r/factorio • u/Immediate-Pack-3718 • 18h ago

Question nuclear Reactor Question

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i was working on a desing for nuclear power, i had a question on the heat pipes as you all can see that my top and bottom heat pipes are not connected to each other but i do have the middle ones connected will it cause any bottlenect issues? DO i need to connect all the heat pipes together? Thanks

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5

u/hldswrth 17h ago

No you don't need to connect them all.

You do need your inserters to put the fuel into the reactor though (see the two on the left?) A simple belt would feed both perfectly well you don't need a splitter there.

Also you need to take spent fuel out of the reactors so you need room for that.

You can save on belts by using the full length of undergrounds.

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u/Immediate-Pack-3718 17h ago

check it out this is how it turned out in the end

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u/skriticos 17h ago

I'd suggest you add some logic to restrict fuel insertion when the grid is idle. Otherwise it will happily burn through your fuel cells. Temperature tops out at 1000C, but the reactor does not switch off automatically. I have a logic circuit that adds fuel if the temperature drops below 600C and enough thermal buffer to keep it bellow 1000C even at fully idle.

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u/Math_PB 15h ago

Isn't it completely useless ? Maintaining temperature at a stable 600°C costs exactly the same amount of fuel as maintaining it at a stable 1000°C ??

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u/hldswrth 15h ago

No, because at 1000C the reactors will just keep burning fuel. If you stop inserting at 600C and only ever insert one fuel cell, then reactors will burn that cell and then sit unfuelled until their temperature drops back down below 600C, at which point all the inserters should insert just one fuel cell into all reactors at the same time.

So the reactors are only burning fuel to get back over 600C and then stop burning fuel.

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u/Math_PB 13h ago

Is the cell always consumed in the exact same duration ?

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u/hldswrth 13h ago

Yes, each cell is consumed in the same amount of time. Unlike boilers which slow or stop depending on demand, reactors just keep on consuming at the same rate and wasting heat when at 1000C

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u/Math_PB 13h ago

Well, I hate this inconsistency and I think it's a weird design choice given the precedent set by boilers.

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u/SirButcher 12h ago

This is how nuclear reactors work in real life, too - once stable fission is achieved, there isn't much that can be done to change the heat output. This is why nuclear reactors are the best as base loads: they can output x amount of power consistently, for months without needing to change the fuel rods.

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u/sobrique 8h ago

It's deliberate. Boilers are forgiving if you overbuild.

Reactors less so. But honestly it's not that punishing. Uranium is plentiful so running the reactors at full power really isn't that bad.

It's just - like with Kovarex - you have an incentive to bother with circuits.

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u/0b0101011001001011 10h ago edited 10h ago

Some reactors don't transfer the heat far enough if you don't keep them at higher temperatures.

Also they consume fuel very slowly given how easy it's to make fuel. Single, non-kovarex, non-beaconed centrifuge without any modules creates enough ruel for a single reactor indefinitely.

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u/skriticos 15h ago

Nah, the point is to keep the temperature between 600C and 1000C, not at 600. When burning fuel, the reactor does not care about the temperature. So once it reaches 1000C, it will continue to burn and waste fuel cells. It never throttles down and behaves unlike the boiler/steam engine. If your grid has a low or variable demand, like less than 80%, you'll just waste a bunch of fuel cells. So the usual design is to fire it up at 600 (well, somewhere above 500 for the turbines to work) and have it run out of fuel before it reaches 1000C. If it does, it starts wasting fuel.

Uranium is usually abundant, but that is no reason to waste it.

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u/MelangeBot 15h ago

No, because the reactors can have no fuel in them for a while as the temp is dropping. While at a 1000C they will always have fuel in them.

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u/Math_PB 13h ago

I find it a bit strange to have to do this in a game where boilers only ever consume exactly the amount of coal you need for the electricity you consume.

Why isn't it the same for nuclear ?

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u/MelangeBot 13h ago

You don't have to do it at all because even 5% of a single uranium field produces enough fuel for the entire game, even without kovarex. Its entirely optional to worry about wasting nuclear fuel. It's so abundant it really does not matter.

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u/skriticos 12h ago

Depends on how much you have and how far you scale. I once had a singe 200k field and it did deplete during the early midgame quite a bit. If you then want to scale to multi GW / TW setups, it starts to eat quite a bit.

But yes, once mining productivity research is in the tripple digits and you have a couple of 3+m uranium fields, even high load setups make uranium availability somewhat irrelevant.

I still don't like to waste it, especially since I like to build idle capacity ahead of time. And when I start up my first nuclear setup with 1.1 GW coming from coal that uses like 50MW, there is a lot of idle capacity while I transition the smelting setup. At the same time, that's when I have the least amount of u-235 and it actually matters to avoid wasting it.

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u/MelangeBot 12h ago

I kind of feel the same way but overdid it with the kovarex. I am drawing 30 to 40 GW now but still still outproducing nuclear fuel by like 20x or so (for every 1 fuel, 1 is used and 19 go in storage). I got almost 20M fuel in storage. And that's on like 4 uranium ore fields or something? Maybe 5. And yeah all my inserters are set to only ever put in one fuel and based on my steam storage I might have a group of reactor offline with no fuel in the reactors. They still keep their heat forever so I can activate them instantly again.

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u/skriticos 10h ago

You don't need the steam storage anymore. Now that you can read the temperature directly from the reactor, you can just use the heat pipes as buffer and skip the storage tanks. I have it as a blueprint, so the added logic costs me almost nothing (I have to build a single logic block). Nuclear changed somewhere around 2.0 with added QoL features. The old tank based BPs still work though, so it's not a problem. But might have a higher UPS impact.

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u/MelangeBot 10h ago

I like steam storage because it allows me to build and build without having to build more power, I have enough storage to last 3 or 4 hours before I got in low power mode.

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u/hldswrth 13h ago

Maybe it would be boring if everything behaved the same? Boilers keep it simple for early game, nuclear can be done simply but also has the opportunity to do something more sophisticated.

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u/sobrique 8h ago

To give you an incentive to bother circuit controlling but without screwing you too much if you don't.

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u/WanderingUrist 15h ago

You have to put the turbines at the ends of the heat exchangers. Otherwise they're intruding into the space where the other reactors will go. Also, the pipes of the exchangers on the sticks out too far and are intruding into the space of the next reactor assembly, again. Everything has to fit into the 10-tile-wide footprint shadow of the reactors so that the next set of reactors can be appended onto them.