March 2016

Five years of change of the perimeter of the evacuated zones
following the Fukushima accident
During and after the accident at the Fukushima nuclear power plant, Japanese
local and national authorities implemented measures to protect the population.
Three types of measure were taken:
 Shelter and evacuation (to minimise external exposure); Administration of iodine (to minimise the effect due to the inhalation ofradioactive iodine isotopes); Restrictions on contaminated foods to limit internal exposure.
This document only concerns the first of these (shelter and, more specifically,evacuation) measures, which were - and still are for evacuation - applied togeographically defined zones. These zones changed first according to reactor
status and, then, according to the results of measurements and predictions ofradioactive doses to the population. This document provides a summary of how
and why these zones have changed over time between March 2011 to thepresent day.
Three phases can be observed in how the different zoning systems were set up:


The first phase covers the period from March to December 2011 when emergency
protection measures were implemented. It lasted until the end of 2011 when the Japanese
government and TEPCO announced that the conditions for cold shutdown of reactors 1 to 3of the Fukushima plant had been met;
The second phase extends over the period from December 2011 to the end of 2013 andled to the creation of zones based on estimated predicted doses over the year following theaccident. These zones were the basis for a decontamination strategy aimed at securingconditions for the eventual return of evacuees to their homes;
Lastly, the third phase, which began in 2014, during which decontamination operations
were completed and some of the evacuation orders given by the government in spring 2011were first lifted.

1) Zone changes from March 2011 to December 2011
This first phase corresponds to the emergency phase, in other words before the stricken reactors
had reached a stable state. Starting on 11 March, the authorities implemented measures to shelter
and evacuate the population from the areas closest to the Fukushima NPP. These measures weregradually extended as release measurements were carried out over a period of weeks and time wasrequired to complete the characterisation of contamination levels. It was not until the end of 2011,
when the authorities and TEPCO deemed that the reactors on the site had reached a stable state,that definitive evacuation zone boundaries were defined. Table 1 and Figure 1 give an overview of
how zones changed over this period.

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Date

Protective measure

Area concerned

Figure11 March 2011, 20:50 Evacuation order (FukushimaPrefecture)

2 km radius around theFukushima NPP

Figure 1aEvacuation order
11 March 2011, 21:23 Sheltering(Japanese government)

3 km radius
3-10 km radiusFigure 1b

12 March 2011, 05:44 Evacuation order

10 km radiusFigure 1c

12 March 2011, 18:25 Evacuation order

20 km radius(represents the evacuationof some 76,000 people from9 municipalities)

Figure 1d

15 March, 11:00

Sheltering order20-30 km radiusFigure 1e25 March 2011

Voluntary evacuation
recommendation

20-30 km radiusFigure 1f

11 April 2011

The Japanese government
announces that a total predictive
dose of 20 mSv per year as from thedate of the accident will be used todetermine the areas from which thepopulation must be evacuatedbeyond the 20 km limit

22 April 2011

Sheltering order lifted

20-30 km radius

22 April 2011

Definition of a "Deliberate
Evacuation Area" to be evacuatedwithin a monthKatsuaro, Namie, Iitate,part of Kawamata, part of
Minamisoma (totallingabout 10,000 people)

Figure 1g

22 April 2011

Definition of an "Evacuation
Preparation Zone" where it isrecommended for residents toremain sheltered or to evacuate thearea voluntarily and by their ownmeans.

All or part of fivemunicipalities (Hirono,Naraha, Kawauchi, Tamuraand Minamisoma).
Represents a population ofaround 59,000

Figure 1g

22 April 2011

Definition of a "Restricted Area"(strict access control measures set
up in this area)

20 km radiusFigure 1g

30 June 2011

The government defines specific hot
spots outside the above areas,
where the projected dose exceeds
20 mSv.

Figure 1h30 September 2011

The evacuation preparation zone isabandoned (the related
recommendations no longer apply)

Figure 1i

Table 1: Location of areas where sheltering and evacuation orders were issued
between 11 March and 30 September 2011.

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1a - 11 March 201120:50
2

1d - 12 March 201118 :251b - 11 March 2011
21 :232

1c - 12 March 201105 :442

1e - 15 March 2011
11 :00

1f - 25 March 20112

2
21g - 22 April 20112

1h - 30 June 2011

1i - 30 September 2011
2

Figure 1: Time-related changes in the boundaries of sheltering and evacuation zones ordered by the Japanese
1government after the accident at the Fukushima Daiichi nuclear power plant from March to December 2011

1Modified from http://wwwpub.iaea.org/books/IAEABooks/Supplementary_Materials/files/10962/100000/The-Fukushima-Daiichi-Accident.

