In Season 5 Episode 2 of Fear the Walking Dead, Morgan and Alicia meet up with Grace who tells them there was a meltdown at a nuclear plant nearby and so some of the walkers are radioactive. Morgan has already killed two of these walkers and so Grace takes his stick and his clothes away because they are contaminated. But my understanding is that wood, when exposed externally to radiation, can't be contaminated. So why did she take it and why won't she give it back? Did the writers get their facts wrong or did I miss something?
Anything, no matter what it's made of, could get contaminated stuff stuck to it if it gets dirty because of contact with a contaminated object. And wood is porous, so when you wash it you won't get every atom of dirt off it. So if you were scared of radiation, yeah, you might just throw out the wooden thing that might have gotten contaminated.
Whether it's strictly necessary or not I don't know, but it's certainly plausible enough that a reasonable person could think it's necessary.