Colossal Reactors in FTB Evolution 2

Colossal Reactors adds multiblock fission reactors, steam turbines and some supporting machines. This pack includes version 2.4.0.0.1 of the mod.^[1][2]

The reactor

A reactor is a hollow shell built from Reactor Casing and Reactor Glass. Inside it you place fuel Reactor Rods, optional heat sinks and optional coolant fluid. Ports go on the casing, and you need exactly one Reactor Controller, which runs the reactor and shows the readouts.^[3]

The mod's own guide gives you two ways to run it. Setup 1 is RF-only: you leave the controller's coolant buffer empty, so no fluid coolant is needed, and you take power from a power port. Setup 2 sets a coolant fluid, typically water, so the reactor produces steam for a turbine.^[4]

The turbine

The turbine is a second multiblock: a shell with a rotor and coils inside. It can run on steam that already exists, or take steam from a reactor running Setup 2 and turn it into more RF.^[5]

Other parts

• Heating coils are driven by datapack-defined recipes. Each coil type may consume items, fluid, energy or a combination, and switches between off and on visuals while running.^[6]
• The machines are standalone processing blocks, separate from the casing ports.^[7]

If you're new to the mod, start with the mod's Getting started guide. It walks you through a complete example reactor before you pick a setup.^[3][4]

Colossal Reactors is about two multiblocks: a fission reactor and a steam turbine. Your first goal is a closed reactor shell with a controller and a power port on one face. Once that makes RF, you can add coolant and a turbine for more power.^[2][4]

Your first reactor, step by step

1. Build a closed shell. Use Reactor Casing for the floor, roof and the four corner pillars, and Reactor Glass for 5x5 panels on the west, east and south walls.^[4]
2. Put the interior in: fuel rods, plus a rod controller on top. The Reactor Builder can place the shell and internals for you (more on that below).^[4]
3. On the fourth wall (north in the guide's example), place one Reactor Controller outside the shell as a single protruding block. Every other cell on that wall uses glass or a port.^[4]
4. On that same wall, replace a glass cell with a power port. Ports can sit anywhere on the controller face.^[4]
5. Leave the controller's coolant buffer empty for now. The RF-only setup needs no fluid coolant.^[4]
6. Add fuel through the controller GUI (or a hopper or pipe), open the controller, check that it says valid, then switch it ON.^[4]
7. Connect the outside of the power port to something that accepts energy, then check that RF/t is above 0.^[4]

If the controller says Invalid, read its status line and fix the shell, rods or rod controllers. If it is ON but gives 0 RF/t, you are most likely missing a power port or an energy acceptor.^[4][8]

Fuel in this pack

The pack defines two reactor fuel recipes, and both turn their input into Nuclear Waste. One takes a single Uranium Ingot from FTB Materials. The other takes 2 azurite ingots (anything in the azurite ingot tag).^[9]

Don't count on finding uranium ore from this mod. The pack sets worldgen.000_disable_uranium_oregen to true, so the mod's uranium ore does not generate (the mod default is false). Lead ore generation is switched off the same way.^[10]

Azurite Ingot is the fuel you can craft yourself. This is its in-pack recipe:^[9]

Azurite IngotMod recipe

Crafting Shapeless

• Nuclear Waste
• Nuclear Waste
• Lapis Lazuli

Recipe id: colossal_reactors:crafting/azurite_ingot_from_waste_lapis

One of the ways to make an Azurite Ingot in this pack.

Here is how the pack lists the azurite fuel entry:^[9]

Nuclear WasteAdded by the pack

Fuel (colossal_reactors)

• 2× any azurite ingot

Recipe id: colossal_reactors:reactor/reactor_fuel_1

Added by the pack: azurite ingots as reactor fuel, producing Nuclear Waste.

