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I'm pretty sure the engineer at the nuclear plant I visited in elementary school drank a glass of water out of that pool to demonstrate how safe it was.

I hope I'm misremembering that but it's a pretty strong memory that totally locked in for me that that water is not necessarily dangerous.



Serious question, as daft as it might sound - do they have to chlorinate the water to stop stuff growing in it? I'd expect it'd be about "swimming pool" warm so just great for all sorts of manky algae growing.


The water is borated and heavily purified. You don’t want stuff growing inside, but at the same time you don’t want to have chlorinated water slowly corroding the metal components.


Check out this study. Pretty wild! [https://pmc.ncbi.nlm.nih.gov/articles/PMC7760952/]


I also read in the XKCD thing that it might be up to about 50° so it's probably a bit uncomfortable for most algae type things.

I bet there's some good chance of getting wacky extremophiles though!


50C is terribly hot for a swim.

Hot spring baths usually top out around 42-43C


Would you mind sharing a link to "the xkcd thing" if you have it?

edit: sorry for being lazy, I scrolled a bit more and found it.



Relevant: "For the kinds of radiation coming off spent nuclear fuel, every 7 centimeters of water cuts the amount of radiation in half."


On the picture, the fuel rods are indeed protected by a huge quantity of water above them. But what happens below them ? They seem to be in direct contact with the ground...


People tend to avoid casually tunneling under nuclear pools.


I would guess that in reality they are either suspended and/or there is enough concrete at the bottom


Chlorinating the water would have adverse effects on material strength and longevity. Even irradiated and heated to 50c, I’ll bet there’s some extremophile bacteria in there somewhere.


Just an update: I finally remembered that it was the UVA research reactor (since decommissioned). https://news.virginia.edu/content/reacting-history

But now 100% sure that actually happened. Also it was likely a professor and not a working engineer drinking the water which makes much more sense.


Had a buddy on a nuclear sub drink water from the primary coolant loop when he joined the team.

While I do see this as a form of hazing which I am morally opposed to-

8oz (.237 liters) of primary coolant in a properly maintained pressurized water reactor might contain up to 13mrem of orally ingestible radiation, or approximately the radiation of a chest x-ray. (For comparison you get between 3-8 milirem on a 7 hour transatlantic flight)

Don’t make it your primary source of hydration and you’ll be ok. If the fuel is degraded or there is a leak (unlikely in properly maintained PWRs) the radiation dose is significantly higher.


That makes zero sense. Radiation is not a component of water; it is literally photons[0]. In the nanosecond after you fill the glass, all the radiation in it has left the volume.

I'd drink it. It's just extremely pure water, with a nuclear flashlight at the bottom of the pool - which no one could see, even if they had gamma-ray glasses on[1], because the water attenuates it so much.

[0] Or ions of hydrogen or helium, in the case of alpha and beta radiation.

[1] Which it turns out were way less cool than the Sea Monkeys(tm).


Radiation isn’t contained in the water as photons, but the coolant itself becomes radioactive through neutron activation. Even with intact fuel rods, oxygen in the water turns into N-16 with a half-life of about seven seconds, and trace metals like nickel and cobalt form isotopes such as Co-58 and Co-60. These emit strong gamma radiation while the reactor operates.

The primary coolant is not simply pure water; it contains boric acid, lithium hydroxide, dissolved hydrogen, and trace corrosion products like iron, nickel, cobalt, and chromium. Under power level neutron flux, some of these elements become short- or medium-lived radionuclides. Once removed from the core, most of the activity decays within minutes, but during operation the water is measurably radioactive.

An eight-ounce sample taken from the loop at power would carry roughly the dose of a chest X-ray before it decayed away, due to these activated isotopes rather than residual photons [EPRI PWR Primary Water Chemistry Guidelines; NUREG-1437][0].

I was on site for the mid cycle outage of three mile island unit 1 around 2005. I did the data sync and transfer for the steam generator inspection, but got tutored by some old PHDs during the down time.

[0] https://downloads.regulations.gov/NRC-2020-0101-0142/content...


Thank you very much! TIL!


I mean, apparently the inventor of lead additive to gasoline used to pour the chemical over his hands to demonstrate how safe it was -- even though he knew it was actually quite toxic. So there are people who will knowingly give themselves small doses of poison to keep the money flowing.

[1] https://www.youtube.com/watch?v=IV3dnLzthDA&t=604s


Fair enough - although this engineer didn't stand much to gain by impressing a bunch of 10 year olds.




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