Dose Statistical Data Based on the Information Registered with the System of Registration and Management of Radiation Exposure Doses for Decontamination and Related Works (2015)
Radiation Dose Registration Center
1. Release of statistical data
The Radiation Dose Registration Center of the Radiation Effects Association （hereinafter referred to as the Radiation Dose Registration Center “RADREC”) assigns and registers an individualized registration number (personal identification number) in RADREC to each worker engaged in decontamination and related works,etc, who works at work areas of primary contractor that join the System of Registration and Management of Radiation Exposure Doses for Decontamination and Related Works (hereinafter referred to as “Decontamination Registration and Management System”), and then performs the systematic regulatory control over radiation exposure doses of the workers. Thereby, even if workers move to different work areas to engage in other decontamination and related works, the system allows RADREC to know each worker’s dose correctly, because the primary contractors who join the Decontamination Registration and Management System have registered workers’ doses at all work sites.

Based on the registered data, RADREC has released the statistical data that represent the radiation control status for workers engaged in radiation work at the work areas of decontamination and related works, etc.

The statistics below are those based on the dose data of the decontamination and related works, etc. conducted during 2015 which were registered into the Decontamination Registration and Management System.

2. Data compilation method
The statistical data based on doses of the workers engaged in decontamination and related works, etc. carried out by the primary contractors that have joined the Decontamination Registration and Management System, are compiled by RADREC.
(1) These statistical data are based on registered data provided by the primary contractors that carried out decontamination works, etc. in the special decontamination area (“decontamination of soil and related works”,　”works for collecting wastes, etc.” and “works for handling designated contaminated soil And wastes”), works under a designated dose rate, and works for disposing nuclear accident-derived wastes both in-side and out-side of the special decontamination area as of 17 May 2016.
(2) The compiled doses are the effective doses which are the total of both external exposure doses and internal exposure doses.
(3) The statistical data for 「Dose distribution by age of workers for decontamination and related works, etc.」,「Dose distribution by gender of workers for decontamination and related works, etc.」, 「Dose distribution by number of engaged projects in a year」 and 「Traditional dose distribution by number of engaged projects in the latest four years」 correspond to the annual dose limit and five-year dose limit specified in the Ionizing Radiation Ordinance for Decontamination. In compiling these radiation exposure doses, the doses before the date of enforcement of the Ionizing Radiation Ordinance of Decontamination(1 January 2012) are handled assuming that these are due to exposure to radiation on January 2012, according to the guidelines for applying the Ionizing Radiation Ordinance of Decontamination
(4) It should be noted that “Dose distribution by areas” were not handled according to the procedure specified in the guidelines above but shown as the actual dose of each year because it is not related to the annual or five–year exposure dose limit control specified in the guidelines above.
* ”Guideline on Prevention of Radiation Hazards for Workers Engaged in Decontamination and Related Works” and “Guideline on Prevention of Radiation Hazards for Workers Engaged in Works under a designated Dose Rate””
【Dose limits for decontamination and related works】
The exposure dose limit for workers is set at 100 millisieverts (mSv) per five years and 50 mSv per one year . The dose limit for female workers (excluding those who are indicated with no possibility of pregnancy, and those who are pregnant) is set at 5 mSv over 3 months. Five years refers to the statutory period that started on 1 January 2012 and will be renewed every subsequent five years.

3．Definition of terminology
(1) Ionization Radiation Ordinance The ordinance on Prevention of Ionizing Radiation Hazards at Works.
(2)
 Ionization Radiation Ordinance for Decontamination The ordinance on Prevention of Ionizing Radiation Hazards at Works to Decontamination Soil and Wastes Contaminated by Radioactive Materials 　　Resulting from the Great East Japan Earthquake and Related Works．
(3) Decontamination workers Workers who are engaged in “decontamination works and related works” and “Works under the designated dose rate” defined in the Ionization Radiation Ordinance for Decontamination and “disposal works of accident-derived Waste, etc.” defined in the Ionizing Radiation Ordinance.
(4) Quarterly exposure Dose Exposure doses (preliminary values) of decontamination workers recorded in RADREC accumulated in each quarterly period of calendar year （1 January to 31 December）.
(5) Annual exposure dose Exposure doses of decontamination workers recorded in RADREC accumulated in calendar year （1 January to 31 December）.
(6) Five years exposure dose Exposure doses accumulated in the statutory five year period to control long-Term dose limit. The first period started on 1 January 2012, with exposure doses accumulating every subsequent five years. Dose data for the present five-year period have been compiling from 2012 to 2016.
(7) Number of engaged projects in a year Number of engaged projects in a year means the number of projects that the workers for decontamination and related works, etc. were engaged in radiation works during the period of statistical data compilation (2015).
Even if a worker was engaged in radiation work at one decontamination project in several times in a year, that counted as only one project.
(8) Number of engaged projects in four years Number of engaged projects in four years means the number of projects that the workers for ntamination and related works, etc. were engaged in radiation works during the period of statistical ta compilation (2012 to 2015).
Even if a worker was engaged in radiation work of one decontamination project in several times in this period, that counted as only one project.
List of statistical data of doses
１．Dose Distribution by Age of Workers for Decontamination and Related Works, etc. ｛2015｝ (Table)
２．Dose Distribution by Age of Workers for Decontamination and Related Works, etc. ｛2015｝ (Figure)
３．Dose Distribution by Gender of Workers for Decontamination and Related Works, etc. ｛2015｝ (Table)
４．Dose Distribution by Number of Engaged Projects in a Year ｛2015｝ (Table)
５．Dose Distribution by Number of Engaged Projects in a Year ｛2015｝ (Figure)
６．Traditional Dose Distribution by Number of Engaged Projects in the Latest Four Years｛2012-2015｝ (Table)
７．Dose Distribution by Areas ｛2015｝ (Table)
８．Dose Distribution by Areas ｛2015｝ (Figure)

HOME　除染登録管理制度　登録管理制度目次