Let the builder do the heavy lifting

The Reactor Builder places the casing shell, rod controllers, reactor rods and heat sinks from the materials in its buffer and tank. It does not place the controller, power ports or resource ports, so you add those by hand afterwards. Stop the build first if red zones show up in the preview. The builder is not part of the multiblock, so you can remove it when it is done.^[11]

Its internal fluid tank holds 64,000 mB in this pack, which is the mod default (builder.001_tankCapacityMb).^[10]

Next step: steam and a turbine

When RF-only works, set a coolant fluid in the controller (typically water) and add two more resource ports on the controller face: coolant INSERT and steam EXTRACT. Pipe the steam into a turbine resource port set to INSERT, and take RF from the turbine power port. Reactor RF/t may drop while steam rises, and that is normal. The turbine has its own Getting started page.^[4][5]

Colossal Reactors is built around fission reactors and steam turbines, both of which are multiblocks. A few supporting machines sit alongside them. This section covers how they fit together and what this pack changes.^[2]

Reactor structure

A reactor is a hollow shell of Reactor Casing and Reactor Glass. Inside it you place fuel Reactor Rods, optional heat sinks and optional coolant. Ports go on the casing, and exactly one Reactor Controller drives the whole thing.^[3]

• The interior must be a closed box with valid faces only on the outside. Leave room for rods, fluids and ports before you seal the last blocks.^[12]
• A Rod Controller sits on the top shell layer, above each fuel rod column. Every interior cell below it in that column must be a Reactor Rod, or validation fails.^[12]
• The Reactor Controller goes on a side face of the casing, not the top or bottom, with its screen facing outward. In the guide's example it protrudes alone as a single block, and the ports sit on that same wall, replacing glass cells.^[4][8]
• In this pack the maximum reactor size is 65 in width, length and height. The structure is re-validated every 200 ticks while the reactor is ON, and only one reactor controller is allowed. See reactor.size.000_maxReactorWidth, reactor.validation.000_reactorValidationIntervalTicks and reactor.validation.001_allowMultipleReactorControllers.^[10]

Rods, heat sinks and coolant

Reactor Rods hold the fuel. Where you place them changes both RF output and fuel consumption, and the controller readouts show the result. You can load fuel through the controller or through automation that targets the fuel slots.^[12]

The pack keeps the mod defaults for the rod maths. Each rod holds up to 10,000 fuel units, and any running reactor makes at least 500 RF/t. Every horizontal neighbour of a rod (another rod or the border) costs a 0.25 penalty. Energy scales with rod count using a power curve with exponent 0.9, while fuel scales linearly (exponent 1). The options are reactor.base.000_rodMaxFuelUnits, reactor.base.101b_minRfPerTick, reactor.rods.106c_rodAdjacencyPenalty, reactor.balance.001_rodEnergyScalingExponent and reactor.balance.004_rodFuelScalingExponent.^[10]

Heat sinks are passive. They can be solid blocks or stationary liquid volumes inside the shell, and they are not consumed. They change RF output and fuel consumption. In the pack's config, cells touching a rod count with weight 1 and cells not touching any rod count with weight 0.5.^[10][12]

Active coolant is different: it is the working fluid and it is consumed while the reactor runs. Some coolants, such as water in steam mode, divert would-be RF into exhaust fluid. With enough conversion the RF can drop to zero while fuel still burns. If you leave the coolant buffer empty, the reactor runs in RF-only mode and needs no fluid.^[4][12]

The pack adds two fuel recipes. One burns a Uranium Ingot, the other burns two azurite ingots, and both produce Nuclear Waste.^[9]

Nuclear WasteAdded by the pack

Fuel (colossal_reactors)

• Uranium Ingot

Recipe id: colossal_reactors:reactor/reactor_fuel_0

Pack-added fuel recipe: uranium in, nuclear waste out.

Nuclear WasteAdded by the pack

Fuel (colossal_reactors)

• 2× any azurite ingot

Recipe id: colossal_reactors:reactor/reactor_fuel_1

Pack-added fuel recipe using azurite ingots.

