[ChuckMcM]

This is the most common reasoning for people who fear nuclear power. They reason that they can't see where the danger (radiation) is so they can't know if they are in danger or not, whereas with an oil spill, a gas pipeline explosion, or an oil refinery event, they have visible boundaries to 'this area is bad' vs 'this area is probably still safe' (note its not of course, you can have odorless and invisible threats like CO but many of the failure modes are visible in a spectrum our unaided senses can detect)

I don't have a good answer for re-assuring these folks. (carrying a counter with them seems to be a non-starter, but perhaps a cell phone app would be ok)