposure of the Japanese population to radiation began on 15 March 2011(see figure II). Although substantial radionuclide deposition occurred later in some areas, forexample on 21 March (see figure II) and over the subsequent weeks, the Committeeconservatively assumed that the deposition densities of all the radionuclides monitored in soil
samples was due to deposition that occurred on 15 March 2011.
Figure II. Change of dose rate in air (µGy/h) with time at some monitoring posts in Japan [NRA,2012]
X-axis = Hours after 00:00 14 March 2011 (JST); Y-axis = Dose rate in air (µGy/h)Ibaraki(Mito)

Tochigi(Utsunomiya)

Gunma(Maebashi)

1.600

1.400

1.200

1.000

0.800

0.600

0.400

0.200

0.000
1

7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103 109 115 121 127 133 139 145 151 157 163 169 175 181 187 193 199 205 211 217 223 229 235 241 247 253

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

B.

26

Composition of deposited radionuclides

91.
The systematic monitoring of the deposition density of radionuclides in the vicinity of
FDNPS was conducted during June and July 2011 [MEXT, 2013]. Soil was sampled on thebasis of a grid of 2-km squares up to a distance of 80 km from the source and of a grid of
10-km squares up to a distance of 100 km and all over Fukushima Prefecture — in total about
2,200 aggregated samples. The measurement results as provided in electronic form by theGovernment of Japan are tabulated in attachments C-1 (131I), C-2 (134Cs, 137Cs), C-3 (110mAg),
C-4 (129mTe) and C-5 (strontium and plutonium isotopes).
92.
Radiocaesium (134Cs and 137Cs) was detected in all the soil samples, 131I (half-life,
8.02 days) in 419 samples, 129mTe (half-life, 33.6 days) in 799 samples, and 110mAg (half-life,
250 days) in 343 samples.
93.
The most long-lived and radiologically significant radionuclide, 137Cs, was chosen as
the standard for area mapping. According to the analysis of all of the 2,200 soil samples, theaverage deposition density of 134Cs on 15 March 2011 was equal to that of 137Cs (see table 9).
94.
The ratios of the deposition densities of radionuclides to those of 137Cs measured innumerous samples were used in the reconstruction of the deposition densities of 110mAg, 129mTeand 131I in the samples where these radionuclides had not been detected.
95.
Figure III shows that the derived ratios of the deposition densities of 129mTe and 131I tothat of 137Cs were significantly elevated (by an average of a factor of six to seven) in the
narrow south trace along the coast within a distance of about 60 km from FDNPS compared tothose for other areas of Japan [MEXT, 2013]. The data for the south trace were therefore
treated differently, using linear regression methods, from the rest of the monitored area. The
deposition densities of both 129mTe and 131I strongly correlated with those of 137Cs. The
respective regression coefficients are given in table 9.
96.

There was also a statistically significant correlation between the deposition density ofAg and that of 137Cs but the correlation coefficient was smaller than those for 129mTe and
131
I. The correlation coefficient for 110mAg is given in table 9 and was used for thereconstruction of the deposition densities of this radionuclide. The unavoidable uncertainty
with this did not substantially influence the dose estimates because the contribution of thisradionuclide to external exposure was small (of the order of 0.1%).
110m

97.
Environmental measurement data have been published for various radioisotopes of one
chemical element that were used in the reconstruction of the deposition densities of a shortlived radioisotope of that element. For example, the deposition densities of 132Te and 136Cs
were reconstructed on the basis of the measurements of the deposition densities of 129mTe and137
Cs, respectively. From measurements on soil samples from various sites in Japan [Endo etal., 2012; Tagami et al., 2011] and air samples from Europe [Kirchner et al., 2012], the average
isotopic ratio 136Cs/137Cs was estimated to be 0.17 on 15 March 2011 with a relatively low
variability (see table 9). The calculated activities of these radioisotopes released from Unit 2 of
FDNPS gave somewhat higher but still similar values, that is, 0.26 [Nishihara, 2012] and 0.25
[Kirchner et al., 2012]. The ratio 132Te/129mTe varied more substantially. It was estimated to be
9.1 ± 1.6 (n = 14) from measurements of soil samples in Japan [Endo et al., 2012] and 5.8 ± 0.1(n = 14) from measurements of air samples collected over Europe [Kirchner et al., 2012]. The
Committee used a rounded average of seven (see table 9), although the calculated activities of

