Final answer:
A nuclear chain reaction requires a critical mass of fissionable material, high neutron flux, and control mechanisms such as control rods and moderators to regulate neutron absorption and flux. These elements allow the nuclear reaction to be controlled to produce energy rather than an explosion.
The correct answer is options a) High neutron flux; controlled release of energy by regulating the number of neutrons.
Step-by-step explanation:
The conditions necessary for a nuclear chain reaction to take place include a sufficient quantity of fissionable material to reach critical mass, a neutron flux high enough to initiate and sustain the reaction, and a mechanism to control the release of energy.
To control a nuclear chain reaction and generate energy instead of an explosion, the neutron flux must be regulated to ensure that the fission reaction is self-sustaining but not increasing at an exponential rate, which could lead to an explosion. This is achieved by using control rods and nuclear moderators. Control rods absorb excess neutrons and can be inserted or withdrawn from the reactor to control the rate of the reaction.
Moderators slow down the neutrons, making them more likely to cause further fission in the nuclear fuel. In a nuclear power plant, the controlled chain reaction produces heat, which is used to boil water, creating steam that drives turbines to generate electricity.
The answer to the student's question about controlling the nuclear chain reaction to produce energy and not an explosion is option a) High neutron flux; controlled release of energy by regulating the number of neutrons.