Hopefully Fusionist is still around and can put the process he developed into clear view. He may insist that it is "anecdotal", but my impression is of great detail and specificity.
I have notes, but I will only post those if Fusionist does not appear here in a few days.
Speaking of replication, I believe we have enough descriptive material to reconstruct some if not all of the essentials. Fusionist (a retired and highly experienced spectroscopist) has warned of some safety issues that might ensue. But, he saw no radioactivity. There was thermal runaway that occurred somewhere at or above 830 degrees C. That runaway resulted in melting of the Fiberfrax (greater than 1790 C).
The "Fusionist" system was apparently completely nickel and hydrogen, no lithium added or present. (I would guess that FiberFrax could have some lithium from incidental spodumene, but it is not supposed to). Of course Fiberfrax has alumina and silica.