Public perception and underlying values regarding final disposal of radioactively contaminated soil from a large nuclear accident

Abstract

Public understanding of the construction of radioactive waste disposal sites, including those for decontamination waste derived from a nuclear accident, is particularly difficult when the disposal site is far from the location in which the waste was generated. Radioactively contaminated soil from the 2011 Fukushima Daiichi Nuclear Power Plant accident is planned for final disposal outside of Fukushima Prefecture by 2045. The purpose of the current study was to identify underlying values influencing public perceptions regarding the final disposal. A total of 40 people were interviewed, including both supporters and opponents of the final disposal policy. The results of quantitative text analysis showed that the opinions of supporters were characterized by perspectives that reflected the Rawlsian maximin principle of sharing the burden of Fukushima and considering the most disadvantaged, while the opinions of opponents were characterized by distrust of the government. Statements of utilitarian perspectives on optimizing the safety and economic aspects of disposal were mentioned regardless of participants’ opinions on the disposal policy. The study clarified the relationship between these underlying values and perception of the disposal policy. The results suggested several considerations for the government regarding final disposal: prioritizing public trust, valuing a fair process, and delivering messages that reflect burden of Fukushima. These findings provided valuable insights into public acceptance and stakeholder involvement in cases where a disposal site is far from the location in which the waste is generated.

Introduction

Without considering public acceptance and stakeholder involvement, decision making about the construction of disposal sites for radioactive and other waste materials has been difficult in recent years (Benn et al. 2009; Bergmans et al. 2015; Ernst, 2019). The significance of societal aspects has been emphasized in guidelines of international organizations, not only for radioactive waste but also in the context of waste from nuclear accidents (IAEA 2011, 2022; ICRP 2018, 2020; NEA 2020, 2022). Such construction plans have occasionally been cancelled because of public protests. There have been numerous reports of failed attempts mainly in North America, Europe and Japan toward the end of the 20th century, particularly because of top-down decisions and imposed approaches (e.g. Armour 1991; Johnson 1987; Joos et al. 1999; Kuhn and Ballard 1998). Furthermore, when a disposal location is far from the site at which the waste was generated, it is challenging to balance between the burdens and benefits, making public acceptance more difficult (Johnson 1987; Li et al. 2019; Nakazawa 2018).

The Fukushima Daiichi Nuclear Power Plant accident in 2011 (hereafter Fukushima accident) resulted in the generation of soil and waste containing radioactive cesium (hereafter removed soil) for environmental decontamination. Selection of a final disposal site for the removed soil is currently a significant social issue in Japan. The removed soil amounts to approximately 13.3 million m³ and is currently stored in an interim storage facility in the vicinity of the Fukushima Daiichi Nuclear Power Plant (Ministry of the Environment 2024d). In line with the Environmental Storage and Safety Corporation Law (Law No. 44 of 2003, promulgated on May 16, 2003, and amended on December 24, 2014, to include provisions for the treatment of removed soil at an interim storage facility), the Japanese government has decided that final disposal of the removed soil will be outside of Fukushima Prefecture within 30 years after the beginning of interim storage (by 2045). The decision regarding final disposal outside of Fukushima was made by the Cabinet in 2011, with the following rationale: “following a comprehensive judgement based on the fact that residents in Fukushima Prefecture are already bearing an excessive burden” (House of Representatives 2014, p18). Currently, technological development of the disposal method is underway, but the selection criteria for (a) candidate site(s), decision making process, and other related factors have not yet been determined.

In terms of radioactivity levels, the removed soil differs significantly from the low-level and high-level radioactive waste resulting from nuclear power generation. Approximately 80% of the removed soil is below 8,000 Bq/kg, which is low enough to be recyclable under certain conditions. To reduce the amount of final disposal, there is a plan to recycle as much of this low-level contaminated soil as possible (IAEA 2024; Ministry of the Environment 2024b). The remaining soil over 8,000 Bq/kg can be disposed of at a facility equivalent to that of municipal solid waste, unlike general radioactive waste from a nuclear facility (Takada et al. 2022). Whereas the disposal of nuclear power-derived radioactive waste has strict geological constraints, there are few geological constraints for removed soil. Accordingly, a large number of potential disposal sites are available in Japan. Because of the legal requirement that the disposal is outside of Fukushima Prefecture, societal difficulty may arise in terms of balancing the burdens and benefits in site selection. As a preliminary measure, the Ministry of the Environment (MOE) views all citizens in Japan as stakeholders and is seeking to enhance public comprehension of the final disposal policy on a national scale (Ministry of the Environment 2024d). The MOE launched a website to provide relevant information, has held nine dialogue meetings, and has conducted on-site tours of the interim storage facility (Ministry of the Environment 2024c).

Regarding public acceptability of disposal sites for waste containing radioactive materials, previous studies reported that risk perception and a sense of inequity have negative effects (Sjöberg 2004). Trust in the government and site operators have a positive influence on acceptability, both directly and indirectly (Ohtomo et al. 2014). Procedural fairness, such as the provision of public access to decision-making processes, has also been reported to enhance acceptability (Kuhn and Ballard 1998). This phenomenon was also confirmed for the disposal of removed soil after the Fukushima accident (Murakami et al. 2024; Shirai et al. 2023; Takada et al. 2022). However, these previous studies examined acceptability on the basis of the assumption that the disposal site was selected in the residents’ vicinity. In the case of the removed soil after the Fukushima accident, understanding public perceptions toward the final disposal policy itself is important because the MOE will first develop a nationwide understanding of the policy, and will then select potential disposal sites from all over Japan, except Fukushima. Additionally, since values influence attitudes toward the acceptability of nuclear energy and nuclear waste (de Groot et al., 2013; Seidl et al., 2013), understanding the underlying values that shape public perceptions toward the policy would also be valuable.

