Your question is somewhat vague. The most (kinetic) energy is in the fan blades. The fan disc is enclosed in a containment chamber whose purpose it is to protect the rest of the airplane from shrapnel in case of a fan disc or fan blade failure. Here's a video of a test where a fan blade failure is simulated:
As you can see, the fan blade more or less completely destroys the engine, but no debris or shrapnel leaves the containment chamber.Engine failures where debris or shrapnel is able to leave the containment chamber is called an uncontained engine failure, and they are very rare, but they still do happen.