Fuel Conserving Nuclear Power Setup

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JDoolin
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Fuel Conserving Nuclear Power Setup

Post by JDoolin »

Nuclear Power Setup
Nuclear Power Layout
Nuclear Power Layout
Nuclear Power Layout
nuclear-power-layout.PNG (828.92 KiB) Viewed 7315 times
I made this design in order to get good use out of the neighbor bonuses of the nuclear power plant. When you put fuel into the box, it gets passed around until there is exactly one fuel outside each reactor. When the count reaches some absurdly high number, the steam levels are checked, and if the steam is below capacity, the six inserters simultaneously insert fuel into the six reactors.

I am curious about optimization for UPS , though. I have heard that using combinators and signals reduces UPS, but I haven't seen any guidelines for how to optimize circuits to keep processor usage low. Incrementing this counter and multiplying it by 1 every sixtieth of a second seems like a bit of a waste of processor time when I only want it to act once every five to ten minutes or so.

Xtrafresh
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Re: Fuel Conserving Nuclear Power Setup

Post by Xtrafresh »

Nice!

Re: optimization. The circuit network doesn't update unless something changes. That counter is going to spam updates in there. What you can do is use a 'belt clock': a trivial item on a circular belt that gets detected each time it comes around. I find it to be less elegant, but when pressed for UPS, it does work.

Can I ask? Why only check once in a while? Don't you want it to just go when ready?

Aru
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Re: Fuel Conserving Nuclear Power Setup

Post by Aru »

It would probably take a lot more combinators than that to slow down the CPU, so I wouldn't worry about it. Use however many you want.

That's not nearly enough heat exchangers and water to keep up with the heat output of 6 reactors. I need 6 rows of 8 (48 exchangers) just for four reactors.

JDoolin
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Re: Fuel Conserving Nuclear Power Setup

Post by JDoolin »

I'll have to check but I think the heat pipes max out at 1000 degrees Celsius. If they never reach that temp then you've got enough heat exchangers.

How should I set up a belt clock? Should I use a combinator to count the laps? I've thought about that a little. I wondered about this though... the game updates the position of the object on the belt 60 times per second. And it adds 1 to a counter 60 times per second... does the object on the belt take less time for the computer to process?

I think the timing is mostly superfluous. It saves fuel once, when operation first begins. When the first six fuel cells are put in, after 120 seconds, the pipes are super hot but there's very little steam. If another 6 cells are put in now, the pipes go to 1000 Celsius and energy gets wasted. But if you wait 5 minutes, those tanks will fill with steam, and get over the threshold.

After that, it's probably okay to put six new cells in as soon as the steam goes below the threshold.

So I guess you could go without the counter. Just, when you first start it, put less than 12 cells in the system.

roothorick
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Re: Fuel Conserving Nuclear Power Setup

Post by roothorick »

I took a similar, but simpler approach, using a clock (combinator clock) to count out how long it takes a fuel cell to burn, and combining that with a "steam low" signal to control the fuel inserters. If the reactors aren't active, the circuit network is dormant; in addition, the reaction to low steam is immediate, and it manages the fuel with single-cell granularity, so it's incredibly stable under fluctuations in demand. I probably should make a post with my version.

In my design, the fuel is managed by enabling/disabling the inserter that's putting the fuel into the reactor. I distributed the fuel on a plain old backed-up slow belt, with inserters pulling off that common belt just 1-3 cells into a buffer chest (wired to chest, enable when fuel < 1) for the inserters facing the reactor to pick up.

mrvn
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Re: Fuel Conserving Nuclear Power Setup

Post by mrvn »

Reactors heat up up to 1000°C. After that they just waste fuel. Heap pipes can only heat up to the temp their neighbours have, so 1000°C top too. Heat exchangers work until they cool to 500°C.

You never want your reactor to reach 1000°C, because then it starts wasting fuel. So you need enough heat pipes to draw out the heat and enough heat exchangers to consume the heat so it never reaches 1000°C. That doesn't mean you need 48 heat exchangers for 4 reactors. Heat pipes have a lot of heat capacity and if you insert fuel cells slow enough then the reactor never reaches 1000°C even with less heat exchangers.

What it does mean though is that you can never run your reactor at 100%. But if your goal is to run it at 50% then you only need half the heat exchangers. Personally I would build enough heat exchangers to run full throttle and then have them idle 50% of the time. Because soon enough you will need 60% power output.