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27

these radioisotopes released from Unit 2 of FDNPS gave higher but diverse values, that is, 22[Nishihara, 2012] and 13 [Kirchner et al., 2012].
137

Table 9. Ratios of the deposition densities of radionuclides to those of Cs as of 15 March 2011
[Endo et al., 2012; Kirchner et al., 2012; MEXT, 2013; Tagami et al., 2011]
Radionuclide (half-life)

a

Area

Characteristic

All ofJapan
exceptfor the
south
trace

Ratio to 137Cs

South
trace aRatio to 137Cs

137

137m

134

Cs+ Ba(30.2 years)

Cs(2.06 years)Cs(13.2 days)

131I(8.02 days)Te(33.6 days)

Te+132I(3.2 days)

Ag(250 days)

1.0

1.0

0.17

11.5

1.1

8

0.00280.074(2181)

0.02 (56)0.72 (339)

0.97
(689)

74

7.9

0.89 (73)

0.85
(110)

Standard
deviation (n)136Correlation
coefficient (n)
1.0

1.0

0.17

Correlation
coefficient (n)

129m

132

110m

0.47
(343)
59

0.0028The towns of Tomioka, Naraha, Hirono and Iwaki of Fukushima Prefecture.

Figure III. Locations of measurements of the ratios of the deposition density of137
Cs in Fukushima PrefectureBlue marks are for where thewas >5 [MEXT, 2012]

129m

137

Te/

Cs ratio was <5; red marks are for where the

129m

129m

Te to that of
137

Te/

Cs ratioATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

C.

Data sets for the assessment of dose from external exposure from
deposited radionuclides

1.

Within 100 km of FDNPS and the entire Fukushima prefecture(Groups 1 and 2)

28

98.
The results of the measurements of the deposition densities of radionuclides on soil
were weighted according to the population density in each of the 59 settlements in Fukushima
Prefecture and of the 33 settlements in the neighbouring prefectures—Yamagata(5 settlements), Tochigi (5 settlements), Ibaraki (5 settlements) and Miyagi (18 settlements).
Measurement data obtained during the Japanese summer of 2011 were available for 134Cs and137
Cs for each settlement (2,200 soil samples). When measurement data were available forother measured radionuclides (e.g. 110mAg, 129mTe, or 131I), their values were used directly.
Missing data were reconstructed from the ratios presented in table 9.
2.

The six prefectures − Iwate, Miyagi, Tochigi, Gunma, Ibaraki and Chiba(Group 3)

99.
The six Group 3 prefectures included those of Iwate, Miyagi, Tochigi, Gunma, Ibaraki
and Chiba, except for the 33 settlements discussed in the previous paragraph above. Data on
the deposition densities of radionuclides on soil were obtained from a series of in situ
measurements and/or soil sampling conducted in late 2011 on the basis of a grid of 10-km
squares with maps showing sampling points for each prefecture. These data were weighted
according to the population density in each of the 130 settlements located in the six Group 3
prefectures. Measurement data were available for 134Cs, 137Cs and, for some locations, 110mAg.
The deposition densities of other radionuclides for which no measurement data were available
were assessed using the ratios in table 9.
3.

