“Not in My Backyard” or “Not in Our Backyard”? Public Opinion on Nuclear Waste

Little is known about the factors influencing public opinion on where to host a long-term repository for nuclear waste. This study investigates the influence of two potential explanatory factors on three dependent variables (DV): individuals’ perceived personal relevance of the selection decision (DV1), their level of acceptance of this decision (DV2), and their likelihood for public opinion expression on the matter (DV3). As first explanatory factor, the study focuses on spatial proximity, i.e., the geographical distance of a person’s place of residence to the location of a potential repository. Spatial proximity is a key driver of public opinion on large infrastructure projects and its influence is often summarized as a “not-in-my-backyard (NIMBY)” mentality. Hence, hypothesis H1 assumes that spatial proximity increases perceived personal relevance (DV1) of the site selection decision for a nuclear waste repository. However, literature also shows that the NIMBY mentality is often moderated by additional factors. We expand this literature by introducing the selected host site’s relevance for social identity as a potential moderator, particularly whether the site is located in a region relevant to a person’s social identity. More precisely, H2 assumes that perceived relevance of the hosting decision (DV1) decreases less strongly for spatially distant sites when the region selected is relevant to social identity than when located in a region not relevant to identity. Finally, research question RQ1 asks whether the co-influence of proximity and identity does not only affect perceived relevance of the selection decision (DV1) but subsequently also individuals’ acceptance of this decision (DV2) and their propensity for opinion expression about the decision (DV3). 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 (H1). 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). Lastly, we tested for indirect mediation effects in a structural equation model (RQ1). Results show that the interaction of spatial proximity * social identity affects perceived relevance. In turn, perceived relevance decreases acceptance while it increases opinion expression. Hence, the smaller effect of spatial proximity on perceived relevance translates into stronger opposition against the decision and a higher likelihood for individuals’ opinion expression when social identity is salient. This study provided 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.