United Nations Scientific Committee on the Effects of Atomic Radiation

ATTACHMENT A-11

EVACUATION SCENARIOS AND
NUMBER OF EVACUEESUNSCEAR 2020/2021 Report, Annex B, Levels and effects of radiation exposure dueto the accident at the Fukushima Daiichi Nuclear Power Station: implications ofinformation published since the UNSCEAR 2013 Report
Content

This attachment describes the methodology used for assessing public exposure to the evacuees
from the accident at the Fukushima Daiichi Nuclear Power Station (FDNPS) in March 2011.
Notes
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This publication has not been formally edited.

ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

3CONTENTS
MODELLING OF EVACUATION SCENARIOS ..................................................................... 5
REFERENCES ........................................................................................................................... 11ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

5MODELLING OF EVACUATION SCENARIOS
1.
The Japanese authorities took extensive measures to reduce radiation exposure. Therewas widespread evacuation at different times following the accident and there were alsorestrictions on food supplies (for an overview of the evacuation see UNSCEAR 2013 Report[UNSCEAR, 2014]). Information on the number of people residing in the evacuated and adjacentareas before the accident and the number of people evacuated is presented in table A-11.1 fromattachment C-12 of the UNSCEAR 2013 Report.
Table A-11.1. Populations of the evacuated areas and some adjacent territories and the numberof evacuees
Population before 11 March 2011 a

Rounded number of evacuees bCity, town orvillage<20 km20–30 km

>30 kmTotal

Evacuated by
15 March 2011Population ofdeliberate
evacuation area

Total cMinamisoma

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 400600

3 000

Futaba

6 900

6 900

6 900

6 900

Okuma

11 50011 50011 50011 500Kawauchi

1 100

2 800

2 800d2 800dTomioka

16 000

16 000

16 000

16 000

Naraha

7 700

7 700

7 700

7 700

Hirono

200

5 400

5 200

5 200

Iitate

1 700

5 200
300

5 900

6 200

6 200

6 200

15 60015 600

1 300

1 300

2 200

340 000

342 200

62 300407 600

548 100

Kawamata
Iwaki
Total

78 2002 700
84 900

10 200117 800aApproximate number based on the 2010 Flash Report of National Census of 2010 [MIC, 2011].
The numbers reported in [MEXT, 2020]; those were adjusted to be consistent with the population data.
cThe number of evacuees may also include evacuees who lived outside of the 30-km radius and people evacuated for other reasons thanradiological protection. (Translation from p. 2 of [MEXT, 2020]). For that reason, the total number of evacuees may be larger than the sum ofpeople evacuated before 15 March 2011 and from the deliberate evacuation area.
dEvacuated 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. (The interim report of the Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo
Electric Power Company.)b

2.
For the UNSCEAR 2013 Report, detailed information about the destinations of thoseevacuated in the precautionary and deliberate evacuations was presented in table 11 ofattachment C-12 [UNSCEAR, 2014]. The dose assessment for the period before and during theevacuation was based on the results from a questionnaire survey issued by the local authorities
to all residents within Fukushima Prefecture (two million people) to ascertain their activities and,specifically, their locations and movements. Approximately 21% of the population completedthe questionnaires. The National Institute for Radiological Science (NIRS) used the results ofthis survey to define 18 scenarios representative of the movements of residents local to FDNPS,
following the accident [Akahane et al., 2013].

6

ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

3.
In a recent study, Ohba et al. further refined the evacuation scenarios by conducting ahierarchical clustering analyses of 100 to 300 randomly sampled behavioural questionnaire
sheets of children from each of the seven municipalities in the evacuation area [Ohba et al.,2020]. This resulted in 37 new representative evacuation scenarios, which have been used forthe assessment of doses to residents of evacuated communities, as outlined in table A-11.2. These37 new evacuation scenarios did not include residents from the evacuated communities of Hirono
Town and Katsurao Village. Thus, the Committee additionally included those three of theoriginal 18 evacuation scenarios representing evacuated residents from Hirono Town andKatsurao Village (resulting in 40 evacuation scenarios in total, see table A-11.2).

Table A-11.2. Evacuation scenarios from Ohba et al. [Ohba et al., 2020] (#01-37) and NIRS survey [Akahane et al., 2013] (#38-40)
Scenario

Location at 11 March 2011

Start > Route > Destination

Destination prefecture

Destination location

Evacuation start timea,bNumber ofevacuees

Futaba Town

Futaba > Kawamata > OOPc

Saitama Ken

Saitama Shi

AM2 on 12 March

5 00902(FT2)

Futaba Town

Futaba > Iwaki > OOP

Ibaraki Ken

Kasama Shi

PM1 on 12 March42103(FT3)

Futaba Town

Futaba > Odaka > Fukushima > OOP

Ibaraki Ken

Yuki Shi

AM2 on 12 March42104(FT4)

Futaba Town

Futaba > Haramachi> Koriyama

Fukushima Ken

Koriyama Shi

PM2 on 12 March42105(FT5)

Futaba Town

Futaba > Namie > Kawamata > OOP

Tochigi Ken

Sano Shi

PM1 on 12 March62806(TM1)

