Fast breeder reactor

The Fast breeder reactor is a nuclear power building that consumes Core Fuel and Blanket Fuel. It is designed to reach a stable operating state by recycling its own waste stream: spent Core Fuel is sent to a Nuclear Reprocessing Plant, while Blanket Fuel can be enriched and fed back into the reactor. In practice, this makes it a late-game reactor that can greatly reduce uranium consumption once the supply loop is established.

To start the reactor, about 40 Core Fuel is needed, and this initial stock must be made the hard way through double uranium enrichment. After startup, the preferred steady-state supply chain is much more efficient:

• Core Fuel priority:

  1. Recover it from Spent Core Fuel in a Nuclear Reprocessing Plant, with an 80% recovery rate.
  2. Make it from Blanket Fuel (Enriched) in an Enrichment Plant; this produces slightly more than enough to cover the remaining 20%.
  3. Make it from Enriched Uranium (20%) in a Chemical Plant II as a startup backup only.

• Blanket Fuel priority:

  1. Recover it from Blanket Fuel (Enriched) as a byproduct of the Core Fuel recipe.
  2. Make it from Depleted Uranium in a Chemical Plant II, if there is leftover material from a regular Nuclear Reactor.
  3. Make it from Yellow Cake in a Chemical Plant II.

Enrichment of Blanket Fuel is optional and does not affect reactor performance if the output storage becomes full. The enrichment process has three operating modes, which change fuel use and output rate:

• 1x mode enriches as much as is used.
• 0x mode does not enrich at all, but halves the use of the relevant input.
• 3x mode triples the enrichment rate, but reduces the produced and consumed amounts to one quarter.

Because the reactor relies on a closed material loop, it is important to size the supporting reprocessing and enrichment chain so that Spent Core Fuel and enriched Blanket Fuel do not back up. A properly arranged supply priority keeps the reactor running with much lower uranium demand than the initial startup phase.