Summary of storage capacity and utilization at the various TEPCO NPPs:
Probably the most important chart: this is the most recent status of spent fuel rods at Fukushima:
This is what a typical storage pool looks like. This is the area that supposedly has no water left in it in Reactor 3. Notable is that a spent fuel rods have a 19 month cooling life.
And below is the actual pool that is supposed to have water in it. It is now most likely empty in Reactor 4 and probably does not exist in the other ones.
And while irrelevant for the current discussion, below we present some details about Dry Cask storage facilities:
Below is the schematic of the containment pod.
On the chart below Alarm Monitor 4.