In a previous study, an online questionnaire was conducted to examine factors affecting individuals’ attitudes toward this policy (Takada et al. 2024). The results revealed that risk perception and the sense of inequity regarding the disposal site affected not only the acceptability to residents in the vicinity of the site, but also their attitudes toward the policy itself (Takada et al. 2024). Additionally, individuals who agreed with the policy tended to prioritize sharing the burden of Fukushima, whereas those who disagreed tended to focus on the rationality of disposal outside Fukushima, and procedural fairness (Takada et al. 2024). Souma et al. (2024) conducted a group discussion experiment exploring ways of dealing with final disposal outside Fukushima among university students. The researchers focused on utilitarianism and the maximin principle from the perspective of societal desirability as points of discussion. In the context of final disposal, minimizing risks and optimizing cost-effectiveness are rational (Fischhoff et al. 1978), leading to maximization of the utility of society from a utilitarian perspective (Bentham 1996). The notion of sharing the burden of Fukushima with the rest of the country reflects a Rawlsian maximin principle that considers the least disadvantaged people (Rawls 1971), in this case, the people of Fukushima (Souma et al. 2022). In Souma et al. 2022 study, presenting participants with the feelings of former residents of the current interim storage facility (e.g., desire to pass on ancestral lands to future generations and the disappointment that the accident and the construction of an interim storage facility have made this impossible) made participants feel as if the events in Fukushima had happened to them, made them consider the people of Fukushima, and consequently made them more likely to choose a maximin-principle option. In other words, participants showed more positive attitudes regarding the final disposal policy than the condition that did not present the feelings of the residents.

The previous studies above have identified trends in public perceptions of the final disposal policy and relevant factors. However, the values underlying individuals’ support or opposition to the policy remain unclear, and it would be useful for further studies to supplement existing research using qualitative data from interview surveys and other methods. Regarding public acceptability of disposal sites for waste as well as the removed soil from Fukushima accident, quantitative studies are available, but few studies have focused on qualitative data, such as interviews. Kim and Kim (2014) conducted interviews of residents of a potential final disposal site for low-level radioactive waste in South Korea. They showed that economic considerations, risk perception, and trust in the government influenced their decisions in a referendum. However, there are few examples employing such qualitative data-based methods, and previous studies tended to examine acceptability among residents within the vicinity of a disposal site. To the best of our knowledge, no previous studies dealing with qualitative data have focused on perception of the disposal policy itself and the underlying values, and its desirability for society.

In the present study, we conducted online interviews with people outside Fukushima Prefecture, as residents of areas that could be potential candidate sites for the final disposal of the removed soil from the Fukushima accident, to identify the underlying values for their positive or negative perceptions regarding the policy from the perspective of societal desirability. Quantitative text analysis was employed to examine interview transcripts of individuals who expressed either support or opposition to the final disposal policy and identified the underlying values influencing their opinions. We expected that utilitarian views regarding safety and economic aspect would be associated with negative opinions, while views including a maximin-principle perspective of sharing burden of Fukushima would be associated with positive opinions. By identifying individuals’ perceptions of positive and negative aspects of the policy, we identified several issues that should be considered by the government in developing socially desirable approaches for enhancing public comprehension and subsequent selection of (a) candidate site(s). The findings provided valuable information from the perspective of public acceptance and stakeholder involvement in the selection of candidate disposal sites for radioactive waste, in situations where the disposal site is far from the location in which the waste was generated.

Methods

Data

The survey participants were individuals aged 20–69 years who lived in the Kanto region (eight prefectures located approximately 60–350 km from the Fukushima Daiichi Nuclear Power Plant [hereafter Fukushima Daiichi NPP]: Tokyo, Kanagawa, Saitama, Chiba, Tochigi, Gunma, Ibaraki, and Yamanashi) or the Kansai region (five prefectures located 500–700 kilometers: Shiga, Kyoto, Osaka, Nara, and Wakayama). Fukushima Prefecture is not included in the Kanto region, but was supplied by the Fukushima Daiichi NPP before the Fukushima accident. The Kansai region did not use electricity from the Fukushima Daiichi NPP, and has the second largest economy after the Kanto region. The Kansai region receives its electricity supply from electric power companies with other nuclear power plants. The two areas were examined in our previous study (Takada et al. 2024).

