Q: 200 MeV energy is released when one nucleus of U235 undergoes fission. Find the number of fission per second required for producing a power of 1 megawatt.
Sol: Energy released = 200 MeV
= 200 × 106 × 1.6 × 10-19 = 3.2 × 10-11 J
P = 1 mega watt = 106 watts.
No. of fission per second (n) = (Total energy)/(Energy per fission)
n = 106/(3.2 × 10-11 ) = 3.125 × 1016 fission.