I understand that- but it generates its own sustained heat from the critical mass.
If that melting stuff was seperated it would no only dissapate all that heat but go below critical mass.
All the ‘meltdown’ scenarios depict the blob of melted matter staying together until it melts to the core of the earth. - and when it hits the water table the steam and possible pressure build up would be catastrophic
I am wondering it it would spread out and cool itself down
Critical mass implies that there is sufficient mass of fissile material to attain criticality. The heat generated has nought to do with criticality.
It generates heat from gamma and beta decays of all the fission products. Not mass. Heat generated per unit volume doesnt change, regardless of the number of units of volume you may have.