Live data from Hacker News

Danube's record low levels force shutdown of Hungary's only nuclear plant

bbc.com

111–120 of 252 posts

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#111
post #57

Here in Switzerland during some heatwaves they have to shut down nuclear plants too because the river water is too warm and adding warm water to it would kill the fish.

Would a cooling pond with controlled discharge into the river maybe mitigate this problem? One could also cycle the water from the cooling pond through the plant's cooling loop. The worse that could happen is evaporate the water from the cooling pond which is gets replaced with new water (sans fish) from the river.

Nuclear plants can run with those hyperboloid cooling towers as the sink for waste heat. They are just a lot more expensive to build, run and maintain compared to using river water.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#113
post #57

Here in Switzerland during some heatwaves they have to shut down nuclear plants too because the river water is too warm and adding warm water to it would kill the fish.

Would a cooling pond with controlled discharge into the river maybe mitigate this problem? One could also cycle the water from the cooling pond through the plant's cooling loop. The worse that could happen is evaporate the water from the cooling pond which is gets replaced with new water (sans fish) from the river.

> Would a cooling pond with controlled discharge...

There are any number of methods of dealing with this. Using natural bodies of water is a lower cost (thus highly popular) method of sinking heat. Palo Verde has been operating 3 large reactors in the Sonoran Desert in Arizona since the 1970s. There is no reason in engineering or physics that a power reactor must be highly sensitive to any particular lake, river or ocean's temperature. This is strictly about money, being cheaper to rely on a big "free" heatsink, and leaving too little margin for changing conditions.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#114
post #43

Of course a 1960's design isn't adapted to current weather conditions. That doesn't mean the whole technology is useless, like so many commenters imply. Any new build can and will include cooling adapted to hotter conditions.

The one that shut down in Romania is a CANDU, built in the 80s.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#115
post #110

Earlier quoted context omitted.

Hungary is already using that (today we were 90% carbon-free thanks to solar), the problem is what to do when it gets dark.

"the problem is what to do when it gets dark" Batteries (or pumped storage hydro, which is more like a gravity-driven capacitor)

Hungary is flat as hell, there's nowhere to build enough hydro storage.

But yeah batteries would be nice.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#116
post #110

Earlier quoted context omitted.

"the problem is what to do when it gets dark" Batteries (or pumped storage hydro, which is more like a gravity-driven capacitor)

Hungary is flat as hell, there's nowhere to build enough hydro storage. But yeah batteries would be nice.

AFAIK the mountains are about as high as Wales? It looks like there's a 600MW storage scheme in the planning stages. That's about a third of the capacity of Wales's largest system (which is the biggest in Europe) and about twice the capacity of the second system.

It's a meaningful contribution I would have thought.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#117

Earlier quoted context omitted.

Begs the question: coul reactors use radiative air cooling? Channel the water through a huge radiator and transfer the heat to the air

The temperatures aren't high enough to do that (or air cooling) efficiently enough. Some experimental designs for high temperature operation would have that as a possibility (e.g. molten salt reactor designs). I think a Chinese research project is looking into air cooling for nuclear power in dry regions.

There's also the potential of co-locating non-evaporative cooling with CO2-scrubbing using a strong KOH solution in the big cooling towers and regenerating the hydroxide with calcium hydroxide (regular process done in kraft process paper mills, though they use NaOH with slightly favoured properties over KOH). KOH is very hygroscopic; it does not have to be humid for a barely-still-liquid solution to actually dehumidify in the process.

Or, if that's too much effort for them, use e.g. LiBr or other such atmospherically-stable salt that can maintain humdity equilibrium with dry ambient air.

The reason for even involving a water-based solution at all is because you can spray it or at least run it over dense corrugation (sheets alternating orientation, but overall with the channels roughly pointed upwards) "packed beds" with free contact between the coolant and the air, instead of having to maintain a barrier layer between the two (typical car/computer radiators, but also AC coils), which notably saves you from even a potential for a there-required barrier layer to leak and from having to clean such a barrier layer. If you make the corrugations large enough and have some simple mesh filters in the intake path that you just roughly shake/rinse/blow/brush off every once in a while, you can prevent particles larger than a rice grain from getting to the coolant in the first place and wash/rinse all the sand grain and smaller dust particles down into the coolant sump where their densities are far better matched (than air vs. dust) and volume flow is much easier to handle/filter.

The big part of these is still that they don't require active fan ventilation to cool radiators, which would be a substantial increase in critical electrical power needed after a SCRAM to keep the core from melting down; vs. the passive evaporative cooling towers and the KOH/LiBr non-humidifying variant I mentioned.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#118
post #54

Earlier quoted context omitted.

Absolutely wrong. A difference of a couple degrees is not going to hamper cooling a reactor that is running at many hundred degrees. Just imagine what it would spell for your car otherwise.

I think both nuclear steam and car engines are affected by high ambient temp, gas and coal engines too. That is after all why they bring in water or air to car radiators, to cool them. Probably only a single percent or so for a few degrees change though.

Convection cooling efficiency is mostly dictated by the delta in temperature between the hot and cold source. Coolant temperature in the core is in the 300C ballpark. So the river going from 20 to 30C is roughly a 0.3% change in cooling efficiency.

For your car, coolant temperature is typically in the 80-90C range. So the same change in external temperature would be a loss of ~10% of cooling efficiency. Still, cars have no issue running in 30C temps, and IME you have to go up to 45 to really need specialized cars.

So if you car can swallow 40C and >10% efficiency loss without a sweat, a NPP will have 0 issue using 30C water to cool their cores.

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#119
post #110

Earlier quoted context omitted.

"the problem is what to do when it gets dark" Batteries (or pumped storage hydro, which is more like a gravity-driven capacitor)

Hungary is flat as hell, there's nowhere to build enough hydro storage. But yeah batteries would be nice.

You can do low(er) head pumped hydro storage [0]

[0] https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power...

Re: Danube's record low levels force shutdown of Hungary's only nuclear plant

#120
post #66

Earlier quoted context omitted.

Very few things are purely technical decisions. In this case, it’s about centralized vs. distributed electricity generation (or freedom vs. dependence if you want to state it that way). One of these options makes it much easier for the billionaire class to continue extracting money out of the people. Edit: I don’t understand how you get from „political decision“ to „state violence“. Politics are at play at all levels…

>In this case, it’s about centralized vs. distributed electricity generation (or freedom vs. dependence if you want to state it that way). The venn diagram between people who act like renewables are "freeing" (which make no mistake, they absolutely could be) and the people who advocate nonstop for government management of how they are deployed is too close to a circle for me to take such commentary seriously. >One of…

> people who act like renewables are "freeing" ... and the people who advocate nonstop for government management

Where did the person you are replying to even hint at that? I think this may be your own prejudice spilling out here.

> The billionares have their money in everything. They get a cut of everything. You're just changing who gets the cut.

Oh ok, I guess let's just accept this as is forever. Any attempt to try to improve this situation is futile and stupid (for example, as said, making it more difficult for them)

>What backs up all those decisions other than credible threat of violence?

I don't know, do you only act in fear of the threat of violence from the state? In democracies politicians are legitimized by their voters, what you are describing sounds more like an autocracy.

Post reply on HN