Nuclear Nightmares talks about how radiophobia (fear of radiation) is common but not based on scientific evidence. After Chernobyl, there were a lot of fatalities in the news, some close to 400,000, but the reality was that only 57 (yes, 57) deaths could be directly or indirectly linked to the accident.
It seems that low doses of radiation are not harmful because the body already has defense mechanisms. Radiation only begins to cause harm to the body when it exceeds a certain threshold. In addition, low doses of radiation appear to activate genes responsible for preventing cancer, so cancer cases are actually lower in areas with higher-than-average background radiation.
Of course, fears of radiation were normal during the Cold War, and now that our fossil fuel reserves are nearly depleted, nuclear power is desperately needed to make up. How much of this documentary is actually about dispelling excessive fear of radiation, and how much is about promoting nuclear energy, is up to you.