Question

Suppose 3 neutrons are released by an atom of U-235 in the first stage of a fission chain reaction. Each of these neutrons has enough energy to cause another fission reaction in another nucleus of U-235, releasing more neutrons. And if all of those 2nd stage neutrons cause other nuclei to fission in a 3rd stage, how many total U-235 atoms will have undergone fission after these 3 stages of the chain reaction? A. 27 B. 9 C. 11 D. 12

Answer 1

I think the question here is how many neurons were released? Because if the question was about the U-235 atoms, the answer would be 3.

In the first stage, 3 neutrons were released. The energy produce from the release of these neutrons would cause another fission. It would yield another 3 neutrons. So, the total neutrons during the 2nd stage is 6. The cycle repeats again on the 3rd stage releasing another 3. Therefore, the total neutrons are 9. The answer is letter B.