Distant prefectures of Japan (Group 4)

100. The distant prefectures of Japan comprise the prefectures that were not covered in theprevious two paragraphs above—the other 40 Japanese prefectures. The measurement data for
134
Cs, 137Cs and sometimes 131I were obtained at one representative point in each prefecture andpresented on a monthly basis over the 13-month period from March 2011 to March 2012.
101. In order to assess the representative deposition densities of radionuclides on soil, themonthly fallout data for 134Cs and 137Cs were summarized for the period from March to July
2011. The results for 134Cs were corrected for radioactive decay to 15 March 2011. The
deposition densities of other radionuclides were assessed using the ratios in table 9.
D.

Data set for the assessment of dose from external exposure for theplume and internal exposure from inhalation

102. For all of Japan, the input data (activity concentrations in air or time-dependent activity
concentrations in air of eight radionuclides: 132Te, 131I, 132I, 133I, 133Xe, 134Cs, 136Cs, and 137Cs)
were obtained from ATDM. These data were converted into time-integrated activity
concentrations.
103. The activity concentrations in air or the time-integrated activity concentrations in air
were averaged over the areas of each of the 59 settlements of Fukushima Prefecture.

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

29

Aggregated deposition velocities were derived from the time-integrated activity concentrations
in air and deposition densities. The median of the values of these aggregated deposition
velocities were then used to derive the time-integrated activity concentrations in air for the restof Japan.
104. The activity concentrations in air or time-integrated activity concentrations in air for theeight radionuclides were directly used for the assessment of doses from external exposure fromthe plume and internal exposure from inhalation for the 18 scenarios for the evacuatedsettlements.
E.

Evacuation data

105. As a result of the FDNPS accident, precautionary evacuation from the potentiallyaffected areas of Fukushima Prefecture (<20 km from FDNPS) to less affected areas [NERHQ,
2011] was carried out by the Government of Japan between 11 and 15 March 2011. In addition,some people evacuated from the adjacent areas voluntarily. A series of evacuations wasdeliberately implemented during late March to June 2011 from the towns and villages locatedto the north-west of FDNPS; the governmental decision was based on the environmental
radiation measurements [NERHQ, 2011].
106. Information on the number of people residing in the evacuated and adjacent areas
before the accident and the number of people evacuated is presented in table 10. More detailed
information about the destinations of those evacuated in the precautionary and deliberate
evacuations are presented in table 11.
Table 10. Populations of the evacuated areas and some adjacent territories and the number of
evacuees
Population before 11 March 2011aa

Rounded number of evacueesb

City, town orvillage<20 km20–30 km

>30 kmTotal

Evacuated by
15 March 2011

Population ofdeliberate
evacuation area

TotalcMinamisoma

14 30047 4009 200

70 90014 300<100

32 000Katsurao

300

1 300

–

1 600

300

1 300

1 600

Namie

19 600

1 000

300

20 90019 600

1 300

20 900

Tamura600

3 200

36 60040 400

600

–

3 000

Futaba

6 900

–

–

6 900

6 900

–

6 900

Okuma

11 500––11 50011 500–11 500Kawauchi

1 100

1 700

–

2 800

2 800d–2 800dTomioka

16 000––

16 000

16 000–

16 000

Naraha

7 700

–

–

7 700

7 700

–

7 700

Hirono

200

5 200

–

5 400

5 200

–

5 200

Iitate

–

300

5 900

6 200

–

6 200

6 200

Kawamata––

15 60015 600

–

1 300

1 300

Iwaki

–

2 200

340 000

342 200

–

–

2 700

Total

78 20062 300407 600

548 100

84 900

10 200117 800

Approximate number based on Japan 2010 Census [MIC, 2011].
The numbers reported in [MEXT, 2011]; those were adjusted to be consistent with the population data.
The number of evacuees reported [MEXT, 2011] may also include evacuees who lived outside of 30-km radius and people evacuated forother reasons than radiological protection. For that reason, the total number of evacuees may be larger than the sum of people evacuatedbefore 15 March 2011 and from the deliberate evacuation area.
d
Evacuated from the evacuation zone (<20 km) by 15 March 2011, and from the whole village immediately after the village mayor’s
instruction on 16 March 2011 [ICANPS, 2011].
bcLocation

