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Short version:
- Tileable design expandable into infinity as long as terrain permits
- Requires landfilling. Works well with tall but narrow stretches of water.
- Throttled design, reactors will only be active when more steam production is needed.
- Production: 640MW per 4 reactors, 560MW drained by heat exchangers per full row.
- No bots (for logistics). Belts only.

It's been a while! The last reactor design I tried broke with the water barreling not working well anymore - and I wasn't happy with it anyway. So, back to the drawing board!
I've encountered several problems when making nuclear reactors:
- Heat exchangers now need to be close to the reactors. At a not-so-insignificant distance they just never activate anymore, even when the reactors are at 1000 degrees.
- Water supply is continuous and high volume. Steam output is continuous and high volume. Both of these facts limit the amount of piping you can do.

With these limitations the only logical way to make an infinite tileable design is to put the water pumps into the plant themselves. Which means shaping the terrain to fit the design. Yes, landfilling required, but I've tried to keep it managable by having the water sections close together, near the reactors.

Overview

This overview is of a ~25GW power plant, which is currently handling the bulk of my base's power demands. Fuel is brought in by rail, spent fuel is pushed out by rail. Around the edges there's still a "scaffold" of roboports that I forgot to clear - these were used to have bots build the incremental rows automatically. And place the concrete.

Reactor Controls:

Reactor controls, rather spartan I suppose but they do what they need to.
On the left we have a simple latch that gets set when fuel is inserted, and gets cleared when the reactors eject their spent fuel cells. While the latch is set, the reactor controls get sent a Red signal. This state is signalled by a yellow light.
On the right we have a levelbased control that gauges steam in the first row's steam tank (which is generally the lowest as it's fed from the bottom row which has slightly less heat available due to the lower neighbour bonus at the edges). While there is sufficient steam, the reactor fuel inserters are blocked by the Red signal, and a Blue light signals this state.
In the middle there's a constant combinator that can be set to manually block the fuel inserters. A Red light signals that state.
Fuel input and Spent Fuel output is also delivered here by red belt. I used red belts since using blue is overkill here. You'd need to require upwards of 1 TW before you'd run into belt capacity issues.

Reactor row:

Reactor design, rather straightforward. Long inserters for spent fuel ejection. These block the fuel inserters as long as any one of them is not able to get rid of that spent fuel cell. Since all of them are synchronized, there should never be a blockage if you have something pack up spent fuel at the end of the belt. The splitters break off a small portion of fuel, and the belts are measured to check if there's sufficient fuel to feed each generator. If not, the entire plant is held until fuel supply is restored. The thought behind this is to ensure that the entire reactor remains synchronized. Every reactor inserts and ejects fuel at the same time. The yellow inserters are set to a stack size of 1.
You can also see the placement of the water pumps here. The basic landfill pattern for this reactor design is: Land - 2 Water - 18 Land - 2 Water - Land. Any lake that's 22 water wide and any length can be used (in vanilla) to make this power plant work.

Heat exchangers:

Just showing the left side, the right side is a mirror image of this. To get around flow limitations, the water pumps are practically glued onto the heat exchangers. The double row of heat pipes is not arbitrary - it's needed to ensure that the final 2 heat exchangers get sufficient heat once the reactors near 850 degrees. Water and heat from the right, as close to the reactor as I could manage it. Steam exits to the left into a large buffer. The buffer is split into 2 sections because flow between the tanks wasn't working when you've got 6 in a row. The first buffer takes steam from the heat exchangers, and should suffice to buffer an entire reactor cycle if the plant is drawing at least 20% of max capacity. The second buffer feeds the turbines and should frankly, never be empty. There are 3 paths from reactor to the steam buffer. This was needed because 2 will run you into flow capacity limits, even with pumps.

