Plutonium Fuel

LEPu-239, ingot form

Plutonium fuel is a category of nuclear fuel consisting of plutonium isotopes. Lower enriched versions often include the contaminant plutonium-240 in significant quantities, which inhibits some of the fuel's performance and causes it to be self-igniting if in sufficient quantities with the fissile plutonium-239, but it breeds into plutonium-241 if it successfully captures a neutron without undergoing fission. It is often used in reactors as an alternative to uranium fuel and sometimes MOX fuel.

Low Enriched Plutonium-239

LEPu-239 is the most common type of plutonium fuel as it is the easiest to produce. It is fairly stronger than MEU-235. Curiously, it is not used in the PWR.

Production

It is produced by mixing reactor grade plutonium with uranium-238.

3

ZIRNOX

Plutonium Fuel

Heat/tick	65
Estimated lifespan	175,000 ticks
Start radiation	4.25 RAD/s
End radiation	187.5 RAD/s

It has a slightly lower lifespan than MEU-235 for the ZIRNOX, but it has a fairly higher heat output of 65.

Assembly

Recycling

• 4 reactor grade plutonium nuggets
• 2 Tc-99 nuggets
• 6 tiny piles of nuclear waste

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

RBMK

Low Enriched Plutonium-239

Composition
Fissile material	Pu-239
Fertile material	U-238 & Pu-241
Statistics
Yield	100,000,000
Self-igniting?	No
Splits with	Slow neutrons
Splits into	Fast neutrons
Flux function	$\log _{10}(x+1)*0.5*35$
Flux function type	Base 10 logarithm
Flux function danger	Medium
Depletion function	Raising slope
Xenon generation function	$x*0.5$
Xenon burn function	$x^{2}*50$
Heat at 100 flux	0.75°C
Diffusion	0.02 1/2
Melting point	2,744°C
Starting radiation	17.0 RAD/s

LEPu-239 is a considerably stronger than MEU-235, roughly twice as reactive and an additional 0.1°C heat output per received flux. However, it is still not quite as strong as MOX fuel in either reactivity or heat output.

Graph

A plot of LEPu-239 flux reactivity in the RBMK. The X-axis is inbound flux bound between 0 - 120 and the Y-axis is outbound flux bound between 0 - 60.

Assembly

Recycling

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

(Xenon poison reduces LEPu-239 by 1%)

• Brand New
  • 84.0% LEPu-239
  • 6.0% Pu-239
  • 7.0% short-lived nuclear waste (Pu-239)
  • 3.0% short-lived nuclear waste (Pu-240)
• Barely Depleted
  • 70.0% LEPu-239
  • 8.0% reactor grade plutonium
  • 15.0% short-lived nuclear waste (Pu-239)
  • 7.0% short-lived nuclear waste (Pu-240)
• Moderately Depleted
  • 56.0% LEPu-239
  • 10.0% reactor grade plutonium
  • 23.0% short-lived nuclear waste (Pu-239)
  • 11.0% short-lived nuclear waste (Pu-240)
• Highly Depleted
  • 42.0% LEPu-239
  • 12.0% reactor grade plutonium
  • 31.0% short-lived nuclear waste (Pu-239)
  • 15.0% short-lived nuclear waste (Pu-240)
• Fully Depleted
  • 28.0% LEPu-239
  • 14.0% reactor grade plutonium
  • 39.0% short-lived nuclear waste (Pu-239)
  • 19.0% short-lived nuclear waste (Pu-240)

Medium Enriched Plutonium-239

MEPu-239 is the same as reactor grade plutonium, as a result, it is a popular choice for its simplicity in production for a generally strong fuel.

Production

See for more information: Reactor Grade Plutonium#Production

PWR

MEPu-239 Fuel

Composition
Fissile material	Pu-239
Fertile material	Pu-240
Statistics
Yield	1,000,000,000
Reaction function	$\log _{10}(x/2500+1)*675$
Function type	Logarithmic
Function danger	Medium
Heat per flux	7.5 TU
Hazards
Start radiation	6.25 RAD/s
End radiation	62.5 RAD/s

MEPu-239 is still one of the weaker fuels due to it using a logarithmic function, though it is stable because of that. It has a stronger function than MEU-235 or MOX and it has the same heat output as the latter at 7.5 TU.