Latitude°N

Longitude°E

Time period (JST)Activity

Building type or vehicle

Fraction of time indoors(adult / child / infant)Scenario 1: Tomioka Town evacuation
Tomioka Town Office37.346141.009

2011-03-11 00:00 --> 2011-03-11 21:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Tomioka Town Office37.346141.009

2011-03-11 21:00 --> 2011-03-12 03:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 03:00 --> 2011-03-12 06:00

Evacuation

Vehicle0/0/0
See table 3

Tomioka Town to Kawauchi
Village
Kawauchi Village Office37.3381140.809

2011-03-12 06:00 --> 2011-03-15 11:00

Normal living conditions

Wooden 1-to-2-storey house

Kawauchi Village Office37.3381140.809

2011-03-15 11:00 --> 2011-03-16 08:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Kawauchi Village Office37.3381140.809

2011-03-16 08:00 --> 2011-03-16 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-16 10:00 --> 2011-03-16 16:00

Evacuation

Vehicle0/0/0

140.3741

2011-03-16 16:00 --> 2012-03-11 00:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Kawauchi Village to Big Pallete
Fukushima
Big Palette Fukushima

37.3699

Scenario 2: Okuma Town evacuation
Okuma Town Office37.4044140.9834

2011-03-11 00:00 --> 2011-03-11 21:23

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Okuma Town Office37.4044140.9834

2011-03-11 21:23 --> 2011-03-12 04:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Okuma Town Office37.4044140.9834

2011-03-12 04:00 --> 2011-03-12 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 10:00 --> 2011-03-12 13:00

Evacuation

Outdoors

0/0/0

37.4352140.5657

2011-03-12 13:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Okuma Town to Funahiki
Funahiki Vocational Improvement
CenterScenario 3: Futaba Town evacuation
Futaba Town Office37.4491141.0123

2011-03-11 00:00 --> 2011-03-11 21:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Futaba Town Office37.4491141.0123

2011-03-11 21:00 --> 2011-03-12 03:00

Evacuation preparation

Wooden 1–to-2-storey house

0/1/1

2011-03-12 03:00 --> 2011-03-12 08:00

Evacuation

Vehicle0/0/0

Kawamata Elementary School

37.6696140.5996

2011-03-12 08:00 --> 2011-03-19 08:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Kawamata Elementary School

37.6696140.5996

2011-03-19 08:00 --> 2011-03-19 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

Futaba to Kawamata

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Table 11. Evacuation scenarios

30Latitude°N

Longitude°E

Kawamata to Saitama

Time period (JST)Activity

Building type or vehicle

Fraction of time indoors(adult / child / infant)2011-03-19 10:00 --> 2011-03-19 17:00

Evacuation

Vehicle0/0/0

Saitama Super Arena

35.8949

139.63072011-03-19 17:00 --> 2011-03-31 08:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Saitama Super Arena

35.8949

139.63072011-03-31 08:00 --> 2011-03-31 10:00

Evacuation preparation

Concrete multi-storey
apartment

0/1/1

2011-03-31 10:00 --> 2011-03-31 11:00

Evacuation

Vehicle0/0/0

139.5704

2011-03-31 11:00 --> 2012-03-11 00:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Saitama to Kisai
Kisai High School

36.1042

Scenario 4: Futaba Town evacuation (2)Futaba Town Office37.4491141.0123

2011-03-11 00:00 --> 2011-03-11 21:23

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Futaba Town Office37.4491141.0123

2011-03-11 21:23 --> 2011-03-12 10:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Futaba Town Office37.4491141.0123

2011-03-12 10:00 --> 2011-03-12 16:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 16:00 --> 2011-03-12 21:00