Challenge: Design a 2xN nuclear reactor with the minimum number of heat exchangers. It must never waste fuel.

roothorick
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Re: Fuel Conserving Nuclear Power Setup

Post by roothorick »

mrvn wrote:Challenge: Design a 2xN nuclear reactor with the minimum number of heat exchangers. It must never waste fuel.
Way simpler than it sounds. For 2x1 and 2x2, lay out a grid of 33 or 193 heat pipes next to each reactor respectively. For 2x3 up to ~2x16, put 193 heat pipes next to the end four reactors, and 257 next to the rest. In all these cases, use a single heat exchanger and two turbines. Once you hit ~2x17, you'll have to add another heat exchanger (and the appropriate ratio of turbines) for every ~17 rows, rounding up. Each exchanger should be attached directly to a reactor and as close to the center of its group of reactors as possible, to maximize the flow out of the heatpipes into the heat exchanger. Use a system very similar to mine to manage fuel based on measuring steam in... just one tank, per exchanger really. Within the full 200 second burn cycle, the heat exchanger will produce 20.6k steam. After that point, there's no new heat entering the system, so the reactors (and heatpipes) are cooling from the exchanger producing steam. Start the reactors again when steam hits ~4k.

Extremely impractical, however -- 2x8 reactors for a piddly 9.6MW? Ew. In practice, utilizing reactor capacity (MW, not MJ) is more important, so you should be piling on the maximum number of heat exchangers.
mrvn wrote:What it does mean though is that you can never run your reactor at 100%. But if your goal is to run it at 50% then you only need half the heat exchangers. Personally I would build enough heat exchangers to run full throttle and then have them idle 50% of the time. Because soon enough you will need 60% power output.
Under the right conditions (demand > reactor capacity, because you're supplementing with solar or simply need to scale up), yes you can. With my "fuel timer" system I achieved 100% fuel utilization under any load with 2x1 reactors, 17 exchangers and 29 turbines. I deliberately did +1 exchanger and rounded the turbine ratio up so that if there was enough demand to push the turbines to full-tilt, the reactors would be incapable of reaching 1000C even at the full 100% duty cycle. The system will still work with more front-loaded ratios, but then the reactors will stop short of 100% duty cycle when the turbines or heat exchangers are overloaded, leaving some reactor capacity on the proverbial table.

mrvn
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Re: Fuel Conserving Nuclear Power Setup

Post by mrvn »

roothorick wrote:
mrvn wrote:What it does mean though is that you can never run your reactor at 100%. But if your goal is to run it at 50% then you only need half the heat exchangers. Personally I would build enough heat exchangers to run full throttle and then have them idle 50% of the time. Because soon enough you will need 60% power output.
Under the right conditions (demand > reactor capacity, because you're supplementing with solar or simply need to scale up), yes you can. With my "fuel timer" system I achieved 100% fuel utilization under any load with 2x1 reactors, 17 exchangers and 29 turbines. I deliberately did +1 exchanger and rounded the turbine ratio up so that if there was enough demand to push the turbines to full-tilt, the reactors would be incapable of reaching 1000C even at the full 100% duty cycle. The system will still work with more front-loaded ratios, but then the reactors will stop short of 100% duty cycle when the turbines or heat exchangers are overloaded, leaving some reactor capacity on the proverbial table.
I ment 100% duty cycle there, not 100% fuel utilization.

Aunte
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Re: Fuel Conserving Nuclear Power Setup

Post by Aunte »

Dang, I'm not first :)

My own attempt to conserve fuel:
nuclear.png
nuclear.png (1.77 MiB) Viewed 6204 times
Stats:
2x2 Reactors (~447 MW under heavy load)
48 heat exchangers
64 steam tanks
bot-fed suppy / waste management
highly controlled curcuit-conditions

There have to be 6 conditions before the inserters are allowed to input a single fuel cell:
- time since the last insertion (210sec timer next to the belt-roundabout)
- free space in the steam storage compound
- 4x at least 1 fuel cell inside the chests
Blueprint

Hedning1390
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Re: Fuel Conserving Nuclear Power Setup

Post by Hedning1390 »

Wire all inserters together
Send a signal telling unload inserters when there is need for power.
Tell unload inserters to send what they are holding.
Limit Loading inserter to 1 item.
Tell loading inserters to activate on unload inserter signal.
Manually supply the first fuel cell.
Wait for the first fuel cell to be consumed before sending the first signal that you need power (meaning they will get synchronized).
Make damn sure the output never gets blocked. This can be done by telling the fuel maker not only insert u-238 from reprocessing as long as there are unprocessed spent cells.

In my powerplant I can fit 16 reactors to 240 heat exchangers (the mathematical minimum for 16 reactors).
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