1 Tile Pool CLRR | A Simple, Start & Forget, Fast (1.1 kg/s coolant in 1 Cycle), Cold+Dry Start, Pre-Space, 34,069 Watts Nuclear Reactor

[Ledah Riviera]

I love watching science videos about clean nuclear energy. So when I learned about @Nedigo's CLRR in @GCFungus's video tutorial about Nuclear Power, I was fascinated by its thermodynamics and curious about other designs, which led me to the Automatic + Cold Start design by u/Xirema and FLiCLiRR by @Charletrom.

But then, I realize these designs have precious Liquid Nuclear Waste (at least for me, who has never launched a rocket yet) lying around, never to be collected. What a waste.. So I tried minimizing the NW pool down to 1 tile, and it worked, with no fallout happening. In the middle of it, u/PrinceMandor told me how a thin layer of NW sitting above that 1 tile is not a big deal, the new dripping hot NW will still exchange heat with the bottom tile anyway.

I also want to avoid deeply nested automation (even Xirema's automation is too nested to my liking, no offense), so when I read u/Nonerror's comment in Xirema's post, it felt right to me. He also pointed out other good points. Check it out, it's a good read.

But what really keeps me from copying other designs is that I game using a somewhat old laptop that often runs ONI below 30 fps. So, I'm afraid fallout will happen at some point, overpressuring the reactor or clogging the ST.

So, I built my version of CLRR that satisfies these goals & requirements:

1. only pre-space material,
2. less NW wasted,
3. fully automated start + not too deep automation,
4. still safe even if fallout does occur,
5. limiting the coolant sooner (detect problem sooner),
6. only supplied by 10 kg/s of water,
7. minimal initial power requirement (as a challenge to myself),
8. all elements and buildings are at 27°C max.

The easiest way to make the build start early is by filling it with hot steam, or pre-heating the entire thing. So, for benchmarking, all elements and buildings are cold. The only exception is the water/steam in the heat reclamation chamber. As long as it doesn't generate power before the main STs do, it doesn't really matter.

And here's the result:

(overview)

Let's start with the elephant in the room.

First, ST are stacked in 8 rows with RR on the side, instead of the usual RR + 4 rows on each side. I chose this design purely because I can't come up with a 4-row design with pre-space material. 4 rows of 10 ST doesn't work (more on these later).

Secondly, there are 2 steam chambers separated by window tiles (and normal tiles). It's inspired by u/Nonerror and gives several benefits:

1. We can keep the steam chamber on the left at low pressure (at 10-20 kg around the Reactor).
2. With that low pressure, there's 0 risk of over-pressuring when fallout occurs.
3. The steam chamber on the right can now get pressurized much higher, so controlling the water intake is easier (more on this soon).

I once had it running too hot and got the entire NW evaporated into fallout, filling >90% of the reactor area. It was still working just fine; until the steam couldn't get enough heat (due to heat deletion from evaporating NW), causing the ST to stop working and the battery to lose power, shutting down the valve for the reactor coolant.. So yeah, the power was dead before the reactor was overpressurized.. (Don't worry, my latest design no longer has NW evaporated in my several long tests)

Thirdly, there are lots of radbolt generators, but they are not important. I built them for my plan to bombard neutronium while waiting for 100s tons of NW.

How It Works - The Essentials

In this section, I will explain how it works and how to build it, but only the essentials. The extra features will be covered in a later section.

[1st Stage - 800°C Reactor]

• Start the reactor efficiently,
• Extract the heat from NW,
• Make the steam gas flow unimpeded.

Spoiler

A. Dry start

One of the goals I want to achieve is a minimal initial power requirement, which is achieved by getting hot steam converted into power as soon as possible. Preparing a large pool of water before running the reactor works against our favor, because the water needs lots of heat before it turns into hot steam. Hence, we start with no water, a.k.a dry-start, like this:

(no water pool before running the reactor)

The water we need will start to be delivered at the same time as the reactor starts running.

B. Coolant-limited start

Along with dry-start, the initial reactor coolant intake is also limited to 2.9 kg/s.

