I just put enough steam tanks for two fulings worth of production, then setup logic so that an inserter fires once to insert fuel in each reactor when the amoun

I just put enough steam tanks for two fulings worth of production, then setup logic so that an inserter fires once to insert fuel in each reactor when the amount crosses under a bit under half remaining (and becomes retriggerable at a bit over half remaining). In theory, since my turbines are slightly oversized for the reactors, under very high load it could possibly never get back above my reinsert level. But I've never had that happen and I have a siren set to go off if the steam tanks get under 25% and a constant combinator button I can press to insert fuel manually if that ever happens. of course, by the time I got that going, I also had the breeder reactors working fine and with them in place the nuclear cells are really hardly expensive anymore.