In order for a nuclear reactor to maintain a perfectly steady power level, what must the effective multiplication factor, or 'k', be exactly equal to?

For a nuclear reactor to maintain a perfectly steady power level, the effective multiplication factor, k, must be exactly equal to 1. The effective multiplication factor, k, is defined as the ratio of the number of neutrons produced in one generation of nuclear fissions to the number of neutrons absorbed or lost in the preceding generation. Nuclear fission is the process where a neutron strikes an atomic nucleus, causing it to split into smaller nuclei, releasing a large amount of energy and additional neutrons. These newly released neutrons can then go on to cause further fissions, sustaining a chain reaction. A perfectly steady power level means that the rate at which these fission reactions occur, and consequently the rate at which energy is released as heat, remains constant over time. If k is exactly 1, it signifies that for every neutron that causes a fission and is absorbed or lost, exactly one new neutron is produced and successfully causes another fission, maintaining a constant neutron population. A constant neutron population directly translates to a constant rate of fission events, which in turn results in a steady, unchanging power output. If k were greater than 1, the neutron population would increase with each generation, leading to an accelerating rate of fission and an increasing power level. Conversely, if k were less than 1, the neutron population would decrease with each generation, causing the fission rate and power level to decline.