Question

A nuclear explosion is required to deliver 1 MeV of heat energy. How many fission events must be required to attain this power level. If this explosion is designed with a nuclear fuel consisting of U²³⁵ to run a reactor at this power level for one year then calculate the amount of fuel needed. It is given that energy released per fission event is 200 MeV.

Answer 1

Energy required by nuclear explosion = 1 MW = 10⁶ Js^–1 

Energy released by fission = 200 MeV

= 200×1.6×10^–13 = 3.2×10^–11 J

No. of fission required per second 

Number of fission required per year by 1 MW energy release

= 3.125 × 10¹⁶ × 365 × 24 × 60 × 60 = 9.9 × 10²³ 

Hence amount of uranium fuel needed is 

= 386.46 g