A total of 40 individuals were interviewed between February and March 2023. To ensure diversity of participants with the aim of theoretically saturating opinions regarding the final disposal policy, participants were selected by region and their agreement or disagreement with the policy. Participants’ attitudes were determined through our previous online questionnaire survey (Takada et al. 2024) administered to 2,000 people in the Kanto and Kansai regions in December 2022. In the pre-survey, they were asked to indicated their level of agreement with the policy (the final disposal of removed soil and other materials outside of Fukushima Prefecture within 30 years after the start of interim storage) on a four-point scale (Agree/Somewhat agree/Somewhat disagree/Disagree). We defined respondents who answered that they “agree” or “somewhat agree” with the policy as individuals who agreed in the pre-survey, and those who answered “disagree” or “somewhat disagree” as individuals who disagreed in the pre-survey. The results of the pre-survey were published previously (Takada et al. 2024). A question asking respondents about their intention to participate in this interview survey was included at the end of the pre-survey, and those who indicated their willingness to participate were recruited by telephone later.

To obtain as many diverse opinions as possible during the interview, we recruited participants who voluntarily provided detailed and specific comments and opinions regarding the final disposal policy in the pre-survey. Therefore, the respondents’ age, interest in the Fukushima accident, and their subjective knowledge of the final disposal policy were not evenly distributed, unlike their region and agreement or disagreement with the policy (Table 1). The individuals included in the current study had higher levels of interest and knowledge compared with those in the pre-survey (Takada et al. 2024).

Table 1.

Attributes of interview participants N (%)

Questionnaire and answers in the pre-survey		Number of participants in the interview			Percentage in the pre-survey (Takada et al., 2024)
		Total (%)	Kanto (%)	Kansai (%)	Kanto	Kansai
Agreement with the final disposal policy	Agree	4 (10.0%)	3 (15.0%)	1 (5.0%)	14.6%	10.4%
	Somewhat agree	16 (40.0%)	7 (35.0%)	9 (45.0%)	50.6%	50.8%
	Somewhat disagree	14 (35.0%)	6 (30.0%)	8 (40.0%)	25.6%	31.0%
	Disagree	6 (15.0%)	4 (20.0%)	2 (10.0%)	14.6%	7.8%
Gender	Male	25 (62.5%)	11 (55.0%)	14 (70.0%)	49.9%	50.0%
	Female	15 (37.5%)	9 (45.0%)	6 (30.0%)	49.4%	49.6%
	No answer/other	0 (0%)	0 (0.0%)	0 (0.0%)	0.7%	0.4%
Age	20 s	6 (15.0%)	3 (15.0%)	3 (15.0%)	20%	20%
	30 s	9 (22.5%)	4 (20.0%)	5 (25.0%)	20%	20%
	40 s	7 (17.5%)	4 (20.0%)	3 (15.0%)	20%	20%
	50 s	10 (25.0%)	3 (15.0%)	7 (35.0%)	20%	20%
	60 s	8 (20.0%)	6 (30.0%)	2 (10.0%)	20%	20%
Interest in Fukushima accident	Very interested	13 (32.5%)	9 (45.0%)	4 (20.0%)	17.5%	11.4%
	Somewhat interested	15 (37.5%)	9 (45.0%)	6 (30.0%)	39.8%	35.3%
	Neutral	7 (17.5%)	1 (5.0%)	6 (30.0%)	20.6%	28.3%
	Not very interested	4 (10.0%)	1 (5.0%)	3 (15.0%)	13.6%	14.6%
	Not interested	1 (2.5%)	0 (0.0%)	1 (5.0%)	8.5%	10.4%
Subjective knowledge of the policy	Know well	3 (7.5%)	3 (15.0%)	0 (0.0%)	6.3%	2.8%
	Know a little	12 (30.0%)	7 (35.0%)	5 (25.0%)	26.8%	19.6%
	Not familiar	14 (35.0%)	7 (35.0%)	7 (35.0%)	25.2%	27.6%
	Never heard of	11 (27.5%)	3 (15.0%)	8 (40.0%)	41.7%	50.0%
Total		40 (100.0%)	20 (100.0%)	20 (100.0%)	-	-

The interview procedure was as follows: A preliminary explanation of the final disposal policy was sent to participants by post by the day before the interview, and they were asked to read it beforehand. The content of the explanation was the same as that used in the pre-survey: information about the environmental contamination caused by the Fukushima accident, the amount of contaminated soil, the amount of money spent on decontamination (approximately 5 trillion Japanese yen), the current situation at the interim storage facility, the law regarding final disposal and the associated cabinet decision (“as a result of a comprehensive judgment based on the fact that residents in Fukushima Prefecture are already bearing an excessive burden”), and an explanation that the specific details of the final disposal have not yet been decided (Takada et al. 2024; Online Resource 1). The interview was conducted in Japanese as a semi-structured interview, and the interviewer asked questions in the following order: the place of residence and the impressions at the time of Fukushima accident as an introduction, followed by (1) impressions about the final disposal policy, (2) support or opposition regarding the policy and what led the participants to their position, and (3) impressions about “removed soil.” The contents of 1–3 were analyzed. The interviews were conducted by a total of three interviewers through an online research company (Cross Marketing Inc.). Therefore, the interviewers were not experts in this topic. Each interview lasted 30 minutes to 1 hour and involved one participant and two interviewers (one was the main interviewer, and the other was present for support). After the interview, participants were given an online gift certificate worth 10,000 Japanese yen (approximately US$70), which could be used to purchase products online.

Analyses

Voice data from the interviews were transcribed, and only statements by the participants were included in the analysis. Words for analysis were extracted using the text data analysis tool KH Coder (Higuchi 2016, 2017). A co-occurrence network was illustrated with lines connecting automatically extracted words with similar patterns of occurrence to identify the main topics and the overview of the interviews. The Jaccard coefficient was used as a measure of co-occurrence.

