A fission reactor operates at 2700 MW level. Assume all this energy comes from the 200 MeV released by fission caused by thermal neutron absorption by 235U. At what daily rate is the mass of 235U used? (In practice, of course, the energy conversion is not 100% efficient, nor is all the 235U in a fuel cell used.) Answer is in kg/day I really don't know how to solve this question. Am I supposed to convert the 2700MW first into MeV/day and then get it into kg by using Avagadro's Number??? I have no idea. Please help!!! If you are supposed to do that then u would do: 2700MW * 1e6 (convert into watts) * (1ev/(1.6e-19)) * (1MeV/1e6)*(86400s/day) ???