Once again, there is a total of 236 protons and neutrons on both sides of the equation. Neutrons are released to go and collide with more uranium nuclei. If not, neutrons can escape. In a chain reaction, the 2.5 n released serve as propagator of the process. The reaction proceeds very quickly.
Fusion is the alternative to fission.
It is more environmentally friendly. Note that it is not as energetic as fission. In 1941 and 1942, there was a push to find a process that could purify uranium. This need stemmed from the American belief that Germans were working on a fission project to be used in warfare. From that belief, Americans established their own controlled nuclear fission project called the Manhattan Project.