(Starting reactor coolant intake: 2.9 kg/s)

At the very start, the reactor needs 30kg of water before it begins to heat its fuel. Hence, the first few batches of NW will be sufficiently cool not to turn into fallout. Furthermore, the Midnight valve (more on this later) will also dump 50kg of water, making it even cooler.

After about 3 drops of NW (around 60s per drop, so 120s), the NW inside the reactor will stabilize and will not go beyond 800°C.

C. Heat extraction method

The rest of the water in the pipe will be sent to the Water Vent area to extract the heat from the NW pool on the left. Some Tempshift Plates are used along with several types of bridges to help extract the heat. This is because using a circulating liquid pipe, like in Nedigo's design, is hard to do here, due to the number of pipes needed for 9 Water Vents (it is still used, but limited; more on this later). Using a gas pipe loop is probably doable, but bridges are much simpler.

(NW Pool & Water Vent area)

D. Steam gas flow

The Water Vent area has a width of 2 tiles, the area above the topmost AT is 3-tiles high, and the area next to it is 4-tiles wide. The size is increasing to ensure the steam travels smoothly and prevents the vent from getting clogged.

(path width for the steam flow)

After a whole cycle, our little 1-tile pool will have 1 ton of NW, enough to handle 2000°C of NW.

[2nd Stage - 2000°C Reactor]

• Transitioning to hot-but-safe NW
• Handling the NW overflow
• Keeping buildings from overheating

Spoiler

A. Disabling the 1st valve 

The 2nd Stage starts by shutting down the 1.8 kg/s liquid valve, limiting the reactor coolant intake further down to 1.1 kg/s. The automations used are a timer sensor (set to cycle mode & 1 cycle green, red doesn't matter), a memory gate, and a NOT gate to disable the valve. Since the timer sensor starts at green and the memory gate will be "locked" if we start at green, 1 additional NOT gate is needed to flip the output of the timer sensor.

(Automation to disable the 1st valve)

B. Handling the NW overflow

Around 0.2 cycles since the 2nd Stage began, the steam will reach ST and start producing power. The initial power required until this moment is about 23kJ, a little over one fully-charged Smart Battery.

The NW will also start to overflow. Since NW overflows only when hot NW is newly dropped, the overflow will also be hot, more than enough to overheat the steel Liquid Pump. Hence, the overflow is caught with a Mechanized Airlock door that opens when the NW is below 260°C. To close the door after dropping cool NW, a hydro sensor is used.

Initially, there's only a small amount of water dumped in the Water Vent area, causing the secondary NW pool to take too long to cool. But, since initially the liquid pump and its surroundings are cool, it can take some hot NW without overheating. Hence, the door will also open when it's cold down there with the help of a thermo sensor set to 150°C threshold.

(secondary NW heat extractor)

To help extract heat from this caught NW, 1 Tempshift Plate + window tiles connecting to the Water Vent area (but not directly connected to the main NW pool) are used, along with more bridges.

C. Pumping the NW

At the bottom, there's a liquid sensor to detect the presence of NW on the left of the pump. This is because the liquid pump leaks a tiny amount of NW every time it pumps NW, causing it to pump that droplets, then leaks again and pumps again every few seconds. And since initially some steam condenses into water and creates a pool of water there, the pump is also disabled if the surrounding temperature is not hot enough.

Before sending NW to the Heat Reclamation Chamber, it is used to cool down both NW pools above and gets its heat extracted in the Water Vent area.

(NW plumbing overlay)

D. Keeping buildings from overheating

In the first 5 cycles, there are too few turbines running to pump out water and cool the NW. This will make the steam around 300°C in the Water Vent area. The ATs will be fine, but other buildings can't get too close. I don't know exactly how, but if other buildings are far enough (batteries, auto-sweeper, pumps), the steam that reaches them will be below 275°C.

This overheating problem is also why a 10-STs-long row won't work. The more STs working early, the more cooling power we have for the NW.

During this first 5 cycles, sometimes the NW can flash-boil into fallout. But strangely, after re-loading to the last save, the random flash-boiling thing often doesn't happen anymore..

