Radiation woo refers to the collection of hysteria, nonsense and quackery loosely collected around the concept of radiation. It is notable for completely failing to distinguish between the various forms of radiation in the environment, particularly between ionising and non-ionising radiation.
A typical radiation woo argument will start by asserting that there are improbably huge numbers of cancers resulting from Chernobyl and from this assert that cellphones, WiFi and similar devices give you cancer because they also give off radiation. What do you mean nobody could be that stupid? It's the gospel according to Mike "Health Danger" Adams, is what.
The inability to distinguish between ionising and non-ionising radiation, low-level EMF, microwaves and radio-frequency communications, and even the different wavelengths of light, leads to the cottage industry around electrosensitivity and eventually to batshit insane devices like the Memoniser.
In an unfortunate and ironic twist, more people are estimated to die of radiation from uranium in the fly ash from coal fired power than in the entire history of the nuclear industry, and the worst single power generation related accident in history, which is estimated to have killed over 170,000 people, was due to the collapse of that tree-hugger's favourite, a hydro-electric dam.