Uranium and lead ore generation are both disabled in this pack's config, so do not expect to find those ores in the world. Boron, chromium and the End californium ore are left on.^[10]

Ports and automation

Power ports have no screen. They push RF out to cables or machines on the outside face, with their inside facing the reactor. The High Conduction variant exists for huge reactors. When the reactor re-validates, each power port resizes its buffer to about estimated RF/t × 10, never below 10,000 RF. The standard port caps at 2.1B RF (2,147,483,647), and the High Conduction port uses 64-bit storage. Capacity grows immediately but only shrinks when the stored energy still fits.^[14]

Resource ports move items and fluids between the outside world and the reactor. Click the top button to cycle the mode:^[15]

• Insert: the reactor accepts solid fuel and a coolant fluid. The filter can be All, Fuel or Coolant.^[15]
• Extract: the reactor outputs nuclear waste and spent coolant. The filter can be All, Waste or Coolant.^[15]
• Eject: the reactor ejects the solid fuel it contains.^[15]

Separate Solid, Liquid and Gas toggles allow or block each medium (gas needs Mekanism). The D button under a tank dumps its contents, and the fluid is discarded. Resource port tanks resize on re-validation to about the estimated mB/t for that port's mode and filter × 10, with a minimum of 16,000 mB and no fixed upper cap.^[15]

For a basic automated setup, put all ports on the controller's wall. Add one INSERT port with the Fuel filter and one EXTRACT port for waste, plus a power port. Reboot the controller after changing modes, filters or coolant, because that re-validates the structure and refreshes port tank sizes.^[4][8][15]

1. Set the coolant fluid in the controller, typically water in steam mode.^[4]
2. Add an INSERT port with the Coolant filter (or Both) to pipe coolant in.^[4]
3. Add an EXTRACT port with the Coolant filter to pipe steam and spent fluid out. Keep the waste EXTRACT port separate.^[4][15]
4. Pipe the steam into a turbine's INSERT resource port, then reboot the reactor controller.^[4]

If you want to stop the reactor without breaking the shell, add a Reactor Redstone Port. Without one, the reactor runs whenever it is valid and ON.^[8][16]

Builders

The Reactor Builder places the shell and interior from its buffer and tank, but it does not place the controller or any ports. It works in this order: casing, rod controllers, rods, fluid heat sinks (1000 mB per cell), then solid heat sinks. Use Preview to check the footprint, and Stop if red zones appear. Simulation only estimates stats and materials, and it does not start the real reactor. In this pack the builder runs 2 build steps per tick and has a 64,000 mB tank.^[10][11]

Turbines

A turbine converts steam into RF. The guide gives the output as steam used × RF per mB of steam × coil strength × blade layout bonus. It describes about 7 RF per mB as typical for standard steam. In this pack's config the fallback when no datapack entry exists is 4, so check JEI for the real value on your steam. Steam comes in through a Turbine Resource Port, and RF leaves through a Turbine Power Port.^[10][17]

Steam use is capped by blades. The pack counts up to 1,000 mB per tick per valid balanced blade, with a steam input buffer of 10,000 mB per blade. Balanced rings (4, 8, 12 and so on per rod) are required. Each ascending ring layer adds a 3% bonus and each descending layer costs 3%. The maximum blade ring is 31, which allows a 63×63 interior span.^[10][17]

The upper interior layers form the coil zone. Fill them with metal storage blocks the mod recognizes, such as gold, copper or netherite. Better blocks give a higher multiplier. Empty space or unrecognised blocks count as weak coil, at 0.3 (30%) efficiency in this pack. Average strength across the whole zone is what matters. Do not use the reactor's heating coil blocks here.^[10][17]

The layout mirrors the reactor: one controller on a side wall, two resource ports (INSERT for steam, EXTRACT for water or exhaust) and one power port on the same face. In the pack, turbines max out at 65 in each dimension, are re-validated every 200 ticks, and allow only one controller. The Turbine Builder offers an Efficient layout (fewer rod columns, blades grow ring by ring) and a Productive layout (rods on every allowed column).^[5][10][18]

Turbine power ports resize like the reactor's: about estimated RF/t × 10, never below 10,000 RF, with a 2.1B RF cap on the normal port. A Turbine Redstone Port can shut the turbine down from outside while leaving the structure intact.^[19][20]

Standalone machines

The Melter turns solid inputs into molten fluid. It has an input slot, a progress bar, a fluid tank with a D dump button, and a redstone mode button. In this pack its tank holds 64,000 mB.^[10][21]

Heating coils are driven by datapack recipes. Depending on the coil, you may see an item slot, a fluid gauge, an energy bar and a redstone mode button, and the unused panels are hidden. They switch between off and on visuals while running.^[6][22]

