Technic Pack Wiki
Logo-IC2 40.png Nuclear Reactor contains information about the Industrial Craft mod.
Nuclear Reactor
Type Generator
Tool Grid Wrench (Industrialcraft).png
Stackable No
Included in Industrial Craft

Ever found that your power grid doesn't have enough power in it? Did your Geo Gens drain the lava lakes? Did you happen to put your base in the sunless End? Then it is time to bring in the Nuclear Reactor!

With IndustrialCraft², the reactor system is fully recoded! Instead of lame Uranium refining, you now have to make a good setup for your reactor with all the reactor stuff you can find in the navigation. But one thing wasn't completely changed: nuclear meltdowns! And yes! They will still transform your house into a rather large hole!

In IC² the reactor can hold a value of heat, which is a byproduct of producing energy with Uranium Cells. This heat can be reduced by Cooling Cells, and Integrated Heat Disperser.

You can enlarge the space of your reactor by attaching up to 6 additional Reactor Chambers.


Advanced Alloy

Reactor Chamber

Advanced Alloy

Advanced Circuit


Advanced Circuit

Advanced Alloy

Reactor Chamber

Advanced Alloy

Nuclear Reactor

((Above) Before IndustrialCraft 1.106)

The total amount of raw materials needed for the above recipe is:

  • 58 iron and 8 cobblestone, or 61 iron
  • 8 lapis
  • 8 glowstone dust
  • 26 redstone
  • 9 sticky resin with an extractor, or 25 without, or 25 of either type of rubber wood, or 25 IndustrialCraft rubber saplings.
  • 53 tin
  • 96 copper
  • 4 water
  • Access to a Compressor, macerator, and a furnace.

Reactor Chamber

Advanced Circuit

Reactor Chamber


Reactor Chamber

Nuclear Reactor

((Above) IndustrialCraft 1.106 and Above)


This is the new GUI (fully upgraded with 6 additional Reactor Chambers):


A reactor will spit out any item that is unrelated to its function. (Other than empty buckets.)

Reactor array.gif


Reactors are complex and not for the faint of heart. A bad design can suddenly replace your house with a nice new crater. In the event of a nuclear meltdown, don’t cry about your house becoming smithereens. However, a good design can provide enough EU for all of your Industrial Craft needs.

Reactor Terms[]

Here are some of the terms often used when describing a reactor and its design.

Reactor Tick
A reactor 'ticks' once every second. This is when heat, EU generation, and cooling is calculated.
Reactor Design
The pattern in which components are placed within a reactor. A good design can give you nice, safe energy, and a bad design can spontaneously crater-ize your home and its contents.
Full Cycle
The time it takes for a full Uranium Cell to be used up. 10,000 reactor ticks, or 2 hours 47 mins.
Uranium Pulse
Pulses occur during a reactor tick, producing heat and EU for each uranium cell. Uranium Cells placed next to each other will interact to produce multiple pulses per reactor tick.
The reactor itself and its components can all store heat. If heat levels get too high, then components will melt, and there will be a risk of a reactor meltdown. (Boom!)
Cooling is provided by internal components like a Cooling Cell and the outside environment like water. Cooling is needed to counteract the effects of heat and hopefully keep your reactor (and home) intact.
Cooldown Period
The time required for an inactive reactor to cool all the excess heat it has collected.
Reactor Hull
This is where heat goes when it's not stored in a component. The maximum heat storage is 10,000, but it can be increased with Reactor Chambers and Integrated Reactor Plating.
Reactor Class
All reactor designs can be a class like "Mark-I-O ED" or "Mark-III EB" which gives an indication of how well a design will perform.
Reactor Efficiency
The average number of pulses per Uranium Cell. (efficiency = pulses / cells)
The more Uranium Cells that are placed next to each other, the higher the efficiency, but also the higher the risk.
Breeder Reactor
A type of reactor design that produces little energy. Its purpose is to recharge Depleted Isotope Cells into full Uranium Cells.

