I would guess a 3x(high number)x3 reactor running at high temperature feeding a MFR laser drill would be the best bet due to its low efficiency.
Or you can process your Yellorium ore in the EnderIO SAG mill for the 5% chance for a bonus cyanite dust.
that's quite a low chance of getting cyanite... I wish there was a machine or reactor design where you can quickly convert yellorium into cyanite for people wanting to use the more efficient tubines instead of just reactors... perhaps smelting yellorium in a furnace?