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Mekanism Fission Reactor

by demux•Feb 17, 2026•redstone•v1.21.1•Mekanism•2.8k•187•3.9 KB
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Description

A high-output nuclear reactor multiblock that consumes fissile fuel to generate extreme amounts of heat. At maximum size (18×18×18), the reactor supports multiple fuel assemblies with a burn rate of up to 1 mB/t per assembly, scaling total heat output linearly.

The reactor produces heat only, requiring active cooling with water or sodium to prevent meltdown. When paired with a Thermoelectric Boiler and Industrial Turbine, it becomes one of Mekanism’s highest-throughput power systems.

This redstone build measures 18 × 18 × 18 and uses 3,784 blocks across 6 different block types, mostly mekanismgenerators:fission fuel assembly, mekanismgenerators:reactor glass, mekanismgenerators:fission reactor casing.

It is made for Minecraft Java Edition 1.21.1. You'll need Mekanism to build it as intended.

Build at a Glance

Dimensions18 × 18 × 18
Footprint324 blocks
Total blocks3,784
Block types6
EditionJava
VersionMinecraft 1.21.1
ModMekanism
File size3.9 KB
DifficultyIntermediate

Blocks in this schematic

3,784 blocks total

Placed blocks, not crafting ingredients. Overlapping regions are counted separately.

Mekanismgenerators:Fission Fuel Assembly1,920
Mekanismgenerators:Reactor Glass1,272
Mekanismgenerators:Fission Reactor Casing456
Mekanismgenerators:Control Rod Assembly128
Mekanismgenerators:Fission Reactor Logic Adapter4
Mekanismgenerators:Fission Reactor Port4
See the full block list in the 3D viewer →

Frequently Asked Questions

What Minecraft version is Mekanism Fission Reactor for?
Mekanism Fission Reactor is built for Minecraft 1.21.1 (Java Edition) and usually works on nearby versions too.
Do I need any mods to build Mekanism Fission Reactor?
Yes - this build uses Mekanism. Install it before pasting the schematic so every block places correctly.
How many blocks does Mekanism Fission Reactor use?
Mekanism Fission Reactor uses 3,784 blocks across 6 block types, and measures 18 × 18 × 18. Use the materials list above to gather everything first.
How do I import Mekanism Fission Reactor into Minecraft?
Download the file above, then: in Litematica (Java), put the .litematic in your .minecraft/schematics folder, open the Litematica menu in-game, load the schematic, and use the placement tools to build it block by block. In WorldEdit (Java), drop the .schem into your WorldEdit schematics folder and run //schem load then //paste. On Bedrock, use a structure-block or add-on workflow that imports .nbt structures.
Is Mekanism Fission Reactor free to download?
Yes. Every schematic on MineSchematic is free to download in .litematic, .schem and .nbt formats, with no account required.

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