Reactor Components[]

A list of the various components that can be used within a reactor.

Reactor Chamber
Not really an internal component, these are placed adjacent to the reactor block in order to increase the number of slots within a reactor, increase the strength of the hull (+1000), and add a small amount of cooling.
Uranium Cell
The key part of a reactor. Each cell will pulse one or more times per tick, producing some heat and 200 EU. On its own, a cell will only pulse once (10 EU/t) per tick, but each adjacent Uranium Cell will add an additional pulse per tick, producing additional heat and packets of 200 EU. A Uranium Cell will last up to 10,000 reactor ticks (2 hours 47 minutes), generating anywhere between 2,000,000 to 10,000,000 EU, depending on the efficiency of the design. Uranium Cells have a chance to turn into Near-Depleted Uranium Cells when they're used up.
Cooling Cell
A single cell can store up to 10,000 heat away from the reactor hull; any more heat will cause the cell to melt. The cell will also cool 1 point of its stored heat each reactor tick.
Integrated Reactor Plating
Plating will distribute heat from an adjacent uranium cells into surrounding cooling cells and also into other plating to be further distributed. Distributing heat to another plating only happens once; the second plating will not distribute to a third plating. Plating also increases the reactor's hull strength (+100) and can store up to 10,000 heat itself if it is unable to direct it into a cooling cell. This stored heat will dissipate at a rate of 0.1 per reactor tick.
Integrated Heat Disperser
These components will attempt to balance out the levels of heat within the reactor hull, itself, and any adjacent component capable of storing heat. During each tick a disperser can exchange up to 25 heat with the reactor hull and up to 6 heat with each of the surrounding components.
For example, if a reactor hull has 120 heat stored and fresh disperser is placed inside and surrounded by 4 cooling cells, then the disperser will begin balancing the heat levels until the hull, itself, and the cooling cells each have 20 heat.
Near-Depleted Uranium Cell
The 'empty' state of an Uranium Cell; these can be made manually, or have a chance of appearing when a Uranium Cell runs dry within a reactor. They produce 1 heat each reactor tick.
Depleted Isotope Cell
A depleted Uranium Cell mixed with Coal Dust. When placed next to a Uranium Cell it recharges into a full cell once again. Isotope cells produce 1 heat and will cause adjacent Uranium Cells to pulse an additional time each tick. This extra pulse will produce heat but not EU. Isotope cells charge much faster if the reactor is running very hot.
Re-Enriched Uranium Cell
The fully charged state of an isotope cell, it will continue to produce only 1 heat and no EU but it will no longer react with adjacent uranium cells. Combined with another Coal Dust, it will become a brand new Uranium Cell.
Water Bucket
When a reactor's hull has more than 4000 heat, it will evaporate the water, reducing the heat level by 250 and leaving the empty bucket behind. (The reactor won't spit it out.)
Ice Block
Each reactor tick, if a reactor's hull has more than 300 heat, it will evaporate 1 ice block, reducing the heat level by 300.
Lava Bucket
A lava bucket will increase a reactor's hull heat level by 2,000, and the empty bucket will remain in the reactor. This is useful for 'breeder' type reactors while recharging isotope cells.

Heating and Cooling[]

Almost every component and the reactor itself can store heat in an effort to stave off a disaster. It is up to the cooling systems (and you) to get rid of this accumulated heat before the reactor cannot take any more.

The reactor's own storage (known as the reactor hull) starts off at 10,000, but that can be increased by up to 6 extra chambers (+1000 each) or placing plating into the reactor (+100). If the reactor hull reaches 50% of its maximum heat storage, then nearby water will begin to evaporate, and at 85% the reactor has a chance of removing itself from existence... violently.

Heat stored in components will be safely tucked away from the hull, but it will need time for the cooling systems to quench it all.

