Is it relevant? It's writing about a pool for storing spent fuel, which is not a part of the actual reactor system.

  This incident report says that the worker fell into a "reactor cavity" containing water and that there was a measurable amount of radiation detected in their hair after the initial clean-up. The two situations don't seem remotely compatible to me.

I guarantee you there's 'a measurable amount of radiation' in your hair right now. Unless you're bald, I suppose.

Yeah, no shit. But, come on, don't play dumb. By measurable, I obviously meant "above normal background". Something that shouldn't have been possible if, as described in the xkcd post, the water should have had less radioactivity than normal background. Combined with the fact that the post was literally about a different kind of pool than the one involved in the accident, it was reasonable to question whether the post was actually relevant.

I agree this was not a serious incident, and I never really though it was. (I'm extremely pro-nuclear, for the record.) But at the time I posted, the comment section was about 8 people posting the xkcd link at once (with no additional commentary), and few others reading it and saying "oh, no problem then", with literally nobody pointing out the discrepancies, or explaining exactly what a "reactor cavity" means in this context.

> You may actually receive a lower dose of radiation treading water in a spent fuel pool than walking around on the street.

Wow

And a video: https://www.youtube.com/watch?v=EFRUL7vKdU8

So if I understand this correctly (solely from reading the xkcd), then the person might actually be okay?

They're totally fine.

I find it highly informative that the required PPE for working in that location is a life jacket so you float in case you fall in, rather than a tether and fall arrest harness so that it's not possible to fall in.

300 CPM is nothing, background levels might be 150.

Background is probably a bit lower depending on where you're at. My counter went through airport security luggage scans 'cause they wouldn't let me wear it through the metal detector. It beeps for a few seconds and then comes out about a days' dose of natural radiation higher. The count was higher than 300 CPM, but obviously only shortly. That poor bloke might stay at 300 (if ingested and he can't scrub it off) for a while but it's still not very discouraging long-term. Pilots have about that at cruising altitude.

> Plant officials today confirmed the worker sustained minor injuries from the fall and has already returned to work. - https://www.mlive.com/news/2025/10/michigan-nuclear-plant-wo...

He went back to work the next day. They don't provide much detail about the minor injuries but it seems that the biggest issue is maybe a bruised shin from the fall.