Because everyone is scared of nuclear contamination, potential terrorist target, and some idiots – pardon me – fear that somehow it’ll turn into a nuclear bomb. Of all of these, nuclear contamination is perhaps the only reasonable one, however the containers they developed for holding nuclear waste are as close to indestructible as anything mankind has created so far. The terrorist threat is unlikely because if there is ever any Nuclear, Biological, or Chemical attacks on American soil, we have an initiative that allows us to nuke whatever country, or region we believe to be behind such action. The rest of the world’s governments more or less agree or submit to this.