Assessment of residual doses to population after decontamination in Fukushima Prefecture

Mori, Airi; Takahara, Shiro; Ishizaki, Azusa; Iijima, Masashi; Sanada, Yukihisa; Munakata, Masahiro

doi:10.1016/j.jenvrad.2016.06.023

Cited by 14 publications

(13 citation statements)

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“…In particular, for spatial variability, although the GSDs used in our assessments were in the range of 1.53–1.76, these values were obtained from limited measurements in residential areas in Fukushima City. As described in a previous study, the GSDs for contamination level in Fukushima Prefecture have larger variability than those used in this study. For example, the differences in contamination levels were caused by differences in the type of land use and the location of a given municipality.…”

Section: Resultsmentioning

confidence: 86%

A Probabilistic Approach to Assess External Doses to the Public Considering Spatial Variability of Radioactive Contamination and Interpopulation Differences in Behavior Pattern

et al. 2017

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Dose assessment is an important issue from the viewpoints of protecting people from radiation exposure and managing postaccident situations adequately. However, the radiation doses received by people cannot be determined with complete accuracy because of the uncertainties and the variability associated with any process of defining individual characteristics and in the dose assessment process itself. In this study, a dose assessment model was developed based on measurements and surveys of individual doses and relevant contributors (i.e., ambient dose rates and behavior patterns) in Fukushima City for four population groups: Fukushima City Office staff, Senior Citizens' Club, Contractors' Association, and Agricultural Cooperative. In addition, probabilistic assessments were performed for these population groups by considering the spatial variability of contamination and interpopulation differences resulting from behavior patterns. As a result of comparison with the actual measurements, the assessment results for participants from the Fukushima City Office agreed with the measured values, thereby validating the model and the approach. Although the assessment results obtained for the Senior Citizens' Club and the Agricultural Cooperative differ partly from the measured values, by addressing further considerations in terms of dose reduction effects due to decontamination and the impact of additional exposure sources in agricultural fields, these results can be improved. By contrast, the measurements obtained for the participants from the Contractors' Association were not reproduced well in the present study. To assess the doses to this group, further investigations of association members' work activities and the related dose reduction effects are needed.

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Section: Resultsmentioning

confidence: 86%

A Probabilistic Approach to Assess External Doses to the Public Considering Spatial Variability of Radioactive Contamination and Interpopulation Differences in Behavior Pattern

et al. 2017

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“…However, the results indicate that the same behavioural patterns and contamination levels should not be assumed for all inhabitants nor all municipalities. Based on the different behaviour of the local population, the 95th percentile doses of indoor workers and pensioners in 53 of the 59 municipalities were below the dosimetric target of 1 mSv yr −1 (0.026-0.73 mSv yr −1 ) (Mori et al, 2017). Radiation dose rates were also measured among different types of workers taking part in professional activities in the village of Kawauchi, where the annual doses of foresters (range: 0.7-1.9 mSv yr −1 ) were not significantly higher than those of farmers (0.7-1.5), builders (0.6-1.5), office workers (0.5-1.5) and unemployed individuals (0.5-1.7).…”

Section: Impact Of Decontamination On Dosimetrymentioning

confidence: 99%

“…The central government of Japan is responsible for remediation works in the SDZ. Second, Intensive Contamination Survey Areas (ICAs) refer to 102 municipalities from 8 prefectures with ambient dose rates exceeding 0.23 µSv h −1 (equivalent to 2 mSv yr −1 ), designated as ICAs by the Ministry of Environment on 28 December 2011 (Mori et al, 2017). The area of the ICAs is 8 times greater than the SDZ (Yasutaka and Naito, 2016).…”

Section: Areas Targeted By Decontaminationmentioning

confidence: 99%

“…a shielding factor of 0.4) per day and that the contribution of natural radiation is 0.04 mSv h −1 (IAEA, 2013b). According to Mori et al (2017), this model has three main challenges. First, the same behavioural pattern is assumed for the entire population.…”

Section: Impact Of Decontamination On Dosimetrymentioning

confidence: 99%

“…houses, workplaces and other environments) in the contamination and for inter-populational variations (i.e. indoor workers, outdoor workers, pensioners) in behavioural patterns was developed by Mori et al (2017). For this approach, the 95th percentile doses for outdoor workers were above 1 mSv yr −1 in 25 of the 59 municipalities in Fukushima Prefecture (1-35 mSv yr −1 ).…”

Section: Impact Of Decontamination On Dosimetrymentioning

confidence: 99%

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Effectiveness of landscape decontamination following the Fukushima nuclear accident: a review

Evrard

Laceby

Nakao

2019

SOIL

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The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 resulted in the contamination of Japanese landscapes with radioactive fallout. Accordingly, the Japanese authorities decided to conduct extensive remediation activities in the impacted region to allow for the relatively rapid return of the local population. The objective of this review is to provide an overview of the decontamination strategies and their potential effectiveness in Japan, focussing on particle-bound radiocesium. In the Fukushima Prefecture, the decision was taken to decontaminate the fallout-impacted landscapes in November 2011 for the 11 municipalities evacuated after the accident (Special Decontamination Zone -SDZ -1117 km 2 ) and for the 40 non-evacuated municipalities affected by lower, although still significant, levels of radioactivity (Intensive Contamination Survey Areas, 7836 km 2 ). Decontamination activities predominantly targeted agricultural landscapes and residential areas. No decontamination activities are currently planned for the majority of forested areas, which cover ∼ 75 % of the main fallout-impacted region. Research investigating the effectiveness of decontamination activities underlined the need to undertake concerted actions at the catchment scale to avoid renewed contamination from the catchment headwaters after the completion of remediation activities. Although the impact of decontamination on the radioactive dose rates for the local population remains a subject of debate in the literature and in the local communities, outdoor workers in the SDZ represent a group of the local population that may exceed the long-term dosimetric target of 1 mSv yr −1 . Decontamination activities generated ∼ 20 million m 3 of soil waste by early 2019. The volume of waste generated by decontamination may be decreased through incineration of combustible material and recycling of the less contaminated soil for civil engineering structures. However, most of this material will have to be stored for ∼ 30 years at interim facilities opened in 2017 in the vicinity of the FDNPP before being potentially transported to final disposal sites outside of the Fukushima Prefecture. Further research is required to investigate the perennial contribution of radiocesium from forest sources. In addition, the re-cultivation of farmland after decontamination raises additional questions associated with the fertility of remediated soils and the potential transfer of residual radiocesium to the plants. Overall, we believe it is important to synthesise the remediation lessons learnt following the FDNPP nuclear accident, which could be fundamental if a similar catastrophe occurs somewhere on Earth in the future.

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2019

Industrial and Medical Nuclear Accidents

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Assessment of residual doses to population after decontamination in Fukushima Prefecture

Cited by 14 publications

References 10 publications

A Probabilistic Approach to Assess External Doses to the Public Considering Spatial Variability of Radioactive Contamination and Interpopulation Differences in Behavior Pattern

A Probabilistic Approach to Assess External Doses to the Public Considering Spatial Variability of Radioactive Contamination and Interpopulation Differences in Behavior Pattern

Effectiveness of landscape decontamination following the Fukushima nuclear accident: a review

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