© W. Thu Zar et al. Published by EDP Sciences 2025

1 Introduction

Futaba Town, the last municipality in Fukushima Prefecture to lift its evacuation order after the 2011 nuclear accident, has faced unique challenges including prolonged inaccessibility, delayed reconstruction, and persistent social and psychological barriers in its recovery process that left a deep impression on its residents’ sense of belonging, trust in authorities and future outlook. While particular attention was paid by previous research to residents’ risk perceptions and health concerns (Canet et al., 2024; Ando et al., 2024; Ito et al., 2023; Ito & Goto, 2024), this study focuses on an underexplored dimension: residents’ and evacuees’ radiation knowledge-seeking behavior, particularly regarding radiation induced health effects. By integrating qualitative and quantitative analyses, the research aims to identify factors that motivate the desire for radiation knowledge and to provide actionable information to experts and authorities to support Futaba’s recovery.

This article is part of the reflection conducted since 2020 on the role of the co-expertise approach recommended by the International Commission on Radiological Protection (ICRP) in terms of radiation risk communication after a nuclear accident. A first article (Thu Zar et al., 2022) had highlighted that, given the complexity of post-accident situations, technically oriented radiation risk communication was not sufficient on its own to restore trust between experts and the people concerned and to develop, among the latter, a practical culture of radiation protection relying on dialogue with experts and radiation measurements. A second article (Thu Zar, 2023) focused on analyzing the willingness among residents of the city of Tomioka, another municipality in Fukushima Prefecture whose residents have been evacuated during a long time, to engage in dialogue with experts and to perform radiation measurements. This article shed light on who are the residents motivated to engage in the co-expertise process after the nuclear accident. It showed that the desire to engage in dialogue with experts on radiation exposure and health effects was mainly found among people over 60 years old who were reluctant to eat food produced in the city and drink tap water, and who had already experience with radiation measurements.

Building on previous research conducted by Nagasaki University, which focused on the perception of risks related to radiation health effects and in particular on genetic concerns (Orita et al., 2015; Takamura et al., 2018; Xiao et al., 2024), this study explores how the type of information sources and the preferences on the forms of communication with experts influence knowledge-seeking behavior in relation to health issues. This exploration aims to refine the risk communication approaches of the authorities in the context of post-disaster recovery. Finally, the study aims to consolidate previous findings regarding residents’ motivations to engage with experts and perform radiation measurements, i.e., to implement the co-expertise process.

2 The Futaba context

Futaba Town is located in the central part of the Hamadori region, between Namie Town to the north and Okuma Town to the south (see Fig. 1). The total area is about 50 km². Although the city is primarily agricultural, its industrial structure experienced significant changes with the construction of the Fukushima Daiichi Nuclear Power Plant (FDNPP) in the late 1960s, which increased employment and favored significant growth in the city.

On March 11, 2011, in the early afternoon, the town of Futaba was severely damaged by the Great East Japan Earthquake and Tsunami. The disaster caused widespread destruction, including homes but also businesses. It also seriously damaged the Fukushima Daichi Nuclear Power Plant (FDNPP), operated by the Tokyo Electric Power Company (TEPCO), located just a few kilometers from the town center. In response to escalating risks at the plant, the Japanese government declared a state of nuclear emergency that evening, initially ordering evacuations within a 2-km radius, then extending it to 10 km the following morning. Eventually, as reactor cores melted, containment breaches occurred, leading to significant radioactive releases into the air and the sea.

