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Actively Cooled Reactors: Limitations and Concerns


BlessedWrath
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Before I start, I would like to point out that I know the current version of Tekkit has an outdated version of Big Reactors. I'm not sure what the new changes will be, so I don't know how much of this post will still be relevant when the new version comes to Tekkit. I just put this here as a commentary on my experiences with the mod.

 

So I began toying around with the Actively-Cooled reactors over the past few days. It's neat, but...I have some questions about the assumption that they're more effective than passive reactors.

 

This may be true of smaller reactors, but the maximum flow rate of steam to a turbine is 2,000 mB/t, meaning that the maximum relevant size of a turbine is much smaller than the maximum possible size. Mine ended up being 13x12 (9 rotor shafts and a rotor bearing on the inside), with four sets of five block long blades. I'm using four complete Enderium coils, with 5/8 blocks on the fifth coil. More about "optimal efficiency" in a moment. For now, I want to focus on the limitations of the active reactor.

 

I built a maximum-dimension reactor with Graphite moderators on all available spaces. The maximum heat on this thing is huge, meaning it can create massive amounts of steam. However, I tested the maximum steam production by placing a Void Fluid Pipe on a Reactor Coolant Port set to output mode. I discovered that, although I have four rows of eight Liquid Transfer Nodes (with maximum upgrades each, that should come to 8,000 mB/t each), I cannot produce more steam than the internal buffer can hold. The rising temperature of the reactor tells me that, were the buffer larger, it would be producing much more steam. It ended up leveling off at about 870C with control rods set in the high 90s.

 

I later confirmed this by building a set of 30 optimal-sized turbines, each directly connected to the reactor via Turbine Fluid Ports so as to avoid limitations on transfer rates. 25 of the turbines spun at full speed (25x2,000 mB/t each max flow rate is 50,000 mB/t; the same size as the internal buffer) while 5 of the turbines did nothing. To confirm that I'd set up those five turbines correctly, I deactivated five of the turbines which were working correctly. The five stopped turbines began spinning as expected.

 

What this really means is that there is a maximum number of turbines you can use with an actively-cooled reactor. That upper limit ended up being (for me) 600,000 RF/t. That's a respectable number, but it doesn't match my highest output in a passively cooled reactor. Actives were supposed to be so much better, but they fell short of my expectations by quite a bit. 90% of the power of my reactor is wasted because I can't generate any more than 50 B/t of steam. Add to that the expense of manufacturing turbine parts and it's basically enough to get me to stop using actives altogether.

 

My passive reactor outperforms on materials, output and convenience. All of its power can be routed through a single tesseract, whereas every individual turbine must be handled separately.

 

I also had a comment on the idea of "optimal" rotor speed. Using the wiki entry, my turbine design should have run with better output by using four complete Enderium coils, and a fifth coil composed of four Enderium and one Iron. It passed just over 1800rpm, and produced at least 600 RF/t less than replacing that iron block with Enderium. Using Enderium in place of iron took my RPM down to 1790-something and gave me that extra 600 RF/t. I know there's a give-and-take between drag on the rotor shaft and generation of RF, but it just feels like the optimal speed concept should have been tighter than that.

 

Now don't get me wrong: I like the idea of turbines. It was a lot of fun to put together and test out. I just have some reservations about the upper limits. Making the maximum turbine size 16x16x16 while the maximum steam input is only 2,000 mB/t pretty much guarantees that an optimal build will never use maximum dimensions. I also think the output should be able to exceed the buffer size; since you're not really storing the steam if it's being used right away, the buffer size should not matter.

 

I also realize that a number of changes have been made size 0.3. I'm hoping that the launch of the V2 platform will bring the newer versions of Big Reactors along with it. I just wonder if it's too much to hope for that we will get some better output.

 

Thoughts?

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You bumped against the hard limit there. 50 buckets per tick is a massive number (that is 1000 buckets every second at standard tick rates), and it will indeed limit your operations at that scale. You could check the config files and see if that cap can be raised. No guarantees that it runs stable at higher numbers even if you can change it, though.