For the reasons above, the most dangerous moment is within the first 5 cycles. As long as the build survive that long, it will be fine. (I've tested it many times over 30 cycles, once about 100 cycles, and once about 200 cycles)

After all the STs are fully working, they will dump a total of 80kg/s of 95°C water, enough to handle 2500°C of NW.

[3rd Stage - 2500°C Reactor]

• Transitioning to even hotter NW
• Preventing meltdown during morning autosave

Spoiler

A. Disabling the 2nd valve & the Water-to-Steam valve

Once the steam reaches all STs (no more vacuum or water below STs), all atmo sensors at the end of each row will send a red signal to the Water-to-Steam valve (because no more steam is needed) and to the 2nd valve (to limit the Reactor coolant further down to 950 g/s, producing up to 2500°C of NW).

(disabling 2nd valve & Water-to-Steam valve with atmo sensor)

After a few cycles, the power generation will stabilize around 20 megajoules per cycle (even with radbolt generators disabled). If my math is correct, 20.4 MJ/cycle = 34 kilowatt. With power consumption of 4 ATs running at 88% uptime on average, a liquid pump with 17% uptime, and some low-power valves, it's safe to say there's about 29 kW of power available.

B. Midnight valve

The autosave that occurs every morning may cause FPS to drop and potentially raise the fuel temperature to a meltdown. So, every midnight, a Cycle Sensor opens a Valve to dump 50kg of water into the reactor (I learn this from u/GrenouilleDuFutur in his post). Additionally, I coupled the Cycle Sensor with a pulse clock for more precision (optional).

(automation for the Midnight valve)

To recap:

1. start Reactor coolant @ 2.9kg/s,
2. after 1 cycle, limit to 1.1kg/s,
3. when all STs are working, limit to 950g/s.

Note that the number works for my laptop running at 20-35 FPS. Adjust according to your rig's performance.

For the materials:

• Buildings that risk overheating: steel
• Liquid pipes:
  • Radiant pipes: copper
  • Insulated pipes: ceramic for AT coolant, ignous rock for ST output and others
  • Normal pipes: igneous rock
• Tempshift Plate & Window Tile: diamond
• Basic Tile:
  • Normal Tile: igneous rock
  • Insulated Tile: ceramic for below ST, ignous rock for others
• Mechanized Airlock: copper ore
• Bridges (tbh, I didn't put much thought into selecting these materials):
  • Wire: copper ore
  • Gas: granite
  • Automation: copper
  • Conveyor: copper ore

Extra Features

1. Liquid Coolant for AT + preventing NW corrosion damage

Spoiler

I want to use NW as the coolant, but using it right from the start kind of defeats the purpose of a Fully Automated Reactor. So I use the NW produced from this reactor itself. Luckily, the NW can be collected as early as the 2nd cycle. Unfortunately, using no coolant will quickly heat the STs up. Hence, water is used as the initial coolant, and flushed when NW is ready to replace it.

Since the NW is too hot, it's sent to the Heat Reclamation Chamber @ 2kg/s (like Nedigo did) to smooth out the temperature, but still not getting the pipe clogged. Now, putting 2kg/s to the AT cooling pipes will lead to inefficiency (cooling 2kg or 10kg of liquid uses the same amount of power), hence I use the Fully Passive, Single-input, Packet Stacker design by @Boxman_90 right after the NW is cooled down to ~100°C. (If you don't mind a little inefficiency, you can feed cooled 2kg/s of NW directly to the AT. The power generated can sustain it. I just want to share this cool Packet Stacker design)

When there's NW available to replace the water, AND there's water ready to be replaced, a valve opens:

(automation to replace AT coolant)

Since NW is used for AT, it must be submerged in a fluid above 1.000 kg. Any fluid works, but I think this one liquid is the best: Liquid Uranium for 2 reasons:

1. When enriching Uranium in Uranium Centrifuge, LU is also created as the byproduct, and more importantly,
2. Max mass of LU is 9.970 kg. Therefore, there's no need to compress it. Just pour normally and that's it. (afaik, this is the only liquid with max mass >1000.1kg that stays liquid around 200°C)

Bonus tip: A Liquid Pipe Thermo Sensor can still work even when entombed in a natural tile. Entombing it will reduce the LU required by 1/3.