Graph

A plot of MEPu-239 flux reactivity in the PWR. The X-axis is inbound flux bound between 0 - 120 and the Y-axis is outbound flux bound between 0 - 240.

Assembly

Recycling

• 2 lead nuggets
• 4 reactor grade plutonium nuggets
• 2 Tc-99 nuggets
• 3 tiny piles of nuclear waste

RBMK

Medium Enriched Plutonium-239 Fuel

Composition
Fissile material	Pu-239
Fertile material	Pu-240
Statistics
Yield	100,000,000
Self-igniting?	No
Splits with	Slow neutrons
Splits into	Fast neutrons
Flux function	${\sqrt {x+20}}*35/10$
Flux function type	Square root
Flux function danger	Medium
Depletion function	Gentle slope
Xenon generation function	$x*0.5$
Xenon burn function	$x^{2}*50$
Heat at 100 flux	1.0°C
Diffusion	0.02 1/2
Melting point	2,744°C
Starting radiation	25.0 RAD/s

MEPu-239 is a very popular choice for the RBMK in particular for its strength, production simplicity, and self-igniting nature, which makes it effective for jumpstarting or sustaining otherwise cold reactors. It's not quite as strong as MOX fuel function-wise at lower flux inputs, but it has higher heat output.

Graph

A plot of MEPu-239 flux reactivity in the RBMK. The X-axis is inbound flux bound between 0 - 120 and the Y-axis is outbound flux bound between 0 - 60.

Assembly

Recycling

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

(Xenon poison reduces reactor grade plutonium by 1%)

• Brand New
  • 85.0% reactor grade plutonium
  • 10.0% short-lived nuclear waste (Pu-239)
  • 5.0% short-lived nuclear waste (Pu-240)
• Barely Depleted
  • 68.4% reactor grade plutonium
  • 21.0% short-lived nuclear waste (Pu-239)
  • 10.5% short-lived nuclear waste (Pu-240)
• Moderately Depleted
  • 50.0% reactor grade plutonium
  • 33.3% short-lived nuclear waste (Pu-239)
  • 16.6% short-lived nuclear waste (Pu-240)
• Highly Depleted
  • 29.4% reactor grade plutonium
  • 47.0% short-lived nuclear waste (Pu-239)
  • 23.5% short-lived nuclear waste (Pu-240)
• Fully Depleted
  • 6.2% reactor grade plutonium
  • 62.5% short-lived nuclear waste (Pu-239)
  • 31.2% short-lived nuclear waste (Pu-240)

Watz Power Plant

MEPu-239 Fuel

Heat per flux	15.0 TU
Reaction function	${\sqrt {x}}*150$
Type	Medium / Square root
Thermal multiplier	${\sqrt {x+100}}*0.1$

Flux-wise, MEPu-239 is one of the strongest fuels the Watz can use.

Graph

A plot of MEPu-239 flux reactivity in the Watz. The X-axis is inbound flux bound between 0 - 1000 and the Y-axis is outbound flux bound between 0 - 5000.

Assembly

Recycling

• 1 solid mud brick
• 12 Pu-239 nuggets
• 6 bismuth nuggets
• 2 pieces of nuclear waste

Highly Enriched Plutonium-239

HEPu-239 is a very powerful fuel, consisting of pure, weapons grade Pu-239. It is even more powerful than HEU-235 and 233.

PWR

HEPu-239 Fuel

Composition
Fissile material	Pu-239
Statistics
Yield	1,000,000,000
Reaction function	${\sqrt {x}}*22.5$
Function type	Square root
Function danger	Medium
Heat per flux	10.0 TU
Hazards
Start radiation	5.0 RAD/s
End radiation	50.0 RAD/s

In the PWR, HEPu-239 is part of the high strength fuels. It has an extremely strong square root function and high heat output of 10 TU.

Graph

A plot of HEPu-239 flux reactivity in the PWR. The X-axis is inbound flux bound between 0 - 120 and the Y-axis is outbound flux bound between 0 - 240.

Assembly

Recycling

• 2 reactor grade plutonium nuggets
• 4 Pu-240 nuggets
• 1 Tc-99 nugget
• 5 tiny piles of nuclear waste