The Radiation Scrubber and Radiation Cure only appear when radiation management is enabled in config. That option is false in this pack, so you will not see them here.^[10][23]

This page follows the materials and recipes in the pack, from the first ore you mine up to a working reactor. Work through the tiers in order: boron, tough alloy, the extras, then the reactor itself.^[4][9]

Unverified The sources here show no quest chapter or quest order for Colossal Reactors. If the pack's quest book covers it, that detail lives in the quest book and is not confirmed here, so the order below comes from the recipes and the in-game guide. This site does hold FTB Evolution 2's own recipes, read from the pack itself: look the item up in the item browser.

Tier 1: Boron

Boron is your entry material. Both the boron ore and the deep boron ore drop Raw Boron and respond to Fortune. With Silk Touch you get the ore block itself instead.^[24][25]

The mod smelts and blasts boron into Boron Ingot from ore, raw boron or dust, and the pack adds more routes. A laser recipe from BBL Dimensional Resources (changed by the pack) lists raw boron among its outputs. Occultism crushing gives 2 raw boron from ore, and the pack adds boron dust recipes for several grinders.^[9]

Boron IngotMod recipe

Smelting

Recipe id: colossal_reactors:smelting/boron_ingot_from_raw

Smelting raw boron is the simplest route to an ingot.

Tier 2: Tough Alloy

Tough Alloy Ingot is the next step. The mod's four Ender IO alloy smelting recipes give 2, 3, 4 and 3 ingots per craft, and a fifth recipe makes a single ingot from an unrefined input. The pack adds a 3-ingot recipe for Energized Power and a 1-ingot recipe for FTB Industrial Contraptions.^[9]

3× Tough Alloy IngotMod recipe

Alloy Smelting (enderio)

Recipe id: colossal_reactors:enderio/alloy_smelting/tough_alloy_from_lead_iron_boron

One of the Ender IO alloy smelting recipes, making 3 ingots.

The pack also adds Hephaestus Forge recipes. Melting makes 90 Molten Tough Alloy per ingot and 810 per block, using 50 lava each time. A casting table turns 90 back into an ingot, and a casting basin turns 810 into a Block of Tough Alloy. The pack adds the same lava melting for Molten Stainless Steel.^[9]

Tier 3: Fuel and rarer materials

The pack defines two reactor fuel recipes, and both produce Nuclear Waste. One takes a single uranium ingot. The other takes 2 azurite ingots of any kind.^[9]

Azurite Ingot has a crafting recipe from waste lapis, and you can pack 9 ingots into a Block of Azurite and unpack them again.^[9]

Californium Crystals come from the California End ore, which drops 2 to 3 crystals and also responds to Fortune. The pack changed the Oritech pulverizer recipe for it, and an Ender IO sag milling recipe exists too.^[9][26]

Chromium ore drops Raw Chromium, and the pack registers chromium as a refining material for FTB Industrial Contraptions.^[9][27]

Reactor components

Heating coils run on datapack-defined recipes, so what a given coil consumes comes from the pack's data and JEI. The pack has crafting recipes for both the energy and resource coils.^[6][9][22]

Energy Heating CoilMod recipe

Crafting Shaped

Crafting Shaped

any graphite ingot	any copper ingot	any graphite ingot
any copper ingot	any redstone storage block	any copper ingot
any graphite ingot	any copper ingot	any graphite ingot

Recipe id: colossal_reactors:crafting/heating_coil_energy_off

The energy heating coil has a second, alternative recipe as well.

Resource Heating CoilMod recipe

Crafting Shaped

Crafting Shaped

any graphite ingot	any copper ingot	any graphite ingot
any copper ingot	Hopper	any copper ingot
any graphite ingot	any copper ingot	any graphite ingot

Recipe id: colossal_reactors:crafting/heating_coil_resource_off

3× Catalyst BreeziumMod recipe

Crafting Shapeless

• any gunpowder
• any redstone dust
• any lapi gems
• Wind Charge
• Wind Charge
• Wind Charge
• Wind Charge
• Wind Charge

Recipe id: colossal_reactors:crafting/catalyst_breezium

This shapeless craft makes 3 catalysts.

