Paint rods and heat sinks, or lay out the same patterns the Reactor Builder uses, and see the RF/t or steam, fuel burn and turbine needs the controller will show. Pick FTB Evolution 2 under Modpack for that pack's config: it changes the numbers a lot.
Drag to rotate. Right-drag, Shift-drag or two-finger drag to pan. Scroll or pinch to zoom.
Build from the bottom up. Step through the layers with ◀ ▶ on the 3D view; it hides everything above the layer you're on.
allowMultipleReactorControllers is on.From ReactorValidation.validate in the Colossal Reactors 26.1.2-2.6.0.0.0 jar.
The numbered keys are in the config file. The rest come from the datapack recipes in data/colossal_reactors/recipe/reactor/ and recipe/turbine/, which packs can replace.
Coolant piped in
Fuel in the rods
The same rods the Reactor Builder places. Its heat sink is the block selected above (pick air for none).
Top-down view of the inside. Rods and heat sinks run the full height; each rod column has a Reactor Rod Controller in the roof above it.
Checked in game with the FTB Evolution 2 config: eight test reactors (air, gold, diamond, emerald, graphite, Ender Goo and Gelid Breezium, uranium and azurite, with and without water) matched the page's RF/t, steam and water to the unit, and fuel burn to four digits. In the full pack, FTB Armory's adamantite, aeternium and aurichalcum blocks and Industrial Coolant matched too.
Assumes fuel is kept topped up, waste is taken out, and the power port (or the steam port and its water supply) keeps up. Reactor instability is off by default and in FTB Evolution 2, so heat sinks' overheating value isn't used.
Every interior cell next to a rod is "adjacent". RF uses the average energy of those cells, and drops if there are fewer of them than rod blocks. Cells further out only change fuel burn, never RF.
RF/t = baseRF × 0.8 × n^exp
× avg energy (adjacent cells)
× min(1, adjacent cells / rods) × 1.16
ReactorSimulation.tick
n above isn't your rod count. Each rod block loses a quarter for every side (of four) touching another rod or the casing. A checkerboard rod touches neither, so it counts in full; a rod against the wall in a corner counts half.
n = Σ rods max(0, 1 − 0.25 × crowded sides)ReactorControllerBlockEntity.rebuildSimulationCaches
Power grows as n to a power below 1. The mod uses 0.9; FTB Evolution 2 sets 0.76, so doubling the effective rods there gives 1.69× the RF, not 2×. Fuel burn grows almost linearly, so small reactors get more RF per ingot.
rodEnergyScalingExponent 0.9 → 0.76 (Evo 2)ReactorSimulation.rodEnergyScaling
With water piped in, the reactor boils RF × factor mB of water a tick and sends no RF at all while the water lasts. Only the share it can't boil comes out as RF.
water/t = RF × 0.45 (Evo 2: 0.085) steam/t = water × 1.0 (Evo 2: 3.93)ReactorSimulation.tick · reactor_coolant.json
Fuel use scales with n too, divided by a curve that flattens as the reactor grows, and by the weighted fuel value of every heat sink cell (cells not touching a rod count half).
fuel/t = 0.03 × n × 1.72 / (n+1)^k
/ heatSinkFuel / 1.35 × 1.21
k = 0.5 × (0.4 + 0.5 × 400/(n+400))
ReactorSimulation.tick
Cells not touching a rod are meant to count for at most 4 per rod block. The controller caps their count but adds their fuel values in full, so a few rods in a big empty reactor burn far less fuel than the formula intends. In game, 9 rod columns in a 15×15×6 of air burned 0.178 units/t; the intended cap gives 0.353.
capNonAdjacentHeatSinks(rods, countNon,
new double[]{fuelNon}, …) // copies, thrown away
ReactorSimulation.computeHeatSinkModifiersFromStaticCache
The pack's in-game guide still describes its 1.3.0 values. Pack 1.3.1 changed the config and the water coolant again; the calculator uses what the pack ships now (1.7.0).
| Guide | Config | |
|---|---|---|
| Rod power exponent | 0.55 | 0.76 |
| Steam per mB water | 0.8 | 3.93 |
| Steam per blade, mB/t | 48 | 150 |