Expanded Nuclear Fission

A deep nuclear chain for Factorio , inspired by the classic Minecraft mod NuclearCraft. Climb the actinide ladder from thorium to californium:
- burn a fuel;
- reprocess the spent cells;
- build the next fuel up from what comes out.

Along the way you collect isotopes that power some very nice toys. You also collect waste, which needs handling.

Requires Space Age (radioactive decay uses spoilage) and CMA Graphics. It adds no new ore patches and uses only vanilla science packs, so it works in existing saves.

The ladder

Thorium → uranium → neptunium → plutonium (and MOX) → americium → curium → berkelium → californium.

Each tier has low- and highly-enriched fuels:
- Low-enriched fuels burn in the vanilla reactor.
- Highly-enriched fuels need the Fission Reactor Mk2.
- The heavy actinides need the Mk3, which burns fuel assemblies with gadolinium control rods.

Each reprocessing pass in the hot cell loses a little and climbs the ladder a little.

Along the way

• Mineral processing: crushing stone gives monazite, zircon and fluorite.
• The thorium cycle: run the neutron irradiator on reactor heat, and wait for protactinium to decay into uranium-233.
• Enrichment: leaching, UF₆ and a centrifuge cascade.
• Radioactive decay: short-lived isotopes spoil into their daughters wherever they are. The decay chamber speeds it up.
• Basic and Enhanced recipes for every core step. Enhanced recipes take one more input from another chain and give a noticeably better output. Examples: TRISO fuel, and partitioning, which recovers every isotope and turns the waste into useful fission products.

Nuclear treats

• RTGs in four tiers (uranium, americium, plutonium, californium): electricity and heat with no fuel, forever.
• Isotope heater: Aquilo's last line of defence when the power fails.
• Tritium lamps: light with no power and no wires.
• Radioisotope beacons: no electricity, they never freeze, and they have more range.
• Nuclear robots in four tiers: they never recharge. Tier 4 flies at 34.6 km/h and carries 3 items.
• Relay roboport: needs no power at all.
• Supercritical steam: a 900 °C heat exchanger and turbine pair.
• Barite concrete flooring.
• Neutron-doped modules: stronger than tier 3, but much dirtier. Optional, via a startup setting.

Waste

Reprocessing fills waste casks.
- Safe: a cask in dry cask storage stays safe.
- Leaking: anywhere else, a cask starts leaking after 30 minutes.
- Rupturing: a leaking cask ruptures soon after, into a pollution burst and a radiation cloud.

To get rid of waste for good, vitrify it and bury it in a geological repository. Or load it into waste artillery shells and give it to the biters.

Other planets

Every chain can be finished on Nauvis alone. Other planets help but are never required:
- Gleba: bioleaching.
- Fulgora: isotope separation in the electromagnetic plant.
- Aquilo: cheap acids and lithium-6.
- Vulcanus: tungsten for the heavy buildings.

Credits

Inspired by NuclearCraft by tomdodd4598. Directed and play-tested by trentmkelly.

All code and graphical design by Claude Opus 5.5, Anthropic's AI model. That includes the hot cell, neutron irradiator, RTGs, isotope heater and nuclear robots, all modelled in Blender. Other building art comes from CMA Graphics (CC0).