Radiation Risk Perception of the Residents Who Provided Land for the Interim Storage Facilities in Okuma and Futaba Towns Adjacent to the Fukushima Daiichi Nuclear Power Plant

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This study provides implications for radiation risk communication in areas where stored soil was generated during decontamination in the reconstruction process following the Fukushima Daiichi Nuclear Power Plant accident.

Abstract

To reduce environmental contamination following the release of various radionuclides during the Fukushima Daiichi Nuclear Power Plant accident, the Japanese government has continued decontamination work and decided to use interim storage facilities (ISFs) in the towns of Okuma and Futaba to house large quantities of contaminated soil and waste until their final disposal. This study aims to clarify whether there are differences in the acceptance of removed soil for recycling between people who provided land for ISFs and those who do not. Furthermore, we analyzed the risk perception of the radiation effects on offspring, trust in information from public authorities, and intention to return to their hometown. A questionnaire survey was conducted at Okuma and Futaba town homes in the ISF area. Compared with those who did not provide land to the ISFs (n = 538, 68.0%), people who provided land (n = 141, 77.9%) responded that they were accepting the building of the ISFs (p = 0.018). Meanwhile, approximately half of the respondents were “unable to decide” concerning the recycling of removed soil in their current region of residence regardless of whether the land provided or not. Similarly, there were no significant differences between the groups regarding radiation risk perceptions of the offspring effects on residents and intention to return, or whether to provide land to the ISFs. The study suggests that it is important to continue radiation risk communication to determine whether people have provided land to the ISFs.

1. Introduction

The accident at the Tokyo Electric Power Company’s Fukushima Daiichi Nuclear Power Plant (hereinafter, “FDNPP”) resulted in the release of artificial radionuclides such as cesium-134, cesium-137, and iodine-131, which spread throughout the atmosphere and were deposited on land in the surrounding areas [1]. The decontamination of areas involves stripping the topsoil and removing tree leaves, branches, and fallen leaves that have been in contact with these radionuclides, and it is essential to reduce additional exposure doses [2]. During the decontamination efforts around the FDNPP, large quantities of contaminated soil and waste were generated, with an estimated volume of 16–22 million m³. It is difficult to clarify the final disposal methods for such large quantities of radioactive materials, and interim storage facilities (hereinafter, “ISFs”) are needed for safe temporary storage until their final disposal. An ISF stores and manages contaminated soil, waste, and specified waste (measured at >100,000 Bq/kg) generated during decontamination [3]. As of 31 December 2023, the land contracted for the construction of these ISFs had steadily increased over time to approximately 1537 ha (approximately 96% of the envisaged area needed), with the cooperation of 1883 landowners (approx. 89.7% of the total population) [4].

Under Japan’s law, individuals can freely purchase land. Hence, before the accident, the areas that have been converted to an ISF belonged to residents and supported a variety of public and private economic activities. Land is a precious personal asset, and maintaining heritage land from forefathers means protecting the traditional family history. To accelerate the reconstruction in the affected areas and return the land to residents who wish to have it restored in the future, the government of Japan enacted legislation to “take the necessary measures to complete final disposal outside Fukushima Prefecture within 30 years (by 2045) of the start of interim storage” as part of the Interim Storage and Environmental Safety Corporation Act. The Act clearly stated the government’s responsibility for matters. Furthermore, to achieve final disposal outside Fukushima Prefecture, the Ministry of the Environment (MOE) has promoted soil recycling based on the basic concept of the safe use of removed soil Processed into recycled materials since June 2016, with the aim of reducing the volume of soil destined for final disposal. The MOE imposed a limitation in that the processed removed soil could only be used in public works where management entities and responsibility-related systems were clarified. Furthermore, it sets an upper limit for radioactivity concentrations in recycled materials to limit the additional exposure doses [5].

Based on these basic concepts, the removed soil can be accurately recycled as a resource and safely managed until its final disposal outside of Fukushima. The ISF is located around the FDNPP in the towns of Okuma and Futaba in Fukushima Prefecture. Evacuation orders were imposed immediately after the accident but then lifted in 2019 for Okuma and in 2022 for Futaba, but the return rates of the town’s former residents have been incredibly low: approximately 3% for Okuma and 2% for Futaba by 2024 [6,7]. It has been clarified in previous studies that the residents had continuous concerns about radiation’s health effects on themselves and their children [8]. The selection of high-level radioactive waste geological disposal sites has been viewed as an inequitable burden allocation issue [9]. Such sitting issues are sometimes labelled “Locally Unwanted Land Usage” (LULU) [10,11] and “Not in My Back Yard” (NIMBY) [12]. However, the government of Japan set up an interim storage facility in the towns of Okuma and Futaba and defined a policy that it will move to other sites in Fukushima by 2045. Although there are complex circumstances regarding ISFs, the investigation has not been conducted with a focus on residents of the ISF area at the time of the FDNPP accident. The decontamination process of contaminated radioactive materials following a nuclear accident was the first in the world in the FDNPP accident. Hence, the issue of soil containing radioactive materials and their storage resulting from decontamination is an unknown topic that has not yet been studied.