 

The way I understand it, actively-cooled reactors are not meant to be maximum size. The maximum frame dimensions are meant to be used with (ludicrously large) passive setups running very advanced rod/coolant configurations. Active reactors can generally be much smaller for the same effective power output, and their increased efficiency comes from burning less fuel for the same power output. Standard setups often have just a small number of fuel rod blocks, and even Laser-Drill-driving active reactors may be as small as 7x7x7 or comparably-sized (excluding the Turbines).

 

The most efficient setup is one that reaches exactly 2000 mB/t of steam with the least possible fuel consumption, feeding into a perfect Turbine that runs at exactly 1800 rpm on these 2000 mB/t. Or multiples thereof with more Turbines. I think the perfect setup is not possible in BR 0.34 (the version in Tekkit, also the last to come out for 1.6.4) because you cannot fine-tune it to that point with the available blocks. At least not manually - maybe you can do it with Redstone or Computer control.

 

Keep in mind that the goal with an active reactor is balance, ideally in a cycle. The core produces steam as a heat agent, which the Turbine uses to produce power while it condenses back to water and returns to the core. Of course you can attach a sufficiently high-throughput water source to the core and void the condensed water from the Turbine, but a loop is both easier and more elegant. The optimal temperature for the core is around 900°C in both variants.

 

Interestingly, passive coolant blocks in the core do have an influence even in active mode. They seem to lower the fuel consumption during steam production.

 

By the way, there are three ways to create a high-throughput fluid connection for the steam/water cycle:

  • direct back-to-back attachment of reactor and Turbine fluid ports
  • deferred back-to-back attachment via Tesseracts
  • Extra Utilities Liquid Transfer Nodes with many stacks of upgrades

BR 0.4 (the current version, which is exclusive to Minecraft 1.7) adds Ludicrite, an expensive new top-tier coil material. It also has clutches now, so you can spin Turbines up without load to shorten waiting times. Apart from that, no fundamental changes.

It can only come to Tekkit after the 1.7 transition is made. The completion of the new Technic Launcher may help here, because it may free up manpower that has been bound in that project, but there has not even been an announcement yet about a new Tekkit version on 1.7.

Edited by Curunir
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Thanks, Curunir.

 

Like I said, I do like the active/passive system. I was just disappointed that the upper limit was so easy to reach. Despite that opinion, I of course still applaud the author. Big Reactors has been such a staple to Tekkit for so many people. It's hard for me to imagine how I would get anything done without it.

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There was a post way back that had the best setup for 2 turbines running at 1800 rpm (I tried to find it through a search but couldn't find it). I followed that to get my BR setup going. To be honest, the hardest part was filling the thing up with Gelid Cryotheum. That stuff is very hard to work with. One wrong step and you lose all your items.

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It's true that Tekkit Main has not many options for power, that's why BR has become so important, even the small setups. Mekanism has filled that gap very nicely, and it will be a prime candidate for inclusion if Tekkit ever moves to 1.7.

As for max-setups, 'easy to reach' is only true for creative building. I think the focus is on Survival, where you have to get your hands on insane amounts of Iron, Coal and Yellorite to build something that big. Also keep in mind that it's hard to find applications that require Mega-RF. One of those "super cubes" can power the installations of many players, even an entire server sometimes. And you will get headaches over creating a grid that can distribute all that power.

 

Handling Cryotheum is not too hard once you know what not to do. I strongly suggest using a Buildcraft Floodgate to fill your reactor core, once everything else is in place. Likewise, use a Buildcraft Pump to get it out again.

Edited by Curunir
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The 50,000mb/tick is not directly a hard coded limit in the mod.  It is entirely limited to the amount of water available too the reactor at any given tick.  No matter the setup, or transfer speed, the internal buffer of the reactor will always limit how much steam can be produced in very large reactors.  And since the reactor can only hold 50,000mb of water at any given time, that is the steam limit.

