We all know that uranium undergoes fission to produce barium , krypton , and three neutrons.If these products are fused ,...Will they form the original Uranium molecule?? If so, a neutron can bombard with the new uranium to undergo controlled chain reaction.is it possible??????. Please help me.

throw some Thorium into the equation and do it again :

n + U —> Kr + Ba + 3n is only an example; many products are formed from fission.

 

Yes, you could put them back together, in principle, but it would take as much energy as you got from the original fission (at a minimum).

throw some Thorium into the equation and do it again :

 

There are far more fission fragments than that.

 

edit: Here is what seems to be a decent intro to nuclear physics.

Doesn't it take an infinitely huge amount of energy to fuse heavier elements?

Doesn't it take an infinitely huge amount of energy to fuse heavier elements?

 

No, just a lot.

Doesn't it take an infinitely huge amount of energy to fuse heavier elements?

 

The net energy to fuse would be on order of 200 MeV per reaction, since that's about how much energy is released in fission. The activation energy due to the coulomb barrier is very high, though, so you need that as well, but that energy would be present after the reaction.

There are far more fission fragments than that.

 

edit: Here is what seems to be a decent intro to nuclear physics.

 

that wasn`t my point at all, look up Breeder Reactors!