This study aimed to clarify whether there are differences in revealing trust concerning information about ISFs provided by public authorities, risk perception of the effects of radiation on offspring, and intention to return (hereinafter, “ITR”) between people who provide land for ISFs and those who do not. Furthermore, this study examined the differences in the acceptance of removed soil for recycling among these groups. The need for ISFs and the risk perceptions of radiation among people who provide land for ISFs have not been previously clarified. These results contribute to conveying information regarding radiation and its health effects in the future regarding ISFs and soils removed from these designated areas.

2. Materials and Methods

2.1. Participants

This study was conducted between November 2023 and February 2024 in the towns of Okuma and Futaba, which are located near the ISF (see Figure 1). The study participants were those aged 18 years and older who still held resident cards for towns at the time of the survey. A questionnaire was enclosed in a public relations magazine sent once or twice a month to all residents who indicated a desire to receive it. Approximately 4900 households in Okuma and 2600 households in Futaba received magazines. After excluding incomplete responses, 562 responses from Okuma and 426 from Futaba were deemed to be valid. Prior to the commencement of the study, all participants received a thorough explanation of the study’s objectives and disclosed details via an information leaflet. Informed consent was obtained from all the participants. This study was approved by Nagasaki University Graduate School of Biomedical Sciences (No. 21082702) under the Declaration of Helsinki.

2.2. Questionnaire

The questionnaire items used in this study were based on a public survey regarding radiation anxiety, which is regularly conducted in the area affected by the Fukushima nuclear accident [13]. In particular, we referred to the risk perception items. The survey included questions about demographic characteristics such as sex and age. Trust in the information concerning the ISF was evaluated by asking the question, “Do you have trust in the information about the ISF you have received from the public authorities?” These questions were answerable as “yes,” “probably yes,” “probably no,” or “no.” The evaluation of the respondents’ acceptance of the ISF and the recycling of the removed soil was as follows: accept, unable to judge, and do not accept. The ITR to Okuma or Futaba was assessed as follows: already returned, wanted to return, undecided, and did not intend to return. Additionally, the survey questioned whether respondents thought offspring effects would occur as a result of living in one of these towns, which judged their radiation risk perception.

2.3. Statistical Methods

For the analysis, respondents’ ages were categorized as <65 and ≥65 years, which is the typical retirement age in Japan. The chi-square test was used to compare whether the respondents had provided land for an ISF and to note their replies concerning each variable. The statistical analysis included IDs with missing items; therefore, the number of respondents for each question was different. The data were analyzed using SPSS software (Statistical Package for Social Science) Statistics Ver. 29.0 (IBM, Armonk, NY, USA), with statistical significance set at p < 0.05.

3. Results and Discussion

Of the 988 respondents, 187 (18.9%) provided land for the ISF and 801 (78.4%) did not.

Table 1. Sociodemographic factors of those who provided land for interim storage facilities.

	Response	Overall % (n)	Yes % (n) 18.9 (187)	No % (n) 78.4 (801)	p-Value
Town of residence	Okuma	56.9 (562)	56.1 (106)	56.9 (456)	0.952
	Futaba	43.1 (426)	43.3 (81)	43.1 (345)
Sex, n = 976	Male	55.2 (539)	59.4 (111)	54.2 (428)	0.206
	Female	44.8 (437)	40.6 (76)	45.8 (361)
Age (years), n = 975	<65	37.3 (364)	35.5 (66)	37.8 (298)	0.562
	≥65	62.7 (611)	64.5 (120)	62.2 (491)
Intention to return, n = 980	Already returned	3.5 (34)	1.6 (3)	3.9 (31)	0.254
	Want to return	13.4 (131)	13.4 (25)	13.4 (106)
	Undecided	26.5 (260)	23.5 (44)	27.2 (216)
	No intention to return	56.6 (555)	61.5 (115)	55.5 (440)
Offspring effects will occur from living in Okuma or Futaba, n = 965	Yes	38.0 (367)	40.7 (74)	37.4 (293)	0.417
	No	62.0 (598)	59.3 (108)	62.6 (490)
Trust in the information about the ISF provided by public authorities, n = 979	Yes	59.3 (581)	62.9 (117)	58.5 (464)	0.272
	No	40.7 (398)	37.1 (69)	41.5 (329)
Acceptance of ISF, n = 975	Accepted	69.9 (679)	77.9 (141)	68.0 (538)	0.018
	Unable to judge	19.2 (187)	16.0 (29)	20.0 (158)
	Do not accept	10.9 (106)	6.1 (11)	12.0 (95)
Acceptance of removed soil for recycling in the current region of residence, n = 975	Accept	24.7 (241)	30.4 (56)	23.4 (185)	0.127
	Unable to judge	54.6 (532)	45.9 (91)	55.8 (441)
	Do not accept	20.7 (202)	20.1 (37)	20.9 (165)

Note: chi-square test. FDNPP: Fukushima Daiichi Nuclear Power Plant. ISF: Interim Storage Facility.

lists the sociodemographic and chi-square test results for each factor.