By referring the top 150 most frequently occurring words (Online Resource 1), themes, or the underlaying values of the purpose of the present study, expected to be related to the formation of opinions were developed. The frequently occurring words included Fukushima, contamination, disposal, and soil, which are specific to the topic of final disposal of soil outside Fukushima. Additionally, words such as safety, burden, risk, decision, explanation, money, and government were identified as possibly related to opinions and we set five themes on the basis of these words: concerns about the safety of transporting the removed soil out of Fukushima, which is related to a utilitarian perspective of minimizing risks; perspective of sharing the burden of Fukushima, which is related to a Rawlsian maximin principle; procedural fairness of the final disposal; distrust of the government; and the economic rationale of the final disposal policy, which is related to a utilitarian perspective of optimizing cost-effectiveness. Each theme was determined by presence of the words specified in the coding rules in the participants’ statements. The words that comprised each coding rule were set in a bottom-up process by reviewing the transcriptions of all participants (Online Resource 2).

A correspondence analysis was employed to evaluate the association of the themes and the participants’ opinions. This method visualizes data on a two-dimensional plane based on a cross-tabulation table of the opinions and the themes, making associations between elements clear. Items with minimal bias are positioned near the origin, while those with greater bias are placed farther away. Closely associated items are aligned in the same direction from the origin.

Prior to the analysis, we reviewed all participants’ statements and classified them into the following four categories: fully supported the policy of disposal outside Fukushima; supported the policy with certain conditions; personally opposed, but willing to accept under certain conditions; and completely opposed. The classification was made by three people (one author [MT] and two non-authors, all of whom had expertise in social sciences), who each read the transcriptions. Agreement of the classifications was moderate, with a Fleiss’ kappa coefficient value of 0.52. For classifications where agreement was not achieved, the three classifiers each presented their reasoning, engaged in discussions, and reached a unified conclusion.

Results

Participants’ Opinions on Final Disposal Outside Fukushima

The opinions of the 40 participants on the disposal policy were as follows: 11 fully supported the policy of disposal outside Fukushima (hereafter “support”); 18 supported the policy with certain conditions (hereafter “conditional support”); 6 were personally opposed but willing to accept the policy under certain conditions (hereafter “opposition (conditional acceptance)”); and 5 were opposed to the policy (hereafter “opposition”). Conditional support was expressed in statements such as “if it can be shown to be absolutely safe” or “if everyone agrees”. Opposition (conditional acceptance) was expressed in statements such as “I am against it, but I am willing to accept it if it is decided by referendum”.

The 40 participants comprised 20 individuals who agreed with the policy and 20 who disagreed with the policy in the pre-survey. Of these participants, 15 participants had changed their opinions by the time of the interviews. Of the 20 participants who disagreed in the pre-survey, 12 participants were in support or conditional support in the interview. In contrast, of the 20 participants who agreed in the pre-survey, three participants expressed opposition (conditional acceptance) or opposition in the interview. The reasons for the change are detailed in section 3.4 Reasons for changing opinions.

Frequent Words and Topics

The total number of words in the 40 participants’ statements was 73,401, and the number of cases (chunks of coherent content separated by major changes in the story and by the interviewer’s response) was 1,438. The most frequently occurring words were think (1st, 1158 times), Fukushima (2nd, 336 times), say (3rd, 299 times), person (4th, 285 times), safety (5th, 199 times), contamination (6th, 153 times), disposal (7th, 152 times), and burden (8th, 146 times) (Online Resource 1). Of these words, following words are specific to the present study: “Fukushima”, “safety”, “contamination”, “disposal”, and “burden”. The words such as “think” and “say” are common words that frequently appear of any sentence analysis (Higuchi 2014).

Figure 1 shows the co-occurrence network for the 72 words that were used more than 45 times, with the 60 pairs with the strongest co-occurrence connected by lines. The word groups connected by lines indicate common topics in the interviews: impressions of the removed soil and final disposal (Fig. 1, 01); the burden of Fukushima (Fig. 1, 02); agreement or disagreement regarding final disposal (Fig. 1, 03); aversion to disposal near oneself (Fig. 1, 04); safety of the final disposal (Fig. 1, 05); decision-making by the government (Fig. 1, 06); unclear points regarding the final disposal (Fig. 1, 07); effects of radiation (Fig. 1, 08); cost of transporting the removed soil (Fig. 1, 09); disposal outside Fukushima Prefecture (Fig. 1, 10).

Fig. 1.

A co-occurrence network of frequently occurring words. Numbers indicate Jaccard coefficients. The network was created by excluding “think,” which was excessively common, to untangle the dense network. The unit of aggregation was a sentence

Themes

Table 2 shows the number of cases (chunks of coherent content separated by major changes in the story and by the interviewer’s response) and participants expressing each theme in the interviews, as determined by the coding rules. The theme with the highest number of occurrences was concerns about the safety of transporting the removed soil out of Fukushima (hereafter “safety”), which was mentioned by all participants, in 338 cases (23.5% of the total number of cases). This was followed by the procedural fairness of the final disposal (hereafter “procedural fairness”), which was mentioned by 39 participants (97.5% of the participants) in 206 cases (14.3% of the total number of cases). The perspective of sharing the burden of Fukushima (hereafter “sharing burden”) was mentioned by all participants in 191 cases (13.3%). Distrust of the government was mentioned by 30 people (75%) in 97 cases (6.8%). The economic rationale for the final disposal (hereafter “economy”) was mentioned by 21 participants (52.5%) in 49 cases (3.4%). We sometimes observed that a single case included more than one theme. There were 772 cases in which none of the five themes appeared, accounting for 53.7% of the total number of cases. These included interjections to the interviewers and participants’ predictions of how the disposal policy would conclude. Opinions related to support or opposition to the policy were grouped into the five themes above, and we considered that theoretical saturation has been reached. The themes were not significantly skewed by region, gender, or age (Table 2).