Turbines:

Pretty straightforward a triple row of turbines with some interruptions for substations to pull the power. You may notice that the substations from the pumps and the ones touching the turbines do not interconnect. This is by design for players who want to have the reactor controls and steam feeding devices on a separate circuit with backup power in case of blackups, for easier recovery. I've never found it neccesary... the only realistic way where the plant could fail, fuel starvation.
If you want to be able to consume slightly more steam then the heat exchangers produce, add one more turbine at the end. The strings posted generate 556MW of power for 560MW of heat exchanger steam production for 640MW reactor energy generation.

Failure modes:
- Overload: Plant produces maximum power, periodically still stalling since the reactors will generate more heat then the turbines can consume. It'll produce the maximum amount of energy the turbines can produce, and as long as the fuel inserters keep working, the plant should operate normally.
- Underload/no load: Plant shuts down once the steam buffer is above the treshold. If the turbines aren't producing power, reactors should stay at around 850 degrees when the fuel cycle ends.
- Fuel starvation: Plant will stop the reactors if there is insufficient fuel to fully fuel all rows. As soon as fuel is resupplied, it'll start working again.
- Spent fuel backup: Plant will stop the reactors if the spent fuel cannot be dropped from the inserter onto the belt. Once all inserters are able to dispose of the spent fuel, reactors will be ready again.
- Water shortage: Does not happen, since the pumps don't need power and are integrated in the design.

Hope this'll be of use to someone. This is a design meant for power-hungry megabases, for loads of more then 1.5GW, with no real upper limit. The tileable design also makes it expandable - power production becoming an issue? Add another row, and you've got 560MW more to play with. There is also some room between the steam tanks and the turbines to add a radar if you want to be able to remotely view your power plant.
One word of warning though: Nuclear power isn't UPS friendly compared to solar. Even idle a big nuclear facility can put a dent into your UPS.

Hi, nice set-up. I have one question. Is this design waste-less in terms of fuel? Just wanted to make sure

Hi,
got this setup working

So steam-side we check if steam tank has more than 15k steam stored -> if yes send blue signal (which also goes to lamp), based on blue signal send red signal to kill yellow inserters.
Not sure why we multiply blue times 2.5k and output as steam but it sound like a latch, right?

Fuel-side:
I had trouble understanding the mechanism but now I noticed that we have combinators hidden that check for 12 fuel cells at the read belt, anyway inserters fill the reactor to full capacity was that an idea or should be have some kind of cooldown.

Only thing to note - if you have (roughly) less then 100MW consumption then even with steam "if" set to 5k you are probably bound to reaching 1000degC

Thanks for sharing.

Just installed this setup over the weekend after starting to need the power during my transition from my starter base to megabase (1000SPM to start with).
It works like a charm and with landfill now able to be added to BP, it is quite easy to now (and safe... I remember landfilling before and just adding one tile to many and having to start over somewhere else!!!).

Only thing to note is that to get the system started you need to load the first fuel cells in the reactors manually. Which is fine, but took me a few minutes to figure out. The lights were blinking with high frequency before this (enabling and disabling the reactor inserters to quickly I think for it to actually get started).

Really great work!

On the second deployment it worked without manual insertion and inserts a single fuel cell into each reactor.

Sorry for FUD

Hi, I just wanted adde a few words here as I'm experimenting with this design.

Mechanism for steam adds hysteresis. In default, if there is less than 15k steam, let the process begin. Otherwise send blue signal. The point is that blue signal triggers addition of 2,5K steam, so now the threshold is 12,5k (15k - 2,5k added by this combinator) thus signal is stable even with slight steam changes when pumps are pumping.
In overall:
- when we have enough steam, threshold is 12,5k
- when we are out of steam, threshold is 15k

- we are out of steam if it drops below threshold
- we have enough steam if it is above threshold

1. At startup you have no steam and have to reach 15k threshold to send blue.
2. Now generating steam is hold until it drops below 12,5k.
3. When it dropped below 12,5k it has to generate steam until 15k is reached again.
I think the whole point is to keep plant running full power without switching off when steam reserves are somewhere between 12,5k and 15k.

Those values can be adjusted at will. I enlarged the tanks getting more peak power (steam reserves) and had to adjust those levels. When you have large difference in power use because of starting and stopping whole blocks of factory, it is useful to have such power reserves.

