How do we start a nuclear chain reaction? For example, if we wanted to do it this weekend, what would we need, and what are the basic steps? I'm not looking for a text book response or highly detailed information. I'm only curious about the most basic components. For example, we need to take A and B and submerge it into C? That's all I'm asking. If you had a daughter, and she asked, "What happens in a nuclear power plant?", what would you tell her?
Nuclear fission is spontaneous. In fact, if you have a critical mass of fuel assembled, you need to take explicit steps to keep it from going into chain reaction, typically by adding neutron-absorbing material, AKA "control rods" to the assembly. When you remove the control rods, the reactor starts up by itself.