Something wrong with my nuclear power plant?

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zoiX
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Something wrong with my nuclear power plant?

Post by zoiX » Mon Apr 16, 2018 8:46 pm

Hello Factorians,

My first post-.15 playthrough has reached the point where I have build a small nuclear power plant. It consists of 8 reactors, 40 exchangers and 80 turbines. I know there's a significant surplus of reactors in the setup, but that's not the point here.
My problem is that I'm not sure wether my setup is feasible for further scaling or not. I have noticed that the power production is a bit less than I would expect and wonder if this is due to a systematic problem in my build or if my expectations are just wrong.
So, to get to the matter, screenshots:

Image
The setup as is. I tried to keep the connections between storage tanks and exchangers as short as possible, because I read in several other threads that steam throughput can become limiting.

Image
The numbers (Don't mind the distinct lack of power in my factory, I am in the process of expanding the power plant. This is why I want to check the feasibility of the setup.)
I get 381 MW out of the plant, which does not fit with the math I did: 40 exchangers produce 40*103.1 = 4123,6 units of steam. 80 turbines would need 4800 units and produce 465,6 MW when supplied with enough steam. However, my 4123.6 units of steam can only cover 85.9% of the demand, so my expected power production would be 399,99 MW (or 10 MW per exchanger. Should have read the wiki earlier.)
That means I am missing 20 MW or 5% of the expected power. Where are those 5%?

Zavian
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Re: Something wrong with my nuclear power plant?

Post by Zavian » Mon Apr 16, 2018 9:15 pm

Just from a quick glance it look like you are trying to pump 3600 water/sec (the output of 3 offshore pumps) through each set of underground pipes. That isn't going to work, for your setup the underground pipes will have a flow rate of around 1500 water/sec. (You can do better if you can reduce the number of pipes, but for most purposes you should consider the maximum flow rate of a pipe to be around 1200-1500 fluid/s over short distances and 1000-1200 fluid/sec over longer distances. There is a table in the wiki. https://wiki.factorio.com/Fluid_system). Heat pipes also have a maximum flow rate, I'm not sure whether you are also going to run into problems there.

Edit: Checking https://www.reddit.com/r/factorio/comme ... ar_ratios/ sugggests that for 40 heat exchangers you only actually need 3.5 offshore pumps, so maybe water flow isn't the problem. But I'm not sure you have enough heatpipes to effectively transfer heat to all your heat exchangers. (8 reactors should also support 112 heat exchangers and 193 turbines).

I would also remove all the cross-connections from your water and steam pipes. Sometimes providing alternate flow routes actually reduces effective throughput. 1 offshore pump -> one underground pipe. Use a pump to repressurise immediately before the heat exchangers. Each heat exchanger should output to one tank, with no cross connections.

For the heat pipes, move the reactors southward, and relocate one of the middle rows of turbines to the south, so you have 2 sets of 5 rows. Then your heatpipes come from your reactor, then head north and south. That will reduce the effective length of the heat pipes. For more throughput you can also try using heat pipes in parallel.
Last edited by Zavian on Mon Apr 16, 2018 10:38 pm, edited 1 time in total.

bobucles
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Re: Something wrong with my nuclear power plant?

Post by bobucles » Mon Apr 16, 2018 10:02 pm

Pipes have a finite flow rate. The safest flow rate is one pump feeding 11 heat exchangers and 20'ish turbines. A single water pump almost nearly saturates a water pipe. Extra pumps are only good for maybe squeaking in some extra water for a short line.

vanatteveldt
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Re: Something wrong with my nuclear power plant?

Post by vanatteveldt » Tue Apr 17, 2018 7:40 pm

IMXP the main problems with scaling nuke plants are water and heat.

Heat simply does not go over long distances. You need to have the exchangers close to the plant. It might not be a problem yet in your setup (which is difficult to diagnose) but it will be if you scale linearly.

Water (and steam) go fine over long distances, but has limited capacity. It's fairly trivial to have 1000 per second, hard to keep up 1500/s, and almost impossible to get more. So, my strategy is just to assume about 1000 per second. For that reason, I decided to go for 8 exchangers per pump, which makes the water piping issues trivial (see viewtopic.php?f=208&t=47895 for my design - I guess it's a rite of passage to post a nuke design here :)).

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disentius
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Re: Something wrong with my nuclear power plant?

Post by disentius » Tue Apr 17, 2018 10:22 pm

yep. I Am testing this one atm. can run full capacity so far without power dips
Can be converted to belt feeding. reheating will get slower then.
1GW reactor with fuelcontrol.PNG
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Optera
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Re: Something wrong with my nuclear power plant?

Post by Optera » Wed Apr 18, 2018 6:31 am

Fluid mechanics, updating one piece a time depending on placment order, seems to work against setups where you merge all boilders and turbines.
The same setup with dedicated fluid path for each row of boiler-turbine is a lot more stable.
My Mods:

bobucles
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Re: Something wrong with my nuclear power plant?

Post by bobucles » Wed Apr 18, 2018 2:08 pm

Indeed flow mechanics tend to favor single clean pipelines that flow directly from start to finish. Try to avoid doom blobs of pipes whenever possible.

zoiX
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Re: Something wrong with my nuclear power plant?

Post by zoiX » Thu Apr 19, 2018 8:51 pm

Well, thanks for the help. I took the advice and isolated the steam lines from each other. Now it's working nicely, was expanded successfully and I'm prepped to crack 1 GW. Maybe needs another rebuild when the factory approaches 2-3 GW, but rebuilding stuff is the name of the game, isn't it?

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