Nuclear Reactor

Nuclear Reactor

The reactor is a multiblock you build yourself, from 3 × 3 × 3 up to 13 × 13 × 13. It heats water into steam, and a turbine turns that steam into power. If it gets too hot, it melts down.

Building it

The reactor is a hollow box.

Edges and corners: Reactor Casing or Neutron Reflector only.

Walls, floor and roof (the faces between the edges): Reactor Casing, Reactor Lead Glass, Neutron Reflector, and the special parts:

Part	Where	How many
Reactor Controller	Any wall	Exactly one
Coolant Port	Any wall	At least one for water, one for steam
Fuel Access Hatch	Any wall	At least one
Reactor Redstone Port	Any wall	Optional
Emergency Coolant System	Any wall	Optional, but you want it
Control Rod Drive	Roof only	One above every fuel column

Inside:

• Fuel Assembly columns that go from the floor up to just below the roof. Each column needs a Control Rod Drive in the roof directly above it.
• Free spots can be air, Graphite Moderator or Heavy Water Moderator.

The controller tells you exactly what's wrong if the structure isn't valid, including the position of the problem block.

Blueprint Projector

The Blueprint Projector shows a ghost of a 5 × 5 × 5 reactor (or a 5 × 7 × 5 turbine) in the world.

• Right-click the ground to place the projection. The front faces you.
• Sneak + right-click to switch between reactor and turbine.
• Right-click into the air to hide it.

It shows the material list and builds layer by layer from the bottom. When a layer is done it tells you.

If you just want to look at one, /atomcraft build reactor places a working one in front of you. See Commands and Config.

Ports

Right-click a port to switch its mode.

Port	Modes
Coolant Port	Water input / Steam output. In steam mode it pushes steam into the pipe or turbine next to it.
Reactor Redstone Port	Output: signal strength shows the temperature (15 = meltdown) / Input: SCRAM on signal / Input: start on signal
Fuel Access Hatch	Put fresh fuel rods in the top slot (hoppers work too). Spent rods come out at the bottom.

You can also fill the coolant port and the emergency coolant with a water bucket directly.

Running it

Open the controller, the Control Panel or a linked Remote Terminal.

The screen shows temperature and its history, fuel, coolant water, steam pressure, burnup, control rods, reactivity, heat per tick, steam, output and size.

• START starts the reactor (and clears a SCRAM)
• STOP shuts it down normally
• Control rods: drag them in or out (or scroll). Deeper means less power.
• SCRAM: emergency shutdown, all rods in at once
• AUTO: automatic SCRAM at 1600 °C

The Control Panel opens the nearest reactor controller within 24 blocks. Put it in your control room.

The fuel glows blue while the reactor has power.

Temperatures

Temperature	What happens
20 °C	Cold
100 °C	Water starts boiling into steam
1200 °C	OVERHEAT warning
1400 °C	Emergency coolant kicks in
1600 °C	CRITICAL. Auto SCRAM if enabled.
2000 °C	Meltdown

Heat and power

At full power every fuel assembly makes 100 heat per tick. 10 heat boils 1 mB of water into steam, so one assembly makes about 10 mB of steam per tick.

The layout changes how much heat you get. For every fuel assembly, each neighbor adds:

Neighbor	Bonus
Another Fuel Assembly	+8 %
Heavy Water Moderator	+10 %
Graphite Moderator	+6 %
Neutron Reflector	+5 %

MOX fuel rods give 15 % more heat on top. A reactor that's almost out of fuel loses power.

More heat means more steam, but also more to cool. If the steam can't go anywhere, the pressure builds up and the reactor heats up.

The controller holds 4 B of water and 4 B of steam.

Alarms

Alarm	When
OVERHEAT	1200 °C or more
CRITICAL	1600 °C or more
WATER	Less than 10 % water while running
PRESSURE	Steam tank over 90 % full
FUEL	Less than 5 % fuel
SCRAM	Reactor was shut down by SCRAM
EMERGENCY	Emergency coolant is being used

Emergency coolant

The Emergency Coolant System holds 32 B of water. Fill it with pipes or buckets, it never gives water back out on its own. When the core reaches 1400 °C it dumps up to 2000 mB per tick into the core. The cold water takes away a lot of heat at once.

Meltdown

At 2000 °C the reactor tears itself apart in a steam explosion. That's a crater with a radius of 28 blocks and the worst contamination in the mod (3.5 × the radiation of a Little Man). Everyone within 600 blocks gets the MELTDOWN warning.

Radiation

The fuel inside a running reactor radiates up to 8 blocks around. Reactor casing and reactor glass let only part of it through, but standing right next to a big reactor all day still adds up. See Radiation and Fallout.

Fuel

Fuel rods, MOX and what to do with spent fuel are on Fuel Cycle.

Recipes

See Recipes.