Table 2.

Number of cases and participants of each theme by opinion, region, gender, and age

		Safety	Procedural fairness	Sharing burden	Distrust of the government	Economy	Others
Support	Cases (%)	78 (21.9%)	31 (8.7%)	49 (13.7%)	16 (4.5%)	8 (2.2%)	211 (59.1%)
	Participants (%)	11 (100.0%)	11 (100.0%)	11 (100.0%)	6 (45.5%)	5 (45.5%)	11 (100.0%)
Conditional support	Cases (%)	136 (20.5%)	90 (13.6%)	86 (13.0%)	31 (4.7%)	22 (3.3%)	367 (55.4%)
	Participants (%)	18 (100.0%)	17 (94.4%)	18 (100.0%)	15 (83.3%)	10 (55.6%)	18 (100.0%)
Opposition (conditional acceptance)	Cases (%)	68 (32.2%)	61 (29.0%)	33 (15.6%)	27 (12.8%)	10 (4.7%)	82 (38.9%)
	Participants (%)	6 (100.0%)	6 (100.0%)	6 (100.0%)	6 (100.0%)	3 (50.0%)	6 (100.0%)
Opposition	Cases (%)	56 (27.1%)	24 (11.6%)	23 (11.1%)	23 (11.1%)	9 (4.4%)	112 (54.1%)
	Participants (%)	5 (100.0%)	5 (100.0%)	5 (100.0%)	3 (60.0%)	3 (60.0%)	5 (100.0%)
Kanto	Cases (%)	174 (24.9%)	96 (13.7%)	88 (12.6%)	31 (4.4%)	15 (2.2%)	380 (54.4%)
	Participants (%)	20 (100.0%)	20 (100.0%)	20 (100.0%)	13 (65.0%)	7 (35.5%)	20 (100.0%)
Kansai	Cases (%)	164 (22.2%)	110 (14.9%)	103 (13.9%)	66 (8.9%)	34 (4.6%)	392 (53.0%)
	Participants (%)	20 (100.0%)	19 (93.3%)	20 (100.0%)	17 (85.0%)	14 (70.0%)	20 (100.0%)
Male	Cases (%)	218 (23.3%)	151 (16.2%)	127 (13.6%)	72 (7.7%)	29 (3.1%)	490 (52.4%)
	Participants (%)	25 (100.0%)	25 (100.0%)	25 (100%)	19 (76.0%)	14 (56.0%)	25 (100.0%)
Female	Cases (%)	120 (23.9%)	55 (10.9%)	64 (12.7%)	25 (5.0%)	20 (4.0%)	282 (56.1%)
	Participants (%)	15 (100.0%)	14 (93.3%)	15 (100%)	11 (73.3%)	7 (46.7%)	15 (100.0%)
20 s	Cases (%)	51 (20.1%)	26 (10.2%)	25 (9.8%)	6 (2.4%)	5 (2.0%)	158 (62.2%)
	Participants (%)	6 (100.0%)	6 (100.0%)	6 (100.0%)	3 (50.0%)	2 (33.3%)	6 (100.0%)
30 s	Cases (%)	83 (22.9%)	62 (17.1%)	56 (15.4%)	39 (10.7%)	6 (1.7%)	189 (52.1%)
	Participants (%)	9 (100.0%)	9 (100.0%)	9 (100.0%)	8 (88.9%)	5 (55.6%)	9 (100.0%)
40 s	Cases (%)	51 (18.5%)	28 (10.1%)	31 (11.2%)	8 (2.9%)	7 (2.5%)	167 (60.5%)
	Participants (%)	7 (100.0%)	6 (85.7%)	7 (100.0%)	5 (71.4%)	3 (42.9%)	7 (100.0%)
50 s	Cases (%)	76 (25.7%)	54 (18.2%)	50 (16.9%)	30 (10.1%)	25 (8.5%)	132 (44.6%)
	Participants (%)	10 (100.0%)	10 (100.0%)	10 (100.0%)	9 (90.0%)	8 (80.0%)	10 (100.0%)
60 s	Cases (%)	77 (30.9%)	36 (14.5%)	29 (11.7%)	14 (5.6%)	6 (2.4%)	126 (50.6%)
	Participants (%)	8 (100.0%)	8 (100.0%)	8 (100.0%)	5 (62.5%)	3 (37.5%)	8 (100.0%)
Total	Cases (%)	338 (23.5%)	206 (14.3%)	191 (13.3%)	97 (6.8%)	49 (3.4%)	772 (53.7%)
	Participants (%)	40 (100.0%)	39 (97.5%)	40 (100.0%)	30 (75.0%)	21 (52.5%)	40 (100.0%)

