What a material:
Video 2.
Burning and Extinguishing Characteristics of Plutonium Metal Fires by RobPlonski
. Source. Commented by this dude: www.linkedin.com/in/robplonski/
Video 1. . Source. Describes conversion from Plutonium nitrate to a plutonium metal slab, which is then sent to final pit.
Strong alpha emitter. Can be used as an atomic battery.
Figure 1.
Plutonium-238-oxide pellet glowing under its own heat
. Source. Unlike for nuclear applications, we don't need the pure metal, so the oxide 238PuO2 is used instead as it is more chemically stable.
This is the isotope that is produced for nuclear weapons by irradiating Uranium-238 with a neutron.
Plutonium-240 is a contaminant.
This isotope shows up as an inevitable contaminant in Plutonium-239 for nuclear weapons, because it emits neutrons too fast and makes it harder to assemble the critical mass without fizzle.
Wikipedia explains that Pu-240 is formed by Pu-239 Neutron capture:
About 62% to 73% of the time when 239Pu captures a neutron, it undergoes fission; the remainder of the time, it forms 240Pu.
so its presence is inevitable.

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