The BWR - safely maintaining 7k heat automatically in vanilla IC2

  • When I came to the point in IC2 to construct my first breeder reactor, I decided I wanted a fully automated system. All I want to do is put fuel in, and take the Re-enriched uranium cells back out. How can you do this in IC2?

    Think about increasingly hot reactors. They cause environmental effects. Can these be detected in-game? Some, such as the ability to harm nearby mobs, can't easily be. But there are three that can be detected by a block update detector in minecraft. Lava is one, but it also destroys random blocks around the machine, and so will eventually cut off both power and the redstone circuit that turns off the reactor - so that's no use. The ability to set fire to flammable stuff at 40% heat is not much better because you need to manually provide flammable stuff. That leaves water - at 50% heat, flowing water evaporates. This effect can readily be detected by a block update detector, and this can provide a trigger to turn off the reactor. We should therefore be able to automatically maintain a reactor at 50% heat. I call this reactor type the BWR - the boiling water reactor.

    For automated breeding purposes, we want to maintain a reactor at 6000 heat or more - or even, adventurously, at 9000 heat or more. In order to do this, all we need is a reactor of the right size. A reactor with no additional chambers melts down at 10,000 heat, and hits 50% heat at 5000 - too cool. A 4 block reactor is better - it melts down at 14,000, and 50% heat for it is 7,000 heat. At that temperature, it should turn a depleted isotope cell back into enriched uranium in one cycle. 9000 heat is only just possible - for that you need a 6 chamber reactor which contains more than 20 pieces of reactor plating to push the overall meltdown point to over 18,000 - the reactor planner says this is possible, but so much cooling capability is lost that it's not really better in my view than a safer model running between 6-8000 heat. The build I used had 8 isotope cells and 2 uranium, and gives a net gain of 6 uranium cells per cycle for the input of one piece of mined uranium. The rest was cooling. You also get 4M Eu, but that's not so important.... Cooling is good because more cooling means the reactor runs a larger % of the time.

    The rest is just engineering. We need a reactor design that continuously gets hotter, so that it will self-heat from zero up to (say) 7000 heat, at which point it will start evaporating water. We don't want that to happen too fast so we have some safety margin. We need falling water in the reactor so that there is a continuously replenished supply of blocks to evaporate. We surround the water with a line of block update detectors (these are not triggered by smoothly falling water) so we can detect when a block is evaporated, and turn off the reactor. And we need a reset circuit that tries to reset the detector and turn the reactor on roughly every minute or so - this can be based on redstone clocks and pistons. And that's a BWR breeder.

    When it's switched on, it will run continuously until it reaches 50% heat. The block update detector approach is actually very sensitive - in my builds, the reactor turns off within about 5 seconds of reaching 50%. Because of this sensitivity, I can use a very crude clock for turning the reactor back on again. If it sometimes turns on again immediately, that doesn't matter, as the BUD system will turn back off again fast if it's too hot. An independent timer that fires every minute or so is sufficient.

    So here are the rest of the components I used. The detector is based on pistons, and the pistons are placed facing outwards around 3 sides of the bottom of 5x5x5 cube containing the reactor. Each piston is primed by powering the block beneath it using a repeater, and it is kept on initially by a redstone wire some distance above. You power the repeater, then the wire, then depower the repeater, then the wire - but the piston will stay extended until a block update occurs. The vertical layout is repeater powered block, piston, block, block, redstone.

    The big advantage of this detector is that if you put these pistons next to each other horizontally, they set each other off. Any block update detected by any of the pistons causes a chain reaction of updates, causing all the pistons surrounding the reactor to retract. I'll leave the problem of turning that into a redstone signal to power off the reactor to you....

    All of this stuff ought to be in a single chunk for safety, and that's doable.

    The simplest reset / repower clock is two circles of repeaters - one slightly quicker than the other - and a circuit that only fires when both circles have a signal at the same local point. It's not terribly safety critical - although I also added an edge detector circuit inside the chunk to ensure I had no problems if the clock unloaded in the powered-on state to ensure I didn't get stuck in continual reset. (You can make an edge detector with a torch and delayed repeater at the end of a line - if both torch and repeater are off, you have an edge..)

    Anyway - it's an arguably safer alternative to perfectly balanced reactors which are manually preheated - I enjoyed making one, and thought I'd pass the idea on.