Ok- so am I correct in saying 5 & 6 are like 4 -having spent fuel?
There are seven total spent fuel pools at Fukushima Daiichi: one at each of the six reactor units and one commonly shared pool. There are over 15,000 spent fuel assemblies stored in those pools. All pools have some number of fuel rods in them, based on that figure and the storage capacity described at #381.