[dhritzkiv]

> Since nuclear uses water, which freezes

I suspect that the water involved in the steam generation (heavy water or otherwise) wouldn't freeze since it's inside/near the core, and constantly temperature regulated.

The water used for cooling would go through heat exchanging and would also not freeze, especially if it's underground, or deep in a lake somewhere.

[oivey]

This isn’t theoretical. A nuclear plant was knocked out of service due to water freezing at the current temperatures.

[dhritzkiv]

I stand corrected.

I had trouble finding articles detailing how the nuclear plant was brought down, but then I found this:

> On Monday, Feb. 15, 2021, at 0537, an automatic reactor trip occurred at South Texas Project in Unit 1. The trip resulted from a loss of feedwater attributed to a cold weather-related failure of a pressure sensing lines to the feedwater pumps, causing a false signal, which in turn, caused the feedwater pump to trip. This event occurred in the secondary side of the plant (non-nuclear part of the unit). The reactor trip was a result of the feedwater pump trips. The primary side of the plant (nuclear side) is safe and secured. […] We evaluated Unit 2 and have confirmed that we do not have the same issues that caused the feedwater pump trips in Unit 1.

and subsequently, an answer to my question of 'how':

> Some people have wondered how “pressure sensing lines” for a feed water pump could have been affected by cold outside air temperatures. There are no turbine halls at STP, both of steam turbines are out in the open air. I’m sure there is a design reason for this choice, but it isn’t apparent.

(from https://atomicinsights.com/south-texas-project-unit-1-trippe...)

[8note]

Which water though?

Water related to the main cycle of the plant? Or something non-essential like the toilets, or some valve froze shut because water froze on the outside of it?

[dhritzkiv]

I didn't want to admit it in my original comment, but I basically thought something along these lines haha

[oivey]

I don’t think the toilets would knock a nuclear power plant out of service.