The Special Decontamination Areas and the Intensive Contamination Survey Areas

Hello, everyone. My name is Daichi, an expert providing the information on the radiation issues in an easy-to-understand manner.

Today I would like to respond to the following questions:

– Which organizations have been mainly responsible for implementation of the decontamination activities?
– What is the basic concept for role sharing for implementation of the decontamination activities?
– What are the ‘Special Decontamination Areas’ and the ‘Intensive Contamination Survey Areas’?

In the following part of this article, abbreviations of the areas are as follows:

SDA: Special Decontamination Areas
ICSA: Intensive Contamination Survey Areas
DRZ: Difficult-to-Return Zones
SRRBA: Specific Reconstruction and Revitalization Base Areas

Table of contents of this article

I have been involved with the radiation-relevant issues, like the policy on the decontamination activities and the management of the Interim Storage Facility, after the accident of the Fukushima Daiichi Nuclear Power Plant in 2011.

I received a doctorate in the field of radiation, while working in Fukushima.

The Special Decontamination Areas and the Intensive Contamination Survey Areas

(Reference) Ministry of the Environment, Japan (Access in May 5, 2022)

First of all, let us begin with confirmation of geographical location of the two areas.

In the upper one of the two following maps, the SDA are the areas bounded by an orange line.

There are areas with gray (the DRZ) as well as blue (the SRRBA), but they are both parts of the SDA.

It is found out, that they are located with in the Fukushima Prefecture and in the vicinity of the Fukushima Daiichi Nuclear Power Plant.

On the other hand, the ICSA are the areas other than the SDA and with yellow-green or yellow color.

You can find out that it spreads in the Iwate and the Miyagi Prefectures, in the northern part of Japan, areas in the Fukushima Prefecture, other than the SDA, as well as the Tochigi, Gumma, Ibaraki, Chiba and Saitama Prefectures.

Yellow-green areas indicate the areas, which are still designated as the ICSA, and yellow areas indicate the areas, whose designation was now lifted, although they were once designated as the ICSA.

Basic concept for practitioner of decontamination activities

Then what is the basic concept to categorize the SDA and the ICSA?

First, please bear in your mind that the areas of the SDA was almost consistent with the evacuation areas, when they were first set out (the former Restricted Areas and the Deliberate Evacuation Areas) (only the part of the Naraha Town was designated as the SDA, although it was not the evacuation areas).

In these areas not only the residents but also the administrative authorities were forced to evacuated, due to the accident of the Fukushima Daiichi Nuclear Power Plant.

Therefore, it was hardly possible for the municipalities in the SDA to be in charge of the decontamination activities.

In addition, taking account of social responsibility of the national government, which had promoted nuclear power, the decontamination activities in the SDA have been implemented under the responsibility of the national government (especially the Ministry of the Environment).

On the other hand, in the ICSA, each municipality has been mainly responsible for the decontamination activities, which are well familiar with local circumstances, with financial and technical supports of the national government.

By the way, the Tokyo Electric Power Company, the operator of the Fukushima Daiichi Nuclear Power Plant, had not become a main practitioner of the decontamination activities.

Part of reasons for this seemed to be that the Tokyo Electric Power Company needed to throw human resources for decommissioning of the Fukushima Daiichi Nuclear Power Plant, and that radioactive materials spread into a wide range of areas, from Tohoku to Kanto Region, that made it difficult for a company to address all the decontamination activities.

I would like to touch upon this role sharing, if necessary, because this has been sometimes controversial issue and caused discussion between stakeholders.

In the following parts more detail information on each area is covered.

The Special Decontamination Areas

As aforementioned the SDA are located in the vicinity of the Fukushima Daiichi Nuclear Power Plant, and 11 municipalities (i.e. Okuma Town, Futaba Town, Namie Town, Tomioka Town, Naraha Town, Kawauchi Village, Tamura City, Minamisoma City, Iitate Village and Kawamata Town) had been designated as the SDA for a long time.

Amongst them, the designation of the SDA of Tamura City was lifted　in March 2022, together with the lift of designation of the ICSA of the same city.

Therefore, the number of the municipalities in the SDA is 10, as of August 2023.

In the municipalities in the SDA, the necessary decontamination activities as well as management of waste arising from the activities, have been implemented by the national government (mainly by the Ministry of the Environment), even after lift of evacuation orders.

Please visit this article for detail of decontamination procedures.

Full-scale decontamination activities were completed by the end of March 2017, other than the DRZ, and currently necessary monitoring and follow-up decontamination activities are being carried out.

In addition, simultaneously, in the DRZ, the SRRBA are under construction, and all evacuation orders of the SRRBA have been lifted by May 2023.

The SRRBA will be covered in another article.

So, policy for the areas other than the SRRBA in the SDA, still remains as issue to be addressed.

The Intensive Contamination Survey Areas

The ICSA is located in the distance from the Fukushima Daiichi Nuclear Power Plant, compared with the SDA and it spreads from Iwate Prefecture in Tohoku Area, to Saitama and Chiba Prefecture in Kanto Area.

Basically each municipality is designated as the ICSA for its whole municipality, but regarding Tamura City, Kawamata Town, Kawauchi Village and Minamisoma City, they all consist of both the SDA and the ICSA (Designation of Tamura City was lifted in March 2022).

Based on the Act on Special Measures concerning the Handling of Environment Pollution by Radioactive Materials Discharged by the NPS Accident Associated with the Tohoku District – Off the Pacific Ocean Earthquake That Occurred on March 11, 2011 (herein after referred to as ‘the Act on Special Measures‘(in Japanese)), the ICSA is subject to be designated for the areas with more than 0.23 μSv/h of air dose rate, where further intensive survey is necessary, also taking account of opinions of relevant municipalities and prefectural governments.

The number: 0.23μSv/h will be elaborated in another article.

Full-scale decontamination activities in the ICSA had been completed by the end of March 2018, and currently necessary monitoring and follow-up decontamination activities are being carried out, as done in the SDA.

By the way, the number of the municipalities designated as the ICSA was 102, when the Act on Special Measures was completely taken into effect on January 1, 2012, which authorizes the SDA and the ICSA, and after that increased up to 104 at maximum.

However, in the wake of decrease of air dose rate, due to progress of decontamination activities, as well as passage of time, the designation as the ICSA has been gradually lifted and the number of the municipalities has decreased to 69, as of the end of March 2023 (Ref: Decontamination Information Site (Ministry of the Environment, Japan)) (in Japanese).

Summary

This article covers the SDA and the ICSA, especially focusing on the basic concept for role sharing, as well as summary of each area and their current situation.

By the way, abovementioned contents are summarized in the following videos.

It would be appreciated to visit them at your convenience.

– Japanese version

– English version

You can read the same article in Japanese here.

Thank you very much for reading this article.

See you next time!