Due to its proximity to the FDNPP, Futaba Town was significantly affected by the radioactive releases. While ambient dose rates recorded in various locations within the town in September 2011 ranged from 1.8 μSv/h to 29.05 μSv/h, earlier data from March 2011 shortly after the accident show that in some areas, dose rates temporarily reached around 1000 μSv/h (1 mSv/h), indicating extremely high initial exposure levels (Fukushima Prefecture, 2011). The Japanese government expanded the evacuation order on April 11, 2011, designating a 20-kilometer radius that included Futaba as a restricted area. According to UNSCEAR, individuals within this evacuation zone were estimated to have received an effective dose of less than 10 mSv before and during the evacuation, with those evacuated early (on March 12, 2011) receiving approximately half that dose. These dose estimates were derived from modeled assessments of external radiation exposure due to radioactive deposition, notably of 137Cs (UNSCEAR, 2013). Specifically, in Futaba town, 82% of evacuees were estimated to have received external radiation doses below 1 mSv, while 14.3% would have been exposed to doses between 1 and 2 mSv, and only 2.4% would have received doses between 2 and 3 mSv. A small proportion of individuals (1.3%) were estimated to have received doses above 3 mSv, with the highest estimated dose being 15 mSv (Fukushima Prefecture, 2012). Despite a gradual decline in ambient dose rates as shown on Figure 2, recent assessments indicate that some spots in the specific residential return zone of the town still record dose rates between 0.35 and 4.50 μSv/h. (Fukushima Prefecture, 2023).

Following the evacuation, many residents were initially relocated to Kawamata, which is located approximately 30 km northwest of the town. Later, they were relocated to Saitama Prefecture, which is located approximately 200 km south of Fukushima Prefecture (Governmental Report, 2012). In Spring 2012, the Japanese government reclassified evacuation zones, and Futaba—alongside six other municipalities, was designated as a “Difficult-to-Return Zone" due to estimated annual radiation doses that could exceed 50 mSv. The town’s status was further complicated in 2015 when public authorities selected Futaba as the site for interim storage facilities to hold radioactive waste from the decontamination efforts across Fukushima Prefecture. As a result, Futaba remained uninhabitable for over a decade. However, after 11 years of displacement, the evacuation order was partially lifted on August 30, 2022, allowing the return of residents to the Specified Reconstruction and Revitalization Base Area around Futaba Station.

The reconstruction process in the town has been ongoing for several years. The Futaba Town Reconstruction Plan was formulated in June 2013, two years after the disaster. Based on this plan, the government finally adopted the implementation plan in March 2016 including the review of areas under evacuation orders, decontamination, and the recovery/reconstruction of the disaster-stricken areas. In August 2022, the Futaba municipal offices were returned to the town in a new building and the town implemented the Futaba Housing Project to provide disaster public housing and rehabilitation rental housing to the Futaba evacuees. Part of this process was the restoration of infrastructure like the long-awaited reopening of the Japan Railway line between Iwaki and Minamisoma in March 2020 which not only re-established crucial connections for the community but has also played a pivotal role in restoring economic activities and nurturing a renewed sense of community. Currently the Fukushima Institute for Research, Education, and Innovation (F-REI) is planned to be implemented in Namie town neighboring municipality of Futaba Town, which are expected to play a significant role in offering job opportunities and particularly attracting skilled professionals from areas outside the Prefecture.

It is also worth noting the opening in September 2020 of the Great East Japan Earthquake and Nuclear Disaster Memorial Museum in Futaba, serving as a tribute to the community’s resilience (Great East Japan Earthquake and Nuclear Disaster Memorial Museum, 2024). It is located nearby the “TEPCO Decommissioning Archive Center” which provides updates on the current status of the decommissioning work, and a few kilometers away from the Ukedo Elementary school which was severely hit by the tsunami and preserved as a memorial opened to the public in 2021 (Namie Town, 2025). Through these diverse museums, visitors from both Japan and overseas can gain insights into the challenges faced during the earthquake, tsunami, and nuclear accident in Futaba and the surrounding municipalities.

Fig. 1 Location of Futaba in the Fukushima Prefecture.

Fig. 2 Changes in air dose rates in the town of Futaba.