3/7March 20162) Zone changes from December 2011 to end of 2013
At the end of 2011, the Japanese authorities, drawing on the "Act on special measures concerning
the handling of radioactive pollution", defined new predictive doses (i.e. doses calculated over the
first year after the accident, based on conservative assumptions) to divide the contaminated region
into two large areas (see Figure 2):the Special Decontamination Area (SDA), which groups together all the evacuation areas
defined in September 2011 (the 20 km evacuation area and the deliberate evacuation area).
It is considered that the annual dose in this area could reach or exceed 20 mSv (calculated
as from the date of the first releases). The government is responsible for decontaminatingthese areas;
the Intensive Contamination Survey Area (ICSA), lying beyond the SDA, which includes
municipalities where it is estimated that the annual dose may be between 1 and 20 mSv(dose plus radiological background) over all or some of their territory. The municipalauthorities are responsible for conducting measurement campaigns to identify areas that
require decontamination and then carrying out the decontamination operations, withtechnical and financial support from the national government.

Figure 2: Location of the Special Decontamination Area (SDA) shown in red, and the Intensive Contamination
2
Survey Area (ICSA) set up by the Japanese authorities at the end of 2011.

2

Taken from http://www-pub.iaea.org/books/IAEABooks/Supplementary_Materials/files/10962/100000/TheFukushima-Daiichi-Accident.

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On 26 December 2011 and following the declaration by the Japanese authorities that the situationof the Fukushima NPP had stabilised (in terms of safety), the Japanese government issued adocument entitled Basic Concept and Issues to be challenged for Rearranging the Restricted Areasand Areas to which Evacuation Orders have been issued, in which it defines new criteria for defining
areas within the SDA. Three types of area are defined:

Zone 1 (or green zone) where the estimated dose during the first year is below 20 mSv(based on actual measurements and conservative assumptions). This zone is considered as
an "area in which evacuation orders are ready to be lifted".
Zone 2 (or orange zone) where the predictive dose for the first year is between 20 and50 mSv. This zone is also referred to as an "area in which residents are not permitted tolive".
Zone 3 (or red zone) where the predictive dose for the first year is greater than 50 mSv andreferred to as an "area where it is expected that residents will face difficulties in returning
for a long time".

The Japanese government initially intended to carry out this zoning throughout the SDA between
December 2011 and March 2012 so that decontamination and infrastructure revitalisation andreconstruction work could begin as soon as possible. Owing to a number of factors, however, such as
characterisation of contamination, the need to reach a local consensus on the implementation ofdecontamination operations, and the search for temporary waste storage sites, it was not until
August 2013, about a year and a half later, that the entire SDA was divided up according to thethree types of defined area. During that period, several versions of SDA zoning (see Figures 3A to3E) were issued reflecting the progress of characterisation work and negotiations at the local level.
The beginning of August 2013 saw the first complete version of the SDA breakdown into green,orange and red zones (see Figure 3E).
3A - 01/04/2012

3B - 15/06/2012

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3C - 30/11/2012

3D - 28/05/2013

3E - 08/08/2013

3F - 01/04/2014

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3G - 01/10/2014

3H - Since 05/09/2015

Figure 3: Zone changes In the Special Decontamination Area between April 2012 and September 2015.

3) Zone changes from December 2013 to end of 2015
In July 2011, the Japanese government defined the conditions to be met for lifting evacuation
orders in a document entitled Basic policy for emergency response on decontamination work. The
document defines three conditions:Confirmation that the annual dose will not exceed 20 mSv;
Confirmation that sufficient progress has been made in restoring essential facilities,
especially those frequented by children;
Confirmation that structures are in place to allow dialogue between local and regional
authorities (municipal councils and prefectures) and residents.

These conditions were met in early 2014 following the completion of decontamination work,
allowing the evacuation order to be lifted in three municipalities (or in certain areas within them):

on 1 April 2014 in Tamura;on 1 October 2014 in Kawauchi;
and on 5 September 2015 in Naraha.

As a result, these municipalities are no longer in the green zone as shown in Figures 3F, 3G and 3H.

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