Evacuation

Vehicle0/0/0

Wooden 1-to-2-storey house

See table 3

Futaba to Kawamata
Kawamata Elementary School

37.6696140.5996

2011-03-12 21:00 --> 2011-03-19 08:00

Normal living conditions

Kawamata Elementary School

37.6696140.5996

2011-03-19 08:00 --> 2011-03-19 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-19 10:00 --> 2011-03-19 17:00

Evacuation

Vehicle0/0/0

Kawamata to Saitama
Saitama Super Arena

35.8949

139.63072011-03-19 17:00 --> 2011-03-31 08:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Saitama Super Arena

35.8949

139.63072011-03-31 08:00 --> 2011-03-31 10:00

Evacuation preparation

Concrete multi-storey
apartment

0/1/1

2011-03-31 10:00 --> 2011-03-31 11:00

Evacuation

Vehicle0/0/0

36.1042139.5704

2011-03-31 11:00 --> 2012-03-11 00:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Saitama to Kisai
Kisai High School

Scenario 5: Naraha Town evacuation
Naraha Town Office37.2826140.9935

2011-03-11 00:00 --> 2011-03-12 03:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Naraha Town Office37.2826140.9935

2011-03-12 03:00 --> 2011-03-12 09:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 09:00 --> 2011-03-12 13:00

Evacuation

Vehicle0/0/0Naraha to Iwaki
Iwaki City Office

37.0505140.8877

2011-03-12 13:00 --> 2011-03-31 08:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Iwaki City Office

37.0505140.8877

2011-03-31 08:00 --> 2011-03-31 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Location31

Latitude°N

Longitude°E

Iwaki to Funahiki
Funabiki Vocational Improvement
Center

37.4352

Time period (JST)Activity

Building type or vehicle

Fraction of time indoors(adult / child / infant)2011-03-31 10:00 --> 2011-03-31 12:00

Evacuation

Vehicle0/0/0

140.5657

2011-03-31 12:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Scenario 6: Naraha Town evacuation (2)Naraha Town Office37.2826140.9935

2011-03-11 00:00 --> 2011-03-12 03:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Naraha Town Office37.2826140.9935

2011-03-12 03:00 --> 2011-03-12 09:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 09:00 --> 2011-03-12 13:00

Evacuation

Vehicle0/0/0Naraha to Iwaki
Iwaki City Office

37.0505140.8877

2011-03-12 13:00 --> 2011-03-16 08:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Iwaki City Office

37.0505140.8877

2011-03-16 08:00 --> 2011-03-16 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-16 10:00 --> 2011-03-16 15:00

Evacuation

Vehicle0/0/0

37.4599139.8412

2011-03-16 15:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Iwaki to Aizumisato
Aizumisato Town Office

Scenario 7: Namie Town evacuation
Namie Town Office37.4949140.9995

2011-03-11 00:00 --> 2011-03-11 21:23

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Namie Town Office37.4949140.9995

2011-03-11 21:23 --> 2011-03-12 06:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Namie Town Office37.4949140.9995

2011-03-12 06:00 --> 2011-03-12 12:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 12:00 --> 2011-03-12 15:00

Evacuation

Vehicle0/0/0

Tsushima Activation Center

37.5611140.764

2011-03-12 15:00 --> 2011-03-15 11:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Tsushima Activation Center

37.5611140.764

2011-03-15 11:00 --> 2011-03-16 08:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Tsushima Activation Center

37.5611140.764

2011-03-16 08:00 --> 2011-03-16 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-16 10:00 --> 2011-03-16 14:00

Evacuation

Vehicle0/0/0

140.4557

2011-03-16 14:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Wooden 1-to-2-storey house

See table 3

Namie to Tsushima

Tsushima to Adachi
Adachi Gymnasium

37.6186

Scenario 8: Tamura Town evacuation
Tamura Town

37.4141140.8080

2011-03-11 00:00 --> 2011-03-12 01:00

Normal living conditions

Tamura Town

37.4141140.8080

2011-03-12 01:00 --> 2011-03-12 07:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 07:00 --> 2011-03-12 08:00

