To sustain a nuclear chain reaction in a fission power plant, what must each uranium nucleus produce after splitting?

In the context of a nuclear chain reaction within a fission power plant, it is essential that each uranium nucleus produces at least one neutron after it undergoes fission. This neutron is crucial because it can strike another uranium nucleus, causing it to also undergo fission. This process creates a self-sustaining reaction as long as there are sufficient uranium nuclei present and the reaction is properly controlled.

When a uranium nucleus splits, it releases not only energy but also one or more neutrons. If at least one of these neutrons successfully collides with another uranium nucleus, it can induce further fission events, thus maintaining the chain reaction. This is the fundamental principle that underlies the operation of nuclear reactors.

Producing more than one neutron—while potentially beneficial—can lead to challenges in controlling the reaction, as too many neutrons could lead to an uncontrolled chain reaction.

The production of no neutrons or alpha particles does not contribute to sustaining a chain reaction; thus, they are not suitable options for this question. Therefore, the requirement for each uranium nucleus to produce at least one neutron ensures that the chain reaction can continue in a controlled manner.