the core is hot because there is a critical amount of uranium in the core. If the amount goes below the critical amount the chain reaction will stop and return to the normal decay rate.
That’s “comforting”.
No. My years of experiecne of nucelar core physics show that a elted mass of former core parts, core poisons, core retention devices and zirconium, and melted core decay and fission products will not “go critical” in any geometry.
And, yes, I have studied and modeled the melted cores of TMI slow neutron water-cooled reactor, the steam explosion that ejected that control rod from Idaho’s test reactor, and the blown-out residue of Ukraine’s Pu-breeder fast-flux reactor. The final core geometry cannot go critical, nor remain critical as you state. Stay hot? Most definite! But the melted residuals remain critical? No.