Among these results, only recognition of the “acceptance of ISF” showed a significant difference. Compared to 538 (68.0%) people who did not provide land to the ISF, 141 (77.9%) of those who had provided land accepted the ISF in their hometowns of Okuma and Futaba. Of those who provided land for the ISF, 16.0% were unable to judge whether to accept the ISF and 6.1% did not accept it (p < 0.018). The results suggest that the construction of the ISF and management of the removed soil were based on considerable understanding and cooperation among locals. However, a survey by the Ministry of the Environment reported that only 14.0% of the Japanese people outside Fukushima knew about the final disposal policy for removed soil [14].

In contrast, the acceptance of recycling removed soil in the current region of residence was 241 (24.7%), and there was no significant difference between those who provided land for the ISF (56; 30.4%) and those who did not (185; 23.4%) (p = 0.127). In addition, approximately half of the respondents were “unable to judge” the recycling of removed soil in their current region of residence. To achieve final disposal outside Fukushima Prefecture by 2045, it is essential to take steps to reuse and reduce the large amount of soil removed. The Japanese government has developed safe recycling technologies to remove soil stored in the ISF. One of the key elements of the decision-making process regarding contaminated soil management is environmental risk assessment, which is the basis for the assessment of contaminated soil and the development of remediation strategies. Based on these environmental assessments, human health effects are evaluated, and the acceptance of contaminated soil is determined [15]. These results suggest that it is essential to disseminate information about the removed soil using effective risk communication techniques to ensure the public’s understanding and to help them make decisions. Effective radiation risk communication is conducted by independent organizations that possess technical knowledge and have demonstrated a clear commitment to the public interest [16]. This suggests that effective radiation risk communication for decision-making can be achieved through collaboration between soil recycling experts and radiation exposure experts from independent organizations, such as universities and research institutes.

Unfortunately, 40.7% of the respondents distrusted the ISF information provided by public authorities. Trust in information from public authorities found no difference in whether the residents were those who provided land. Many studies have revealed that trust in information depends on personal judgments regarding the credibility of the sources [17]. Public understanding and acceptance are essential for the reuse of large amounts of removed soil that contains radioactive materials. These results imply that it is necessary to consider an information strategy by reusing the removal of soil, even among residents of ISF areas.

Furthermore, ITR was not significantly related to the land provided for the ISF. The percentage of ITR responses did not differ from that of a previous survey in Okuma and Futaba [18]. In other words, this result suggests that the distribution of each ITR was the same regardless of whether the residents provided their land for the ISF. The Japanese government assesses residents’ ITR, and if they wish to return, it will support their return to their hometown, excluding the restricted area. Hence, it is important to maintain the current strategy in Japan to support those who wish to return to the area around the FDNPP, regardless of whether they were living in ISF areas at the time of the accident [19].

Radiation risk perception was not significant, regardless of whether land was provided to the ISF. A previous study indicated that people living increasingly distant from the FDNPP tended to think offspring effects would occur as a result of living in the affected area of the FDNPP [20,21]. Although 38.0% of the respondents still thought that offspring effects would occur in towns with an ISF, the genetic effects of radiation due to the FDNPP accident have not been scientifically proven [22]. The ISF will be relocated outside Fukushima by 2045, and some respondents may pass the land down to their children or grandchildren. With this in mind, it is necessary to continue efforts to resolve the misunderstanding, discrimination, and prejudice regarding the effects of radiation on children and grandchildren, which will be passed on to future generations.

A limitation of the study was that it did not include much information on socio-demographic factors, such as education, socioeconomic status, marital status, and employment status. The questionnaire was enclosed in a public magazine, which may have resulted in self-selection bias. The response rate in this study was low. Despite these limitations, this study provides valuable insights regarding ITR, radiation risk perception, and trust in information from public authorities among people who provided their land and accepted large amounts of soil that included radioactive materials.

4. Conclusions

The study clarified that there was no difference in the ITR and radiation risk perception based on whether land was provided to the ISF. Furthermore, the trust in ISF information from the public authorities and acceptance of recycling removed soil did not differ based on whether land was provided to the ISF. These results indicate the importance of providing radiation risk communication, including support to return and whether the residents were living in the ISF area at the time of the accident. Decontamination is an essential process that occurs after radioactive materials are dispersed in the environment, as in the case of the FDNPP accident. Therefore, proper storage and reuse of the soil removed during decommissioning and understanding its process in not only the affected area but also the entire nation is an urgent issue. It is essential for countries that rely on nuclear power generation, including Japan, to consider this accident as a valuable lesson and incorporate it into future risk management and nuclear disaster prevention strategies.