Tomioka Town and Kawauchi Villaged

Kawauchi > OOP

Niigata Ken

Niigata Shi

PM2 on 15 March

3 384

07(TM2)

Tomioka Town

Tomioka > Ono > OOP

Chiba Ken

Chiba Shi

PM1 on 12 March

1 504

08(TM3)

Tomioka Town

Tomioka > Kawauchi > Koriyama > OOP

Chiba Ken

Chiba Shi

AM2 on 12 March

12 97209(TM4)

Tomioka Town

Tomioka > Iwaki

Fukushima Ken

Iwaki Shi

PM1 on 12 March

940

10(NR1)

Naraha Town

Naraha > Iwaki > OOPTochigi Ken

Nasushiobara Shi

AM2 on 12 March862

11(NR2)

Naraha Town

Naraha > Iwaki > OOP

Chiba Ken

Chiba Shi

AM2 on 12 March

2 672

12(NR3)

Naraha Town

Naraha > Iwaki

Fukushima Ken

Iwaki Shi

AM2 on 12 March

470

13(NR4)

Naraha Town

Naraha > Hirono > Aizu> OOP

Tochigi Ken

Mooka Shi

AM2 on 12 March

3 457

14(NR5)

Naraha Town

Naraha > Iwaki > OOP > Iwaki

Fukushima Ken

Iwaki

AM2 on 12 March

239

15(OK1)

Okuma Town

Okuma > Tamura > Aizu

Fukushima Ken

Aizuwakamatsu Shi

PM1 on 12 March

4 205

16(OK2)

Okuma Town

Okuma > Tamura

Fukushima Ken

Tamura Shi

AM2 on 12 March

5 80017(OK3)

Okuma Town and Futaba Townd

Futaba > Kawamata > Iwaki > OOPTokyo Metropolitan

Shinjuku Ku

AM2 on 12 March

1 015

18(OK4)

Okuma Town and Tamura Cityd

TamuraFukushima Ken

Tamura Shi(no further evacuation)

2 755

19(OK5)

Okuma Town

Okuma Town > Odaka > Haramachi >Sukagawa > OOP

Tochigi Ken

Nasushiobara Shi

AM1 on 12 March

725

20(NM1)

Namie Town

Namie > Haramachi > OOPTokyo Metropolitan

Shinjuku Ku

AM2 on 12 March3 344

21(NM2)

Namie Town

Namie > Soma

Fukushima Ken

Soma Shi

PM1 on 12 March

1 254

22(NM3)

Namie Town

Namie > Tsushima > Koriyama

Fukushima Ken

Koriyama Shi

AM2 on 12 March

11 49523(NM4)

Namie and Tsushimad

Tsushima > Nihonmatsu

Fukushima Ken

Nihonmatsu Shi

AM2 on 16 March

1 463

ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

01(FT1)

7Location at 11 March 2011

Start > Route > Destination

Destination prefecture

Destination location

Evacuation start timea,bNumber ofevacuees

Namie TownNamie > Kawamata > OOP

Yamagata Ken

Yonezawa Shi

AM2 on 13 March

3 34425(IT1)

Iitate Village

Iitate > Koriyama

Fukushima Ken

Koriyama Shi

AM2 on 16 March

1 86026(IT2)

Iitate Village

Iitate > Kawamata > Fukushima > Aizu

Fukushima Ken

Kitashiobara Mura

AM2 on 15 March

1 48827(IT3)

Iitate Village

Iitate > OOP

Saitama Ken

Saitama Shi

AM2 on 19 March

1 55028(IT4)

Iitate Village

IitateFukushima Ken

Iitate Mura

22 June1 30229(OD1)

Odaka ward of Minamisoma City

Odaka > Haramachi > Iwaki > OOPTokyo Metropolitan

Shinjuku Ku

PM2 on 12 March

1 00830(OD2)

Odaka ward of Minamisoma City

Odaka > Kawamata > Aizu > OOP

Yamagata Ken

Tsuruoka Shi

PM1 on 12 March

1 53631(OD3)Haramachi ward of Minamisoma City

Haramachi > Date > Haramachi > OOP

Kanagawa Ken

Yokohama Shi

AM2 on 12 March

1 00832(OD4)

Odaka ward of Minamisoma City

Odaka > Haramachi > Fukushima >OOPTokyo Metropolitan

Shinjuku Ku

PM2 on 12 March

11 44033(OD5)

Odaka ward of Minamisoma City

Odaka > Haramachi > Soma > OOP

Saitama KenSaitama Shi

PM1 on 12 March

1 00834(HK1)Haramachi ward of Minamisoma City

Haramachi > Fukushima > OOP

Kanagawa Ken

Yokohama Shi

PM1 on 17 March

12 88035(HK2)

Iitate Village

Iitate > Koriyama > OOP

Yamagata Ken

Yamagata Shi

AM1 on 12 March

1 088

36(HK3)

Kashima ward of Minamisoma City

Kashima > Haramachi > Iitate > OOP

Kanagawa Ken

Yokohama Shi

AM2 on 12 March608

37(HK4)

