[hrst]

My understanding is that newer plants do have a convection cooling system.

As said, there was such a system there, too.

AFAIK it works only as long as water in torus is still water. After a certain amount of heat generated, it stops working, so it cannot remove all of the heat. In addition, it needs some control battery power. Newer systems may have a better convection cooling that work longer, or may not, but in any case, there was a convection cooling system present.