"Wait, didn't you say it must be below 27°C?"

Yup. I use cold, frozen Solid Uranium tiles for benchmarking.

2. Safety reactor coolant intake

Spoiler

To ensure the reactor's ST feed to the reactor coolant's valves, a liquid bridge is used (labeled as "ST bridge" below). In case that ST fails (either during early cycles or during fallout), another liquid bridge is used (labeled as "failsafe bridge").

During the day, the pipes should naturally be filled with water all the way to the ST bridge (because the ST output of 2kg/s is more than the reactor input from the 2nd Stage onwards). During the night, the Midnight valve will drain the pipes (actually a little less because of newly added water). To prevent the failsafe bridge from being used needlessly, the minimum distance between the two bridges needs to be the same amount of the Midnight valve delivers divided by 10 (so in my design, 50kg valve = 5 tiles distance).

(safety bridges for reactor coolant)

3. Fallout gas condenser + Radbolt to NW

Spoiler

In the previous version of my build, sometimes the NW randomly flash-boils into fallout, which strangely doesn't happen again when I reload the previous autosave. I couldn't reproduce it consistently, so I just put a gas pump below with a simple gas element sensor and a filter gate. After being pumped, I condense it back into NW using the same liquid that is cooled by the AT.

The random flash boil doesn't happen anymore in the latest version (except for the first 5 cycles mentioned earlier in 2nd Stage), but the radbolt sometimes collides with each other and turn into a little fallout gas. So I don't remove the gas pump.

I also combine the fallout condenser with the radbolt catcher just for fun. On average, the radbolt generator produces around 800 radbolt/cycle. So 50 of them produce ~40k radbolts/cycle = ~40kg Nuclear fallout per cycle. Meanwhile, the reactor itself produces 25 times that amount lol.

(fallout gas condenser)

The radiant pipe can't be too close to the bombarded Airflow Tile to let the gas cool that Airflow Tile. Otherwise, it will eventually melt even wolframite, the highest melting point of all Airflow/Mest Tile material. This makes a counter-intuitive phenomena: the Airflow Tile is cooler when there are frequent radbolts (at over 50 cycles) than infrequent radbolts (at ~15 cycles).

4. Conduction Panel to cool the Steam Turbines

Spoiler

I experiment on using the Conduction Panel instead of fluid + Radiant Pipes to cool the STs.

• For the 41 STs cooled by AT, I use lead for the ST and copper for the conduction panel. 1 panel isn't enough to cool ST, so I use 2.
• For the 5 self-cooled STs, I use copper for both the ST and the conduction panel. At least 4 panels are used for each ST.

(conduction panels)

Additionally, I use a Thermo sensor + a steel Mechanized Airlock to get a little cooling power from the AT cooling loop. A little inaccuracy in cooling doesn't really matter, so I leave the door unpowered.

(cooling door)

With these setups, I don't need to deliver another liquid / gas to the STs.

Optimizing

1. Initial power requirement:
   1. In survival build, there's no reason at all to adhere to <=27°C rule. In fact, using 8 tiles of 1100kg, 150°C of Liquid Uranium (while all buildings are still cold, for benchmarking) makes the power requirement drop to 19.2 kJ, almost a fully-charged Smart Battery (tested with 1 Smart Battery, it drops to 800 Joule minimum).
   2. Adding a bridge or tempshift plate on the opening of each ST row (where the water will collect initially) will help boil the stagnant water and let the ST sucks its first steam faster. Just one closest to the Water Vent area is enough.
2. Faster last stage:
   1. The 2nd Stage is actually an intermediary stage, because cooling 2500°C of NW needs a lot of cooling power. Maybe there's another way to skip the intermediary stage while keeping all requirements satisfied?
   2. If you want more energy earlier, you can use another way to disable the 2nd reactor coolant valve (e.g., thermo sensor + filter gate on the main NW pool, or right outside the Water Vent area). I use what I use simply because it's simple.
   3. Adding another intermediary stage may also help.
3. Saving space:
   1. If you have thermium, you can put a thermium liquid pump right above the main NW pool, shifted 1 tile to the side to prevent draining the pool. This way, you no longer need the secondary NW pool all the way down. You can also put another conducting wall on the left, moving 4 rows of STs there to make the build more horizontal, like Nedigo's build.
   2. The reactor area doesn't need to be that big. Just be careful not to overheat the auto-sweeper if you want it smaller.
   3. The heat exchange area can also be made shorter. Especially with Super Coolant, as in theory, 41 STs can be cooled with just 3 ATs.
   4. The reactor area and the heat exchange area both can be moved up and down, independently of each other, to suit your needs. The steam flow will be different, though, so it probably will need some calibrations.

