You have to connect a single steam tank, and the inserters managing the reactors, to the green wire network which is on the power poles. There are 4 reactors here, but it produces enough fuel rods to continuously supply up to 9 reactors, if I remember right. (8 reactors is ~16.7% more fuel efficient than 4, as long as you have enough steam tanks.) You set the number of reactors, and the steam threshold under which the reactors will turn on, at the constant combinator, with the reactor and fluid tank signals. Leave the T signal alone, it increments the timer. Adjacent to the reactors is 3 heat pipes to 6 rows of 8 heat exchangers each, each row with a dedicated water pipe and offshore pump to ensure adequate flow at reasonable distance. And, it requires 40 U-235 for Kovarex enrichment, which (I think) should always be done before you start using nuclear power.