The most common source of heat is Uranium Cells, which will produce heat for each pulse they perform. The amount of heat depends on how many cooling components are adjacent to the cell:

No. of Components Heat Generated
0 10 per pulse into the reactor hull
1 10 per pulse into component
2 8 per pulse, 4 for each component
3 6 per pulse, 2 for each component
4 4 per pulse, 1 for each component

More cooling systems around a uranium cell mean less overall heat to deal with, making the reactor safer, but it also reduces the potential amount of EU a cell can produce. Risk vs. Reward.

Depleted Isotope cells only produce 1 heat per tick themselves, but they still react with adjacent Uranium Cells and make them pulse additional times.

Near-Depleted Uranium Cells and Re-Enriched Uranium Cells produce 1 heat per tick.

There are several ways to reduce a reactor's heat each tick:

Outside Source Cooling provided
The reactor itself 1 heat
Each reactor chamber added 2 heat per chamber
Water blocks within a 3x3x3 area* 1 heat per block
Air 'blocks' within a 3x3x3 area** 0.25 per block
  • Both still and flowing water count.
    • Torches, Redstone, and similar items won't count.
Internal Source Cooling provided
Cooling Cell 1 heat***
Integrated Reactor Plating 0.1 heat***
Ice blocks (single use) 300 heat per block
Water Buckets (single use) 250 heat per bucket
      • Cooling only occurs if the component in question has any heat stored.

The maximum outside cooling possible is 33 (reactor, 6 chambers and 20 water blocks).

If the amount of cooling available is less than the amount of heat produced then the reactor will gradually collect heat. There are various ways to deal with this:

  • Make a design that only has a slight amount of excess heat so that even when the Uranium Cells are used up the heat levels are still not dangerous.
  • Manually drop Ice blocks and/or Water buckets into the reactor.
  • Apply Redstone current to the reactor (or one of its chambers), causing it to stop generating heat and EU for as long as the Redstone current is active.

Heat management for a 'Breeder' type reactor is different. Breeders work best when running hot, so it's best to make a design that has exactly the same heat and cooling amount, then manually boost the heat by adding lava buckets, removing cooling, or temporarily adding extra uranium cells.

Reactors will emit smoke particles when warm and fire particles when hot. Be careful when using lava buckets, as the 2000 heat goes directly into the hull, and the heat dispersers need time to pull it into the cooling systems.

Environmental Effects of Reactor Heat[]

As reactors heat up, they will start having detrimental effects on their immediate surroundings. Each additional chamber increases the threshold by 1000 heat, to a maximum of +6000 with 6 chambers. Each piece of hull plating further increases the heat threshold by 100.

The exact heat effects for reactors are:

% of max hull heat Environmental effect
40% Flammable blocks within a 5x5x5 cube have a chance of burning.
50% Water blocks within a 5x5x5 cube (both sources and flowing) will have a chance of evaporating.
70% Entities within a 7x7x7 cube (instead of a 3x3x3 cube) will get hurt from the radiation exposure.
85% Blocks within a 5x5x5 cube have a chance of burning or turning into lava ('moving' lava only, no source blocks).
100% Reactor Explodes; Destroys everything within a large radius

Reactor Classification[]

All reactor designs fall into a set of pre-defined categories. This makes it easier to see, at a glance, how effective a design can be when either looking up designs on the IC forums or posting a design yourself.

mark I explosion range on superflat

Mark I /[]

Mark I reactors generate no excess heat each reactor tick and thus are safe to use continuously for as long as you supply Uranium. Mark Is tend have a low efficiency, but that's the price of a completely safe reactor. In fact, they're SO safe, you actually have to TRY to blow it up!

Mark I reactors have two sub-classes: Mark I-I for designs that don't rely on outside cooling in any way and Mark I-O for those that do.

Mark II[]

Mark II designs produce a small amount of excess heat and will need to be given a cool down period eventually to prevent the hull reaching 85% maximum heat or melting component. A Mark II must complete at least one full cycle before encountering heat complications.