3 Methodology

3.1 The atomic bomb disease institute survey

The present article is based on data from a questionnaire distributed to Futaba residents and evacuees in 2022 by researchers of the Atomic Bomb Disease Institute of Nagasaki University, a few weeks before the partial lifting of the evacuation order of the city. Its objective was to better understand the methods and contents for providing information to residents on radiation related issues in an easy-to-understand manner. This survey was developed based on previous researches (Orita et al., 2015), (FHMS, 2018), (Takamura et al., 2018) following discussions with officers of the town. As of May 31, 2022, the town office of Futaba town indicated that 5582 individuals (2684 men and 2898 women) were officially registered as Futaba town residents at the time of the nuclear accident. Most of them became evacuees living either elsewhere in Fukushima Prefecture or in other parts of Japan. With the assistance of the town office, questionnaires were attached to public relations magazines sent by the Futaba government to each household in June 2022. Each household received two questionnaires, and a total of 4,358 questionnaires were distributed.

The survey consisted of 22 questions covering various topics, including the respondents’ demographic information, their current situation and concerns related to radiation, their expectations for the reconstruction and development of Futaba Town, and their self-reported health status over the past months. A final open-ended question (Question 22) worded as follow “Please describe any concerns or questions you have about radiation or health effects” gave respondents the opportunity to freely express their concerns, difficulties or expectations (see Tab. 1).

3.2 The qualitative and quantitative analysis

A qualitative analysis of responses to the open-ended Question 22 was conducted to understand concerns about radiation among Futaba residents in 2022. Of the 496 survey respondents (11.4% rate of response) only 42 (8.5%) provided responses on question 22, with five stating they had no radiation-related concerns. Responses were first translated from Japanese by native speakers into English to ensure accuracy and cultural sensitivity. Then each individual answer was examined using prior knowledge of the disaster to identify the salient and recurring themes. Next, responses were re-examined and a total of 20 codes were created based on their content. More than one code was applied to each answer if suitable. A final review was conducted to resolve any coding discrepancies. Finally, an online tool was used to create a word cloud illustrating the frequency of applied codes. See next section for results (WordClouds.com, 2025)

To complement the qualitative findings, a quantitative analysis using a chi-square test (χ2) and a logistic regression analysis was conducted on responses from 496 participants. IBM SPSS Statistics (Pallant, 2013) was used to identify relationships between desire to acquire knowledge (Question 9) and demographic variables, information sources (Question 20), and preferred communication methods (Question 21).

4 The results

The results of the survey provide insights into Futaba residents’ concerns regarding disaster recovery issues, particularly regarding health, their demographic characteristics, and their knowledge-seeking behaviors.

A total of 496 responses were received from the 4,358 questionnaires distributed, resulting in a response rate of 11.4%. The respondents were categorized into youth (18–29 years, 3.8%), middle-aged (30–49 years, 26.0%), senior (50–69 years, 48.2%), and elderly (70 years and above, 22.0%). In terms of gender, 49.6% were female and 50.4% were male. At time of the questionnaire response, 65.5% of respondents were living within Fukushima Prefecture and 13.5% lived with children under 18. Regarding employment status, only 23.3% were employed, which largely reflects the age distribution of the sample, as many respondents were in retirement age categories. The survey respondents were predominantly from older generations, with seniors (aged 65 and above) making up a significant portion of the sample.

Although the questionnaire included other items, such as Question 7 (on willingness to return) and Questions 13–18 (covering other aspects of daily life and recovery), the present analysis focuses on Questions 8–12 and 20–21, which directly address knowledge-seeking behavior, communication preferences, and sources of radiation-related information. In terms of radiation-related knowledge seeking, 39.5% of respondents were aware of places where they could consult about radiation and health effects, while 60.5% were not. A majority (64.1%) expressed a desire to acquire more knowledge about radiation, and 70.9% wanted to learn more about treated water from the Fukushima Daiichi Nuclear Power Plant. When asked about their main source of radiation information, 90.3% relied on formal sources such as government agencies, experts, and scientific reports, while 9.7% relied on informal sources, including family, friends, and acquaintances. Regarding preferred communication methods, most respondents (85.0%) preferred group-based interactions, either through gatherings or round-table discussions or large lecture meetings. Only 15.0% of respondents preferred individual consultations with experts.