Evacuation

Vehicle0/0/0

Tamura to Denso
Denso Higashinihon

37.4338140.5284

2011-03-12 08:00 --> 2011-03-31 08:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Denso Higashinihon

37.4338140.5284

2011-03-31 08:00 --> 2011-03-31 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Location32

Latitude°N

Longitude°E

Denso to Big Palette
Big Palette Fukushima

37.3699

Time period (JST)Activity

Building type or vehicle

Fraction of time indoors(adult / child / infant)2011-03-31 10:00 --> 2011-03-31 11:00

Evacuation

Vehicle0/0/0

140.3741

2011-03-31 11:00 --> 2012-03-11 00:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Scenario 9: Minamisoma City evacuation
Minamisoma City

37.5761140.9131

2011-03-11 00:00 --> 2011-03-15 04:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Minamisoma City

37.5761140.9131

2011-03-15 04:00 --> 2011-03-15 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-15 10:00 --> 2011-03-15 16:00

Evacuation

Vehicle0/0/0

Minamisoma City to Date City
OfficeDate City Office37.8191140.563

2011-03-15 16:00 --> 2011-03-31 08:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Date City Office37.8191140.563

2011-03-31 08:00 --> 2011-03-31 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-31 10:00 --> 2011-03-31 11:00

Evacuation

Vehicle0/0/0

37.7248140.3649

2011-03-31 11:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Date City to Azuma Gymnasium
Azuma Gymnasium

Scenario 10: Hirono Town evacuation
Hirono Town

37.2422140.9887

2011-03-11 00:00 --> 2011-03-11 19:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Hirono Town

37.2422140.9887

2011-03-11 19:00 --> 2011-03-12 01:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-12 01:00 --> 2011-03-12 08:00

Evacuation

Vehicle0/0/0

140.6263

2011-03-12 08:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Hirono to Ono
Ono Town Office37.2868

Scenario 11: Kawauchi Village evacuation
Kawauchi Village

37.3510140.8503

2011-03-11 00:00 --> 2011-03-13 04:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Kawauchi Village

37.3510140.8503

2011-03-13 04:00 --> 2011-03-13 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-13 10:00 --> 2011-03-13 11:00

Evacuation

Vehicle0/0/0

Kawauchi Village to Kawauchi
Mura Elementary School
Kawauchi Mura Elementary
School37.3435140.803

2011-03-13 11:00 --> 2011-03-15 11:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Kawauchi Mura Elementary
School37.3435140.803

2011-03-15 11:00 --> 2011-03-16 08:00

Sheltering

Concrete multi-storey
apartment

1/1/1

Kawauchi Mura Elementary
School37.3435140.803

2011-03-16 08:00 --> 2011-03-16 10:00

Evacuation preparation

Concrete multi-storey
apartment

0/1/1

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Location

33

Latitude°N

Longitude°E

Kawauchi Mura Elementary
School to Big Palette Fukushima
Big Palette Fukushima

37.3699

Time period (JST)Activity

Building type or vehicle

Fraction of time indoors(adult / child / infant)2011-03-16 10:00 --> 2011-03-16 16:00

Evacuation

Vehicle0/0/0

140.3741

2011-03-16 16:00 --> 2012-03-11 00:00

Normal living conditions

Concrete multi-storey
apartment

See table 3

Scenario 12: Katsurao Village evacuation
Katsurao Village

37.5131140.7962

2011-03-11 00:00 --> 2011-03-14 04:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Katsurao Village

37.5131140.7962

2011-03-14 04:00 --> 2011-03-14 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-14 10:00 --> 2011-03-14 18:00

Evacuation

Vehicle0/0/0

2011-03-14 18:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Katsurao to Azuma
Azuma Gymnasium

37.7248140.3649

Scenario 13: Tsushima Activation Center evacuation (in deliberate evacuation area)
Tsushima Activation Center

