To answer your other question, you are not creating any energy. You have an energy supply, probably the power grid. You are transferring it into kinetic energy to make the disk spin. When the disk breaks, that energy is now in the form of metal fragments flying in random directions at high speed. When designing a jet engine this is the one failure that we cannot tolerate because we cannot armore the rest of the aircraft well enough to prevent damage serious enough to cause a crash. The pieces will fly straight through the airplane as if it were not there and maybe also the engine on the other wing. So we design the engine so as to make this failure impossible, and we do whatever testing we need to make sure of it. I'm designing a three disk system right now which is completely within the critical radius, so disk failure is impossible. But if the turbine were bigger or hotter, I'd have to take additional measures to prove that disk failure was impossible.