Little is known about public opinion on where to host a long-term repository for high-level radioactive waste. This study tests first whether spatial proximity - i.e., the distance in kilometers of a person's place of residence to the location of a repository - affects three dependent variables: whether proximity a) increases personal relevance of the hosting decision, b) decreases acceptance of this decision, and c) increases the likelihood for opinion expression. Second, it examines whether the effect of proximity weakens when the site selected is located in a region relevant to a person's social identity, so that acceptance for the site selected decreases not only for geographically close but also for geographically distant locations.
Results come from two representative CATI-CAWI survey experiments exposing different participants to different vignettes concerning the hypothetical selection of a site for a nuclear waste repository (n = 3,015).
The first 5x1-experiment only manipulated spatial proximity of the site selected to respondent's place of residence (5/30/50/100/200 km). Results confirm that spatial proximity increases personal relevance of the hosting decision. The second 3x2-experiment tested whether the effect of spatial proximity (5/30/50 km) changes when telling respondents that the site selected is located in their own (vs. another) region. Results reveal a significant interaction between both factors: While spatial distance significantly decreases personal relevance when located in another region, personal relevance does not decrease by spatial distance when still located in respondent's own region (H2). Further mediation analysis shows that personal relevance subsequently influences acceptance and opinion expression about the hosting decision.
This study provides evidence for in-group favoritism for geographically distant communities considered to host a nuclear waste repository. Thus, future research should go beyond the simple idea of "not-in-my-backyard" but should consider public opinion on environmentally relevant infrastructure projects as a result of a "not-in-our-backyard" mentality.