Actinium-227

Actinium-227 is a highly radioactive radioisotope. It forms naturally as the decay product of Uranium and Thorium, though in minuscule quantities.

Production
Actinium-227 can be produced in the cyclotron by bombarding either Caesium with Copper or Astatine with Carbon, but it is easier to breed it from Radium-226 in a Breeding Reactor.

Uses
Currently, its only use it a high strength RTG pellet. Each RTG pellet provides 20 power. If RTG decay is enabled, each will have a lifespan of 15,620,000 ticks, computing to ~3 IRL months, with a stated in-game lifespan of 131 years and 55 days (assuming a 100 day year). They decay to Lead pellets. This also means it will make 3,124,800,000 power in total over that time.

It has planned uses for a high strength neutron source.

It can make Thorium-232 in a cyclotron by bombarding it with Lithium.

Trivia

 * IRL, it glows an "eerie" blue due to the rapid decay and ionization from α particles.
 * It neither glows in NTM nor is it pyrophoric even though it technically should be.