Statements about “safety” with the highest number of cases were exemplified by comments such as (words selected under the coding rules are indicated in italics):

“I don’t think it should be transported (out of Fukushima) if it is really dangerous and risky.” (Female, 60 s, Support)

“I think transport of radioactive materials is dangerous. I assume it will be transported by trucks, but if there is an accident and it is scattered, it will cause a lot of problems.” (Male, 20 s, Opposition)

Statements about “procedural fairness” were exemplified by comments such as:

“As long as it is transparent and there is a clear process and absolute safety: as long as it is safe, fair, and operated properly, there is no problem.” (Male, 30 s, Opposition (conditional acceptance))

“I think there needs to be a briefing, leaflet, or pamphlet that everyone can understand, explaining in simple language that there is no danger, and describing what will happen in future.” (Female, 60 s, Conditional support)

Statements about “sharing burden” were exemplified by comments such as:

“The people of Fukushima Prefecture have suffered enough damage, so I think it is not good to put more burden on them.” (Female, 30 s, Support)

“Fukushima Prefecture has already been burdened with decontamination and interim storage. I agree with final disposal outside of Fukushima Prefecture.” (Male, 20 s, Conditional support)

Statements about “distrust of the government” were exemplified by comments such as:

“Maybe the government is hiding it (health problems) because it would be difficult to disclose such a thing, or maybe they haven’t said anything because everyone is healthy.” (Male, 60 s, Opposition (conditional acceptance))

“I am sure there are explanations for other prefectures, but I feel like I can’t trust them.” (Male, 30 s, Opposition)

Statements about “economy” were exemplified by comments such as:

“It costs money to transport the soil. Considering a large amount of taxpayers’ money is spent on accommodating the waste at another place, it would be most cost-effective to locate a disposal site near the nuclear power plant.” (Male, 50 s, Opposition (conditional acceptance))

“When I consider the cost for each prefecture to build a storage facility and transport the soil … It might be realistic to build an excellent facility at Fukushima Daiichi and keep it there.” (Female, 60 s, Support)

The results of the correspondence analysis for the five themes and participants’ opinions are shown in Fig. 2. The themes are indicated by circles, and participants’ opinions are indicated by squares as external variables. A theme near the origin is not associated with opinions, and a theme located outside of an opinion from the origin is characteristic of the opinion. Safety and economy were common themes regardless of participants’ opinions. Sharing the burden was a characteristic theme both for individuals who supported and those who conditionally supported the policy. Distrust of the government was a characteristic theme for both those who opposed the policy and those who opposed the policy but were willing to accept it under certain conditions. Procedural fairness was a characteristic theme among those who supported the policy with certain conditions and those who opposed the policy but would accept it under certain conditions.

Fig. 2.

Correspondence analysis of five themes and four participants’ opinions

Reasons for Changing Opinions

Three of the participants who agreed with the policy in the pre-survey but opposed it (or opposed it with conditional acceptance) in the interviews had the following characteristics. In the pre-survey, they agreed to the policy, emphasizing the importance of sharing burden. However, between the time of the pre-survey and the interview, they became aware of the importance of economic rationality and safety, or reconsidered their views regarding sharing the burden and became opposed. For example, the following statements were observed regarding the change in opinion:

“At first, I had thought that the burden should be borne equally outside of Fukushima Prefecture because the people of Fukushima Prefecture had experienced a difficult time. However, when I thought about the risks and costs involved … I thought that it should not be done.” (Male, 20 s, Opposition)

Of the 20 participants who disagreed with the policy in the pre-survey, 12 changed their opinion to support or conditionally support the policy in the interview; of these 12 participants, seven said that they disagreed with the policy in the pre-survey because of safety concerns; one said he disagreed because of distrust of the government. By the time they were interviewed, however, these eight participants had realized the importance of sharing the burden and changed their opinion to support the policy. For example, the following statements were observed:

“I didn’t like it because I thought it was horrible, but then I heard that it was already putting burden on the people of Fukushima Prefecture and I felt sorry for them, so I guess I changed my mind.” (Female, 40 s, Conditional support)

“I thought it would be better if it could be disposed of there (in Fukushima) if possible, considering the risk of moving it … but on the other hand, I feel that it is wrong that only some of the people there bear the burden.” (Female, 60 s, Support)

Two of the 12 participants opposed the policy because they thought the time frame of 30 years was too long, but supported the disposal of soil outside Fukushima; two participants made mistakes in answering the pre-survey.

Discussion

Underlying Values Influencing Opinions Regarding Final Disposal Outside Fukushima

Participants’ opinions on the final disposal policy were not limited to just support or opposition. They also included conditional support and opposition (conditional acceptance). This relates to the discussion around the distinction between acceptance and acceptability: acceptance refers to people’s approval after implementation, whereas acceptability describes their positive attitude before implementation (Klaus et al. 2020; Moesker et al. 2024). Moesker et al. (2024) argue for the precise distinction and use of these terms to facilitate accurate comparisons of study results and to support the formulation of effective strategies. The present study also suggests that a difference between acceptance and acceptability exists in the public perceptions.