The qualitative responses were analyzed using a word cloud analysis (see Fig. 3) based on the open-ended responses to Question 22. This analysis highlighted key themes. “Health effects of radiation" appeared most frequently (15 times including 5 times health effects on children), followed by’ knowledge seeking’ (10 times),’lack of trust’ and ‘decontamination and waste’ (6 times), then ‘food products and water’ and ‘returning in Futaba’ (5 times), finally ‘tritium in seawater’ and ‘uncertainties’ (2 times). Other points of interest included “the authorities’ failure to listen,” “the need for attractive activities,” and “stop nuclear energy,” which were each mentioned once.

Further statistical analysis (Tab. 2) confirmed significant associations between age and knowledge-seeking behavior. Younger and middle-aged respondents showed a higher interest in acquiring radiation-related knowledge compared to senior and elderly individuals. Preferred sources of radiation-related information also varied by age: younger respondents relying more on informal networks, whereas older individuals preferring traditional sources such as newspapers, books, and government bulletins. In terms of preferred consultation methods, older respondents favored large lecture meetings, while middle-aged and younger respondents were more inclined toward smaller round-table discussions or individual consultations.

Table 3 presents the binary logistic regression analysis examining factors associated with seeking radiation-related knowledge and information sources. The results indicate that individuals who relied on formal sources were 4.61 times more likely to seek additional radiation-related knowledge compared to those relying on informal sources (OR = 4.61, 95% CI: 1.73–12.30, p =.002). This suggests that formal sources may play an important role in stimulating continued interest in radiation-related information. Furthermore, age was also a significant predictor of obtaining information from formal sources, with older individuals significantly more likely to rely on formal sources compared to younger respondents (OR = 0.239, 95% CI: 0.107–0.533, p < .001). This highlights a potential gap between information source preference and motivation to learn more, especially among older residents. Other factors such as gender, employment, hospital visits, and living location did not significantly influence information source preferences

In summary, the study results highlight that many residents expressed concerns about the effects of radiation, including its potential links to thyroid cancer and its long-term consequences for the health of their children and grandchildren. Despite assurances regarding food safety, some residents noted that uncertainties persisted, particularly regarding the impact of consuming food produced in Fukushima Prefecture. Concerns about the quality of drinking water and the radioactivity levels of seafood were also frequently mentioned. Some residents wondered whether their lives would return to normal after decontamination and whether they would be able to safely garden, grow crops, or consume local produce.

Furthermore, residents expressed distrust of official explanations regarding the effects of radiation and the current risk at Futaba, and noted that experts’ opinions on radiological risks sometimes diverged, making it difficult to know who to trust. Some reported not knowing where to turn for information about radiation and its health effects and requested clear explanations of the risks associated with returning to Futaba, particularly regarding everyday activities such as gardening, farming, and visiting forests.

Beyond health concerns, respondents highlighted broader social and economic challenges. Several individuals questioned whether Futaba could ever fully recover, while others called for more job opportunities to encourage younger generations to return. A few respondents voiced opposition to nuclear energy, suggesting that the accident had irreversibly changed their views. These themes underscore the multifaceted challenges Futaba residents are facing in the recovery phase after the accident, with concerns about health effects and distrust in official information emerging as key drivers behind knowledge-seeking behavior.

Finally, the study results also shed light on the type of information and support residents seek from professionals, experts, and authorities to address their practical concerns and the challenges they face. They highlight the need for age-appropriate communication strategies that foster trust. The preference of young and middle-aged respondents for small group discussions suggests that interactive engagement methods may be more effective at improving radiation knowledge and addressing concerns than large lecture meetings.

Fig. 3 The word cloud using wordclouds.com.

