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Lessons learned from the eurados survey on individual monitoring data and internal dose assessments of foreigners exposed in Japan following the Fukushima Daiichi NPP accident
Abstract
European Radiation Dosimetry Group e.V. (EURADOS) survey on individual monitoring data and dose assessment has been carried
out for 550 foreigners returning home after being exposed in Japan to intakes of radionuclides (mainly 131I, 132I, 132Te, 134Cs and 137Cs) as a consequence of the Fukushima Daiichi NPP accident. In vivo and in vitro measurements were performed in their respective countries at an early stage after that accident. Intakes of radionuclides
were detected in 208 persons from Europe and Canada, but the committed effective dose E(50) was below the annual dose limit for the public (<1 mSv) in all the cases. Lessons learned from this EURADOS survey are
presented here regarding not only internal dosimetry issues, but also the management of the emergency situation, the perception
of the risk of health effects due to radiation and the communication with exposed persons who showed anxiety and lack of trust
in monitoring data and dose assessments.
... The HPGe detector-based system has shown as an excellent option for discriminating all the gamma emissions in the spectrum when all the expected radionuclides (radiotellurium, radioiodine, radiocesium) were present in the contaminated person being monitored. [17] In vivo measurement of 40 K ...
... The adipose contents of the individual can be measured by some techniques like bioelectrical impendence instrument. [17] A study can be conducted to measure total body potassium and adipose contents in of persons. The correlation between lean body mass and total body potassium content in the person can give valuable information on the health condition of the Indian. ...
... Studies and projects of individual exposure dose assessments carried out after the FDNSP and Chernobyl Nuclear Power Station (CNPS) accidents have been reviewed at different viewpoints. Lopez et al. surveyed individual monitoring data and dose assessment for foreigners exposed in Japan and summarized issues of dosimetry and dose assessments [7]. Methodological findings and approaches of retrospective dosimetry after the CNPS accident were reviewed, and applicability to the case in Fukushima was proposed [8]. ...
After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, individual exposure doses to residents have been assessed by many municipalities, governments and research institutes. Various methods including measurements with personal dosimeters and simulations have been used for this evaluation depending on purposes, but the information of assessments and methods has not been systematically organized. A comprehensive review of the knowledge and experiences of individual exposure doses assessments accumulated so far and understanding the characteristics of the assessment methods will be very useful for radiation protection and risk communication, following to governmental policy planning. We reviewed the efforts made by the Japanese government and research institutes to assess radiation doses to residents after the FDNPS accident in Part 1. On the other hand, each method of assessing individual exposure doses includes uncertainties and points to be considered for the appropriate assessment. These knowledge and experiences are important for the assessment implementation and applying the assessment results to the governmental policy planning, and are summarized in Part 2 of this article.
... Thyroid monitoring data from Europeans contaminated in Japan shortly after the releases of the Fukushima Daiichi NPP (low doses, Lopez et al., 2016;Champion et al., 2013) were used to complement the sensitivity study, considering 16 exposure scenarios leading to 16 different dose estimates of low level doses. This approach was used in case of a Czech volunteer in Ibaraki and Sendai locations in 20-28 March 2011, travelling to Tokyo on 28 March and finally to Prague where the in vivo monitoring took place on 6 April 2011 with a result of 52.0 ± 9.0 Bq (2s) of 131 I in the thyroid. ...
The aim of CONFIDENCE WP2 is to improve the situation awareness in the early phase of a nuclear accident by trying to reduce the uncertainty in individual dose assessment when dealing with external and internal exposures. Main WP2 research actions to improve external dosimetry in this emergency frame were the development of destruction-free protocols using electronic components in smartphones for external dose measurements, Monte Carlo (MCNP) calculations for organ dose assessment with associated uncertainties and the organization of a workshop for integration of biodosimetry into emergency response. On the other hand, one of the main concerns after the release of radioactive material in case of a nuclear reactor accident is the intake of radioiodines in workers and population. A smartphone/tablet application for direct calculation of thyroid doses from monitoring data of the content of ¹³¹ I (and ¹³² I) in the thyroid was developed during the project (Prototype of processing unit for thyroid dose monitor [IDOSE]). Up to date age-dependent ICRP dose per content values are used by this tool, allowing a rapid screening of exposed persons. A sensitivity analysis on thyroid doses was carried out, considering 16 exposure scenarios leading to 16 different dose estimates, using ICRP56/119 (ICRP60) vs. ICRP130/137 iodine models for adults, varying the time of intake, the time pattern (acute vs. chronic) and considering not well defined relative abundance of short-lived radioiodines and ¹³² Te. Real cases of Europeans contaminated in Japan shortly after the Fukushima NPP accident (low doses), and artificial cases of high doses generated to see the impact of the different parameters in this study, were used for applying this multi-intake scenario approach. Main conclusions of the study are presented here.
