Find below a conversation between Master Deepak, PUC student and Mr. Mathew Abraham, Physics teacher.
Deepak asked: “nuclear fusion or fission in which of these energy released is more and why?”
Energy released per fission is more than energy released per fusion. But energy released per unit mass during fusion is very much greater than energy released per unit mass during fission
But why energy released is more
The fission of a U-235 releases about 200 MeV of energy
whereas the fusion of 4H to form He releases only about 20 MeV
But, the 200 MeV is obtained from 236 amu
and the 20 MeV is obtained from just 4 amu
Then why dont we use nuclear fusion as source of energy and electricity
Nuclear fusion requires very high temperature to start. It is difficult to maintain such a huge temperature (of the order of million degrees).
Tokamak magnetic field and plasma current. (Photo credit: Wikipedia)
Research is going on to construct nuclear fusion reactor
The international prototype is named tokamak
In that the nuclear fusion is carried out in plasma state held at high temperature confined in magnetic field produced by huge torroidal solenoids