[djtriptych]

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.

[ErroneousBosh]

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.

[rcruzeiro]

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.

[lazide]

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

[ErroneousBosh]

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!

[Zacharias030]

50C is terribly hot for a swim.

Hot spring baths usually top out around 42-43C

[luckman212]

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.

[johnisgood]

https://what-if.xkcd.com/29/

[ethbr1]

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

[wiz21c]

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...

[dundercoder]

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.

[djtriptych]

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.

[dundercoder]

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.

[IAmBroom]

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).

[dundercoder]

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...

[IAmBroom]

Thank you very much! TIL!

[gwd]

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

[djtriptych]

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