Haramachi ward of Minamisoma City

Haramachi > Soma

Fukushima Ken

Soma Shi

PM1 on 18 March

1 42438(10 in UNSCEAR
2013 Report)

Hirono Town

Ono Town Office

Fukushima Ken

Ono Shi

12 March

5 20039(12 in UNSCEAR
2013 Report)

Katsurao Village

Azuma Gymnasium

Fukushima Ken

Fukushima Shi

14 March

800

40(14 in UNSCEAR
2013 Report)

Katsurao Village Office

Azuma General Gymnasium

Fukushima Ken

Fukushima Shi

21 March800

a AM1, AM2, PM1, PM2 refer to early morning, late morning, early afternoon and late afternoon, respectively.
b The focus of Ohba et al. [Ohba et al., 2020] was on evacuation before 26 March 2011. The timings of later evacuations (in particular, of the municipalities of Iitate Village and parts of Tamura City inMay and June 2011) are as set out in the UNSCEAR 2013 Report [UNSCEAR, 2014].
c OOP denotes out of prefecture and indicates that the destination was a prefecture other than Fukushima Prefecture.
d In these scenarios, people were evacuated from the first named location to the second named location on the day of the earthquake (11 March 2011).

ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

24(NM5)

8Scenario

ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

4.

9Within these 40 evacuation scenarios, four types of human activities were considered:(a) Normal living conditions;(b) Residents preparing for evacuation;(c) Evacuation; and(d) Sheltering.

5.
For the normal living conditions, the assumptions on human behaviour were the same as
those used in the external and inhalation exposure calculations for the non-evacuated areas. For
the evacuation preparation, evacuation and sheltering activities, the Committee assumed
occupancy factors, dose reduction factors (see table A-11.3) and breathing rates that reflected
the nature of activities undertaken (distinct from those considered for normal living conditions).
The dose reduction factor for “normal living” is lower than the dose reduction factor for“sheltering” since it is assumed that people stay indoors in wooden houses (with a shielding
factor of 0.4) during sheltering 100% of the time, while for “normal living” it is assumed thatthey stay:(a) Indoors in wooden houses for 60% of the time (for adults; for children 70% is assumed);(b) In concrete buildings (with a shielding factor of 0.1) for 30% of the time (for adults) and20% (for children) is assumed; and(c) Outdoors for the remaining 10% of the time (without shielding, i.e., a shielding factor of 1.0).
Table A-11.3. Dose reduction factors for different exposure pathways and types of activities
related to the modelling of evacuation scenarios
Infant 1 year/Child 10 years

Indoor worker

Type of activity
Groundshine

Cloudshine

Inhalation

Groundshine

Cloudshine

Inhalation

Normal living

0.37

0.37

0.55

0.34

0.34

0.55

Sheltering

0.4

0.4

0.5

0.4

0.4

0.5

Evacuation (also Evacuationpreparation)

0.675

0.675

1.0

0.675

0.675

1.0

6.
The assessments of public exposure for the 40 evacuation scenarios used the deposition
density and air concentration results from atmospheric transport, dispersion and deposition
model simulations of Terada et al. [Terada et al., 2020]. Otherwise, the same input parametersand methods as for the assessment for external exposure and dose from inhalation for the nonevacuated areas were applied (see attachments A-1 and A-10).

ANNEX B, ATTACHMENT A-11: EVACUATION SCENARIOS AND NUMBER OF EVACUEES

11REFERENCES
Akahane, K., S. Yonai, S. Fukuda et al. NIRS external dose estimation system for Fukushimaresidents after the Fukushima Dai-ichi NPP accident. Sci Rep 3: 1670 (2013).
MEXT. Current status of evacuees. Ministry of Education, Culture, Sports, Science andTechnology, Japan. [Internet] Available from (ww.mext.go.jp/b_menu/shingi/chousa/kaihatu/016/shiryo/__icsFiles/afieldfile/2011/10/14/1305309_1.pdf) on 30 September 2020.
(Japanese).
MIC. Population census 2010. Ministry of Internal Affairs and Communications. [Internet]Available from (https://www.e-stat.go.jp/en/stat-search/files?page=1&toukei=00200521&bunya_l=02&tstat=000001039448&cycle=0&result_page=1&cycle_facet=cycle ) on
23 March 2020.
Ohba, T., T. Ishikawa, H. Nagai et al. Reconstruction of residents' thyroid equivalent doses frominternal radionuclides after the Fukushima Daiichi nuclear power station accident. Sci
Rep 10(1): 3639 (2020).
Terada, H., H. Nagai, K. Tsuduki et al. Refinement of source term and atmospheric dispersion
simulations of radionuclides during the Fukushima Daiichi Nuclear Power Stationaccident. J Environ Radioact 213: 106104 (2020).
UNSCEAR. Sources, Effects and Risks of Ionizing Radiation. Volume I: Report to the General
Assembly and Scientific Annex A. UNSCEAR 2013 Report. United Nations ScientificCommittee on the Effects of Atomic Radiation. United Nations sales publication
E.14.IX.1. United Nations, New York, 2014.