... In practice, all of the radionuclides released in a nuclear accident cannot be detected by in vivo measurements: some are released in relatively small amount and others are short-lived. The Fukushima Daiichi and Chernobyl experience have shown that in most cases only 134,137 Cs and 131 I are measured (Kurihara et al., 2014;Stepanenko et al., 1996) even if other radionuclides such as 132 I, 133 I, 132 Te have been detected in early measurements (Balonov et al., 2003;Lopez et al., 2016). ...
... Lessons learned (Lopez et al., 2016) since the Fukushima Daiichi NPP accident suggest that procedures of in vivo measurement of internal contamination in exposed population can be improved, particularly in children. The Whole Body Counter (WBC) of the Center for Energy, Environmental and Technological Research (CIEMAT) in Madrid, Spain, has implemented techniques to determine the activity of radioiodine in the thyroid and gamma emitters throughout the total body in exposed population, by calibrating detector systems for different age groups of children (1, 5, 10, 15 years old) and adults (male and female). ...
Nuclear and radiological accidents can result in internal exposures of workers (including first responders) and general population. For this reason it is necessary precise and rapid methods are developed in order to ensure capabilities for monitoring and dose assessments of internally contaminated persons. The Whole Body Counter (WBC) of the Center for Energy, Environmental and Technological Research (CIEMAT) in Madrid, Spain, has implemented techniques to determine radioiodine in the thyroid and gamma emitters throughout the body of various age groups of children and adults. In addition, the WBC laboratory has developed a new in vivo calibration and measurement method with germanium detectors in case of contamination of gamma emitting radionuclides in wounds at different depths.
Two detection systems have been calibrated accordingly: a Fastscan counter, consisting of two NaI(Tl) detectors, and a low-energy germanium (LEGe) detection system (four detectors), which is highly efficient at low gamma energies.
A family of Lucite thyroid neck phantoms for children and adults was designed and manufactured at CIEMAT for thyroid calibration purposes. A set of whole-body phantoms of the BOMAB type was fabricated with polyethylene, and filled with distilled water in an acid medium and with a known gamma emitter mixture for in vivo monitoring calibration. In addition simulators of contaminated wounds with circular pieces of Ethyl Vinyl Acetate (EVA) were provided by Institut de Radioprotection et de Sûreté Nucléaire (IRSN) from France.
Efficiency curves depending on energy are obtained in the different counting geometries, which facilitate calculating the activities of the gamma emitting radionuclides retained in the organism when monitoring real contaminated persons. In case of intake of radionuclides retained in the thyroid or in the whole body, a curve is obtained for each age specific phantom. Moreover in case of contamination in wounds a set of efficiency curves was developed depending on the contamination depth.
The detection limits (DL) of the in vivo measurement techniques for radionuclides have been calculated from the measurements of blank phantoms or persons according to ISO 28218 standard obtaining results for each method and age. Using the limits of detection for the estimation of the minimum committed effective dose, the values obtained were lower than 1 mSv.y⁻¹, which is below the limit for the public recommended by ICRP.
... In the Fukushima nuclear accident, although the number of such measurements was only about 1300 (Kim et al., 2016), direct whole-body measurements of Fukushima residents for 134 Cs and 137 Cs have been extensively performed: about 300,000 measurements as of September 2016 (Kurihara et al., 2018). On the other hand, European citizens staying in Japan at the time of the accident were examined for internal contamination after they returned to their home countries (Lopez et al., 2016). Assuming such a situation, inter-laboratory comparison exercises related to individual monitoring would be help assure the accuracy of measurements made by different institutes. ...
The Asian Radiation Dosimetry Group (ARADOS) was established in 2015 with the aim of promoting collaborations among Asian countries on relevant activities in the field of radiation dosimetry. Since then, annual meetings have been organized by the Republic of Korea, China and Japan in order to share information on the researches done in each country. In past annual meetings, members have discussed the missions and structure of ARADOS, and several collaborative projects were also launched by working groups of ARADOS. This paper introduces an outline of ARADOS and discuss its recent activities.
... In practice, all of the radionuclides released in a nuclear accident cannot be detected by in vivo measurements: some are released in relatively small amount and others are short-lived. The Fukushima Daiichi and Chernobyl experience have shown that in most cases only 134,137 Cs and 131 I are measured (Kurihara et al. 2014;Stepanenko et al., 1996) even if other radionuclides such as 132 I, 133 I, 132 Te have been detected in early measurements (Balonov et al., 2003;Lopez et al., 2016). ...
