What blew in that photo was, I believe, some relatively inert, mostly non radioactive gases (with a little radioactivity mixed in). Apparently as a result of the great heat in the cooling-less reactor vessel. Whether it melts through, and to where it goes after that, isn’t known yet.
You are not doubt right - the reactor is finished with the loss of it cooling system although they now say it is begining to cool again. Even so, the work now for the next two years is just to render it safe and bury it.
Another aftershock magnitude 6+ has been reported in the area, anything can happen with a weakened or perhaps partially destroyed containment building.