Efficient BR Passive Design?

[Digdug83]

Ordinarily I would just dive right into making turbines and such but for the moment I'd rather focus on getting the most bang for my buck out of a passive reactor. Some lurking on my part has not yielded any personally useful information though so here I am.

 

I'm working with a rather limited space (14x14x14) and wanted to get impressions on potential dimensions and the number of rods to use. I'm using gelid cryotheum in my current 7x7x7 (5x 5m rods in an X) and getting around 12K RF/t. This is fine for normal power needs but I wanted to try and build a passive that could support a full laser drill set. Is there a ratio of rods:coolant I should be aware of? Does height matter more than length/width or vice versa? Does objective reality really exist?

[Curunir]

It depends a little on what coolant you want to use. The best configurations produce a lot of heat and require Gelid Cryotheum or at least Resonant Ender to be useful. As Cryo is subject to gravity like sand and gravel are, you won't get away with a single top layer of it, as you could with Resonant Ender. So you should ask yourself if you can manufacture enough Cryo to fill all the non-rod blocks in that casing, or plan with the green stuff right away.

As for configuration, you want to pack the rods tightly for high core irradiation (also called fertility, the percent value in the interface). Fuel consumption is antiproportional to this, so the higher you get it, the less fuel is consumed. The percentage can go over 500% in very efficient reactors.

The recommended basic layout is a five-rod "plus" shape with just four columns of coolant at the corners. Go taller if you need more power, as increased reactor height is also beneficial for fertility.

If that doesn't cut it, you can of course go wider. I had good results with a 3x3 fuel column block surrounded by coolant, so frame size was 7x7 at base. If your frame is even larger, consider building several groups of columns. You may even opt to have a massive 5x5 fuel block or even larger right in the middle. Keep in mind that you can fine-tune the Reactor with Control Rod settings. Many of the most efficient setups run with Control Rods extended to a certain degree. Zero percent means "uninhibited reaction", and the more you extend the Rods, the more you moderate it (=slow it down).

 

Have fun building.

Edited June 19, 2014 by Curunir

[Digdug83]

Given that information, I'm thinking of doing an 8x8x10 solid rod group, with a surrounding 1m layer of cryotheum. I did a test reactor in creative with 3 8x2x10 banks with 1m in between in a 12x12x12 reactor. I was able to get just over 500% fertility with it so if I add two more strips of 8x1x10 rods in between those banks I should be able to push the percentage even higher.

[Curunir]

Just keep in mind that this setup will generate lots of heat, so you probably need to keep the rods at 80-90% to keep it in an efficient heat range. Rule of thumb is keeping it below 1000°C, optimal point is around 900°C iirc.

[efflandt]

Some ways to retain or gain efficiency without overheating or reducing efficiency with control rods is a couple of methods to pulse the reactor either using redstone ports with timer to state cell (both set for short time) AND temperature, or rednet PRC to turn it on when less than set temperature OR square wave [timer] (set for short time) to pulse it down when over temperature.

 

For the first method the timer and state cell should be set short enough to make the power you need without overshooting too much, so when it kicks out on temperature, it is just brief. So it maintains stable output without the wide swings and catch up of controlling on temperature alone. However, the frequent clickity-clickity of timer and state cell can be annoying if you hang around there.

 

For the rednet PRC method the square wave is set to a time that does not quite get it up to temperature, so it runs steady below temperature and pulses down when it hits the temperature limit. Temperature may rise quickly, but the bottom does not drop out of energy production when it hits the temperature limit because it pulses down. There may be a better method once I learn more about the PRC, but an advantage over the mechanical timer is that rednet is silent.

 

CC could likely do that too, but a bit more of a learning curve and the program would need to run in a tight loop to control a rapidly heating reactor. So far all I do with CC is control steam flow as a turbine winds up and monitor reactor fuel and case temperature along with rednet histogram of the ON-OFF cycles of the reactor controlled by rednet

[Digdug83]

Why do I need to keep it below 1000C? Wouldn't that just cut my power production down to nothing? My current reactor is set up to only switch on when the internal battery is below 50% so it basically pulses itself every so often depending on power use. The goal is to have enough production capacity to maintain a full laser drill set without having my batteries drained in 10 minutes.

[Curunir]

You wanted an efficient design. Efficiency drops sharply if you allow the heat to rise above 1000°C.

Of course you can allow the core temperature to max out, but it will eat through your Yellorium much, much faster that way. At least the meltdown feature is not implemented yet, so you risk nothing except running out of fuel quickly.

Edited June 20, 2014 by Curunir

[Digdug83]

I was actually referring more to efficiency of design, not operation per se. I apologize for the misunderstanding. At any rate I have found an optimal (for now) design in a 12x12x12 with 9 2x2 groups spaced 1m apart from each other and the reactor walls. When they're set to 90% (~900C) they produce right around 31K which is more than enough to power my drill and the rest of my base. With ~0.2mB/t fuel use and 500% fertility it looks pretty solid. Any other suggestions or tips though would be appreciated.