Pyroprocessing (from Greek Πυρος = fire) is a process in which materials are subjected to high temperatures (typically over 800 °C) in order to bring about a chemical or physical change.
Argonne National Laboratory pioneered the development of pyrochemical processing, or pyroprocessing, a high-temperature method of recycling reactor waste into fuel, demonstrating it paired with the EBR-II and then proposed commercializing it in the Integral Fast Reactor.
[1] In 2016, Argonne National Laboratory researchers are developing and refining several pyroprocessing technologies for both light water and fast reactors, with most based on electrorefining rather than conventional wet-chemical/PUREX, to improve the technologies’ commercial viability by increasing their process efficiency and scalability.
Theoretically, you could still reuse mixed, pyroprocessed plutonium to generate nuclear power, but it wouldn’t be pure enough for other uses.
[5] In South Korea due to the historical Section 123 Agreement between ROK and the U.S,[6] neither enrichment nor PUREX related reprocessing were permitted, with researchers therefore increasingly viewing the "proliferation resistant" pyroprocessing cycle, as the solution for the nation's growing spent fuel inventory, in 2017 forming a collaboration with the U.S and Japan to advance the economics of the process.