Reactor setups

The mod's own guide gives you two setups for the same closed shell: casing floor and roof, casing corner pillars, glass walls, and one controller on a side face with the ports beside it.^[4]

• Setup 1 is RF only. You leave the coolant buffer empty, add fuel, switch the reactor ON and connect the power port to an energy acceptor. No turbine is needed.^[4]
• Setup 2 adds coolant. You set the coolant fluid in the controller, add an insert port for coolant and an extract port for steam, and pipe the steam into a turbine. Reactor RF per tick may drop while steam rises, which is normal.^[4]

The Reactor Builder can place the casing, rods and heat sinks for you, but it never places the controller or ports. You add those by hand afterwards.^[4][11]

The connections between Colossal Reactors and the rest of the pack come from recipes. They cover where you get boron, what the reactor's fuel recipe uses, what its molten metals are good for, and one fabricating recipe that uses a reactor coolant item.^[9]

Getting boron

Raw Boron doesn't only come from boron ore. The pack adds an Energized Power filtration plant recipe that has no item inputs and outputs Raw Boron along with Stone Pebble.^[9]

Raw Boron, Stone PebbleAdded by the pack

Filtration Plant (energizedpower)

Recipe id: ftb:unification/energizedpower/filtration_plant/raw_ore_filtration/boron

Filtration plant recipe added by the pack. It gives Raw Boron and a Stone Pebble.

BBL Dimensional Resources also drops Raw Boron. Its asteroid laser recipe is marked as changed by the pack, and Raw Boron is one of many raw ores it outputs, including several from FTB Materials.^[9]

Raw Boron, Raw Aluminum, Raw Iridium, Raw Lead, Raw Nickel, Raw Platinum, Raw Silver, Raw Tin +7 moreChanged by the pack

Laser (dimresources)

Recipe id: dimresources:asteroid

Asteroid laser recipe, changed by the pack. Raw Boron is one of its outputs.

For ingots, the pack adds smelting recipes that turn three FTB Industrial Contraptions ore-processing stages into Boron Ingot: Crushed Ore, Washed Ore and Refined Concentrate.^[9]

Boron IngotAdded by the pack

Smelting

• Crushed Ore

Recipe id: ftbic:refining/c/boron/smelting/crushed_ore

Smelting the crushed stage.

Boron IngotAdded by the pack

Smelting

• Washed Ore

Recipe id: ftbic:refining/c/boron/smelting/washed_ore

Smelting the washed stage.

Boron IngotAdded by the pack

Smelting

• Refined Concentrate

Recipe id: ftbic:refining/c/boron/smelting/refined_concentrate

Smelting the refined stage.

Fuel and waste

The pack adds a reactor fuel recipe that ties the reactor to FTB Materials. It takes Uranium Ingot and produces Nuclear Waste. Raw Uranium is also on the asteroid recipe's output list.^[9]

Nuclear WasteAdded by the pack

Fuel (colossal_reactors)

• Uranium Ingot

Recipe id: colossal_reactors:reactor/reactor_fuel_0

Fuel recipe added by the pack.

Molten metals and Hephaestus casting

Molten Stainless Steel is the fluid behind the pack's stainless steel casting. Hephaestus Forge casting recipes added by the pack turn it into Stainless Steel Nugget, Stainless Steel Ingot (casting table) and Block of Stainless Steel (casting basin).^[9]

Stainless Steel NuggetAdded by the pack

Casting Table (hephaestus)

• 10× Molten Stainless Steel

Recipe id: ftb:hephaestus_materials/casting/stainless_steel/nugget

Casting table recipe for the nugget.

Stainless Steel IngotAdded by the pack

Casting Table (hephaestus)

• 90× Molten Stainless Steel

Recipe id: ftb:hephaestus_materials/casting/stainless_steel/ingot

Casting table recipe for the ingot.

Block of Stainless SteelAdded by the pack

Casting Basin (hephaestus)

• 810× Molten Stainless Steel

Recipe id: ftb:hephaestus_materials/casting/stainless_steel/block

Casting basin recipe for the block.