The sub-class for Mark IIs denotes how many cycles the design can run before reaching critical heat levels. For example Mark II-3 will need a cool down period after running 3 cycles in a row. Mark II s that can run 16 times or more gets the special sub-class 'E' (Mark II-E) for almost being a Mark I.

Mark III[]

Mark III reactors tend to have an emphasis on efficiency at the cost of safety. Mark IIIs are unable to complete a full cycle without going into meltdown and thus need to be shutdown mid-cycle in order to deal with the high amount of excess heat. This can be done manually or by using Redstone.

Mark IIIs have the additional condition that they must run at least 10% of a cycle (16 mins 40 secs) before reaching critical heat or losing any components.

Mark IV[]

Mark IVs still have to run at least 10% of a cycle, just like Mark IIIs. The difference being that Mark IVs are allowed to lose components to overheating, and that must be replaced before the reactor goes critical.

Mark V[]

Mark Vs are for those who want to squeeze every last scrap of EU from their uranium cells; they cannot run long without needing a cool down period. You'd better have great Redstone timer skills, or you'll never be able to turn your back on these things.

Additional Suffixes[]

As well as being Mark I to V, reactor designs also have one or more suffixes to better inform people about their performance.

Single Use Coolants
A reactor that relies on a supply of ice and/or water buckets in order to maintain its classification should be suffixed with '-SUC'.
To calculate efficiency, take the number of uranium pulses a design makes per tick and divide it by the number of uranium cells it possesses.
The number provided will show the efficiency rating a design has:
Number Rating
Exactly 1 EE
Greater than 1 but less than 2 ED
2 or greater but less than 3 EC
3 or greater but less than 4 EB
4 or greater EA
This suffix is for designs that also recharge isotope cells. Isotope cells charge up faster when the reactor runs hot, so heat management is important. There are three breeder types:
  • Negative-Breeders slowly lose heat over time and will need heat to be added manually, or they can be left for a safe slow way to recharge isotopes.
  • Equal-Breeders have exactly the same heat generation as they do cooling ability and usually only require a user to boost the reactor's heat level manually at the beginning.
  • Positive-Breeders gain heat over time and will require more precise cool down management for the reactor to remain hot.
Reactors whose sole purpose is to recharge cells may not even have a 'Mark' classification and are simply called Breeders instead, with the efficiency/SUC suffix added.
Heat Ticks Required
0-2,999 40,000
3,000-5,999 20,000
6,000-8,999 10,000
9,000+ 5,000

Example Classifications[]

Mark I-O EE
A reactor design that can run continuously, but relies on outside cooling and only produces one pulse for each Uranium Cell.
Mark II-1 ED Positive-Breeder
A reactor with recharging capabilities that can only run one full cycle before needing a cool down.
Mark II-2 EC
A reactor design that can run two full cycles before needing a cool down period, producing at least 2 pulses per Uranium per reactor tick on average.
A reactor that can run at least 16 times before needing a cool down, relying on a supply of ice or water and has average efficiency.
Breeder EA
A heat-neutral reactor designed for the sole purpose of recharging Isotope Cells. Each Uranium Cell is capable of charging 3 or more Isotope Cells.

Tips and Tricks[]

--The more uranium cells you put in the reactor, the more output EU you get. So the trick is to put as many cells as possible in the chamber without causing an immediate explosion.

--The default state of a reactor is on, applying a redstone signal will turn it off.

-- Follow this Link to the IndustrailCraft Reactor Planner v2 to safely play around with setups before risking your world.

Video Tutorial[]



Minecraft Technic Part 17 Nuclear Reactor and Reactor Chambers!

Building the Reactor & the Reactor Chambers


Minecraft Technic Part 18 Firing up the Reactor and hooking up the Mass Fabricator!

Setting up the Reactor