Here's the save file. To start the reactor, connect the liquid pipe below the Dev Liquid Pump. If you want to emulate starting the 3rd Stage, fill the steam chamber with 200kg of steam per tile.

1-Tile-Pool CLRR.sav

[Ledah Riviera]

I forgot to add: The liquid bypass method I use is from this video by Tony Advanced. It occupies 1 less space than Nedigo's design, I use that space to bridge a pipeline from ST output to the vent.

[Charletrom]

So cool! I really like the automated startup. The midnight valve gave me a chuckle

Surprised to hear you didn’t have issues with the small amount of NW on top of the full tile… I had problems with that at similar fuel temperatures.

 

 

[Ledah Riviera]

I think it's a fitting name, haha. Midnight valve to prepare for the morning freeze, as the original designer called it.

.

I thought it would be a problem too. Designing a complicated "overflow cleaner" because the reactor doesn't drop NW exactly every 60s..

[Prince Mandor]

9 hours ago, Charletrom said:

Surprised to hear you didn’t have issues with the small amount of NW on top of the full tile… I had problems with that at similar fuel temperatures.

 

 

Liquid in droplets form teleports down to last suitable tile. So new hot waste always mixes with full tile at bottom. Yes, it looks like liquid will join topmost liquid tile, but from game mechanic point of view, liquid adds to most bottom tile available. (There must not be anything turning waste into bead form, in this case it bursts to fallout)

[Charletrom]

1 hour ago, Prince Mandor said:

Liquid in droplets form teleports down to last suitable tile. So new hot waste always mixes with full tile at bottom. Yes, it looks like liquid will join topmost liquid tile, but from game mechanic point of view, liquid adds to most bottom tile available. (There must not be anything turning waste into bead form, in this case it bursts to fallout)

If you look at my FLiCLiRR design linked above, you’ll see that it relies on an offensively massive pool of nuclear waste. Whenever the RR dropped waste, the temp (and mass) of the pool would spike in the top-most tile, not the bottom. I suppose it could be possible that the droplets exchange temp as they fall through the waste toward the bottom tile, but as far as I know droplets don’t exchange temp. Even if they did you would still encounter an issue with low-mass tiles on the top.

I’m not saying you’re wrong, just that I’m confused haha. RRs are mysterious

[6Havok9]

20 minutes ago, Charletrom said:

If you look at my FLiCLiRR design linked above, you’ll see that it relies on an offensively massive pool of nuclear waste. Whenever the RR dropped waste, the temp (and mass) of the pool would spike in the top-most tile, not the bottom. I suppose it could be possible that the droplets exchange temp as they fall through the waste toward the bottom tile, but as far as I know droplets don’t exchange temp. Even if they did you would still encounter an issue with low-mass tiles on the top.

I’m not saying you’re wrong, just that I’m confused haha. RRs are mysterious

I think it's because the droplet materializes as a liquid in the bottom tile, which is "full" and overpressurized. The newly created liquid merges with the bottom tile, overpressurizing it even more, which forces the liquid to go up. The resulting liquid mass is hotter than the liquid above, which also forces it to go up, imitating convection. At the end of the transfer, you see a mass and temperature spike in the top-most tile.

At least, that's my crude understanding.

[Charletrom]

But why then would you not see a higher temp increase, and thus boiling, in a low-mass top-most tile? If the temperature (rather than heat) rise is the same as a high-mass tile, which is the only way you would not see boiling, then you would have massive heat deletion.

The convection mechanic is quite slow, but I see an immediate temp spike in the top tile when the droplet reaches it.