The same fluid also casts Hephaestus Tools parts, and so does Molten Tough Alloy. The pack adds casting table recipes for both fluids covering the adze head, broad axe head, hammer head, large blade, large plate, pickaxe head, small axe head, small blade, tool binding, tool handle, tough binding and tough handle. Part costs are the same for both fluids.^[9]

Pickaxe HeadAdded by the pack

Casting Table (hephaestus)

• 180× Molten Stainless Steel

Recipe id: ftb:hephaestus_materials/part_casting/stainless_steel/pick_head

Pickaxe Head from Molten Stainless Steel.

Pickaxe HeadAdded by the pack

Casting Table (hephaestus)

• 180× Molten Tough Alloy

Recipe id: ftb:hephaestus_materials/part_casting/tough_alloy/pick_head

The same part from Molten Tough Alloy.

Dynamo Matrix

Refrigerant Gelid Breezium is an input to a fabricating recipe from FTB Evolution 2 Companion, alongside the Just Dire Things fluid Refined T3 Fluid Source. It makes Dynamo Matrix.^[9]

2× Dynamo MatrixAdded by the pack

Fabricating (ftbevolutioncompanion)

• 8000× Refrigerant Gelid Breezium
• 8000× Refined T3 Fluid Source

Recipe id: ftb:fabricating/dynamo_matrix

Fabricating recipe added by the pack. It uses 8,000 of each fluid and makes 2 Dynamo Matrix.

Almost everything in the Colossal Reactors common config is left at the mod default in this pack. The one place the pack deviates is ore generation, so start there.^[10]

What the pack changed

• worldgen.000_disable_uranium_oregen is true in this pack (mod default false), so uranium ore generation is switched off in the world.^[10]
• worldgen.001_disable_lead_oregen is also true here (mod default false), so lead ore generation is off too.^[10]
• Boron, chromium and californium ore generation are left on: worldgen.002_disable_boron_oregen, worldgen.003_disable_chromium_oregen and worldgen.004_disable_californium_oregen are all false.^[10]

Reactor size and output

The reactor can be up to 65 blocks in each direction: reactor.size.000_maxReactorWidth, reactor.size.001_maxReactorLength and reactor.size.002_maxReactorHeight are all 65. Turbines have the same 65 limit on each axis.^[10]

Output is not boosted or nerfed. The reactor reactor.efficiency.002_productionMultiplier and reactor.efficiency.003_consumptionMultiplier are both 1, and so are the turbine turbine.balance.000_productionMultiplier and turbine.balance.001_consumptionMultiplier. Any running reactor produces at least 500 RF/t (reactor.base.101b_minRfPerTick).^[10]

Structures are re-validated every 200 ticks, about 10 seconds (reactor.validation.000_reactorValidationIntervalTicks). A reactor is only valid with exactly one controller, because reactor.validation.001_allowMultipleReactorControllers is false. The turbine has the same rule through turbine.validation.001_allowMultipleTurbineControllers.^[10]

Turbines

turbine.blade.003_requireBalancedBladeRings is true, so blade rings must be balanced (4, 8, 12 and so on per rod) for the turbine to validate and for the steam cap to apply. The maximum blade ring is 31 (turbine.blade.000_maxBladeRing). Each valid balanced blade counts up to 1,000 mB of steam per tick (turbine.blade.004_steamMbPerBladePerTick).^[10]

Builders and tanks

The Reactor Builder and Turbine Builder both run 2 build steps per tick (builder.000_buildStepsPerTick, turbine_builder.000_buildStepsPerTick). Their internal tanks, and the Melter tank, hold 64,000 mB each (builder.001_tankCapacityMb, turbine_builder.001_tankCapacityMb, melter.000_tankCapacityMb).^[10]

Meltdowns and radiation are off

evil_things.000_reactor_unstability is false, and so are the Mekanism radiation, Iska Utils explosion and Alex's Caves explosion integrations. The stability settings under the same section only apply when unstability is enabled, so they do nothing here.^[10]

dev.003_enable_radiation_management is false too. That keeps the Radiation Scrubber and Radiation Cure features off. The option's own description says that turning it on does not enable radiation in the reactors themselves.^[10]