Plutonium-241

Plutonium-241 is a rare but highly fissile Plutonium isotope. It has a use for high performance Plutonium based fuels stronger than even Plutonium-239.

Production
Pu-241 makes up 25% of Plutonium-239-based, and 15% of Plutonium-240-based Short-Lived Nuclear Waste, which require the SILEX to extract.

Pu-241 can be bred using Plutonium-241 Zirconium Fast Breeders which yields 43.3% Pu-241 fully depleted, with an initial investment of 1 Pu-241 nugget per billet, making a total of 8 nuggets in investment per rod to potentially get ~20-21 nuggets (assuming normal distribution).

Uses
Highly Enriched Plutonium-241 Fuel, an extremely strong RBMK fuel and Reactor Grade Americium and Bismuth Zirconium Fast Breeders to quickly produce Reactor Grade Americium and Bismuth, respectively.

Trivia

 * It is known for decaying into Americium-241, which is used for long lifespan RTGs and ionization-type smoke detectors.
 * Am-241 is also fissile, but requires fast neutrons to do so.
 * It is formed through the neutron capture of Plutonium-240.