Now the latch mechanism. This is typical switch which is locked in one of two states. Any provided state will be kept. If you send green (old cells are being taken out) it will keep it green letting the plant to start. If you get yellow signal (new cells put in) it will stay in yellow signal preventing new cells to be put in before cycle ends.
The only problem with such switch is that they require initial input, otherwise state is logically unknown. You can reproduce it by switching power for whole circuit when it was first built. By default deciders and other devices have no output, so when you power them on, they both see no signal and emit their signal (if no green, then yellow, if no yellow, then green). In next cycle they both see both signals and emit nothing. Thus flickering. There are two manual solutions.
1. Prime reactors manually. Even one is enough. It will send signal about old cells being taken out when it finishes and it will initialize latch by stable signal.
2. Put another constant combinator which sends this signal (used fuel cell > 0) to decider that expects it. I'd call it manual feeder. It will switch latch to green and let all reactors to fuel up. Simply switch it on and off to insert single cells into reactor.

It should be possible to make it automatic using that knowledge but any design I made had similar problems.


I'm working on my powerbook with desings I'll use later (Now playing in peaceful but I plan to start again in more hardcore environment, I still did not play with attacking enemies, so I never developed weapons). My goal is to get nice and useful design which will be also easy to setup. I used this design as base. In result I'll start new thread and share whole blueprint book with several blueprints.
- drawing blueprint just to draw what has to be cleared and landfilled
- similarly as here, blueprints for core, core controls, left and right turbines

I also want to make it more robust at startup. It means no manual filling, no special roboports etc. To build just place one roboport near core and ensure you have poles near both turbine sections (due to separation between control and powered grid). Then it will continue. Maybe some nice messages about low fuel, full waste etc.

TL:DR
Make sure you are feeding both lanes. Circuit expects 12 fuel cells for two reactors. If you feed only one lane, then it will only detect 4 cells on each and not start due to fuel starvation. Otherwise ensure you are feeding only one side of lanes and change detection to 6 on each reactor side.

When you have this high frequency blinking, prime reactors or place constant combinator, connect it to decider checking for empty cells and send empty cells signal > 0 for short awhile so it is initialized. It happens when you place circuit before connecting power.

Bonaducci wrote: ↑Sat May 25, 2019 2:38 am Hi, I just wanted adde a few words here as I'm experimenting with this design.

Mechanism for steam adds hysteresis. In default, if there is less than 15k steam, let the process begin. Otherwise send blue signal. The point is that blue signal triggers addition of 2,5K steam, so now the threshold is 12,5k (15k - 2,5k added by this combinator) thus signal is stable even with slight steam changes when pumps are pumping.
In overall:
- when we have enough steam, threshold is 12,5k
- when we are out of steam, threshold is 15k

That is by design. It prevents the latch from flicking off and on rapidly if there are some turbines and heat exchangers still producing power. It basically prevents rapid switching of the latch, requiring the buffer to be raised to 15k before turning off, then drop below 12.5k before turning the steam production on again.

The only problem with such switch is that they require initial input, otherwise state is logically unknown.

Yep, sometimes it just starts to oscillate when first built. Just toss a single unit of fuel in a reactor while you're building it to have some spent fuel come out a few minutes later, that'll prime the mechanism. I don't consider the need to initialize the latch to be that big a design flaw, once it's running it will keep running.

Dumb question but in what order to these go in? I have the left and right turbine sections, then the controls under that and the reactor row above it.

Also, what is tileable, the entirety of the 3 sections or just one of the rows?

Great design! Thank you so much. I had trouble using this with the Waterfill mod which wouldn't let me create water areas in the space required. At least, not without doing both waterfill and landfill.

I also wanted it to be self-building so worked in some roboports. Then a few other small changes. You know how it goes.

Anyway... I've posted the final result here, fully attributed:
https://factorioprints.com/view/-MJURcCFL-9L_cbihLys

If you'd rather I didn't post this modification of your design, let me know and I'll remove it.

-- Brian