Before revision: In nuclear engineering, neutrons which have not yet undergone a collision are termed the 1st generation, those which have undergone a single collision the 2nd generation, those which have undergone two collisions the 3rd generation, and so on.
After revision: In nuclear engineering, neutrons that have not yet undergone a collision are called the 1st generation, those that have undergone a single collision the 2nd generation, those thatareare have undergone two collisions the 3rd generation, and so on.