Nuclear Power Engineering Practice Exam 2025 – Your All-In-One Guide to Exam Success!

In the context of neutron fission, the notation η typically represents the number of neutrons released per fission event. This concept is crucial in nuclear chain reactions, particularly in understanding how many neutrons generated from one fission event can go on to cause additional fission events in surrounding fissile material.

When a fissile nucleus undergoes fission, it splits into lighter nuclei, and this process releases energy along with neutrons. The value of η is indicative of the efficiency of the fission process in sustaining a chain reaction. For a fissionable material to sustain a chain reaction, η must be greater than one, meaning that each fission reaction produces more than one neutron, allowing for continued reactions.

The other notations mentioned relate to different aspects of nuclear fission. The average energy of emitted neutrons is more a specific energy parameter, the neutron capture cross-section describes the probability of a neutron being captured by a nucleus, and the measure of radiation dosage pertains to the absorbed dose from radiation exposure, which are distinctly different concepts from the intended definition of η in this context.