The Nuclear Reactor is a machine which generates large amounts of Steam Hi from Water for use in generators by means of consuming Uranium Rods. The machine itself is self-sufficient with regards to power and requires no Electricity from outside sources.
Power is generated by passing the output Steam Hi though High-pressure Turbines and Low-pressure Turbines with their output shaft connected to Power Generators, typically Tier 2 variants of each. A majority of the Water can subsequently be recovered for reuse using a Cooling Tower (Large).
The reactor has two different systems to convert Water into Steam Hi. The three grouped ports at the edge of the reactor are the main heat exchangers of the reactor. These ports are used to create the steam to run the turbines. The separate port on the main reactor building is used for emergency cooling in case the reactor overheats. This port will not provide steam under normal operations.
If the Reactor Heat reaches on the red marker in UI, the emergency cooling will start. However, when no water for the emergency cooling is stored or the "Power Level" is x2 or x3, increasing Reactor Heat will not stop. And reaching the heat to maximum causes critical overheating and the death of hundreds of people.
As above, emergency cooling cannot prevent critical overheating when the "Power Level" is x2 or x3. So, do not rely too much on emergency cooling.
All recipes have the same input and outputs, the only difference is the time it takes to consume the input materials and the amount of output materials. The speed of conversion is variable.