Summary of the problem Yellorium from Blutonium Pack Version 2.5.5 What is the bug? This may not be easily fixable, but when you put blutonium into a Big Reactor mod Reactor, then eject the fuel it becomes yellorium. Mod & Version Big Reactors, Sky Factory 2.5.6 Link to log file Is it repeatable? Put a Blutonium ingot into a Reactor of anny size that already has fuel in it, then eject the fuel. It will give you a Yellorium ingot instead of Blutonium. Known Fix I do not know any fixes, but it does not seem overly obvious to find and not all that helpful to exploit. Maybe for a bit of extra reactor material, I dunno.