I am trying to set up some realistic conditions for a game I am designing, and need a bit of help. I am speaking very generally in this context. What are the percentages of mass released as usable energy in a uranium fission reaction, a D-T fusion reaction, and a positron-electron annihilation event. Notice I say USABLE, and these numbers do not have to be exact. I am simply trying to get a realistic basis for some numbers. The numbers I have so far are these uranium fission - 0.1% of the mass-energy conversion energy. D-T fusion - 0.7% of the mass-energy conversion energy positron-electron - 100% PLEASE correct me if I have made a mistake. EDIT: The percentages represent this: Take the entire mass of the reactants and convert it completely to energy. The percent is the usable energy from that caclulation. If it should only be the energy from the matter that was ACTUALLY converted, please let me know.