[ceejayoz]

> How are dozens of nuclear power plants a single point of failure?

https://www.wired.com/story/nuclear-power-plants-struggling-...

"Amidst a slow-burning heat wave that has killed hundreds and sparked intense wildfires across Western Europe, and combined with already low water levels due to drought, the Rhône’s water has gotten too hot for the job. It’s no longer possible to cool reactors without expelling water downstream that’s so hot as to extinguish aquatic life. So a few weeks ago, Électricité de France (EDF) began powering down some reactors along the Rhône and a second major river in the south, the Garonne. That’s by now a familiar story: Similar shutdowns due to drought and heat occurred in 2018 and 2019. This summer’s cuts, combined with malfunctions and maintenance on other reactors, have helped reduce France’s nuclear power output by nearly 50 percent."

France is about the best existing case for nuclear, incidentally.

[Manuel_D]

The issue outlined above is a problem for all thermal plants. Coal and gas plants would suffer from the same issue.

Furthermore, nuclear plants don't need to be cooled with potable water. They can be cooled with ocean water, or with waste water. In fact, seawater cooling is the most popular form of cooling. Only 15% of nuclear plants are cooled with river water.

https://world-nuclear.org/information-library/current-and-fu....

[numpad0]

Off topic question. Can a large nuclear reactor be completely air-cooled? I think a full-scale reactor cluster expelling hot jet upwards and providing air conditioning in form of negative static pressure to its surrounding megalopolis would be very cyberpunk.

[Manuel_D]

Air doesn't have much thermal mass, so you'd have to move a lot of air through the heat exchangers to make it work. It's probably possible, but there's much more viable alternatives. In particular, you can use wastewater to cool plants where water is scarce: https://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_...

[ceejayoz]

https://www.npr.org/2018/07/27/632988813/hot-weather-spells-...

> Nuclear power plants in Europe have been forced to cut back electricity production because of warmer-than-usual seawater.

[Manuel_D]

This can be addressed by expanding heat exchangers. Unlike the river water cooling which is constrained by how much the plants are allowed to heat the river.

[numpad0]

Primary coolant loop runs at arbitrary temperature, there's never going to be a point that a nuke can't be cooled. It's only matter of designed capacity.

[Ghaenergyyy]

So a coolant loop can run at 100.000 degree? How?

[Log_out_]

Could part of that waste heat be transfered underground so that a city could use it as a differential source for heatpumps?

[Ghaenergyyy]

Yes but not solar or wind.

And YES It is a problem which needs to be fixed, increases risk and costs. Don't say its not a problem.

[cryptonector]

To be fair, and as a non-fan of wind (kills birds, annoys animals and humans) and solar (lowers the albedo of the planet, denies sunlight to parts of the local ecosystem), wind and solar do not have this cooling requirement. So that's nice. But anyways, you can always use sea water if you have access to the sea, or rely on a geographically-very-large grid for the diversity of sources that GP says we need.

[Manuel_D]

A geographically large grid will require extensive transmission network upgrades. That has to be factored into the cost competitiveness of these sources.

Renewable generation itself is cheap. But what's expensive (or straight up unfeasible) is everything required to mitigate the intermittent production. Storage at the scale of tens of terawatt hours can't even be feasibly built with current technologies. Moving electricity over thousands of miles, across mountain ranges, would require HVDC lines to be constructed in very rugged terrain.

[cryptonector]

Europe's and the U.S.'s grids are geographically large.

[Manuel_D]

Correct, but most generation is still produced close to demand. If you look at a map of where power plants are located (https://synapse.maps.arcgis.com/apps/dashboards/201fc98c0d74...) you'll see they're concentrated near cities. The grid spans a large area, but most energy is transmitted over a short distance.

Renewables, due to their low energy density and specific weather requirements, need to be built in remote areas. This has led to situations where the grid cannot accommodate transmitting the amount of energy that proposed renewable plants will produce: https://www.vox.com/videos/22685707/climate-change-clean-ene...

People often cite the decentralized nature of renewables as an advantage. It's not. It's a significant disadvantage as it has a much bigger burden on the transmission infrastructure.

[Ghaenergyyy]

Good studies showed that wind doesn't kill birds.

solar on roofs doesn't take anything from local ecosystem. Solar above car parks neither.

Solar on a home is such a simple, affordable and save solution, why are you 'non-fan'? which indicates you hate it? How much are you against it? So much that you prefer burning coal over it?

[oakwhiz]

It's possible to use "dry cooling" for a nuclear reactor. [1][2] The thermodynamic efficiency would be much lower, but it is possible to use alternative thermodynamic cycles/methods, for example reactors sent into space have used radiative cooling since there is no realistic way to use fluids to finally reject the heat.

1. http://large.stanford.edu/courses/2018/ph241/duboc2/

2. https://world-nuclear.org/information-library/current-and-fu...

[cryptonector]

So basically radiators. They would have to be huge, and they would have to move huge amounts of air through them. As a backup that might work, probably using a hybrid where a water body is used for cooling and air is the fallback.

[panick21_]

Air-cooling is possible. This only effect certain type of reactor. As soon as you go to higher temp reactor air-cooling is very efficient.

And even in France this was only a problem because of their terrible delayed maintenance.

> France is about the best existing case for nuclear, incidentally.

No it isn't. France has done essentially nothing for 30+ years. Has done little maintained, their reactors aren't up to date.

The generation after the generation that built the reactor has always resented the system and wanted to rip it out. They literally decided to retire it by 2035 despite having no plan to replace it.

[ceejayoz]

> No it isn't. France has done essentially nothing for 30+ years. Has done little maintained, their reactors aren't up to date.

I mean, we aren’t disagreeing.

They’re the best case, and that’s not great. It a bit like true communism - real success is just over that next hill.

[kjkjadksj]

Thats one of the shortcomings of using a river with variable flow over an ocean or large lake

[Loughla]

Ocean yes, but then that opens you up to hurricanes and/or tsunamis.

Lakes can dry up. So that's no better than a river I would think.

Either way, there are no fully safe and permanent sources of cooling water, is what I'm taking away from this.

[kjkjadksj]

Certain lakes aren’t going to dry up within human timescales. And disaster risk is present in a lot of places. Just something you take into account when you build it.

[addaon]

> Certain lakes aren’t going to dry up within human timescales.

Which ones? The North American Great Lakes, maybe? Anything else?

The Aral Sea was the third largest lake in the world. Within the human time scale of the last six decades, it's lost 90% of its area.

[kjkjadksj]

Aral sea was milked for agriculture. Not all lakes are like that.