...and as such, any large monumental works are more likely to attract attention than to repel it. May even become a cult place of worship. More effective to bury and obfuscate the site entirely?
If it becomes a "cult place of worship", then that's probably Mission Accomplished; the faithful have a tendency to defend holy places against those seeking to defile them (read: dig into them and expose the world to nuclear waste). If they can be convinced that such sites are "God's Temples" and that defiling them will unleash all sorts of plagues (which they very likely will), then the current generation's job is done.
Religion in the service of natural selection? A nice twist. (E.g. all cultures without worship of holy places eventually perish.)
Maybe. On the other hand if the place is visibly menacing, and anyone who visits it gets sick and/or dies, then wouldn't a culture otherwise ignorant of the dangers of nuclear waste quickly put two and two together and stay away from the haunted, evil place? Shrug I don't have the expertise to judge whether this will be effective or not so it's all just supposition on my part.