[CaptSkip]

The reactors in question were all shut down four days ago. The control rods have been inserted, and the cores have been salted with boron. It is physically impossible for them to sustain a fission reaction of any kind at this point, let alone cause another Chernobyl.

So if the control rods that house the nuclear fuel pellets melt, what then?

[Windflier]

So if the control rods that house the nuclear fuel pellets melt, what then?

The control rods don't hold the nuclear fuel pellets. The fuel rods do. The control rods are inserted to stop the nuclear chain reaction, which was done automatically by the system when the earthquake first hit.