Following a severe nuclear reactor accident large amounts of radioactive iodine are released in the atmosphere. Health consequences estimation for the affected population is based on the dose assessment which can be derived from in vivo measurements. Since the uptake of radioactive iodine increases the thyroid cancer risk of children it is of particular interest to dispose of technical recommendations on thyroid monitoring, particularly for children. This paper summarizes recommendations that have been issued by a group of European radiation protection specialists during the CAThyMARA project. It covers technical aspects such as the choice of instruments, the calibration process, the measurement preparedness, the dose assessment and communication issues. This paper also discusses remaining gaps and serves as an introduction to other papers of this special issue.
... Activity measurements of 131 I in the thyroid should be performed soon. Intakes of short-lived radionuclides such as 132 Te/ 132 I or 133 I also occur at an early phase and can be missed if individual monitoring is not performed soon after the accident ( Lopez et al., 2016). Radiocaesium intakes (in- corporation mainly to 134 Cs and 137 Cs) are easily detected in total body by gamma spectrometry (using whole-body counters) and doses can be well determined at any time of this early phase due to their longer half- life. ...
The main aim of internal dosimetry in the frame of operational radiation protection is the evaluation of committed doses to verify the compliance of internal exposures with regulatory dose limits. To better understand the biological effects of internal exposures (cancer and non-cancer diseases), epidemiological studies can be conducted for estimating radiation-induced risks associated with intakes of radionuclides. In case of high levels of exposure when radiological events occur and for risk assessment, appropriate calculations of absorbed doses in Grays (Gy) to organs and tissues of exposed persons are required, but no reference methodology is currently available for internal dose assessments using data collected for epidemiology studies. Epidemiological studies and radiological emergency response in case of exposure to internal emitters may require different approaches, tools and methods for dose assessment comparing with operational internal dosimetry. This publication presents an overview of specific procedures associated with internal dosimetry for emergency response and epidemiology studies.
... Task Group 7.3 is dealing with the development of a biokinetic model of DTPA therapy including collaborators from France, Germany, and the USA. Another topic of common interest is internal dosimetry in emergency scenarios (Task Group 7.4) (Lopez et al., 2016). Members of Working Group 7 have been involved in research projects such as CAThyMARA 'Child and Adult Thyroid Monitoring After Reactor Accident' (EC FP7, 2016-2017 and CONFIDENCE, which is a collaboration of the four European platforms on radiological protection -NERIS, EURADOS, MELODI, and ALLIANCE -in the frame of the CONCERT action (EC H2020, 2017-2019). ...
Since the early 1980s, the European Radiation Dosimetry Group (EURADOS) has been maintaining a network of institutions interested in the dosimetry of ionising radiation. As of 2017, this network includes more than 70 institutions (research centres, dosimetry services, university institutes, etc.), and the EURADOS database lists more than 500 scientists who contribute to the EURADOS mission, which is to promote research and technical development in dosimetry and its implementation into practice, and to contribute to harmonisation of dosimetry in Europe and its conformance with international practices. The EURADOS working programme is organised into eight working groups dealing with environmental, computational, internal, and retrospective dosimetry; dosimetry in medical imaging; dosimetry in radiotherapy; dosimetry in high-energy radiation fields; and harmonisation of individual monitoring. Results are published as freely available EURADOS reports and in the peer-reviewed scientific literature. Moreover, EURADOS organises winter schools and training courses on various aspects relevant for radiation dosimetry, and formulates the strategic research needs in dosimetry important for Europe. This paper gives an overview on the most important EURADOS activities. More details can be found at www.eurados.org.
... In vivo counting facilities have developed calibration and measurement procedures for monitoring workers but a gap was identified after Fukushima NPP accident regarding available calibration protocols for children (2) . The use of different phantoms simulating neck and thyroid of members of different groups of age are crucial for a proper calibration and accurate determination of the 131 I activity in thyroid, in order to estimate reliable internal doses. ...
Iodine-131 is one of the main concerns from the point of view of radiological protection in a short term after a nuclear accident. The WBC Laboratory of CIEMAT has developed a methodology for in vivo monitoring of radioiodine in the thyroid of exposed individuals in case of emergency. Thyroid-neck phantoms of different sizes are required for calibrating the detection systems in appropriate counting geometries for the measurement of exposed population. A Low-Energy Germanium (LEGe) detector and a Fastscan Counter were calibrated using a set of thyroid phantoms fabricated by CIEMAT. Each neck phantom consists of a Lucite cylinder with a vial source of 131I. Counting efficiencies depending on age and thyroid sizes were obtained to be used to determine the activity of 131I in internally contaminated people. DL of 131I varies with the age, being in the range of 5-8 Bq for the LEGe detector and 26-42 Bq for the Fastscan. Detection of intakes resulting in Committed Effective doses far below 1 mSv are guaranteed for thyroid monitoring in a few days after the accidental exposure assuming a scenario of acute inhalation or ingestion of 131I by members of the public.
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