As the plutonium 238 dioxide undergoes natural radioactive decay, it gives off heat, which is converted into electric power.
After heating in a mixture of 5% hydrogen and 95% argon will form a mixture of uranium dioxide and plutonium dioxide.
The material is nonweapons-grade plutonium dioxide.
It's plutonium dioxide, Pu-238.
In most cases, the additional oxide will be plutonium dioxide, sometimes thorium dioxide.
Any reactor that uses uranium-based fuel will produce plutonium dioxide.
One of the benefits of using MOX-type fuel is that the plutonium dioxide that is produced, can be re-used for energy generation.
In the form of plutonium dioxide it has a half-life of 87.7 years, reasonable energy density and exceptionally low gamma and neutron radiation levels.
NASA says the chance that any plutonium dioxide will be released in a launching is low - even assuming that the rocket blows up.
If so, plutonium dioxide could be released into the atmosphere and fine particles could be released.