[6Havok9]

1 hour ago, Charletrom said:

But why then would you not see a higher temp increase, and thus boiling, in a low-mass top-most tile? If the temperature (rather than heat) rise is the same as a high-mass tile, which is the only way you would not see boiling, then you would have massive heat deletion.

The convection mechanic is quite slow, but I see an immediate temp spike in the top tile when the droplet reaches it.

Because the liquid has exchanged temp with the bottom tile, and it is still a liquid. The excess mass then goes up.

[Charletrom]

That I understand but why the immediate temp increase in the top tile? The convection mechanic is too slow for that

[Prince Mandor]

20 minutes ago, Charletrom said:

That I understand but why the immediate temp increase in the top tile? The convection mechanic is too slow for that

There are no real convection in this game. But heat transferred through liquid at dramatic speed. Tile to tile have x1000 multiplier and liquid to liquid x625 for nuclear waste it means 3750 kDTU/s°C. Also I remember to read something like there are some vertical tile-swapping mechanic in same liquid/gas if bottom tile have greater temperature. But I never can research it fully. At old times Mathmanican was the person knowing most about ingame hydrodynamics. Don't know who is most knowledgeable now on this topic. May be some forum elders can point us to necessary direction

[6Havok9]

48 minutes ago, Charletrom said:

That I understand but why the immediate temp increase in the top tile? The convection mechanic is too slow for that

Because that extra mass is hot!

-droplet goes to the bottom tile

-droplet becomes liquid

-droplet merges with present liquid so it does not boil, heats the present liquid

-resulting tile is overpressure

-tile sends excess hot mass up

-hot mass ends up in the top layer > temperature and mass spike

 

[Charletrom]

I’ve done some testing and have interesting and controversial results. The droplet of NW merges with the first NW tile that has more than ~500kg (50% of max mass). If the top-most tile has less than 500kg, it will skip that tile and merge with the full tile below it. This is definitely true for both mass and heat, at least on my system. 

[Tigin]

It looks at default mass for droplet merging 

[6Havok9]

2 hours ago, Charletrom said:

I’ve done some testing and have interesting and controversial results. The droplet of NW merges with the first NW tile that has more than ~500kg (50% of max mass). If the top-most tile has less than 500kg, it will skip that tile and merge with the full tile below it. This is definitely true for both mass and heat, at least on my system. 

Interesting. So, almost never the first tile, almost always the second. That tile becomes the bottom tile. If I understand correctly. It also means that one layer, or even one full tile of liquid is often enough. As the OP's build shows 

[Charletrom]

Yep. Looks like the worst-case scenario for NW flashing to fallout in builds like this is a 501kg tile (on top of a full NW tile of course)

Thanks to @Ledah Riviera for giving me an opportunity to learn something new! An interesting build for sure

 

[Ledah Riviera]

5 hours ago, Charletrom said:

I’ve done some testing and have interesting and controversial results. The droplet of NW merges with the first NW tile that has more than ~500kg (50% of max mass). If the top-most tile has less than 500kg, it will skip that tile and merge with the full tile below it. This is definitely true for both mass and heat, at least on my system. 

3 hours ago, Tigin said:

It looks at default mass for droplet merging 

Oh so that's why in my previous design (using door to drain the overflow, but the overflow often reach above 500kg), it tends to flashboil and idk why!

Thank you too!

2 hours ago, 6Havok9 said:

If I understand correctly. It also means that one layer, or even one full tile of liquid is often enough. As the OP's build shows 

Yup. 1 ton of 300°C NW can safely mix with 100kg of 2500°C NW.

And if you can cool down the NW even lower, you can catch even hotter NW. If only the meltdown temp is higher haha

[Prince Mandor]

13 hours ago, Charletrom said:

I’ve done some testing and have interesting and controversial results. The droplet of NW merges with the first NW tile that has more than ~500kg (50% of max mass). If the top-most tile has less than 500kg, it will skip that tile and merge with the full tile below it. This is definitely true for both mass and heat, at least on my system. 

Isn't it a mass at which tile below it start to contain more than max mass and became unsuitable for liquid droplets?