Five distinctive themes in the interviews appeared to influence the formation of opinions regarding final disposal policy: sharing the burden, safety, economic rationality, distrust of the government, and procedural fairness. Concerns regarding the safety of disposal (“safety”) and economic rationality (“economy”) were conveyed in statements that considered maximizing the benefits to society, such as minimizing risk and optimizing cost-effectiveness, both of which reflect a utilitarian perspective (Bentham 1996; Fischhoff et al. 1978; Souma et al. 2024). This perspective was expected to be associated with negative opinions about disposal outside Fukushima. However, the results revealed that this perspective was frequently mentioned regardless of participants’ support or opposition regarding the policy. This finding suggests that participants who commented from a utilitarian perspective did not necessarily have an opposing opinion, but the formation of their opinions may have been influenced by other perspectives. A previous group discussion experiment focusing on ways to deal with the final disposal reported that participants finally chose an option that prioritized the maximin principle of reducing inequality of burdens and considering the most disadvantaged (i.e., the people of Fukushima), but that the content of the discussion often included a utilitarian perspective (Souma et al. 2022). This is consistent with the results of the present study.

Participants in the present study who expressed statements that reflected the Rawlsian maximin principle of sharing the burden of Fukushima (Rawls 1971; Souma et al. 2024) tended to support the policy. This perspective may lead individuals to have positive opinions regarding the disposal policy. In a previous study, presenting information about the people of Fukushima made participants feel as if the events of Fukushima had happened to them, made them think about the people of Fukushima, and made them more likely to choose a maximin-principle option (Souma et al. 2024). In the present study, the preliminary explanation given to participants included the decision by the Cabinet that “following a comprehensive judgement based on the fact that residents in Fukushima Prefecture are already bearing an excessive burden” (House of Representatives 2014), which may have made participants aware of the burden of Fukushima. In our pre-survey (Takada et al. 2024), many comments mentioning sharing the burden of Fukushima were made by participants who agreed with the policy, which is consistent with the present results.

Responses of participants with negative opinions regarding the disposal policy were characterized by frequent statements of distrust of the government, which may have affected their opinions. Many previous studies have confirmed that a lack of trust in government and site operators negatively affects acceptability of disposal sites of radioactive waste (Ohtomo et al. 2014; Shirai et al. 2023). The current findings suggest that trust also affected opinions regarding the disposal policy itself.

Individuals expressing conditional support and opposition (conditional acceptance; i.e., individuals who might support the policy depending on the conditions) were characterized by statements mentioning procedural fairness as a distinctive theme, which may have influenced their opinion formation. Procedural fairness has been reported to positively influence acceptability of radioactive waste sites (Kuhn and Ballard 1998; Murakami et al. 2024; Ohtomo et al. 2014; Takada et al. 2022). Hirose (2007) reported that people with particularly strong opposing views placed more importance on procedural fairness. The findings of the present study suggested that procedural fairness affected not only acceptability, but also opinions regarding the policy.

Changing Opinions

Fifteen of the 40 participants changed their opinion regarding the policy from the time of the pre-survey to the time of the interview. Participants’ statements indicated that the reasons for the change were related to changes in the relative importance of the five themes described above. Half of the 15 participants who changed their opinion disagreed with the policy on the basis of a utilitarian perspective of emphasizing safety in the pre-survey, but by the time of the interview they had come to value the maximin principle perspective of sharing the burden and supported the policy. As a result, two thirds of the participants supported or conditionally supported the policy, even though we had selected 20 individuals who agreed and 20 who disagreed in the pre-survey.

A previous study reported that when people deliberate alone, they often find arguments and evidence to support their initial view and do not change their minds (Nickerson 1998). Ueshima et al. (2021) conducted deliberation experiments on resource allocation with university students, and found that under the conditions of pair discussion, participants were more likely to change their opinions from their initial choice and re-select an option that included the Rawlsian maximin principle, compared with those under a solo deliberation condition. In the present study, the participants who changed their opinion did not report that they changed their opinions after discussing the topic with others, suggesting that most of them changed their opinions after solo deliberation, which appears to be inconsistent with previous studies. However, Ueshima et al. (2021) reported several cases in which the participants changed their opinions from their initial choice and re-selected an option that reflected the Rawlsian maximin principle after solo deliberation. Stefanelli et al. (2017) conducted longitudinal surveys on public opinion regarding nuclear waste repositories and found that, over a year, participants became more favorable toward the policy, with shifts in the points of arguments. These findings are consistent with those of the present study. In addition, multiple interviews with the same person have been reported to sometimes lead to rethinking triggered by the previous conversation (Tokuda 2013). Some participants in the present study may have changed their opinions for similar reasons.

Implications

In cases where a disposal facility is located far from the location in which the waste was generated, public acceptance of a disposal site for radioactive waste is a critical issue. The current analysis of qualitative data from interviews suggested that emphasizing a utilitarian perspective, such as safety and economic rationality, was not necessarily associated with negative opinions about the site, and these considerations were common regardless of individuals’ opinions about the policy. Procedural fairness was also a particularly important consideration for individuals who might support the policy under certain conditions, implying the essentials of non-consequentialism that would be useful in the decision-making process.