37.5611140.764

2011-03-11 00:00 --> 2011-03-15 11:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Tsushima Activation Center

37.5611140.764

2011-03-15 11:00 --> 2011-03-23 04:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Tsushima Activation Center

37.5611140.764

2011-03-23 04:00 --> 2011-03-23 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-23 10:00 --> 2011-03-23 14:00

Evacuation

Vehicle0/0/0

2011-03-23 14:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Tsushima to Adachi
Adachi Gymnasium

37.6186140.4557

Scenario 14: Katsurao Village Office evacuation (in deliberate evacuation area)
Katsurao Village Office37.5036140.7644

2011-03-11 00:00 --> 2011-03-15 11:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Katsurao Village Office37.5036140.7644

2011-03-15 11:00 --> 2011-03-21 04:00

Sheltering

Wooden 1-to-2-storey house

1/1/1

Katsurao Village Office37.5036140.7644

2011-03-21 04:00 --> 2011-03-21 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-03-21 10:00 --> 2011-03-21 12:00

Evacuation

Vehicle0/0/0

37.7248140.3649

2011-03-21 12:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Katsurao to Azuma
Azuma General Gymnasium

Scenario 15: Iitate Village Office evacuation (in deliberate evacuation area)
Iitate Village Office37.6788

140.7344

2011-03-11 00:00 --> 2011-03-29 04:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Iitate Village Office37.6788

140.7344

2011-05-29 04:00 --> 2011-03-29 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-05-29 10:00 --> 2011-03-29 11:00

Evacuation

Vehicle0/0/0

2011-05-29 11:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Iitate to Fukushima City, Lino
branchLino branch of Fukushima City

37.6573140.5376

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Location34

Latitude°N

Longitude°E

Time period (JST)Activity

Building type or vehicle

Fraction of time indoors(adult / child / infant)Wooden 1-to-2-storey house

See table 3

Scenario 16: Iitate Village evacuation (2) (in deliberate evacuation area)
Iitate Village Office37.6788

140.7344

2011-03-11 00:00 --> 2011-03-21 04:00

Normal living conditions

Iitate Village Office37.6788

140.7344

2011-06-21 04:00 --> 2011-03-21 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-06-21 10:00 --> 2011-03-21 11:00

Evacuation

Vehicle0/0/0

2011-06-21 11:00 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Iitate to Fukushima City, Lino
branchLino branch of Fukushima City

37.6573140.5376

Scenario 17: Minamisoma City evacuation (2) (in deliberate evacuation area)
Minamisoma City

37.6535140.8375

2011-03-11 00:00 --> 2011-03-20 04:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Minamisoma City

37.6535140.8375

2011-05-20 04:00 --> 2011-03-20 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-05-20 10:00 --> 2011-03-20 10:30

Evacuation

Vehicle0/0/0

2011-05-20 10:30 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

Minamisoma City to Minamisoma
City Office
Minamisoma City Office37.6422140.957

Scenario 18: Yamakiya District, Kawamata Town evacuation (in deliberate evacuation area)
Yamakiya District, Kawamata
Town
Yamakiya District, Kawamata
Town
Yamakiya District, Kawamata
Town to Kawamata Town Office
Kawamata Town Office37.6201140.6725

2011-03-11 00:00 --> 2011-03-01 04:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

37.6201140.6725

2011-06-01 04:00 --> 2011-03-01 10:00

Evacuation preparation

Wooden 1-to-2-storey house

0/1/1

2011-06-01 10:00 --> 2011-03-01 10:30

Evacuation

Vehicle0/0/0

2011-06-01 10:30 --> 2012-03-11 00:00

Normal living conditions

Wooden 1-to-2-storey house

See table 3

37.665140.598

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

Location

35

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

36

ATTACHMENT C-12: METHODOLOGY FOR THE ASSESSMENT OF DOSE FROM EXTERNAL EXPOSURE AND INHALATION ...

37

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