5 Discussion

First, it should be noted that the number of survey response rate was low. Beyond the fact that this may be explained by the fatigue of those who are approached by repeated and numerous surveys (Kobayashi et al., 2020), the low response rate certainly reflects the fact that, given the time that has passed since the evacuation, the majority of residents have decided not to return to Futaba and have become disinterested in the questionnaires. Furthermore, most of the respondents were elderly, meaning that the results may not fully reflect the opinions of younger people who have decided against returning to Futaba. In addition, while the analysis highlights the main concerns related to health and confidence, other factors influencing return decisions, such as employment, education, and housing, were not fully taken into account. Nevertheless, this study sheds light on several important aspects of the complex challenges faced by residents following long-term evacuation. Japanese authorities have prioritized decontamination efforts to reduce radiation exposure. However, the decontamination process took much longer than initially expected, resulting in evacuation orders being lifted much later in the most heavily contaminated municipalities, including Futaba. As a result, many evacuees rebuilt their lives elsewhere and chose not to return, even after the restrictions were lifted. As of February 28, 2025 only about 100 residents—around 1.4% of the original registered population prior to the evacuation—have actually returned to live in the town. The remaining 98.6% of registered residents continue to reside outside Futaba, either within Fukushima Prefecture or elsewhere in Japan (Futaba City Hall). Despite considerable infrastructure efforts, Futaba remains largely uninhabited and currently the number of residents who have chosen to return remains marginal.

The situation faced by residents when the evacuation order was lifted raised many unique challenges, particularly regarding information about radiological risks. Unlike residents of the municipalities, who were only allowed to return after a few years due to relatively favorable radioactivity conditions and, as a result, were exposed to radiation in their daily lives and mobilized to participate in co-expertise processes, the residents of Futaba remained displaced for a significantly longer period, with very limited access to their places of residence in difficult conditions that in no way encouraged any desire to learn more about radiological risks.

The results of the analysis show that the issue of informing residents about radiological risk and, more generally, about the radiological situation at Futaba should be addressed taking into account the residents’ age. Older residents tend to expect formal information delivered through newspapers, books, and official bulletins, or even at large conference-type meetings or seminars, while younger and middle-aged residents are more attracted to informal information delivered at small roundtable discussions or even individual consultations. Given that this second group of residents shows a greater interest than older residents in acquiring knowledge about radiological risk, it might be interesting to explore the extent to which younger residents would be willing to engage in co-expertise processes, as recommended by the International Commission on Radiological Protection in the context of post-nuclear accident management (ICRP, 2020). As developed in a previous analysis (Thu Zar et al., 2022), the co-expertise process is based on three pillars: dialogue, which allows everyone to express their ideas, concerns and expectations; radioactivity measurements, which allow everyone to objectively assess and understand the surrounding radiological situation; and local projects, individual or collective, which promote self-confidence and the development of those involved in their implementation.

The experiences of co-expertise after the Fukushima accident (Brooks et al., 2020; Takamura et al., 2018; Igarashi, 2022; Yasutaka and Kanai, 2020) have shown that the success of these three pillars largely depends on the long-term commitment of experts dedicated to serving residents, to listen to them and introduce them to radiation measurement, or even support them in the implementation of local projects. For the latter, experience has also shown that financial support and the establishment of a governance framework by the authorities (local and/or national) are essential.

Mistrust and dissatisfaction toward the authorities among residents, as revealed in this research, have not been easily resolved even after the evacuation orders were lifted, as confirmed in discussions held during the Fukushima Dialogue in the fall of 2023, held in Futaba on the theme of “Living Together after the Nuclear Accident” (NPO Fukushima Dialogue, 2023). During this dialogue, local residents highlighted the difficulty of establishing continuous communication with the public authorities in charge of the reconstruction process. Many participants highlighted a significant gap between statements by national authorities regarding reconstruction efforts, particularly the return of residents, and the public’s opinions on these topics.

In order to address these issues, it is essential for authorities and experts to work together with residents through processes such as co-expertise so that residents can actively engage with their own situation. The findings of this study indicate that it is the younger generation, rather than the elderly, who tend to have a stronger willingness to be proactively involved. In light of such generational tendencies, it is desirable to develop and implement the process accordingly. The fact that Futaba Town was the last municipality to have its evacuation order lifted can be seen as an advantage in that it allows the town to make use of the experiences of other municipalities where the orders had already been lifted. Alongside the findings presented in this study, it is expected that future measures will be implemented by drawing on both the strengths and shortcomings of previous cases.