 

The other limitation in the current version of BR, as has been said, is the limited control you have with fine tuning the control rods.  Newer versions for minecraft 1.7.x have addressed this limitation, but for now, in Tekkit, we have to live with it as is.  But there are always ways around it.  A redstone clock hooked up to a reactor redstone port can be used as a fine tuner when you can not adjust the control rods enough.  By controlling the length of each pulse, and delay between them, you can cycle the reactor on and off in rapid succession, reducing fuel burn and controlling steam output.  But this option has it's own limits and risks...

 

But on the other hand, the sheer size of the reactor required to match the power generation of the turbines, does favor the actively cooled reactor in the long run.  That, and the much lower fuel usage of an active reactor.  Even though the active reactor + turbine can be just as, if not more, expensive to make then the passive reactor that can output its equivalent power.

Edited by jakalth
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It's true that Tekkit Main has not many options for power, that's why BR has become so important, even the small setups. Mekanism has filled that gap very nicely, and it will be a prime candidate for inclusion if Tekkit ever moves to 1.7.

As for max-setups, 'easy to reach' is only true for creative building. I think the focus is on Survival, where you have to get your hands on insane amounts of Iron, Coal and Yellorite to build something that big. Also keep in mind that it's hard to find applications that require Mega-RF. One of those "super cubes" can power the installations of many players, even an entire server sometimes. And you will get headaches over creating a grid that can distribute all that power.

 

Handling Cryotheum is not too hard once you know what not to do. I strongly suggest using a Buildcraft Floodgate to fill your reactor core, once everything else is in place. Likewise, use a Buildcraft Pump to get it out again.

Curunir,

You sir, are a wealth of information and handy tips. I've been playing on tekkit servers for a while and didn't even know flood gates existed. Filling up reactors was the one and only limiting factor preventing me from making more. Now that I know that I can use one of those, I plan on making a new actively cooled power station. I'm thinking of a large reactor with two tall turbines on each vertical face. Before I do that I think I will make a factory that will auto craft all the separate components that I will need. I'll put off going to the moon while I work on this new project.

Edited by The_Glaive
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Glad to be of service. Floodgates are a bit overlooked, as most people only fall back to old Buildcraft for the Quarry and Pump. Cryotheum is also the only liquid that really benefits from them, as most other coolants work fine as a single layer below the reactor roof, and have no ill effects.

When placing the Floodgate, remember that it will fill all empty layers below it, so it should only be applied to a completely finished setup. Arrange it so that you can pick it up again from the side when breaking it (not from the top), otherwise it will fall into the Cryotheum and be destroyed.

 

Now that I think of it, it would be quite nice if BigReactors had a reactor port for this kind of thing.

Edited by Curunir
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I've actually begun messing with Atomic Science after my brush with hard limits in Big Reactors. The Fusion Reactor has a much smaller footprint, but outputs enough power to run two Laser Drills fully (and a third partially). The production-to-volume ratio is much higher with AS than with BR, from what I've seen, but that's not all. It's also entirely self-fueling.

 

I managed to hook up a Chemical Extractor which could manufacture Deuterium continuously. Wired up to a Tesseract, it feeds the Fusion Reactor non-stop. I can layer these reactors on top of one another, as many as I need to, with the only obvious limits being build height and materials needed.

 

BR has some inarguable potential, but I also think it has some limitations which should really be looked at with a critical eye. I'm not really sure how the costs compare with AS, since I built those reactors in creative, but the long-run favors those smaller, self-fueling reactors. Unless they've been nerfed in recent updates, I'm going with them.

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Atomic Science vs Big Reactors.  Well, no answer too that debate, it's all preference, but...

 

Latest version of tekkit using AS has the reactors from that mod nearly unusable.  The mod its self had a major change done to it's core functions that did not get ironed out in the version of the mod used in the latest versions of tekkit.  later versions of AS were getting close to being fully functional, but then the mod on its own was dumped in favor of an integrated mob/pack called resonant induction.  Due too these things, AS reactors are unreliable...

 

I really do miss the big fusion reactor builds that were possible in the past.  The mod its self was fun to use and had a lot of experimentation and automation possible.

 

Big Reactors on the other hand operates just fine.  It does have limitations and smaller issues with it, but it is still a young mod that has a lot of features yet to be implemented.  There is nearly as much experimentation potential in BR as there was in AS.

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