Big Reactors — Guide

Getting Started

Before building a reactor you need to gather materials and craft the reactor parts.

• Mine Yellorium. Yellorium ore is the mod's core resource - it is both a crafting ingredient and the reactor fuel. Smelt/process it into ingots as needed.
• Craft the reactor blocks. The main parts you need are:
• Reactor Casing - the walls, floor, and ceiling of the reactor.
• Reactor Glass - optional see-through casing so you can watch the fuel rods inside.
• Reactor Controller - the "brain"; every reactor needs exactly one. This is where you open the control GUI.
• Fuel Rod - vertical columns inside the reactor that hold the fuel and where the reaction happens.
• Control Rod - sits on top of a fuel rod column to regulate the reaction.
• Access Port - lets you insert fuel and pull out waste (by hand, hopper, or pipes).
• Power Tap - outputs the generated power to your machines or storage.

Building a Reactor

A reactor is a hollow multiblock box with fuel rods inside. The smallest reactor is a 3x3x3 with a 1x1x1 interior, but a 5x5x5 gives room for real fuel columns.

1. Build the outer shell from Reactor Casing (and Reactor Glass where you want windows). Every block of the outer surface - all six faces, including corners and edges - must be a reactor block. Leave the inside hollow.
2. Place at least one Reactor Controller somewhere on the outer wall. You need exactly one controller.
3. Add the working parts to the wall: at least one Access Port (for fuel in / waste out) and at least one Power Tap (for power out). Add a Control Rod for each fuel-rod column.
4. Fill the interior with Fuel Rods. Fuel rods are placed as full-height vertical columns from the floor to the ceiling of the interior, each topped by a Control Rod on the ceiling.
5. Complete the structure. When the box is valid the multiblock assembles into a working reactor; right-click the Controller to open its GUI. If it will not form, check for gaps, a missing controller, or fuel rods that do not run the full interior height.

Running and Tuning the Reactor

Once the reactor is assembled, open the Reactor Controller to run it.

• Add fuel. Put Yellorium into the reactor through the Access Port (by hand, hopper, or item pipe). The fuel fills an internal fuel tank shown on the controller.
• Activate the reactor. Toggle the reactor on from the controller. The core heats up, the fuel begins to fission, waste (Cyanite) builds up over time, and the internal energy buffer fills with power.
• Pull power out. Connect machines, cables, or energy storage to a Power Tap to draw power from the buffer. The reactor keeps the buffer topped up while it runs and has fuel.
• Tune with Control Rods. Lowering the control rods (higher insertion) slows the reaction, lowering heat and fuel use; raising them speeds it up for more output and more heat. Use the control-rod setting to balance power output, fuel efficiency, and heat.
• Manage waste. Spent fuel becomes waste; pull it out through the Access Port and keep feeding fresh Yellorium so the reactor keeps generating.

Reactor Turbines

For even more power, a reactor can be run in a steam-producing mode and paired with a Reactor Turbine - a second multiblock.

• Instead of generating power directly, the reactor heats a coolant and produces steam.
• The steam is piped into a Reactor Turbine, another hollow multiblock that houses a rotor shaft lined with turbine blades and surrounded by metal coils.
• The steam spins the rotor; the coils convert that rotation into power, which you again pull out through a power tap.
• Turbines let a large reactor drive far more output than direct generation, at the cost of a bigger, more complex build. The reactor is the core of the system; turbines are the advanced scale-up.