6 Concluding remarks

Both qualitative and quantitative findings of the present research confirm that concerns about health, particularly for children and future generations, remain central among evacuees and residents. Persistent anxiety is driven by uncertainty about radiation risks and deep-rooted distrust in official information. Although a significant portion of respondents expressed a desire to acquire more knowledge about radiation, the way information is communicated plays a critical role in shaping perceptions. It has been underlined that in a context of distrust technical information about the risk and the effects of radiation plays a limited role (Murakami et al., 2017; Lochard, 2020; Ando, 2021). Moreover, official information is often presented with the objective of convincing people that the situation is under control. As one resident expressed in the open-ended question 22 “We would like the meeting to be one where the dangers and safety of radioactive contaminants and radiation are explained, rather than an educational meeting that emphasizes safety and aims to persuade people.” This statement, which reflects the perception of some Futaba residents, underscores the need for authorities to adopt a transparent communication strategy such as the co-expertise process that primarily addresses residents’ real concerns.

The study also revealed generational differences in knowledge-seeking behaviors. While older individuals tend to rely on formal sources and large lecture meetings, younger and middle-aged evacuees prefer interactive discussions. These findings suggest that effective risk communication should not only provide accessible and scientifically grounded information but also align with the diverse preferences of different demographic groups.

Finally, the results of this study argue for a more systematic implementation of the co-expertise process recommended by the ICRP taking into account the specificity of the Futaba situation as underlined in the discussion. Based on dialogue between all stakeholders and the involvement of residents in radioactivity measurements alongside experts, this process gradually enables those affected to better understand the radiological situation they face and make informed decisions on how to protect themselves (ICRP, 2020). Experience gained in this area following the Chernobyl and Fukushima accidents has amply demonstrated the effectiveness of the process.

In the future, the focus at Futaba should certainly be on promoting interdisciplinary collaboration and stakeholder engagement, as well as ensuring sustained dialogue between returning evacuees and newcomers. Ultimately, rebuilding Futaba goes beyond physical reconstruction and requires addressing the long-term concerns of the people who permanently reside in the municipality and those who come to work there every day, gradually rebuilding trust with experts and authorities, and empowering residents to make informed decisions about their future. The Futaba case demonstrates that technical recovery (e.g., decontamination, infrastructure reconstruction) alone is not sufficient to ensure social recovery (Schneider & Lochard 2021). Emotional, psychological, and community aspects are essential to rebuild trust and encourage a return to normalcy. This study, which focuses on a period immediately preceding the town’s full reopening, provides a baseline for future monitoring studies. It will be important to understand how residents’ concerns evolve, particularly as more people move in and the town reestablishes basic services and community functions. Continued monitoring of risk perception, social integration, and the effectiveness of communication strategies is necessary to support long-term recovery goals and inform future policies in disaster-affected areas.

Acknowledgments

The authors would like to express their special thanks to the residents of Futaba town for their cooperation. They also thank their colleagues from the Departments of Global Health, Medicine, and Welfare, and of Health Risk Control at the Atomic Bomb Disease Institute, Nagasaki University, for their useful comments, their encouragement all along the preparation of the article.

Funding

No specific funding was received for this study.

Conflicts of interest

The authors declare that they have no conflicts of interest in relation to this article.

Author contribution statement

Win Thu Zar: Conceptualization, literature review, qualitative and quantitative analysis, drafting; Varsha Hande: drafting and qualitative analysis; Makiko Orita; Hitomi Matzunanga; Jacques Lochard; Thierry Schneider and Noboru Takamura: advice and internal reviewing.

Ethics approval

Ethics approval was not required.

Informed consent

Informed consent was not required.

References

All Tables

All Figures

	Fig. 1 Location of Futaba in the Fukushima Prefecture.
In the text

	Fig. 2 Changes in air dose rates in the town of Futaba.
In the text

	Fig. 3 The word cloud using wordclouds.com.
In the text