Thorium fuel is one of the weakest fuels available for your reactor, but it is one of the cheapest as well. It is 1/3rd U-233 and 2/3rds Th-232 and since the former is bred from the latter, this introduces its key mechanic of breeding more fissile material than it consumes in its fuel lifespan.

Thorium Breeding Rods

Thorium with MEU-233 Driver Fuel
Composition
Fissile material	U-233
Fertile material	Th-232
Statistics
Yield	100,000,000
Self-igniting?	No
Splits with	Slow neutrons
Splits into	Fast neutrons
Flux function
Flux function type	Euler
Flux function danger	Safe
Depletion function	Boosted slope
Xenon generation function
Xenon burn function
Heat at 100 flux	0.65°C
Diffusion	0.02 1/2
Melting point	3350°C
Starting radiation	7.0 RAD/s

ZIRNOX Thorium Fuel
Heat/tick	40
Estimated lifespan	200,000 ticks
Start radiation	1.75 RAD/s
End radiation	112.5 RAD/s

Thorium-232 Breeding Rod
Heat/tick	0
Estimated lifespan	20,000 ticks
Start radiation	0.1 RAD/s
End radiation	1.75 RAD/s
Breeds into	Thorium Fuel

Thorium breeding rods are a unique item for the ZIRNOX reactor. They're used to produce thorium fuel through the neutron activation of the thorium-232 eventually into uranium-233. It provides no flux or heat to the reactor until it finishes breeding into fuel, but it has a short lifespan of 20k ticks.

Assembly

Thorium Fuel

Thorium fuel is a 2:1 mixture of thorium-232 and uranium-233. It is not particularly strong, but it is cheap and produces more U-233 than is needed to produce it, making it very useful during recycling due to its self-breeding nature.

Production

It can either be bred in a breeding reactor or manufactured with pure isotopes:

50010001500

6

3

ZIRNOX

Thorium fuel in the ZIRNOX is neither particularly strong nor weak, sitting right between natural uranium and medium enriched uranium fuel at 40 heat output. Its lifespan is also average at 200k ticks, same as MEU.

Assembly

Recycling

2 U-238 nuggets
2 Th-232 nuggets
4 U-233 nuggets
4 piles of nuclear waste

Per rod, divide by 2 to get a billet's worth of material.

RBMK

In the RBMK, thorium fuel is a somewhat weak but very stable and safe fuel thanks to its Euler function, it is slightly weaker than MEU-235. By itself, it is incapable of going super critical as its function plateaus very quickly and at a low level. For this reason, it is commonly used to stabilize high strength, dangerous function fuels, such as linear and negative-quadratic functions. It can also use the flux output of those fuels to burn quicker and thus be recycled quicker, to yield its bred U-233. Additionally, it has a "boosted slope" depletion function, meaning it becomes stronger as it depletes, due to the breeding nature.

Graph

Assembly

Recycling

Requires a SILEX with an infrared laser from the associated FEL.

(Xenon poison reduces ThMEU by 1%)

Brand New
- 84.0% ThMEU
- 6.0% U-233
- 10.0% long-lived nuclear waste (Th-232)
Barely Depleted
- 64.0% ThMEU
- 10.0% U-233
- 26.0% long-lived nuclear waste (Th-232)
Moderately Depleted
- 44.0% ThMEU
- 14.0% U-233
- 42.0% long-lived nuclear waste (Th-232)
Highly Depleted
- 24.0% ThMEU
- 18.0% U-233
- 58.0% long-lived nuclear waste (Th-232)
Fully Depleted
- 4.0% ThMEU
- 22.0% U-233
- 74.0% long-lived nuclear waste (Th-232)