Regarding final disposal of the removed soil from Fukushima accident, the following consideration could be effective for positive public perception. Acknowledgment of the “excessive burden of Fukushima (House of Representatives 2014)” as the rationale for disposing of the soil outside Fukushima, or the perspective of sharing the burden of Fukushima which includes the maximin principle, may serve as compelling messages to the public. The MOE’s current efforts to inform the public about the situation in Fukushima (Ministry of the Environment 2024c) may lead people to feel that the situation is personal to them and encourage them to care about the people of Fukushima, which may ultimately lead to positive attitudes regarding the final disposal outside Fukushima.

Some participants in the present study changed their opinions between the pre-survey and the interviews. Thus, we speculate that the pre-survey may have provided an opportunity for participants to reconsider the issue of final disposal. The government should provide time and opportunities for deliberation and discussion at a nationwide level, and to enable as many people as possible to have thoughtful and considered discussions. The present results and the findings of previous studies (Souma et al. 2024; Ueshima et al. 2021) indicate that having time for deliberation and discussion may have possibility to bring public opinion closer to a maximin-principle option (in this case, final disposal outside Fukushima). At this time, it would be better to include a message that reflect consideration for the burden on Fukushima.

Individuals with negative opinions regarding final disposal were more likely to attribute their position to a distrust of the government rather than to risks and economic rationality. Rebuilding lost trust is difficult and takes time (Slovic et al. 1991). When trust is low, procedural fairness becomes particularly important (Krütli et al. 2012). Addressing procedural fairness carefully in the implementation of final disposal could help change the perceptions of such individuals. It is necessary to ensure accessibility to the public’s decision-making processes and transparency of information (Slovic et al. 1991). Safety and economic aspects were the most frequently mentioned issues regardless of opinion, and transparent information sharing (i.e., procedural fairness) is necessary from the viewpoint of preventing distrust of the government (Hirose and Ohtomo 2014).

Limitations

The current study included interviews of 40 participants. However, the participants were registered with an online survey company, and may differ from the general population in terms of income, education, and other factors (Fleming and Bowden 2009). Additionally, to ensure efficient recruitment of participants and to obtain various opinions in the interviews, we preferentially chose individuals who expressed their opinions in the optional comments and opinion section of the pre-survey. These two aspects of the selection process may have been a source of bias among the participants in the present study.

The participants in the current study were limited to residents of the Kanto and Kansai regions, and the pre-survey of 2000 people confirmed that, in areas closer to Fukushima, more people agreed to the disposal policy and had more interest and knowledge regarding the topic (Takada et al. 2024). Although we did not observe any clear differences in participants’ opinions by region in the present study, we did not conduct surveys in regions outside of the Kanto and Kansai regions. Thus, it should be noted that the opinions of participants in the current study may not accurately reflect those of the wider population of Japan.

The present study was conducted in 2023, and the pre-survey results indicated that 20% to 30% of participants had knowledge about the final disposal policy (Takada et al. 2024). Depending on how the government implements the policy from this point forward (e.g., the process for selecting candidate sites), there could be significant changes in public attitudes. In addition, the present study targeted public opinion toward the policy, focusing on public comprehension on a national scale. A different approach would be needed to examine the process of selecting a candidate site(s).

Conclusion

The purpose of the present study was to identify underlying values that influence the formation of public opinions on the final disposal policy for soil removed from the site of the Fukushima accident. To examine this issue, online interviews were conducted. The participants were 40 residents who lived outside of Fukushima Prefecture, in areas that could potentially be considered as candidate sites for final disposal, and included both supporters and opponents of the policy. Quantitative text analysis of the interviews confirmed that supporters’ statements tended to reflect themes related to sharing the burden of Fukushima (a maximin principle perspective), whereas opponents’ statements tended to reflect distrust of the government. Utilitarian statements regarding the risks and economic rationale were mentioned regardless of support or opposition regarding the policy. The current results suggest that a maximin-principle perspective regarding sharing the burden of Fukushima among all citizens in Japan as a basis for disposal outside Fukushima may be effective, and that procedural fairness is essential for individuals with negative opinions toward the policy. The present study revealed that the underlying values relating public perception of a disposal policy for the removed soil generated by a nuclear accident are a maximin principle and trust in the government, while a utilitarian perspective does not have an influence. The current results will be useful for developing public comprehension of the disposal policy for the removed soil from Fukushima accident on a national scale, and identifying issues that should be given special consideration by the government. In addition, our findings will provide valuable information from the perspective of public acceptance and stakeholder involvement in the selection of candidate radioactive waste disposal sites, including those for decontamination waste derived from a nuclear accident, especially in cases where such sites are located far from the waste generation site.

Data availability

No datasets were generated or analysed during the current study.

Compliance with Ethical Standards

Conflict of interest

Financial interests: All authors received financial support from the Environment Research and Technology Development Fund (JPMEERF22S20930) of the Environmental Restoration and Conservation Agency provided by Ministry of the Environment of Japan. Michio Murakami received financial support from a private company, Mitsubishi Research Institute, Inc. for meetings and hearings unrelated to this study. Non-financial interests: none.

Consent to participate

The study was approved by the research ethics committee of Hokkaido University (receipt number, FY2022-22). Participants were given detailed information about their participation in advance by text, including an overview of the survey and the intended use of the data, and only those who responded to the email agreeing to cooperate with the survey were interviewed.

Consent to publish

The participants have consented to the use and publication of their responses for research purposes.

Supplementary information

The online version contains supplementary material available at 10.1007/s00267-025-02124-2.