Going Nuclear: 5×5×6 boiling water reactor build guide
Handbook · Fuel · Next: Steam loop
This version's water reactor is a boiling water reactor (BWR): it produces steam inside its vessel. This 5×5×6 plan is derived from the bundled Reactor Builder. Tanks, turbines, pumps, desks and external containment are additional.
Materials and space
Leave access below the floor for waste, beside the vessel for water and steam, and above it for fuel, relief and rod drives. Keep pipes accessible after adding external shielding.
| Component | Count |
|---|---|
| Reactor Casing | 99 |
| Reactor Glass | 4 |
| Fuel Channel | 15 |
| Graphite Moderator | 8 |
| Control Rod Drive | 5 |
| Reactor Nozzle | 5 |
| Reactor Controller | 1 |
These counts apply to the exact windows and ports shown below. Replacing other permitted wall surfaces with glass changes the casing count. Edges and corners must remain casing. See the crafting reference for ingredients.
Orientation and key
Each layer is viewed from above, north at the top and south at the bottom. Stack the squares without shifting them. Layer 0 is the bottom and layer 5 the roof.
| Symbol | Component |
|---|---|
| C | Reactor Casing |
| G | Graphite Moderator |
| F | Fuel Channel |
| R | Control Rod Drive |
| V | Reactor Glass |
| K | Reactor Controller, front facing south |
| H | Nozzle set to Hot Leg |
| W | Nozzle set to Cold Leg |
| B | Nozzle set to Fuel |
| A | Nozzle set to Waste |
| E | Nozzle set to Relief |
| . | Leave interior space free for coolant |
Layer 0: floor
CCCCC
CCCCC
CCACC
CCCCC
CCCCC
Set the centre nozzle to Waste and connect the underside to a spent-fuel pool. Close the remainder of the floor.
Layer 1: core base
CCCCC
CGFGC
CFFFC
CGFGC
CCCCC
The five fuel channels form a cross. Put graphite in the four interior corners. Each fuel column rests on the floor; channels are not horizontal pipes between ports.
Layer 2: core and controller
CCCCC
CGFGC
CFFFC
CGFGC
CKVVC
Stack channels and graphite directly on their matching blocks in layer 1. Put the Controller in the south wall with its front facing outwards, away from an edge. Two glass blocks sit next to it.
Layer 3: upper fuel and fluid ports
CCCCC
C.F.H
CFFFW
C.F.C
CCVVC
Add the third level of five fuel channels. Leave the four inner corners free. The east wall carries Hot Leg and Cold Leg. Place two more windows in the south wall. Water and steam need separate pipes and the correct pump directions. Right-click nozzles until their displayed mode matches the plan.
Layer 4: open coolant space
CCCCC
C...C
C...C
C...C
CCCCC
Do not fill this level with more fuel, graphite or ordinary blocks. The scanner requires coolant space. Fill the vessel through the water supply later.
Layer 5: roof
CCCCC
CBRCC
CRRRC
CCREC
CCCCC
Place a Control Rod Drive above every one of the five fuel columns. Fuel and Relief occupy other roof positions. Keep a usable discharge area around the relief outlet when constructing the external enclosure.
Five nozzle modes
| Mode | Role in this BWR | Position in this plan |
|---|---|---|
| Hot Leg | Steam out | East wall, layer 3 |
| Cold Leg | Feed/return water in | East wall, layer 3 |
| Fuel | Enriched uranyl nitrate, or later MOX, in | Roof |
| Waste | Spent fuel solution out | Floor |
| Relief | Pressure relief | Roof |
Older tooltips still call the Hot Leg output hot primary coolant. The current Ponder steam-and-water instructions describe this loop. Do not substitute an older external-heat-exchanger design for the steam line in this guide.
Scan before starting
Right-click the Controller to request a scan. Leave power off. Fix each reported cause at its stated position and scan again. Typical problems include holes, incorrect edges, multiple controllers, missing rod drives and incorrect nozzle modes.
The scanner generally supports exterior dimensions of 3–15 blocks per axis. That does not validate every possible interior or promise proportional power from larger vessels. Start with a comprehensible design and change it only after successful structural validation.
External containment is separate from the vessel. The mod describes closed concrete or lead enclosures. Check that the desk recognises containment: a decorative hall does not prove containment, and recognised containment can still fail.