[Charletrom]

8 hours ago, Prince Mandor said:

Isn't it a mass at which tile below it start to contain more than max mass and became unsuitable for liquid droplets?

The tile immediately below the top tile will of course always have approximately the maximum tile mass for that element. However, the droplet will still merge with it unless the top tile has more than 50% max mass. When the droplet merges with the tile below the top tile, it will then have more than the max mass and the extra mass will be displaced upward into the top tile.

In the case of a CLRR, where the droplet is 100kg of ~2500°C NW, it will merge into the full tile below the top tile (presuming the top tile is under 500kg), thus adding the heat it contains to the full tile resulting in a temperature increase. When the mass is displaced upward it carries this new temp, (which in a functional CLRR is less than the boiling point of NW) thus you do not see boiling.

If the top tile is 501kg, the 100kg droplet will merge with it instead, and due to the lower combined mass the temperature increase of the new 601kg tile will be greater than in the condition described above, leading to NW boiling at lower pre-droplet temperatures than if the droplet were to merge with a 1000kg tile.

So, bringing it all together, the best case scenario for a CLRR is a full tile of NW below a ~499kg tile (maybe), and the worst case is if the top tile is 501kg. The reason a 499kg tile could be good is because the game actually tolerates temps higher than the boiling point for a few tics (maybe only 1?) so as long as you can pull heat out of a tile fast enough it wont boil. A 499kg top tile should help with that since it will require more heat transfer to reach temperature equilibrium with the full tile below it (tempshift plates should help too). To be clear, I haven’t tested whether the 499kg tile actually helps but it could.

 

[Prince Mandor]

16 hours ago, Charletrom said:

The tile immediately below the top tile will of course always have approximately the maximum tile mass for that element

 

Yes, I understand mechanics you describe. But mechanics was different earlier and I just don't find any notices about it be changed. So, may be it is not 500kg of top tile, but 1000.1 kg of tile below what makes difference (coincidental with 500kg in a tile above)?

[6Havok9]

1 hour ago, Prince Mandor said:

Yes, I understand mechanics you describe. But mechanics was different earlier and I just don't find any notices about it be changed. So, may be it is not 500kg of top tile, but 1000.1 kg of tile below what makes difference (coincidental with 500kg in a tile above)?

It seems like that if the first available tile is not a valid target then the tile below will always be a valid target.

Assuming a pool of the same liquid:

So.. the topmost tile with not enough liquid mass is skipped. The droplets are gonna merge with the tile below it, which must be a valid target and cannot be overpressurized, since there is not a max pressure liquid tile above it. If it's a single layer they are gonna hit the floor and inevitably merge with the already present liquid.

Crude understanding as always 

[Ledah Riviera]

2 hours ago, Prince Mandor said:

may be it is not 500kg of top tile, but 1000.1 kg of tile below what makes difference (coincidental with 500kg in a tile above)?

I tried painting 550kg on top tile 3 times. After that, I checked the bottom tile, it is at 998 kg.

Then I drop the hot NW on them, and pause before the heat is spreading. The bottom tile is at 236°C while the top is 526°C

[Prince Mandor]

33 minutes ago, Ledah Riviera said:

I tried painting 550kg on top tile 3 times. After that, I checked the bottom tile, it is at 998 kg.

Thank you very much for your testing

So, now we know droplets no longer go to last available tile, but uses some non-trivial logic. Something like: finding last available tile and after that if it is filled with same liquid up to more than half of max.mass, it finds topmost tile filled this way

Ugh. I hate non-trivial logic

Interesting, how it will works on checkerboard stacks, like with liquid uranium, molten gold and molten lead (they all have same sorting order as nuclear waste and can be placed one above another in any order)

[Ledah Riviera]

19 hours ago, Prince Mandor said:

finding last available tile and after that if it is filled with same liquid up to more than half of max.mass, it finds topmost tile filled this way

From my observation, the droplets merge with the 550kg tile the moment they touch it—not: the droplet falls to the bottom > the new 100kg NW is teleported to the top > and the temperature mixes.

By the way, NW default.mass just happens to be 1/2 of its max.mass. @Tigin said the algorithm checks for default.mass. I haven't tested with other liquids tho